Set SendEpoch instead of cumulating it (#86)

`CalculateNextEpoch` should set `SendEpoch` instead of cumulating it.

.gitignore

@@ -10,3 +10,8 @@
 
 # Output of the go coverage tool, specifically when used with LiteIDE
 *.out
+
+# Ignore Intellij config
+.idea
+
+mvds

.travis.yml

@@ -0,0 +1,39 @@
+notifications:
+  email: false
+
+language: go
+
+install: true
+
+branches:
+  only:
+    - master
+
+before_install:
+  - |
+      if ! git diff --name-only $TRAVIS_COMMIT_RANGE | grep -qvE '(.md)|(.html)|^(LICENSE)|^(docs)'
+      then
+        echo "Only docs were updated, not running the CI."
+        exit 0
+      fi
+
+env:
+- GO111MODULE=on
+
+before_script:
+- make install-linter
+
+matrix:
+  include:
+  - go: "1.11.x"
+    env: GOFLAGS=-mod=vendor
+    script:
+    - make lint
+    # fails without -a
+    - go test -a ./... # make test
+  - go: "1.12.x"
+    env: GOFLAGS=-mod=vendor
+    script:
+    - make lint
+    # fails without -a
+    - go test -a ./... # make test

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2019 Status
+Copyright (c) 2019 Vac
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Makefile

@@ -2,6 +2,57 @@ SHELL := /bin/bash
 
 GO111MODULE = on
 
+build:
+	go build
+.PHONY: build
+
+test:
+	go test -v ./...
+.PHONY: test
+
 protobuf:
 	protoc --go_out=. ./protobuf/*.proto
 .PHONY: protobuf
+
+lint:
+	golangci-lint run -v
+.PHONY: lint
+
+install-linter:
+	# install linter
+	curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(shell go env GOPATH)/bin v1.17.1
+.PHONY: install-linter
+
+mock-install:
+	go get -u github.com/golang/mock/mockgen
+	go get -u github.com/golang/mock
+.PHONY: mock-install
+
+mock:
+	mockgen -package=internal -destination=node/internal/syncstate_mock.go -source=state/state.go
+.PHONY: mock
+
+vendor:
+	go mod tidy
+	go mod vendor
+	modvendor -copy="**/*.c **/*.h" -v
+.PHONY: vendor
+
+generate:
+	go generate ./...
+.PHONY: generate
+
+create-migration:
+	@if [ -z "$$DIR" ]; then \
+		echo 'missing DIR var'; \
+		exit 1; \
+	fi
+
+	@if [ -z "$$NAME" ]; then \
+		echo 'missing NAME var'; \
+		exit 1; \
+	fi
+
+	mkdir -p $(DIR)
+	touch $(DIR)/`date +"%s"`_$(NAME).down.sql ./$(DIR)/`date +"%s"`_$(NAME).up.sql
+.PHONY: create-migration

README.md

@@ -1,15 +1,28 @@
 # Minimal Viable Data Sync
 
-![Version](https://img.shields.io/github/tag/status-im/mvds.svg)
+![Version](https://img.shields.io/github/tag/vacp2p/mvds.svg)
 [![MIT License](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)
 [![API Reference](
 https://camo.githubusercontent.com/915b7be44ada53c290eb157634330494ebe3e30a/68747470733a2f2f676f646f632e6f72672f6769746875622e636f6d2f676f6c616e672f6764646f3f7374617475732e737667
-)](https://godoc.org/github.com/status-im/mvds) [![Go Report Card](https://goreportcard.com/badge/github.com/status-im/mvds)](https://goreportcard.com/report/github.com/status-im/mvds)
+)](https://godoc.org/github.com/vacp2p/mvds) 
+[![Go Report Card](https://goreportcard.com/badge/github.com/vacp2p/mvds)](https://goreportcard.com/report/github.com/vacp2p/mvds)
+[![Build Status](https://travis-ci.com/vacp2p/mvds.svg?branch=master)](https://travis-ci.com/vacp2p/mvds)
 
-Experimental implementation of the [minimal viable data sync protocol specification](https://github.com/status-im/bigbrother-specs/blob/master/data_sync/mvds.md).
+Experimental implementation of the [minimal viable data sync protocol specification](https://specs.vac.dev/specs/mvds.html) including the [metadata format specification](https://specs.vac.dev/specs/mdf.html).
 
 ## Usage
 
+Listening to MVDS messages is fairly simple:
+
+```go
+sub := node.Subscribe()
+
+for {
+    msg := <-sub
+    print(msg)
+}
+```
+
 ### Prerequisites
 
 Ensure you have `protoc` (Protobuf) and Golang installed. Then run `make`.

dependency/migrations/migrations.go

@@ -0,0 +1,317 @@
+// Code generated by go-bindata. DO NOT EDIT.
+// sources:
+// 1572614870_initial_schema.down.sql (30B)
+// 1572614870_initial_schema.up.sql (157B)
+// doc.go (377B)
+
+package migrations
+
+import (
+	"bytes"
+	"compress/gzip"
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+func bindataRead(data []byte, name string) ([]byte, error) {
+	gz, err := gzip.NewReader(bytes.NewBuffer(data))
+	if err != nil {
+		return nil, fmt.Errorf("read %q: %v", name, err)
+	}
+
+	var buf bytes.Buffer
+	_, err = io.Copy(&buf, gz)
+	clErr := gz.Close()
+
+	if err != nil {
+		return nil, fmt.Errorf("read %q: %v", name, err)
+	}
+	if clErr != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+type asset struct {
+	bytes  []byte
+	info   os.FileInfo
+	digest [sha256.Size]byte
+}
+
+type bindataFileInfo struct {
+	name    string
+	size    int64
+	mode    os.FileMode
+	modTime time.Time
+}
+
+func (fi bindataFileInfo) Name() string {
+	return fi.name
+}
+func (fi bindataFileInfo) Size() int64 {
+	return fi.size
+}
+func (fi bindataFileInfo) Mode() os.FileMode {
+	return fi.mode
+}
+func (fi bindataFileInfo) ModTime() time.Time {
+	return fi.modTime
+}
+func (fi bindataFileInfo) IsDir() bool {
+	return false
+}
+func (fi bindataFileInfo) Sys() interface{} {
+	return nil
+}
+
+var __1572614870_initial_schemaDownSql = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x72\x09\xf2\x0f\x50\x08\x71\x74\xf2\x71\x55\xc8\x2d\x4b\x29\x8e\x4f\x49\x2d\x48\xcd\x4b\x49\xcd\x4b\xce\x4c\x2d\xb6\xe6\x02\x04\x00\x00\xff\xff\x13\x64\x97\xf6\x1e\x00\x00\x00")
+
+func _1572614870_initial_schemaDownSqlBytes() ([]byte, error) {
+	return bindataRead(
+		__1572614870_initial_schemaDownSql,
+		"1572614870_initial_schema.down.sql",
+	)
+}
+
+func _1572614870_initial_schemaDownSql() (*asset, error) {
+	bytes, err := _1572614870_initial_schemaDownSqlBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "1572614870_initial_schema.down.sql", size: 30, mode: os.FileMode(0644), modTime: time.Unix(1572706379, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0xfc, 0xb3, 0xc3, 0x5e, 0x81, 0xae, 0x77, 0x21, 0x3b, 0xd0, 0xa0, 0x6a, 0xf4, 0x7b, 0xb2, 0x1c, 0x92, 0xd7, 0x5d, 0x4c, 0xa6, 0x4f, 0xe, 0xc6, 0x2d, 0xe4, 0x18, 0x5d, 0x56, 0xe, 0x18, 0x6a}}
+	return a, nil
+}
+
+var __1572614870_initial_schemaUpSql = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x72\x0e\x72\x75\x0c\x71\x55\x08\x71\x74\xf2\x71\x55\xc8\x2d\x4b\x29\x8e\x4f\x49\x2d\x48\xcd\x4b\x49\xcd\x4b\xce\x4c\x2d\x56\xd0\xe0\x52\x50\x50\x50\xc8\x2d\x4e\x8f\xcf\x4c\x51\x70\xf2\xf1\x77\x52\x08\x08\xf2\xf4\x75\x0c\x8a\x54\xf0\x76\x8d\xd4\x01\x4b\xc2\xd5\x57\x42\x14\xf8\xf9\x87\x28\xf8\x85\xfa\xf8\x70\x69\x5a\x73\x71\x41\x8d\xf7\xf4\x73\x71\x8d\x50\xc8\x4c\xa9\x88\x47\x52\xed\xef\x87\x69\xa1\x06\x42\x5e\xd3\x9a\x0b\x10\x00\x00\xff\xff\x11\xfa\x7b\x28\x9d\x00\x00\x00")
+
+func _1572614870_initial_schemaUpSqlBytes() ([]byte, error) {
+	return bindataRead(
+		__1572614870_initial_schemaUpSql,
+		"1572614870_initial_schema.up.sql",
+	)
+}
+
+func _1572614870_initial_schemaUpSql() (*asset, error) {
+	bytes, err := _1572614870_initial_schemaUpSqlBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "1572614870_initial_schema.up.sql", size: 157, mode: os.FileMode(0644), modTime: time.Unix(1572742027, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0xad, 0x62, 0x2e, 0xb1, 0x1c, 0x65, 0x39, 0xb9, 0xe4, 0xae, 0xf6, 0x28, 0x6d, 0xbe, 0x62, 0xba, 0x93, 0x80, 0x6c, 0x47, 0x4f, 0x98, 0x5b, 0xf0, 0xfa, 0x16, 0x2, 0x7e, 0xaa, 0x15, 0x63, 0xf2}}
+	return a, nil
+}
+
+var _docGo = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x84\x8f\xbb\x6e\xc3\x30\x0c\x45\x77\x7f\xc5\x45\x96\x2c\xb5\xb4\x74\xea\xd6\xb1\x7b\x7f\x80\x91\x68\x89\x88\x1e\xae\x48\xe7\xf1\xf7\x85\xd3\x02\xcd\xd6\xf5\x00\xe7\xf0\xd2\x7b\x7c\x66\x51\x2c\x52\x18\xa2\x68\x1c\x58\x95\xc6\x1d\x27\x0e\xb4\x29\xe3\x90\xc4\xf2\x76\x72\xa1\x57\xaf\x46\xb6\xe9\x2c\xd5\x57\x49\x83\x8c\xfd\xe5\xf5\x30\x79\x8f\x40\xed\x68\xc8\xd4\x62\xe1\x47\x4b\xa1\x46\xc3\xa4\x25\x5c\xc5\x32\x08\xeb\xe0\x45\x6e\x0e\xef\x86\xc2\xa4\x06\xcb\x64\x47\x85\x65\x46\x20\xe5\x3d\xb3\xf4\x81\xd4\xe7\x93\xb4\x48\x46\x6e\x47\x1f\xcb\x13\xd9\x17\x06\x2a\x85\x23\x96\xd1\xeb\xc3\x55\xaa\x8c\x28\x83\x83\xf5\x71\x7f\x01\xa9\xb2\xa1\x51\x65\xdd\xfd\x4c\x17\x46\xeb\xbf\xe7\x41\x2d\xfe\xff\x11\xae\x7d\x9c\x15\xa4\xe0\xdb\xca\xc1\x38\xba\x69\x5a\x29\x9c\x29\x31\xf4\xab\x88\xf1\x34\x79\x9f\xfa\x5b\xe2\xc6\xbb\xf5\xbc\x71\x5e\xcf\x09\x3f\x35\xe9\x4d\x31\x77\x38\xe7\xff\x80\x4b\x1d\x6e\xfa\x0e\x00\x00\xff\xff\x9d\x60\x3d\x88\x79\x01\x00\x00")
+
+func docGoBytes() ([]byte, error) {
+	return bindataRead(
+		_docGo,
+		"doc.go",
+	)
+}
+
+func docGo() (*asset, error) {
+	bytes, err := docGoBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "doc.go", size: 377, mode: os.FileMode(0644), modTime: time.Unix(1572706379, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0xef, 0xaf, 0xdf, 0xcf, 0x65, 0xae, 0x19, 0xfc, 0x9d, 0x29, 0xc1, 0x91, 0xaf, 0xb5, 0xd5, 0xb1, 0x56, 0xf3, 0xee, 0xa8, 0xba, 0x13, 0x65, 0xdb, 0xab, 0xcf, 0x4e, 0xac, 0x92, 0xe9, 0x60, 0xf1}}
+	return a, nil
+}
+
+// Asset loads and returns the asset for the given name.
+// It returns an error if the asset could not be found or
+// could not be loaded.
+func Asset(name string) ([]byte, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return nil, fmt.Errorf("Asset %s can't read by error: %v", name, err)
+		}
+		return a.bytes, nil
+	}
+	return nil, fmt.Errorf("Asset %s not found", name)
+}
+
+// AssetString returns the asset contents as a string (instead of a []byte).
+func AssetString(name string) (string, error) {
+	data, err := Asset(name)
+	return string(data), err
+}
+
+// MustAsset is like Asset but panics when Asset would return an error.
+// It simplifies safe initialization of global variables.
+func MustAsset(name string) []byte {
+	a, err := Asset(name)
+	if err != nil {
+		panic("asset: Asset(" + name + "): " + err.Error())
+	}
+
+	return a
+}
+
+// MustAssetString is like AssetString but panics when Asset would return an
+// error. It simplifies safe initialization of global variables.
+func MustAssetString(name string) string {
+	return string(MustAsset(name))
+}
+
+// AssetInfo loads and returns the asset info for the given name.
+// It returns an error if the asset could not be found or
+// could not be loaded.
+func AssetInfo(name string) (os.FileInfo, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return nil, fmt.Errorf("AssetInfo %s can't read by error: %v", name, err)
+		}
+		return a.info, nil
+	}
+	return nil, fmt.Errorf("AssetInfo %s not found", name)
+}
+
+// AssetDigest returns the digest of the file with the given name. It returns an
+// error if the asset could not be found or the digest could not be loaded.
+func AssetDigest(name string) ([sha256.Size]byte, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return [sha256.Size]byte{}, fmt.Errorf("AssetDigest %s can't read by error: %v", name, err)
+		}
+		return a.digest, nil
+	}
+	return [sha256.Size]byte{}, fmt.Errorf("AssetDigest %s not found", name)
+}
+
+// Digests returns a map of all known files and their checksums.
+func Digests() (map[string][sha256.Size]byte, error) {
+	mp := make(map[string][sha256.Size]byte, len(_bindata))
+	for name := range _bindata {
+		a, err := _bindata[name]()
+		if err != nil {
+			return nil, err
+		}
+		mp[name] = a.digest
+	}
+	return mp, nil
+}
+
+// AssetNames returns the names of the assets.
+func AssetNames() []string {
+	names := make([]string, 0, len(_bindata))
+	for name := range _bindata {
+		names = append(names, name)
+	}
+	return names
+}
+
+// _bindata is a table, holding each asset generator, mapped to its name.
+var _bindata = map[string]func() (*asset, error){
+	"1572614870_initial_schema.down.sql": _1572614870_initial_schemaDownSql,
+	"1572614870_initial_schema.up.sql":   _1572614870_initial_schemaUpSql,
+	"doc.go":                             docGo,
+}
+
+// AssetDir returns the file names below a certain
+// directory embedded in the file by go-bindata.
+// For example if you run go-bindata on data/... and data contains the
+// following hierarchy:
+//     data/
+//       foo.txt
+//       img/
+//         a.png
+//         b.png
+// then AssetDir("data") would return []string{"foo.txt", "img"},
+// AssetDir("data/img") would return []string{"a.png", "b.png"},
+// AssetDir("foo.txt") and AssetDir("notexist") would return an error, and
+// AssetDir("") will return []string{"data"}.
+func AssetDir(name string) ([]string, error) {
+	node := _bintree
+	if len(name) != 0 {
+		canonicalName := strings.Replace(name, "\\", "/", -1)
+		pathList := strings.Split(canonicalName, "/")
+		for _, p := range pathList {
+			node = node.Children[p]
+			if node == nil {
+				return nil, fmt.Errorf("Asset %s not found", name)
+			}
+		}
+	}
+	if node.Func != nil {
+		return nil, fmt.Errorf("Asset %s not found", name)
+	}
+	rv := make([]string, 0, len(node.Children))
+	for childName := range node.Children {
+		rv = append(rv, childName)
+	}
+	return rv, nil
+}
+
+type bintree struct {
+	Func     func() (*asset, error)
+	Children map[string]*bintree
+}
+
+var _bintree = &bintree{nil, map[string]*bintree{
+	"1572614870_initial_schema.down.sql": &bintree{_1572614870_initial_schemaDownSql, map[string]*bintree{}},
+	"1572614870_initial_schema.up.sql":   &bintree{_1572614870_initial_schemaUpSql, map[string]*bintree{}},
+	"doc.go":                             &bintree{docGo, map[string]*bintree{}},
+}}
+
+// RestoreAsset restores an asset under the given directory.
+func RestoreAsset(dir, name string) error {
+	data, err := Asset(name)
+	if err != nil {
+		return err
+	}
+	info, err := AssetInfo(name)
+	if err != nil {
+		return err
+	}
+	err = os.MkdirAll(_filePath(dir, filepath.Dir(name)), os.FileMode(0755))
+	if err != nil {
+		return err
+	}
+	err = ioutil.WriteFile(_filePath(dir, name), data, info.Mode())
+	if err != nil {
+		return err
+	}
+	return os.Chtimes(_filePath(dir, name), info.ModTime(), info.ModTime())
+}
+
+// RestoreAssets restores an asset under the given directory recursively.
+func RestoreAssets(dir, name string) error {
+	children, err := AssetDir(name)
+	// File
+	if err != nil {
+		return RestoreAsset(dir, name)
+	}
+	// Dir
+	for _, child := range children {
+		err = RestoreAssets(dir, filepath.Join(name, child))
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func _filePath(dir, name string) string {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	return filepath.Join(append([]string{dir}, strings.Split(canonicalName, "/")...)...)
+}

dependency/migrations/sqlite/1572614870_initial_schema.down.sql

@@ -0,0 +1 @@
+DROP TABLE mvds_dependencies;

dependency/migrations/sqlite/1572614870_initial_schema.up.sql

@@ -0,0 +1,6 @@
+CREATE TABLE mvds_dependencies (
+    msg_id BLOB PRIMARY KEY,
+    dependency BLOB NOT NULL
+);
+
+CREATE INDEX idx_dependency ON mvds_dependencies(dependency);

dependency/migrations/sqlite/doc.go

@@ -0,0 +1,9 @@
+// This file is necessary because "github.com/status-im/migrate/v4"
+// can't handle files starting with a prefix. At least that's the case
+// for go-bindata.
+// If go-bindata is called from the same directory, asset names
+// have no prefix and "github.com/status-im/migrate/v4" works as expected.
+
+package sqlite
+
+//go:generate go-bindata -pkg migrations -o ../migrations.go .

dependency/tracker.go

@@ -0,0 +1,12 @@
+package dependency
+
+import (
+	"github.com/vacp2p/mvds/state"
+)
+
+type Tracker interface {
+	Add(msg, dependency state.MessageID) error
+	Dependants(id state.MessageID) ([]state.MessageID, error)
+	Resolve(msg state.MessageID, dependency state.MessageID) error
+	IsResolved(id state.MessageID) (bool, error)
+}

dependency/tracker_memory.go

@@ -0,0 +1,71 @@
+package dependency
+
+import (
+	"reflect"
+	"sync"
+
+	"github.com/vacp2p/mvds/state"
+)
+
+// Verify that Tracker interface is implemented.
+var _ Tracker = (*inMemoryTracker)(nil)
+
+type inMemoryTracker struct {
+	sync.Mutex
+
+	dependents map[state.MessageID][]state.MessageID
+	dependencies map[state.MessageID]int
+
+}
+
+func NewInMemoryTracker() *inMemoryTracker {
+	return &inMemoryTracker{
+		dependents: make(map[state.MessageID][]state.MessageID),
+		dependencies: make(map[state.MessageID]int),
+	}
+}
+
+func (md *inMemoryTracker) Add(msg, dependency state.MessageID) error {
+	md.Lock()
+	defer md.Unlock()
+	// @todo check it wasn't already added
+	md.dependents[dependency] = append(md.dependents[dependency], msg)
+	md.dependencies[msg] += 1
+	return nil
+}
+
+func (md *inMemoryTracker) Dependants(id state.MessageID) ([]state.MessageID, error) {
+	md.Lock()
+	defer md.Unlock()
+
+	return md.dependents[id], nil
+}
+
+func (md *inMemoryTracker) Resolve(msg state.MessageID, dependency state.MessageID) error {
+	md.Lock()
+	defer md.Unlock()
+
+	for i, item := range md.dependents[dependency] {
+		if !reflect.DeepEqual(msg[:], item[:]) {
+			continue
+		}
+
+		md.dependents[dependency] = remove(md.dependents[dependency], i)
+		md.dependencies[msg] -= 1
+		return nil
+	}
+
+	return nil
+}
+
+func (md *inMemoryTracker) IsResolved(id state.MessageID) (bool, error) {
+	md.Lock()
+	defer md.Unlock()
+
+	return md.dependencies[id] == 0, nil
+}
+
+func remove(s []state.MessageID, i int) []state.MessageID {
+	s[len(s)-1], s[i] = s[i], s[len(s)-1]
+	return s[:len(s)-1]
+}

dependency/tracker_persistency_test.go

@@ -0,0 +1,42 @@
+package dependency
+
+import (
+	"io/ioutil"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/vacp2p/mvds/dependency/migrations"
+	"github.com/vacp2p/mvds/persistenceutil"
+	"github.com/vacp2p/mvds/state"
+)
+
+func TestTrackerSQLitePersistence(t *testing.T) {
+	tmpFile, err := ioutil.TempFile("", "")
+	require.NoError(t, err)
+	db, err := persistenceutil.Open(tmpFile.Name(), "", persistenceutil.MigrationConfig{
+		AssetNames:  migrations.AssetNames(),
+		AssetGetter: migrations.Asset,
+	})
+	require.NoError(t, err)
+	d := NewPersistentTracker(db)
+
+	msg := state.MessageID{0x01}
+	dependency := state.MessageID{0x02}
+
+	err = d.Add(msg, dependency)
+	require.NoError(t, err)
+	dependants, err := d.Dependants(dependency)
+	require.NoError(t, err)
+	require.Equal(t, msg, dependants[0])
+
+	res, err := d.IsResolved(msg)
+	require.NoError(t, err)
+	require.False(t, res)
+
+	err = d.Resolve(msg, dependency)
+	require.NoError(t, err)
+
+	res, err = d.IsResolved(msg)
+	require.NoError(t, err)
+	require.True(t, res)
+}

dependency/tracker_sqlite.go

@@ -0,0 +1,71 @@
+package dependency
+
+import (
+	"database/sql"
+
+	"github.com/vacp2p/mvds/state"
+)
+
+// Verify that Tracker interface is implemented.
+var _ Tracker = (*sqliteTracker)(nil)
+
+type sqliteTracker struct {
+	db *sql.DB
+}
+
+func NewPersistentTracker(db *sql.DB) *sqliteTracker {
+	return &sqliteTracker{db: db}
+}
+
+func (sd *sqliteTracker) Add(msg, dependency state.MessageID) error {
+	_, err := sd.db.Exec(`INSERT INTO mvds_dependencies (msg_id, dependency) VALUES (?, ?)`, msg[:], dependency[:])
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (sd *sqliteTracker) Dependants(id state.MessageID) ([]state.MessageID, error) {
+	rows, err := sd.db.Query(`SELECT msg_id FROM mvds_dependencies WHERE dependency = ?`, id[:])
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var msgs []state.MessageID
+
+	for rows.Next() {
+		var msg []byte
+		err := rows.Scan(&msg)
+		if err != nil {
+			return nil, err
+		}
+
+		msgs = append(msgs, state.ToMessageID(msg))
+	}
+
+	return msgs, nil
+}
+
+func (sd *sqliteTracker) Resolve(msg state.MessageID, dependency state.MessageID) error {
+	_, err := sd.db.Exec(
+		`DELETE FROM mvds_dependencies WHERE msg_id = ? AND dependency = ?`,
+		msg[:],
+		dependency[:],
+	)
+
+	return err
+}
+
+func (sd *sqliteTracker) IsResolved(id state.MessageID) (bool, error) {
+	result := sd.db.QueryRow(`SELECT COUNT(*) FROM mvds_dependencies WHERE msg_id = ?`, id[:])
+	var num int64
+	err := result.Scan(&num)
+	if err != nil {
+		return false, err
+	}
+
+	return num == 0, nil
+}
+

go.mod

@@ -1,14 +1,16 @@
-module github.com/status-im/mvds
+module github.com/vacp2p/mvds
 
 go 1.12
 
 require (
-	github.com/btcsuite/btcd v0.0.0-20190427004231-96897255fd17 // indirect
-	github.com/ethereum/go-ethereum v1.8.27
-	github.com/golang/protobuf v1.3.1
-	github.com/kr/pretty v0.1.0 // indirect
+	github.com/golang-migrate/migrate/v4 v4.6.2 // indirect
+	github.com/golang/mock v1.2.0
+	github.com/golang/protobuf v1.3.2
+	github.com/mutecomm/go-sqlcipher v0.0.0-20190227152316-55dbde17881f // indirect
 	github.com/pkg/errors v0.8.1
-	golang.org/x/crypto v0.0.0-20190513172903-22d7a77e9e5f // indirect
-	golang.org/x/tools v0.0.0-20190525145741-7be61e1b0e51
-	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
+	github.com/status-im/migrate/v4 v4.6.2-status.2
+	github.com/stretchr/testify v1.3.1-0.20190712000136-221dbe5ed467
+	go.uber.org/atomic v1.4.0 // indirect
+	go.uber.org/multierr v1.1.0 // indirect
+	go.uber.org/zap v1.10.0
 )

go.sum

@@ -1,56 +1,242 @@
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 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/tools v0.0.0-20190525145741-7be61e1b0e51 h1:RhYYBLDB5MoVkvoNGMNk+DSj7WoGhySvIvtEjTyiP74=
-golang.org/x/tools v0.0.0-20190525145741-7be61e1b0e51/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
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+golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
+golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
+golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
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+google.golang.org/api v0.3.1/go.mod h1:6wY9I6uQWHQ8EM57III9mq/AjF+i8G65rmVagqKMtkk=
+google.golang.org/api v0.3.2/go.mod h1:6wY9I6uQWHQ8EM57III9mq/AjF+i8G65rmVagqKMtkk=
+google.golang.org/api v0.4.0/go.mod h1:8k5glujaEP+g9n7WNsDg8QP6cUVNI86fCNMcbazEtwE=
+google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
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+google.golang.org/appengine v1.5.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
+google.golang.org/genproto v0.0.0-20180817151627-c66870c02cf8/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=
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+google.golang.org/grpc v1.17.0/go.mod h1:6QZJwpn2B+Zp71q/5VxRsJ6NXXVCE5NRUHRo+f3cWCs=
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+google.golang.org/grpc v1.20.1/go.mod h1:10oTOabMzJvdu6/UiuZezV6QK5dSlG84ov/aaiqXj38=
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+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
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+gopkg.in/inf.v0 v0.9.1/go.mod h1:cWUDdTG/fYaXco+Dcufb5Vnc6Gp2YChqWtbxRZE0mXw=
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+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gotest.tools v2.2.0+incompatible/go.mod h1:DsYFclhRJ6vuDpmuTbkuFWG+y2sxOXAzmJt81HFBacw=
+honnef.co/go/tools v0.0.0-20180728063816-88497007e858/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
+honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
+honnef.co/go/tools v0.0.0-20190106161140-3f1c8253044a/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=

main.go

@@ -8,10 +8,13 @@ import (
 	math "math/rand"
 	"time"
 
-	"github.com/status-im/mvds/node"
-	"github.com/status-im/mvds/state"
-	"github.com/status-im/mvds/store"
-	"github.com/status-im/mvds/transport"
+	"github.com/vacp2p/mvds/dependency"
+	"github.com/vacp2p/mvds/node"
+	"github.com/vacp2p/mvds/peers"
+	"github.com/vacp2p/mvds/state"
+	"github.com/vacp2p/mvds/store"
+	"github.com/vacp2p/mvds/transport"
+	"go.uber.org/zap"
 )
 
 var (
@@ -23,18 +26,19 @@ var (
 	interactive   int
 )
 
-func init() {
+func parseFlags() {
 	flag.IntVar(&offline, "offline", 90, "percentage of time a node is offline")
 	flag.IntVar(&nodeCount, "nodes", 3, "amount of nodes")
 	flag.IntVar(&communicating, "communicating", 2, "amount of nodes sending messages")
 	flag.IntVar(&sharing, "sharing", 2, "amount of nodes each node shares with")
 	flag.Int64Var(&interval, "interval", 5, "seconds between messages")
-	flag.IntVar(&interactive, "interactive", 3, "amount of nodes to use INTERACTIVE mode, the rest will be BATCH") // @todo should probably just be how many nodes are interactive
+	flag.IntVar(&interactive, "interactive", 3, "amount of nodes to use InteractiveMode mode, the rest will be BatchMode") // @todo should probably just be how many nodes are interactive
 	flag.Parse()
 }
 
 func main() {
 
+	parseFlags()
 	// @todo validate flags
 
 	transports := make([]*transport.ChannelTransport, 0)
@@ -48,14 +52,18 @@ func main() {
 		input = append(input, in)
 		transports = append(transports, t)
 
-		mode := node.INTERACTIVE
+		mode := node.InteractiveMode
 		if i+1 >= interactive {
-			mode = node.BATCH
+			mode = node.BatchMode
 		}
 
+		node, err := createNode(t, peerID(), mode)
+		if err != nil {
+			log.Printf("Could not create node: %+v\n", err)
+		}
 		nodes = append(
 			nodes,
-			createNode(t, peerID(), mode),
+			node,
 		)
 	}
 
@@ -69,14 +77,14 @@ func main() {
 			peer := nodes[p].ID
 
 			transports[i].AddOutput(peer, input[p])
-			n.AddPeer(group, peer)
+			_ = n.AddPeer(group, peer)
 
 			log.Printf("%x sharing with %x", n.ID[:4], peer[:4])
 		}
 	}
 
 	for _, n := range nodes {
-		n.Start()
+		n.Start(1 * time.Second)
 	}
 
 	chat(group, nodes[:communicating-1]...)
@@ -105,17 +113,26 @@ OUTER:
 	return peers
 }
 
-func createNode(transport transport.Transport, id state.PeerID, mode node.Mode) *node.Node {
-	ds := store.NewDummyStore()
+func createNode(transport transport.Transport, id state.PeerID, mode node.Mode) (*node.Node, error) {
+	ds := store.NewMemoryMessageStore()
+	logger, err := zap.NewDevelopment()
+	if err != nil {
+		return nil, err
+	}
+
 	return node.NewNode(
-		&ds,
+		ds,
 		transport,
-		state.NewSyncState(),
+		state.NewMemorySyncState(),
 		Calc,
 		0,
 		id,
 		mode,
-	)
+		peers.NewMemoryPersistence(),
+		dependency.NewInMemoryTracker(),
+		node.EventualMode,
+		logger,
+	), nil
 }
 
 func chat(group state.GroupID, nodes ...*node.Node) {
@@ -135,22 +152,16 @@ func Calc(count uint64, epoch int64) int64 {
 	return epoch + int64(count*2)
 }
 
-func peerID() state.PeerID {
-	bytes := make([]byte, 65)
-	rand.Read(bytes)
+func peerID() (id state.PeerID) {
+	_, _ = rand.Read(id[:])
+	return
+}
 
-	id := state.PeerID{}
-	copy(id[:], bytes)
 
+
+
+func groupId() (id state.GroupID) {
+	_, _ = rand.Read(id[:])
 	return id
 }
 
-func groupId() state.GroupID {
-	bytes := make([]byte, 32)
-	rand.Read(bytes)
-
-	id := state.GroupID{}
-	copy(id[:], bytes)
-
-	return id
-}

mvds_batch_test.go

@@ -0,0 +1,139 @@
+package main
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/suite"
+	"github.com/vacp2p/mvds/dependency"
+	"github.com/vacp2p/mvds/node"
+	"github.com/vacp2p/mvds/peers"
+	"github.com/vacp2p/mvds/state"
+	"github.com/vacp2p/mvds/store"
+	"github.com/vacp2p/mvds/transport"
+	"go.uber.org/zap"
+)
+
+func TestMVDSBatchSuite(t *testing.T) {
+	suite.Run(t, new(MVDSBatchSuite))
+}
+
+type MVDSBatchSuite struct {
+	suite.Suite
+	client1 *node.Node
+	client2 *node.Node
+	ds1     store.MessageStore
+	ds2     store.MessageStore
+	state1  state.SyncState
+	state2  state.SyncState
+	peers1  peers.Persistence
+	peers2  peers.Persistence
+	groupID state.GroupID
+}
+
+func (s *MVDSBatchSuite) SetupTest() {
+
+	logger := zap.NewNop()
+
+	in1 := make(chan transport.Packet)
+	t1 := transport.NewChannelTransport(0, in1)
+	s.ds1 = store.NewMemoryMessageStore()
+	s.state1 = state.NewMemorySyncState()
+	s.peers1 = peers.NewMemoryPersistence()
+	p1 := [65]byte{0x01}
+	s.client1 = node.NewNode(s.ds1, t1, s.state1, Calc, 0, p1, node.BatchMode, s.peers1, dependency.NewInMemoryTracker(), node.EventualMode, logger)
+
+	in2 := make(chan transport.Packet)
+	t2 := transport.NewChannelTransport(0, in2)
+	s.ds2 = store.NewMemoryMessageStore()
+	s.state2 = state.NewMemorySyncState()
+	p2 := [65]byte{0x02}
+	s.peers2 = peers.NewMemoryPersistence()
+	s.client2 = node.NewNode(s.ds2, t2, s.state2, Calc, 0, p2, node.BatchMode, s.peers2, dependency.NewInMemoryTracker(), node.EventualMode, logger)
+
+	t2.AddOutput(p1, in1)
+	t1.AddOutput(p2, in2)
+
+	s.groupID = [32]byte{0x01, 0x2, 0x3, 0x4}
+
+	s.Require().NoError(s.client1.AddPeer(s.groupID, p2))
+	s.Require().NoError(s.client2.AddPeer(s.groupID, p1))
+
+	// We run the tick manually
+	s.client1.Start(10 * time.Millisecond)
+	s.client2.Start(10 * time.Millisecond)
+}
+
+func (s *MVDSBatchSuite) TearDownTest() {
+	s.client1.Stop()
+	s.client2.Stop()
+}
+
+func (s *MVDSBatchSuite) TestSendClient1ToClient2() {
+	subscription := s.client2.Subscribe()
+	content := []byte("message 1")
+
+	messageID, err := s.client1.AppendMessage(s.groupID, content)
+	s.Require().NoError(err)
+
+	// Check message is in store
+	message1Sender, err := s.ds1.Get(messageID)
+	s.Require().NoError(err)
+	s.Require().NotNil(message1Sender)
+
+	message := <-subscription
+	s.Equal(message.Body, content)
+
+	message1Receiver, err := s.ds2.Get(messageID)
+	s.Require().NoError(err)
+	s.Require().NotNil(message1Receiver)
+}
+
+func (s *MVDSBatchSuite) TestSendClient2ToClient1() {
+	subscription := s.client1.Subscribe()
+	content := []byte("message 1")
+
+	messageID, err := s.client2.AppendMessage(s.groupID, content)
+	s.Require().NoError(err)
+
+	// Check message is in store
+	message1Sender, err := s.ds2.Get(messageID)
+	s.Require().NoError(err)
+	s.Require().NotNil(message1Sender)
+
+	message := <-subscription
+	s.Equal(message.Body, content)
+
+	message1Receiver, err := s.ds1.Get(messageID)
+	s.Require().NoError(err)
+	s.Require().NotNil(message1Receiver)
+}
+
+func (s *MVDSBatchSuite) TestAcks() {
+	subscription := s.client2.Subscribe()
+	messageID, err := s.client1.AppendMessage(s.groupID, []byte("message 1"))
+	s.Require().NoError(err)
+
+	// Check message is in store
+	message1Sender, err := s.ds1.Get(messageID)
+	s.Require().NoError(err)
+	s.Require().NotNil(message1Sender)
+
+	// Check state is updated correctly
+	states, err := s.state1.All(s.client1.CurrentEpoch())
+	s.Require().NoError(err)
+	s.Require().Equal(1, len(states))
+
+	<-subscription
+
+	message1Receiver, err := s.ds2.Get(messageID)
+	s.Require().NoError(err)
+	s.Require().NotNil(message1Receiver)
+
+	// Check state is removed
+	s.Require().Eventually(func() bool {
+		states, err := s.state1.All(s.client1.CurrentEpoch())
+		return err == nil && len(states) == 0
+
+	}, 1*time.Second, 10*time.Millisecond)
+}

mvds_interactive_test.go

@@ -0,0 +1,103 @@
+package main
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/suite"
+	"github.com/vacp2p/mvds/dependency"
+	"github.com/vacp2p/mvds/node"
+	"github.com/vacp2p/mvds/peers"
+	"github.com/vacp2p/mvds/state"
+	"github.com/vacp2p/mvds/store"
+	"github.com/vacp2p/mvds/transport"
+	"go.uber.org/zap"
+)
+
+func TestMVDSInteractiveSuite(t *testing.T) {
+	suite.Run(t, new(MVDSInteractiveSuite))
+}
+
+type MVDSInteractiveSuite struct {
+	suite.Suite
+	client1 *node.Node
+	client2 *node.Node
+	ds1     store.MessageStore
+	ds2     store.MessageStore
+	state1  state.SyncState
+	state2  state.SyncState
+	peers1  peers.Persistence
+	peers2  peers.Persistence
+	groupID state.GroupID
+}
+
+func (s *MVDSInteractiveSuite) SetupTest() {
+
+	logger := zap.NewNop()
+
+	in1 := make(chan transport.Packet)
+	t1 := transport.NewChannelTransport(0, in1)
+	s.ds1 = store.NewMemoryMessageStore()
+	s.state1 = state.NewMemorySyncState()
+	s.peers1 = peers.NewMemoryPersistence()
+	p1 := [65]byte{0x01}
+	s.client1 = node.NewNode(s.ds1, t1, s.state1, Calc, 0, p1, node.InteractiveMode, s.peers1, dependency.NewInMemoryTracker(), node.EventualMode, logger)
+
+	in2 := make(chan transport.Packet)
+	t2 := transport.NewChannelTransport(0, in2)
+	s.ds2 = store.NewMemoryMessageStore()
+	s.state2 = state.NewMemorySyncState()
+	p2 := [65]byte{0x02}
+	s.peers2 = peers.NewMemoryPersistence()
+	s.client2 = node.NewNode(s.ds2, t2, s.state2, Calc, 0, p2, node.InteractiveMode, s.peers2, dependency.NewInMemoryTracker(), node.EventualMode, logger)
+
+	t2.AddOutput(p1, in1)
+	t1.AddOutput(p2, in2)
+
+	s.groupID = [32]byte{0x01, 0x2, 0x3, 0x4}
+
+	s.Require().NoError(s.client1.AddPeer(s.groupID, p2))
+	s.Require().NoError(s.client2.AddPeer(s.groupID, p1))
+
+	s.client1.Start(10 * time.Millisecond)
+	s.client2.Start(10 * time.Millisecond)
+}
+
+func (s *MVDSInteractiveSuite) TearDownTest() {
+	s.client1.Stop()
+	s.client2.Stop()
+}
+
+func (s *MVDSInteractiveSuite) TestInteractiveMode() {
+	subscription := s.client2.Subscribe()
+	messageID, err := s.client1.AppendMessage(s.groupID, []byte("message 1"))
+	s.Require().NoError(err)
+
+	// Check message is in store
+	message1Sender, err := s.ds1.Get(messageID)
+	s.Require().NoError(err)
+	s.Require().NotNil(message1Sender)
+
+	// Check state is updated correctly
+	states, err := s.state1.All(s.client1.CurrentEpoch())
+	s.Require().NoError(err)
+	s.Require().Equal(1, len(states))
+
+	// Check we store the request
+	s.Require().Eventually(func() bool {
+		states, err := s.state2.All(s.client2.CurrentEpoch())
+		return err == nil && len(states) == 1 && states[0].Type == state.REQUEST
+	}, 1*time.Second, 10*time.Millisecond, "An request is stored in the state")
+
+	<-subscription
+	message1Receiver, err := s.ds2.Get(messageID)
+	s.Require().NoError(err)
+	s.Require().NotNil(message1Receiver)
+
+	// Check state is removed
+	s.Require().Eventually(func() bool {
+		states, err := s.state1.All(s.client1.CurrentEpoch())
+		return err == nil && len(states) == 0
+
+	}, 1*time.Second, 10*time.Millisecond, "We clear all the state")
+}

node/epoch_persistency.go

@@ -0,0 +1,33 @@
+package node
+
+import (
+	"database/sql"
+
+	"github.com/vacp2p/mvds/state"
+)
+
+type epochSQLitePersistence struct {
+	db *sql.DB
+}
+
+func newEpochSQLitePersistence(db *sql.DB) *epochSQLitePersistence {
+	return &epochSQLitePersistence{db: db}
+}
+
+func (p *epochSQLitePersistence) Get(nodeID state.PeerID) (epoch int64, err error) {
+	row := p.db.QueryRow(`SELECT epoch FROM mvds_epoch WHERE peer_id = ?`, nodeID[:])
+	err = row.Scan(&epoch)
+	if err == sql.ErrNoRows {
+		err = nil
+	}
+	return
+}
+
+func (p *epochSQLitePersistence) Set(nodeID state.PeerID, epoch int64) error {
+	_, err := p.db.Exec(`
+		INSERT OR REPLACE INTO mvds_epoch (peer_id, epoch) VALUES (?, ?)`,
+		nodeID[:],
+		epoch,
+	)
+	return err
+}

node/epoch_persistency_test.go

@@ -0,0 +1,38 @@
+package node
+
+import (
+	"io/ioutil"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/vacp2p/mvds/node/migrations"
+	"github.com/vacp2p/mvds/persistenceutil"
+	"github.com/vacp2p/mvds/state"
+)
+
+func TestEpochSQLitePersistence(t *testing.T) {
+	tmpFile, err := ioutil.TempFile("", "")
+	require.NoError(t, err)
+	db, err := persistenceutil.Open(tmpFile.Name(), "", persistenceutil.MigrationConfig{
+		AssetNames:  migrations.AssetNames(),
+		AssetGetter: migrations.Asset,
+	})
+	require.NoError(t, err)
+	p := newEpochSQLitePersistence(db)
+
+	err = p.Set(state.PeerID{0x01}, 1)
+	require.NoError(t, err)
+	epoch, err := p.Get(state.PeerID{0x01})
+	require.NoError(t, err)
+	require.Equal(t, int64(1), epoch)
+
+	err = p.Set(state.PeerID{0x01}, 2)
+	require.NoError(t, err)
+	epoch, err = p.Get(state.PeerID{0x01})
+	require.NoError(t, err)
+	require.Equal(t, int64(2), epoch)
+
+	epoch, err = p.Get(state.PeerID{0xff})
+	require.NoError(t, err)
+	require.Equal(t, int64(0), epoch)
+}

node/internal/syncstate_mock.go

@@ -0,0 +1,91 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: state/state.go
+
+// Package internal is a generated GoMock package.
+package internal
+
+import (
+	gomock "github.com/golang/mock/gomock"
+	state "github.com/vacp2p/mvds/state"
+	reflect "reflect"
+)
+
+// MockSyncState is a mock of SyncState interface
+type MockSyncState struct {
+	ctrl     *gomock.Controller
+	recorder *MockSyncStateMockRecorder
+}
+
+// MockSyncStateMockRecorder is the mock recorder for MockSyncState
+type MockSyncStateMockRecorder struct {
+	mock *MockSyncState
+}
+
+// NewMockSyncState creates a new mock instance
+func NewMockSyncState(ctrl *gomock.Controller) *MockSyncState {
+	mock := &MockSyncState{ctrl: ctrl}
+	mock.recorder = &MockSyncStateMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use
+func (m *MockSyncState) EXPECT() *MockSyncStateMockRecorder {
+	return m.recorder
+}
+
+// Add mocks base method
+func (m *MockSyncState) Add(newState state.State) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Add", newState)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// Add indicates an expected call of Add
+func (mr *MockSyncStateMockRecorder) Add(newState interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Add", reflect.TypeOf((*MockSyncState)(nil).Add), newState)
+}
+
+// Remove mocks base method
+func (m *MockSyncState) Remove(id state.MessageID, peer state.PeerID) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Remove", id, peer)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// Remove indicates an expected call of Remove
+func (mr *MockSyncStateMockRecorder) Remove(id, peer interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Remove", reflect.TypeOf((*MockSyncState)(nil).Remove), id, peer)
+}
+
+// All mocks base method
+func (m *MockSyncState) All(epoch int64) ([]state.State, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "All", epoch)
+	ret0, _ := ret[0].([]state.State)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// All indicates an expected call of All
+func (mr *MockSyncStateMockRecorder) All(epoch interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "All", reflect.TypeOf((*MockSyncState)(nil).All), epoch)
+}
+
+// Map mocks base method
+func (m *MockSyncState) Map(epoch int64, process func(state.State) state.State) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Map", epoch, process)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// Map indicates an expected call of Map
+func (mr *MockSyncStateMockRecorder) Map(epoch, process interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Map", reflect.TypeOf((*MockSyncState)(nil).Map), epoch, process)
+}

node/migrations/migrations.go

@@ -0,0 +1,317 @@
+// Code generated by go-bindata. DO NOT EDIT.
+// sources:
+// 1565345162_initial_schema.down.sql (23B)
+// 1565345162_initial_schema.up.sql (86B)
+// doc.go (377B)
+
+package migrations
+
+import (
+	"bytes"
+	"compress/gzip"
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+func bindataRead(data []byte, name string) ([]byte, error) {
+	gz, err := gzip.NewReader(bytes.NewBuffer(data))
+	if err != nil {
+		return nil, fmt.Errorf("read %q: %v", name, err)
+	}
+
+	var buf bytes.Buffer
+	_, err = io.Copy(&buf, gz)
+	clErr := gz.Close()
+
+	if err != nil {
+		return nil, fmt.Errorf("read %q: %v", name, err)
+	}
+	if clErr != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+type asset struct {
+	bytes  []byte
+	info   os.FileInfo
+	digest [sha256.Size]byte
+}
+
+type bindataFileInfo struct {
+	name    string
+	size    int64
+	mode    os.FileMode
+	modTime time.Time
+}
+
+func (fi bindataFileInfo) Name() string {
+	return fi.name
+}
+func (fi bindataFileInfo) Size() int64 {
+	return fi.size
+}
+func (fi bindataFileInfo) Mode() os.FileMode {
+	return fi.mode
+}
+func (fi bindataFileInfo) ModTime() time.Time {
+	return fi.modTime
+}
+func (fi bindataFileInfo) IsDir() bool {
+	return false
+}
+func (fi bindataFileInfo) Sys() interface{} {
+	return nil
+}
+
+var __1565345162_initial_schemaDownSql = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x72\x09\xf2\x0f\x50\x08\x71\x74\xf2\x71\x55\xc8\x2d\x4b\x29\x8e\x4f\x2d\xc8\x4f\xce\xb0\xe6\x02\x04\x00\x00\xff\xff\xd3\x00\xf3\x23\x17\x00\x00\x00")
+
+func _1565345162_initial_schemaDownSqlBytes() ([]byte, error) {
+	return bindataRead(
+		__1565345162_initial_schemaDownSql,
+		"1565345162_initial_schema.down.sql",
+	)
+}
+
+func _1565345162_initial_schemaDownSql() (*asset, error) {
+	bytes, err := _1565345162_initial_schemaDownSqlBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "1565345162_initial_schema.down.sql", size: 23, mode: os.FileMode(0644), modTime: time.Unix(1569335635, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0x7c, 0x69, 0xd2, 0x3, 0xea, 0x82, 0x7c, 0xb3, 0x44, 0x6c, 0xef, 0x64, 0x2c, 0x99, 0x62, 0xa2, 0x8b, 0x6f, 0x96, 0x4f, 0x34, 0x41, 0x87, 0xd5, 0x4e, 0x3, 0x7f, 0x4a, 0xd1, 0x91, 0x9, 0x99}}
+	return a, nil
+}
+
+var __1565345162_initial_schemaUpSql = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x72\x0e\x72\x75\x0c\x71\x55\x08\x71\x74\xf2\x71\x55\xc8\x2d\x4b\x29\x8e\x4f\x2d\xc8\x4f\xce\x50\xd0\xe0\x52\x50\x50\x50\x28\x48\x4d\x2d\x8a\xcf\x4c\x51\x70\xf2\xf1\x77\x52\x08\x08\xf2\xf4\x75\x0c\x8a\x54\xf0\x76\x8d\xd4\x01\xcb\x42\x54\x7a\xfa\x85\xb8\xba\xbb\x06\x29\xf8\xf9\x87\x28\xf8\x85\xfa\xf8\x70\x69\x5a\x73\x01\x02\x00\x00\xff\xff\x51\x96\x2d\xcb\x56\x00\x00\x00")
+
+func _1565345162_initial_schemaUpSqlBytes() ([]byte, error) {
+	return bindataRead(
+		__1565345162_initial_schemaUpSql,
+		"1565345162_initial_schema.up.sql",
+	)
+}
+
+func _1565345162_initial_schemaUpSql() (*asset, error) {
+	bytes, err := _1565345162_initial_schemaUpSqlBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "1565345162_initial_schema.up.sql", size: 86, mode: os.FileMode(0644), modTime: time.Unix(1569335635, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0x78, 0x7c, 0xdd, 0x67, 0x61, 0x3e, 0x7f, 0xd4, 0xce, 0xb0, 0x17, 0xbe, 0x5a, 0xa7, 0x9e, 0x93, 0x34, 0xe8, 0xbb, 0x44, 0xfb, 0x88, 0xd6, 0x18, 0x6d, 0x9f, 0xb4, 0x22, 0xda, 0xbc, 0x87, 0x94}}
+	return a, nil
+}
+
+var _docGo = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x84\x8f\xbb\x6e\xc3\x30\x0c\x45\x77\x7f\xc5\x45\x96\x2c\xb5\xb4\x74\xea\xd6\xb1\x7b\x7f\x80\x91\x68\x89\x88\x1e\xae\x48\xe7\xf1\xf7\x85\xd3\x02\xcd\xd6\xf5\x00\xe7\xf0\xd2\x7b\x7c\x66\x51\x2c\x52\x18\xa2\x68\x1c\x58\x95\xc6\x1d\x27\x0e\xb4\x29\xe3\x90\xc4\xf2\x76\x72\xa1\x57\xaf\x46\xb6\xe9\x2c\xd5\x57\x49\x83\x8c\xfd\xe5\xf5\x30\x79\x8f\x40\xed\x68\xc8\xd4\x62\xe1\x47\x4b\xa1\x46\xc3\xa4\x25\x5c\xc5\x32\x08\xeb\xe0\x45\x6e\x0e\xef\x86\xc2\xa4\x06\xcb\x64\x47\x85\x65\x46\x20\xe5\x3d\xb3\xf4\x81\xd4\xe7\x93\xb4\x48\x46\x6e\x47\x1f\xcb\x13\xd9\x17\x06\x2a\x85\x23\x96\xd1\xeb\xc3\x55\xaa\x8c\x28\x83\x83\xf5\x71\x7f\x01\xa9\xb2\xa1\x51\x65\xdd\xfd\x4c\x17\x46\xeb\xbf\xe7\x41\x2d\xfe\xff\x11\xae\x7d\x9c\x15\xa4\xe0\xdb\xca\xc1\x38\xba\x69\x5a\x29\x9c\x29\x31\xf4\xab\x88\xf1\x34\x79\x9f\xfa\x5b\xe2\xc6\xbb\xf5\xbc\x71\x5e\xcf\x09\x3f\x35\xe9\x4d\x31\x77\x38\xe7\xff\x80\x4b\x1d\x6e\xfa\x0e\x00\x00\xff\xff\x9d\x60\x3d\x88\x79\x01\x00\x00")
+
+func docGoBytes() ([]byte, error) {
+	return bindataRead(
+		_docGo,
+		"doc.go",
+	)
+}
+
+func docGo() (*asset, error) {
+	bytes, err := docGoBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "doc.go", size: 377, mode: os.FileMode(0644), modTime: time.Unix(1569335635, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0xef, 0xaf, 0xdf, 0xcf, 0x65, 0xae, 0x19, 0xfc, 0x9d, 0x29, 0xc1, 0x91, 0xaf, 0xb5, 0xd5, 0xb1, 0x56, 0xf3, 0xee, 0xa8, 0xba, 0x13, 0x65, 0xdb, 0xab, 0xcf, 0x4e, 0xac, 0x92, 0xe9, 0x60, 0xf1}}
+	return a, nil
+}
+
+// Asset loads and returns the asset for the given name.
+// It returns an error if the asset could not be found or
+// could not be loaded.
+func Asset(name string) ([]byte, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return nil, fmt.Errorf("Asset %s can't read by error: %v", name, err)
+		}
+		return a.bytes, nil
+	}
+	return nil, fmt.Errorf("Asset %s not found", name)
+}
+
+// AssetString returns the asset contents as a string (instead of a []byte).
+func AssetString(name string) (string, error) {
+	data, err := Asset(name)
+	return string(data), err
+}
+
+// MustAsset is like Asset but panics when Asset would return an error.
+// It simplifies safe initialization of global variables.
+func MustAsset(name string) []byte {
+	a, err := Asset(name)
+	if err != nil {
+		panic("asset: Asset(" + name + "): " + err.Error())
+	}
+
+	return a
+}
+
+// MustAssetString is like AssetString but panics when Asset would return an
+// error. It simplifies safe initialization of global variables.
+func MustAssetString(name string) string {
+	return string(MustAsset(name))
+}
+
+// AssetInfo loads and returns the asset info for the given name.
+// It returns an error if the asset could not be found or
+// could not be loaded.
+func AssetInfo(name string) (os.FileInfo, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return nil, fmt.Errorf("AssetInfo %s can't read by error: %v", name, err)
+		}
+		return a.info, nil
+	}
+	return nil, fmt.Errorf("AssetInfo %s not found", name)
+}
+
+// AssetDigest returns the digest of the file with the given name. It returns an
+// error if the asset could not be found or the digest could not be loaded.
+func AssetDigest(name string) ([sha256.Size]byte, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return [sha256.Size]byte{}, fmt.Errorf("AssetDigest %s can't read by error: %v", name, err)
+		}
+		return a.digest, nil
+	}
+	return [sha256.Size]byte{}, fmt.Errorf("AssetDigest %s not found", name)
+}
+
+// Digests returns a map of all known files and their checksums.
+func Digests() (map[string][sha256.Size]byte, error) {
+	mp := make(map[string][sha256.Size]byte, len(_bindata))
+	for name := range _bindata {
+		a, err := _bindata[name]()
+		if err != nil {
+			return nil, err
+		}
+		mp[name] = a.digest
+	}
+	return mp, nil
+}
+
+// AssetNames returns the names of the assets.
+func AssetNames() []string {
+	names := make([]string, 0, len(_bindata))
+	for name := range _bindata {
+		names = append(names, name)
+	}
+	return names
+}
+
+// _bindata is a table, holding each asset generator, mapped to its name.
+var _bindata = map[string]func() (*asset, error){
+	"1565345162_initial_schema.down.sql": _1565345162_initial_schemaDownSql,
+	"1565345162_initial_schema.up.sql":   _1565345162_initial_schemaUpSql,
+	"doc.go":                             docGo,
+}
+
+// AssetDir returns the file names below a certain
+// directory embedded in the file by go-bindata.
+// For example if you run go-bindata on data/... and data contains the
+// following hierarchy:
+//     data/
+//       foo.txt
+//       img/
+//         a.png
+//         b.png
+// then AssetDir("data") would return []string{"foo.txt", "img"},
+// AssetDir("data/img") would return []string{"a.png", "b.png"},
+// AssetDir("foo.txt") and AssetDir("notexist") would return an error, and
+// AssetDir("") will return []string{"data"}.
+func AssetDir(name string) ([]string, error) {
+	node := _bintree
+	if len(name) != 0 {
+		canonicalName := strings.Replace(name, "\\", "/", -1)
+		pathList := strings.Split(canonicalName, "/")
+		for _, p := range pathList {
+			node = node.Children[p]
+			if node == nil {
+				return nil, fmt.Errorf("Asset %s not found", name)
+			}
+		}
+	}
+	if node.Func != nil {
+		return nil, fmt.Errorf("Asset %s not found", name)
+	}
+	rv := make([]string, 0, len(node.Children))
+	for childName := range node.Children {
+		rv = append(rv, childName)
+	}
+	return rv, nil
+}
+
+type bintree struct {
+	Func     func() (*asset, error)
+	Children map[string]*bintree
+}
+
+var _bintree = &bintree{nil, map[string]*bintree{
+	"1565345162_initial_schema.down.sql": &bintree{_1565345162_initial_schemaDownSql, map[string]*bintree{}},
+	"1565345162_initial_schema.up.sql":   &bintree{_1565345162_initial_schemaUpSql, map[string]*bintree{}},
+	"doc.go":                             &bintree{docGo, map[string]*bintree{}},
+}}
+
+// RestoreAsset restores an asset under the given directory.
+func RestoreAsset(dir, name string) error {
+	data, err := Asset(name)
+	if err != nil {
+		return err
+	}
+	info, err := AssetInfo(name)
+	if err != nil {
+		return err
+	}
+	err = os.MkdirAll(_filePath(dir, filepath.Dir(name)), os.FileMode(0755))
+	if err != nil {
+		return err
+	}
+	err = ioutil.WriteFile(_filePath(dir, name), data, info.Mode())
+	if err != nil {
+		return err
+	}
+	return os.Chtimes(_filePath(dir, name), info.ModTime(), info.ModTime())
+}
+
+// RestoreAssets restores an asset under the given directory recursively.
+func RestoreAssets(dir, name string) error {
+	children, err := AssetDir(name)
+	// File
+	if err != nil {
+		return RestoreAsset(dir, name)
+	}
+	// Dir
+	for _, child := range children {
+		err = RestoreAssets(dir, filepath.Join(name, child))
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func _filePath(dir, name string) string {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	return filepath.Join(append([]string{dir}, strings.Split(canonicalName, "/")...)...)
+}

node/migrations/sqlite/1565345162_initial_schema.down.sql

@@ -0,0 +1 @@
+DROP TABLE mvds_epoch;

node/migrations/sqlite/1565345162_initial_schema.up.sql

@@ -0,0 +1,4 @@
+CREATE TABLE mvds_epoch (
+    peer_id BLOB PRIMARY KEY,
+    epoch INTEGER NOT NULL
+);

node/migrations/sqlite/doc.go

@@ -0,0 +1,9 @@
+// This file is necessary because "github.com/status-im/migrate/v4"
+// can't handle files starting with a prefix. At least that's the case
+// for go-bindata.
+// If go-bindata is called from the same directory, asset names
+// have no prefix and "github.com/status-im/migrate/v4" works as expected.
+
+package sqlite
+
+//go:generate go-bindata -pkg migrations -o ../migrations.go .

node/node.go

@@ -1,34 +1,51 @@
-// Package Node contains node logic.
+// Package node contains node logic.
 package node
 
 // @todo this is a very rough implementation that needs cleanup
 
 import (
-	"bytes"
 	"context"
+	"database/sql"
+	"encoding/hex"
 	"fmt"
-	"log"
 	"sync/atomic"
 	"time"
 
-	"github.com/status-im/mvds/protobuf"
-	"github.com/status-im/mvds/state"
-	"github.com/status-im/mvds/store"
-	"github.com/status-im/mvds/transport"
+	"github.com/vacp2p/mvds/dependency"
+	"go.uber.org/zap"
+
+	"github.com/vacp2p/mvds/peers"
+	"github.com/vacp2p/mvds/protobuf"
+	"github.com/vacp2p/mvds/state"
+	"github.com/vacp2p/mvds/store"
+	"github.com/vacp2p/mvds/transport"
 )
 
 // Mode represents the synchronization mode.
 type Mode int
 
 const (
-	INTERACTIVE Mode = iota
-	BATCH
+	InteractiveMode Mode = iota + 1
+	BatchMode
 )
 
-type calculateNextEpoch func(count uint64, epoch int64) int64
+// ResolutionMode defines how message dependencies should be resolved.
+type ResolutionMode int
+
+const (
+	// EventualMode is non-blocking and will return messages before dependencies are resolved.
+	EventualMode ResolutionMode = iota + 1
+	// ConsistentMode blocks and does not return messages until dependencies have been resolved.
+	ConsistentMode
+)
+
+// CalculateNextEpoch is a function used to calculate the next `SendEpoch` for a given message.
+type CalculateNextEpoch func(count uint64, epoch int64) int64
 
 // Node represents an MVDS node, it runs all the logic like sending and receiving protocol messages.
 type Node struct {
+	// This needs to be declared first: https://github.com/golang/go/issues/9959
+	epoch  int64
 	ctx    context.Context
 	cancel context.CancelFunc
 
@@ -37,18 +54,92 @@ type Node struct {
 
 	syncState state.SyncState
 
-	peers map[state.GroupID][]state.PeerID
+	peers peers.Persistence
 
 	payloads payloads
 
-	nextEpoch calculateNextEpoch
+	dependencies dependency.Tracker
+
+	nextEpoch CalculateNextEpoch
 
 	ID state.PeerID
 
-	epoch int64
-	mode  Mode
+	epochPersistence *epochSQLitePersistence
 
-	subscription chan<- protobuf.Message
+	mode       Mode
+	resolution ResolutionMode
+
+	subscription chan protobuf.Message
+
+	logger *zap.Logger
+}
+
+func NewPersistentNode(
+	db *sql.DB,
+	st transport.Transport,
+	id state.PeerID,
+	mode Mode,
+	resolution ResolutionMode,
+	nextEpoch CalculateNextEpoch,
+	logger *zap.Logger,
+) (*Node, error) {
+	ctx, cancel := context.WithCancel(context.Background())
+	if logger == nil {
+		logger = zap.NewNop()
+	}
+
+	node := Node{
+		ID:               id,
+		ctx:              ctx,
+		cancel:           cancel,
+		store:            store.NewPersistentMessageStore(db),
+		transport:        st,
+		peers:            peers.NewSQLitePersistence(db),
+		syncState:        state.NewPersistentSyncState(db),
+		payloads:         newPayloads(),
+		epochPersistence: newEpochSQLitePersistence(db),
+		nextEpoch:        nextEpoch,
+		dependencies:     dependency.NewPersistentTracker(db),
+		logger:           logger.With(zap.Namespace("mvds")),
+		mode:             mode,
+		resolution:       resolution,
+	}
+	if currentEpoch, err := node.epochPersistence.Get(id); err != nil {
+		return nil, err
+	} else {
+		node.epoch = currentEpoch
+	}
+	return &node, nil
+}
+
+func NewEphemeralNode(
+	id state.PeerID,
+	t transport.Transport,
+	nextEpoch CalculateNextEpoch,
+	currentEpoch int64,
+	mode Mode,
+	logger *zap.Logger,
+) *Node {
+	ctx, cancel := context.WithCancel(context.Background())
+	if logger == nil {
+		logger = zap.NewNop()
+	}
+
+	return &Node{
+		ID:           id,
+		ctx:          ctx,
+		cancel:       cancel,
+		store:        store.NewMemoryMessageStore(),
+		transport:    t,
+		syncState:    state.NewMemorySyncState(),
+		peers:        peers.NewMemoryPersistence(),
+		payloads:     newPayloads(),
+		dependencies: dependency.NewInMemoryTracker(),
+		nextEpoch:    nextEpoch,
+		epoch:        currentEpoch,
+		logger:       logger.With(zap.Namespace("mvds")),
+		mode:         mode,
+	}
 }
 
 // NewNode returns a new node.
@@ -56,12 +147,19 @@ func NewNode(
 	ms store.MessageStore,
 	st transport.Transport,
 	ss state.SyncState,
-	nextEpoch calculateNextEpoch,
+	nextEpoch CalculateNextEpoch,
 	currentEpoch int64,
 	id state.PeerID,
 	mode Mode,
+	pp peers.Persistence,
+	md dependency.Tracker,
+	resolution ResolutionMode,
+	logger *zap.Logger,
 ) *Node {
 	ctx, cancel := context.WithCancel(context.Background())
+	if logger == nil {
+		logger = zap.NewNop()
+	}
 
 	return &Node{
 		ctx:          ctx,
@@ -69,26 +167,33 @@ func NewNode(
 		store:        ms,
 		transport:    st,
 		syncState:    ss,
-		peers:        make(map[state.GroupID][]state.PeerID),
+		peers:        pp,
 		payloads:     newPayloads(),
 		nextEpoch:    nextEpoch,
 		ID:           id,
 		epoch:        currentEpoch,
+		logger:       logger.With(zap.Namespace("mvds")),
 		mode:         mode,
+		dependencies: md,
+		resolution:   resolution,
 	}
 }
 
+func (n *Node) CurrentEpoch() int64 {
+	return atomic.LoadInt64(&n.epoch)
+}
+
 // Start listens for new messages received by the node and sends out those required every epoch.
-func (n *Node) Start() {
+func (n *Node) Start(duration time.Duration) {
 	go func() {
 		for {
 			select {
 			case <-n.ctx.Done():
-				log.Print("Watch stopped")
+				n.logger.Info("Watch stopped")
 				return
 			default:
 				p := n.transport.Watch()
-				go n.onPayload(p.Group, p.Sender, p.Payload)
+				go n.onPayload(p.Sender, p.Payload)
 			}
 		}
 	}()
@@ -97,14 +202,22 @@ func (n *Node) Start() {
 		for {
 			select {
 			case <-n.ctx.Done():
-				log.Print("Epoch processing stopped")
+				n.logger.Info("Epoch processing stopped")
 				return
 			default:
-				log.Printf("Node: %x Epoch: %d", n.ID[:4], n.epoch)
-				time.Sleep(1 * time.Second)
-
-				n.sendMessages()
+				n.logger.Debug("Epoch processing", zap.String("node", hex.EncodeToString(n.ID[:4])), zap.Int64("epoch", n.epoch))
+				time.Sleep(duration)
+				err := n.sendMessages()
+				if err != nil {
+					n.logger.Error("Error sending messages.", zap.Error(err))
+				}
 				atomic.AddInt64(&n.epoch, 1)
+				// When a persistent node is used, the epoch needs to be saved.
+				if n.epochPersistence != nil {
+					if err := n.epochPersistence.Set(n.ID, n.epoch); err != nil {
+						n.logger.Error("Failed to persisten epoch", zap.Error(err))
+					}
+				}
 			}
 		}
 	}()
@@ -112,259 +225,509 @@ func (n *Node) Start() {
 
 // Stop message reading and epoch processing
 func (n *Node) Stop() {
+	n.logger.Info("Stopping node")
+	n.Unsubscribe()
 	n.cancel()
 }
 
 // Subscribe subscribes to incoming messages.
-func (n *Node) Subscribe(sub chan <-protobuf.Message) {
-	n.subscription = sub
+func (n *Node) Subscribe() chan protobuf.Message {
+	n.subscription = make(chan protobuf.Message)
+	return n.subscription
+}
+
+// Unsubscribe closes the listening channels
+func (n *Node) Unsubscribe() {
+	if n.subscription != nil {
+		close(n.subscription)
+	}
+	n.subscription = nil
 }
 
 // AppendMessage sends a message to a given group.
-func (n *Node) AppendMessage(group state.GroupID, data []byte) (state.MessageID, error) {
-	m := protobuf.Message{
-		GroupId:   group[:],
+func (n *Node) AppendMessage(groupID state.GroupID, data []byte) (state.MessageID, error) {
+	p, err := n.store.GetMessagesWithoutChildren(groupID)
+	parents := make([][]byte, len(p))
+	if err != nil {
+		n.logger.Error("Failed to retrieve parents",
+			zap.String("groupID", hex.EncodeToString(groupID[:4])),
+			zap.Error(err),
+		)
+	}
+
+	for i, id := range p {
+		parents[i] = id[:]
+	}
+
+	return n.AppendMessageWithMetadata(groupID, data, &protobuf.Metadata{Ephemeral: false, Parents: parents})
+}
+
+// AppendEphemeralMessage sends a message to a given group that has the `no_ack_required` flag set to `true`.
+func (n *Node) AppendEphemeralMessage(groupID state.GroupID, data []byte) (state.MessageID, error) {
+	return n.AppendMessageWithMetadata(groupID, data, &protobuf.Metadata{Ephemeral: true})
+}
+
+// AppendMessageWithMetadata sends a message to a given group with metadata.
+func (n *Node) AppendMessageWithMetadata(groupID state.GroupID, data []byte, metadata *protobuf.Metadata) (state.MessageID, error) {
+	m := &protobuf.Message{
+		GroupId:   groupID[:],
 		Timestamp: time.Now().Unix(),
 		Body:      data,
+		Metadata:  metadata,
 	}
 
 	id := m.ID()
 
-	peers, ok := n.peers[group]
-	if !ok {
-		return state.MessageID{}, fmt.Errorf("trying to send to unknown group %x", group[:4])
-	}
-
 	err := n.store.Add(m)
 	if err != nil {
 		return state.MessageID{}, err
 	}
 
-	go func() {
-		for _, p := range peers {
-			if !n.IsPeerInGroup(group, p) {
-				continue
+	err = n.broadcastToGroup(groupID, n.ID, m)
+	if err != nil {
+		return state.MessageID{}, err
 	}
 
-			t := state.OFFER
-			if n.mode == BATCH {
-				t = state.MESSAGE
-			}
-
-			n.insertSyncState(group, id, p, t)
-		}
-	}()
-
-	log.Printf("[%x] node %x sending %x\n", group[:4], n.ID[:4], id[:4])
-	// @todo think about a way to insta trigger send messages when send was selected, we don't wanna wait for ticks here
+	n.logger.Debug("Appending Message to Sync State",
+		zap.String("node", hex.EncodeToString(n.ID[:4])),
+		zap.String("groupID", hex.EncodeToString(groupID[:4])),
+		zap.String("id", hex.EncodeToString(id[:4])))
+	// @todo think about a way to insta trigger pushToSub messages when pushToSub was selected, we don't wanna wait for ticks here
 
 	return id, nil
 }
 
 // RequestMessage adds a REQUEST record to the next payload for a given message ID.
 func (n *Node) RequestMessage(group state.GroupID, id state.MessageID) error {
-	peers, ok := n.peers[group]
-	if !ok {
+	peers, err := n.peers.GetByGroupID(group)
+	if err != nil {
 		return fmt.Errorf("trying to request from an unknown group %x", group[:4])
 	}
 
-	go func() {
 	for _, p := range peers {
-			if !n.IsPeerInGroup(group, p) {
-				continue
+		n.insertSyncState(&group, id, p, state.REQUEST)
 	}
 
-			n.insertSyncState(group, id, p, state.REQUEST)
-		}
-	}()
-
 	return nil
 }
 
 // AddPeer adds a peer to a specific group making it a recipient of messages.
-func (n *Node) AddPeer(group state.GroupID, id state.PeerID) {
-	if _, ok := n.peers[group]; !ok {
-		n.peers[group] = make([]state.PeerID, 0)
-	}
-
-	n.peers[group] = append(n.peers[group], id)
+func (n *Node) AddPeer(group state.GroupID, id state.PeerID) error {
+	return n.peers.Add(group, id)
 }
 
 // IsPeerInGroup checks whether a peer is in the specified group.
-func (n Node) IsPeerInGroup(g state.GroupID, p state.PeerID) bool {
-	for _, peer := range n.peers[g] {
-		if bytes.Equal(peer[:], p[:]) {
-			return true
-		}
-	}
-
-	return false
+func (n *Node) IsPeerInGroup(g state.GroupID, p state.PeerID) (bool, error) {
+	return n.peers.Exists(g, p)
 }
 
-func (n *Node) sendMessages() {
-	err := n.syncState.Map(n.epoch, func(g state.GroupID, m state.MessageID, p state.PeerID, s state.State) state.State {
-		if !n.IsPeerInGroup(g, p) {
-			return s
-		}
+func (n *Node) sendMessages() error {
 
+	var toRemove []state.State
+
+	err := n.syncState.Map(n.epoch, func(s state.State) state.State {
+		m := s.MessageID
+		p := s.PeerID
 		switch s.Type {
 		case state.OFFER:
-			n.payloads.AddOffers(g, p, m[:])
+			n.payloads.AddOffers(p, m[:])
 		case state.REQUEST:
-			n.payloads.AddRequests(g, p, m[:])
-			log.Printf("[%x] sending REQUEST (%x -> %x): %x\n", g[:4], n.ID[:4], p[:4], m[:4])
+			n.payloads.AddRequests(p, m[:])
+			n.logger.Debug("sending REQUEST",
+				zap.String("from", hex.EncodeToString(n.ID[:4])),
+				zap.String("to", hex.EncodeToString(p[:4])),
+				zap.String("messageID", hex.EncodeToString(m[:4])),
+			)
+
 		case state.MESSAGE:
-			msg, err := n.store.Get(m)
+			g := *s.GroupID
+			exist, err := n.IsPeerInGroup(g, p)
 			if err != nil {
-				log.Printf("failed to retreive message %x %s", m[:4], err.Error())
 				return s
 			}
 
-			n.payloads.AddMessages(g, p, &msg)
-			log.Printf("[%x] sending MESSAGE (%x -> %x): %x\n", g[:4], n.ID[:4], p[:4], m[:4])
+			if !exist {
+				return s
+			}
+
+			msg, err := n.store.Get(m)
+			if err != nil {
+				n.logger.Error("Failed to retreive message",
+					zap.String("messageID", hex.EncodeToString(m[:4])),
+					zap.Error(err),
+				)
+
+				return s
+			}
+
+			n.payloads.AddMessages(p, msg)
+			n.logger.Debug("sending MESSAGE",
+				zap.String("groupID", hex.EncodeToString(g[:4])),
+				zap.String("from", hex.EncodeToString(n.ID[:4])),
+				zap.String("to", hex.EncodeToString(p[:4])),
+				zap.String("messageID", hex.EncodeToString(m[:4])),
+			)
+
+			if msg.Metadata != nil && msg.Metadata.Ephemeral {
+				toRemove = append(toRemove, s)
+			}
 		}
 
 		return n.updateSendEpoch(s)
 	})
 
 	if err != nil {
-		log.Printf("error while mapping sync state: %s", err.Error())
+		n.logger.Error("error while mapping sync state", zap.Error(err))
+		return err
 	}
 
-	n.payloads.MapAndClear(func(id state.GroupID, peer state.PeerID, payload protobuf.Payload) {
-		err := n.transport.Send(id, n.ID, peer, payload)
+	return n.payloads.MapAndClear(func(peer state.PeerID, payload protobuf.Payload) error {
+		err := n.transport.Send(n.ID, peer, payload)
 		if err != nil {
-			log.Printf("error sending message: %s", err.Error())
-			//	@todo
+			n.logger.Error("error sending message", zap.Error(err))
+			return err
 		}
+		return nil
 	})
+
 }
 
-func (n *Node) onPayload(group state.GroupID, sender state.PeerID, payload protobuf.Payload) {
+func (n *Node) onPayload(sender state.PeerID, payload protobuf.Payload) {
 	// Acks, Requests and Offers are all arrays of bytes as protobuf doesn't allow type aliases otherwise arrays of messageIDs would be nicer.
-	n.onAck(group, sender, payload.Acks)
-	n.onRequest(group, sender, payload.Requests)
-	n.onOffer(group, sender, payload.Offers)
-	n.payloads.AddAcks(group, sender, n.onMessages(group, sender, payload.Messages)...)
+	if err := n.onAck(sender, payload.Acks); err != nil {
+		n.logger.Error("error processing acks", zap.Error(err))
+	}
+	if err := n.onRequest(sender, payload.Requests); err != nil {
+		n.logger.Error("error processing requests", zap.Error(err))
+	}
+	if err := n.onOffer(sender, payload.Offers); err != nil {
+		n.logger.Error("error processing offers", zap.Error(err))
+	}
+	messageIds := n.onMessages(sender, payload.Messages)
+	n.payloads.AddAcks(sender, messageIds)
 }
 
-func (n *Node) onOffer(group state.GroupID, sender state.PeerID, offers [][]byte) {
+func (n *Node) onOffer(sender state.PeerID, offers [][]byte) error {
 	for _, raw := range offers {
-		id := toMessageID(raw)
-		log.Printf("[%x] OFFER (%x -> %x): %x received.\n", group[:4], sender[:4], n.ID[:4], id[:4])
+		id := state.ToMessageID(raw)
+		n.logger.Debug("OFFER received",
+			zap.String("from", hex.EncodeToString(sender[:4])),
+			zap.String("to", hex.EncodeToString(n.ID[:4])),
+			zap.String("messageID", hex.EncodeToString(id[:4])),
+		)
 
+		exist, err := n.store.Has(id)
 		// @todo maybe ack?
-		if n.store.Has(id) {
-			continue
-		}
-
-		n.insertSyncState(group, id, sender, state.REQUEST)
-	}
-}
-
-func (n *Node) onRequest(group state.GroupID, sender state.PeerID, requests [][]byte) {
-	for _, raw := range requests {
-		id := toMessageID(raw)
-		log.Printf("[%x] REQUEST (%x -> %x): %x received.\n", group[:4], sender[:4], n.ID[:4], id[:4])
-
-		if !n.IsPeerInGroup(group, sender) {
-			log.Printf("[%x] peer %x is not in group", group[:4], sender[:4])
-			continue
-		}
-
-		if !n.store.Has(id) {
-			log.Printf("message %x does not exist", id[:4])
-			continue
-		}
-
-		n.insertSyncState(group, id, sender, state.MESSAGE)
-	}
-}
-
-func (n *Node) onAck(group state.GroupID, sender state.PeerID, acks [][]byte) {
-	for _, raw := range acks {
-		id := toMessageID(raw)
-
-		err := n.syncState.Remove(group, id, sender)
 		if err != nil {
-			log.Printf("error while removing sync state %s", err.Error())
+			return err
+		}
+
+		if exist {
 			continue
 		}
 
-		log.Printf("[%x] ACK (%x -> %x): %x received.\n", group[:4], sender[:4], n.ID[:4], id[:4])
+		n.insertSyncState(nil, id, sender, state.REQUEST)
 	}
+	return nil
 }
 
-func (n *Node) onMessages(group state.GroupID, sender state.PeerID, messages []*protobuf.Message) [][]byte {
+func (n *Node) onRequest(sender state.PeerID, requests [][]byte) error {
+	for _, raw := range requests {
+		id := state.ToMessageID(raw)
+		n.logger.Debug("REQUEST received",
+			zap.String("from", hex.EncodeToString(sender[:4])),
+			zap.String("to", hex.EncodeToString(n.ID[:4])),
+			zap.String("messageID", hex.EncodeToString(id[:4])),
+		)
+
+		message, err := n.store.Get(id)
+		if err != nil {
+			return err
+		}
+
+		if message == nil {
+			n.logger.Error("message does not exist", zap.String("messageID", hex.EncodeToString(id[:4])))
+			continue
+		}
+
+		groupID := state.ToGroupID(message.GroupId)
+
+		exist, err := n.IsPeerInGroup(groupID, sender)
+		if err != nil {
+			return err
+		}
+
+		if !exist {
+			n.logger.Error("peer is not in group",
+				zap.String("groupID", hex.EncodeToString(groupID[:4])),
+				zap.String("peer", hex.EncodeToString(sender[:4])),
+			)
+			continue
+		}
+
+		n.insertSyncState(&groupID, id, sender, state.MESSAGE)
+	}
+
+	return nil
+}
+
+func (n *Node) onAck(sender state.PeerID, acks [][]byte) error {
+	for _, ack := range acks {
+		id := state.ToMessageID(ack)
+
+		err := n.syncState.Remove(id, sender)
+		if err != nil {
+			n.logger.Error("Error while removing sync state.", zap.Error(err))
+			return err
+		}
+
+		n.logger.Debug("ACK received",
+			zap.String("from", hex.EncodeToString(sender[:4])),
+			zap.String("to", hex.EncodeToString(n.ID[:4])),
+			zap.String("messageID", hex.EncodeToString(id[:4])),
+		)
+
+	}
+	return nil
+}
+
+func (n *Node) onMessages(sender state.PeerID, messages []*protobuf.Message) [][]byte {
 	a := make([][]byte, 0)
 
 	for _, m := range messages {
-		err := n.onMessage(group, sender, *m)
+		groupID := state.ToGroupID(m.GroupId)
+		err := n.onMessage(sender, m)
 		if err != nil {
-			// @todo
+			n.logger.Error("Error processing message", zap.Error(err))
 			continue
 		}
 
 		id := m.ID()
-		log.Printf("[%x] sending ACK (%x -> %x): %x\n", group[:4], n.ID[:4], sender[:4], id[:4])
+
+		if m.Metadata != nil && m.Metadata.Ephemeral {
+			n.logger.Debug("not sending ACK",
+				zap.String("groupID", hex.EncodeToString(groupID[:4])),
+				zap.String("from", hex.EncodeToString(n.ID[:4])),
+				zap.String("", hex.EncodeToString(sender[:4])),
+				zap.String("messageID", hex.EncodeToString(id[:4])),
+			)
+			continue
+		}
+
+		n.logger.Debug("sending ACK",
+			zap.String("groupID", hex.EncodeToString(groupID[:4])),
+			zap.String("from", hex.EncodeToString(n.ID[:4])),
+			zap.String("", hex.EncodeToString(sender[:4])),
+			zap.String("messageID", hex.EncodeToString(id[:4])),
+		)
+
 		a = append(a, id[:])
 	}
 
 	return a
 }
 
-func (n *Node) onMessage(group state.GroupID, sender state.PeerID, msg protobuf.Message) error {
+// @todo cleanup this function
+func (n *Node) onMessage(sender state.PeerID, msg *protobuf.Message) error {
 	id := msg.ID()
-	log.Printf("[%x] MESSAGE (%x -> %x): %x received.\n", group[:4], sender[:4], n.ID[:4], id[:4])
+	groupID := state.ToGroupID(msg.GroupId)
+	n.logger.Debug("MESSAGE received",
+		zap.String("from", hex.EncodeToString(sender[:4])),
+		zap.String("to", hex.EncodeToString(n.ID[:4])),
+		zap.String("messageID", hex.EncodeToString(id[:4])),
+	)
 
-	err := n.syncState.Remove(group, id, sender)
+	err := n.syncState.Remove(id, sender)
+	if err != nil && err != state.ErrStateNotFound {
+		return err
+	}
+
+	if msg.Metadata == nil || !msg.Metadata.Ephemeral {
+		err = n.store.Add(msg)
+		if err != nil {
+			return err
+		}
+	}
+
+	err = n.broadcastToGroup(groupID, sender, msg)
 	if err != nil {
 		return err
 	}
 
-	go func() {
-		for _, peer := range n.peers[group] {
+	n.resolve(sender, msg)
+
+	return nil
+}
+
+func (n *Node) broadcastToGroup(group state.GroupID, sender state.PeerID, msg *protobuf.Message) error {
+	p, err := n.peers.GetByGroupID(group)
+	if err != nil {
+		return err
+	}
+
+	id := msg.ID()
+
+	for _, peer := range p {
 		if peer == sender {
 			continue
 		}
 
-			n.insertSyncState(group, id, peer, state.OFFER)
-		}
-	}()
-
-	if n.subscription != nil {
-		n.subscription <- msg
+		t := state.OFFER
+		if n.mode == BatchMode || (msg.Metadata == nil && !msg.Metadata.Ephemeral) {
+			t = state.MESSAGE
 		}
 
-	err = n.store.Add(msg)
-	if err != nil {
-		return err
-		// @todo process, should this function ever even have an error?
+		n.insertSyncState(&group, id, peer, t)
 	}
 
 	return nil
 }
 
-func (n *Node) insertSyncState(group state.GroupID, id state.MessageID, p state.PeerID, t state.RecordType) {
+// @todo I do not think this will work, this needs be some recrusive function
+// @todo add method to select depth of how far we resolve dependencies
+
+func (n *Node) resolve(sender state.PeerID, msg *protobuf.Message) {
+	if n.resolution == EventualMode {
+		n.resolveEventually(sender, msg)
+		return
+	}
+
+	n.resolveConsistently(sender, msg)
+}
+
+func (n *Node) resolveEventually(sender state.PeerID, msg *protobuf.Message) {
+	if msg.Metadata == nil || len(msg.Metadata.Parents) == 0 {
+		n.pushToSub(msg)
+		return
+	}
+
+	for _, parent := range msg.Metadata.Parents {
+		pid := state.ToMessageID(parent)
+
+		if has, _ := n.store.Has(pid); has {
+			continue
+		}
+
+		group := state.ToGroupID(msg.GroupId)
+		n.insertSyncState(&group, pid, sender, state.REQUEST)
+	}
+
+	n.pushToSub(msg)
+}
+
+func (n *Node) resolveConsistently(sender state.PeerID, msg *protobuf.Message) {
+	id := msg.ID()
+
+	// We push any messages whose parents have now been resolved
+	dependants, err := n.dependencies.Dependants(id)
+	if err != nil {
+		n.logger.Error("error getting dependants",
+			zap.Error(err),
+			zap.String("msg", hex.EncodeToString(id[:4])),
+		)
+	}
+
+	for _, dependant := range dependants {
+		err := n.dependencies.Resolve(dependant, id)
+		if err != nil {
+			n.logger.Error("error marking resolved dependency",
+				zap.Error(err),
+				zap.String("msg", hex.EncodeToString(dependant[:4])),
+				zap.String("dependency", hex.EncodeToString(id[:4])),
+			)
+		}
+
+		resolved, err := n.dependencies.IsResolved(dependant)
+		if err != nil {
+			n.logger.Error("error getting unresolved dependencies",
+				zap.Error(err),
+				zap.String("msg", hex.EncodeToString(dependant[:4])),
+			)
+		}
+
+		if !resolved {
+			continue
+		}
+
+		dmsg, err := n.store.Get(dependant)
+		if err != nil {
+			n.logger.Error("error getting message",
+				zap.Error(err),
+				zap.String("messageID", hex.EncodeToString(dependant[:4])),
+			)
+		}
+
+		if dmsg != nil {
+			n.pushToSub(dmsg)
+		}
+	}
+
+	// @todo add parent dependencies to child, then we can have multiple levels?
+	if msg.Metadata == nil || len(msg.Metadata.Parents) == 0 {
+		n.pushToSub(msg)
+		return
+	}
+
+	hasUnresolvedDependencies := false
+	for _, parent := range msg.Metadata.Parents {
+		pid := state.ToMessageID(parent)
+
+		if has, _ := n.store.Has(pid); has {
+			continue
+		}
+
+		group := state.ToGroupID(msg.GroupId)
+		n.insertSyncState(&group, pid, sender, state.REQUEST)
+		hasUnresolvedDependencies = true
+
+		err := n.dependencies.Add(id, pid)
+		if err != nil {
+			n.logger.Error("error adding dependency",
+				zap.Error(err),
+				zap.String("msg", hex.EncodeToString(id[:4])),
+				zap.String("dependency", hex.EncodeToString(pid[:4])),
+			)
+		}
+	}
+
+	if hasUnresolvedDependencies {
+		return
+	}
+
+	n.pushToSub(msg)
+}
+
+func (n *Node) pushToSub(msg *protobuf.Message) {
+	if n.subscription == nil {
+		return
+	}
+
+	n.subscription <- *msg
+}
+
+func (n *Node) insertSyncState(groupID *state.GroupID, messageID state.MessageID, peerID state.PeerID, t state.RecordType) {
 	s := state.State{
+		GroupID:   groupID,
+		MessageID: messageID,
+		PeerID:    peerID,
 		Type:      t,
 		SendEpoch: n.epoch + 1,
 	}
 
-	err := n.syncState.Set(group, id, p, s)
+	err := n.syncState.Add(s)
 	if err != nil {
-		log.Printf("error (%s) setting sync state group: %x id: %x peer: %x", err.Error(), group[:4], id[:4], p[:4])
+		n.logger.Error("error setting sync states",
+			zap.Error(err),
+			zap.String("groupID", hex.EncodeToString(groupID[:4])),
+			zap.String("messageID", hex.EncodeToString(messageID[:4])),
+			zap.String("peerID", hex.EncodeToString(peerID[:4])),
+		)
+
 	}
 }
 
-func (n Node) updateSendEpoch(s state.State) state.State {
+func (n *Node) updateSendEpoch(s state.State) state.State {
 	s.SendCount += 1
-	s.SendEpoch += n.nextEpoch(s.SendCount, n.epoch)
+	s.SendEpoch = n.nextEpoch(s.SendCount, n.epoch)
 	return s
 }
-
-func toMessageID(b []byte) state.MessageID {
-	var id state.MessageID
-	copy(id[:], b)
-	return id
-}

node/node_test.go

@@ -0,0 +1,130 @@
+package node
+
+import (
+	"crypto/rand"
+	"reflect"
+	"testing"
+	"time"
+
+	"github.com/golang/mock/gomock"
+	"github.com/vacp2p/mvds/dependency"
+	"github.com/vacp2p/mvds/node/internal"
+	"github.com/vacp2p/mvds/protobuf"
+	"github.com/vacp2p/mvds/state"
+	"github.com/vacp2p/mvds/store"
+)
+
+func TestNode_resolveEventually(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	syncstate := internal.NewMockSyncState(ctrl)
+
+	node := Node{
+		syncState: syncstate,
+		store: store.NewMemoryMessageStore(),
+	}
+
+	channel := node.Subscribe()
+
+	peer := peerID()
+	group := groupID()
+	parent := messageID()
+
+	msg := &protobuf.Message{
+		GroupId: group[:],
+		Timestamp: time.Now().Unix(),
+		Body: []byte{0x01},
+		Metadata: &protobuf.Metadata{Ephemeral: false, Parents: [][]byte{parent[:]}},
+	}
+
+	expectedState := state.State{
+		GroupID:   &group,
+		MessageID: parent,
+		PeerID:    peer,
+		Type:      state.REQUEST,
+		SendEpoch: 1,
+	}
+
+	syncstate.EXPECT().Add(expectedState).Return(nil)
+
+	go node.resolveEventually(peer, msg)
+
+	received := <-channel
+
+	if !reflect.DeepEqual(*msg, received) {
+		t.Error("expected message did not match received")
+	}
+}
+
+func TestNode_resolveConsistently(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	syncstate := internal.NewMockSyncState(ctrl)
+
+	node := Node{
+		syncState: syncstate,
+		store: store.NewMemoryMessageStore(),
+		dependencies: dependency.NewInMemoryTracker(),
+	}
+
+	channel := node.Subscribe()
+
+	peer := peerID()
+	group := groupID()
+
+	parent := &protobuf.Message{
+		GroupId: group[:],
+		Timestamp: time.Now().Unix(),
+		Body: []byte{0x02},
+	}
+
+	parentID := parent.ID()
+
+	msg := &protobuf.Message{
+		GroupId: group[:],
+		Timestamp: time.Now().Unix(),
+		Body: []byte{0x01},
+		Metadata: &protobuf.Metadata{Ephemeral: false, Parents: [][]byte{parentID[:]}},
+	}
+
+	// @todo we need to make sure to add the message cause we are going through a subset of the flow
+	_ = node.store.Add(msg)
+
+	syncstate.EXPECT().Add(gomock.Any()).DoAndReturn(func(state.State) error {
+		return nil
+	})
+
+	node.resolveConsistently(peer, msg)
+
+	go node.resolveConsistently(peer, parent)
+
+	received := <-channel
+
+	if !reflect.DeepEqual(*msg, received) {
+		t.Error("expected message did not match received")
+	}
+
+	received = <-channel
+
+	if !reflect.DeepEqual(*parent, received) {
+		t.Error("expected message did not match received")
+	}
+
+}
+
+func peerID() (id state.PeerID) {
+	_, _ = rand.Read(id[:])
+	return id
+}
+
+func groupID() (id state.GroupID) {
+	_, _ = rand.Read(id[:])
+	return id
+}
+
+func messageID() (id state.MessageID) {
+	_, _ = rand.Read(id[:])
+	return id
+}

node/payloads.go

@@ -3,92 +3,90 @@ package node
 import (
 	"sync"
 
-	"github.com/status-im/mvds/protobuf"
-	"github.com/status-im/mvds/state"
+	"github.com/vacp2p/mvds/protobuf"
+	"github.com/vacp2p/mvds/state"
 )
 
 type payloads struct {
 	sync.Mutex
 
-	payloads map[state.GroupID]map[state.PeerID]protobuf.Payload
+	payloads map[state.PeerID]protobuf.Payload
 }
+
 // @todo check in all the functions below that we aren't duplicating stuff
 
 func newPayloads() payloads {
 	return payloads{
-		payloads: make(map[state.GroupID]map[state.PeerID]protobuf.Payload),
+		payloads: make(map[state.PeerID]protobuf.Payload),
 	}
 }
 
-func (p *payloads) AddOffers(group state.GroupID, peer state.PeerID, offers ...[]byte) {
+func (p *payloads) AddOffers(peer state.PeerID, offers ...[]byte) {
 	p.Lock()
 	defer p.Unlock()
 
-	payload := p.get(group, peer)
+	payload := p.get(peer)
 
 	payload.Offers = append(payload.Offers, offers...)
 
-	p.set(group, peer, payload)
+	p.set(peer, payload)
 }
 
-func (p *payloads) AddAcks(group state.GroupID, peer state.PeerID, acks ...[]byte) {
+func (p *payloads) AddAcks(peer state.PeerID, acks [][]byte) {
 	p.Lock()
 	defer p.Unlock()
 
-	payload := p.get(group, peer)
+	payload := p.get(peer)
 
-	payload.Requests = append(payload.Requests, acks...)
+	payload.Acks = append(payload.Acks, acks...)
 
-	p.set(group, peer, payload)
+	p.set(peer, payload)
 }
 
-func (p *payloads) AddRequests(group state.GroupID, peer state.PeerID, request ...[]byte) {
+func (p *payloads) AddRequests(peer state.PeerID, request ...[]byte) {
 	p.Lock()
 	defer p.Unlock()
 
-	payload := p.get(group, peer)
+	payload := p.get(peer)
 
 	payload.Requests = append(payload.Requests, request...)
 
-	p.set(group, peer, payload)
+	p.set(peer, payload)
 }
 
-func (p *payloads) AddMessages(group state.GroupID, peer state.PeerID, messages ...*protobuf.Message) {
+func (p *payloads) AddMessages(peer state.PeerID, messages ...*protobuf.Message) {
 	p.Lock()
 	defer p.Unlock()
 
-	payload := p.get(group, peer)
+	payload := p.get(peer)
 	if payload.Messages == nil {
 		payload.Messages = make([]*protobuf.Message, 0)
 	}
 
 	payload.Messages = append(payload.Messages, messages...)
-	p.set(group, peer, payload)
+	p.set(peer, payload)
 }
 
-func (p *payloads) MapAndClear(f func(state.GroupID, state.PeerID, protobuf.Payload)) {
+func (p *payloads) MapAndClear(f func(state.PeerID, protobuf.Payload) error) error {
 	p.Lock()
 	defer p.Unlock()
 
-	for g, payloads := range p.payloads {
-		for peer, payload := range payloads {
-			f(g, peer, payload)
+	for peer, payload := range p.payloads {
+		err := f(peer, payload)
+		if err != nil {
+			return err
 		}
 	}
 
-	p.payloads = make(map[state.GroupID]map[state.PeerID]protobuf.Payload)
+	// TODO: this should only be called upon confirmation that the message has been sent
+	p.payloads = make(map[state.PeerID]protobuf.Payload)
+	return nil
 }
 
-func (p *payloads) get(id state.GroupID, peer state.PeerID) protobuf.Payload {
-	payload, _ := p.payloads[id][peer]
-	return payload
+func (p *payloads) get(peer state.PeerID) protobuf.Payload {
+	return p.payloads[peer]
 }
 
-func (p *payloads) set(id state.GroupID, peer state.PeerID, payload protobuf.Payload) {
-	_, ok := p.payloads[id]
-	if !ok {
-		p.payloads[id] = make(map[state.PeerID]protobuf.Payload)
-	}
-
-	p.payloads[id][peer] = payload
+func (p *payloads) set(peer state.PeerID, payload protobuf.Payload) {
+	p.payloads[peer] = payload
 }

peers/migrations/migrations.go

@@ -0,0 +1,317 @@
+// Code generated by go-bindata. DO NOT EDIT.
+// sources:
+// 1565249278_initial_schema.down.sql (23B)
+// 1565249278_initial_schema.up.sql (140B)
+// doc.go (377B)
+
+package migrations
+
+import (
+	"bytes"
+	"compress/gzip"
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+func bindataRead(data []byte, name string) ([]byte, error) {
+	gz, err := gzip.NewReader(bytes.NewBuffer(data))
+	if err != nil {
+		return nil, fmt.Errorf("read %q: %v", name, err)
+	}
+
+	var buf bytes.Buffer
+	_, err = io.Copy(&buf, gz)
+	clErr := gz.Close()
+
+	if err != nil {
+		return nil, fmt.Errorf("read %q: %v", name, err)
+	}
+	if clErr != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+type asset struct {
+	bytes  []byte
+	info   os.FileInfo
+	digest [sha256.Size]byte
+}
+
+type bindataFileInfo struct {
+	name    string
+	size    int64
+	mode    os.FileMode
+	modTime time.Time
+}
+
+func (fi bindataFileInfo) Name() string {
+	return fi.name
+}
+func (fi bindataFileInfo) Size() int64 {
+	return fi.size
+}
+func (fi bindataFileInfo) Mode() os.FileMode {
+	return fi.mode
+}
+func (fi bindataFileInfo) ModTime() time.Time {
+	return fi.modTime
+}
+func (fi bindataFileInfo) IsDir() bool {
+	return false
+}
+func (fi bindataFileInfo) Sys() interface{} {
+	return nil
+}
+
+var __1565249278_initial_schemaDownSql = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x72\x09\xf2\x0f\x50\x08\x71\x74\xf2\x71\x55\xc8\x2d\x4b\x29\x8e\x2f\x48\x4d\x2d\x2a\xb6\xe6\x02\x04\x00\x00\xff\xff\x58\x44\x68\xf7\x17\x00\x00\x00")
+
+func _1565249278_initial_schemaDownSqlBytes() ([]byte, error) {
+	return bindataRead(
+		__1565249278_initial_schemaDownSql,
+		"1565249278_initial_schema.down.sql",
+	)
+}
+
+func _1565249278_initial_schemaDownSql() (*asset, error) {
+	bytes, err := _1565249278_initial_schemaDownSqlBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "1565249278_initial_schema.down.sql", size: 23, mode: os.FileMode(0644), modTime: time.Unix(1569335635, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0x4, 0xfb, 0x5, 0x92, 0xf0, 0x93, 0xaa, 0x83, 0xb7, 0xdf, 0x66, 0xe2, 0x97, 0x53, 0x9d, 0x34, 0xd3, 0xca, 0x97, 0xd8, 0xe1, 0xed, 0xf0, 0x4a, 0x94, 0x1a, 0xb1, 0x8f, 0xcf, 0xc, 0xa4, 0x6}}
+	return a, nil
+}
+
+var __1565249278_initial_schemaUpSql = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x72\x0e\x72\x75\x0c\x71\x55\x08\x71\x74\xf2\x71\x55\xc8\x2d\x4b\x29\x8e\x2f\x48\x4d\x2d\x2a\x56\xd0\xe0\x52\x50\x50\x50\x48\x2f\xca\x2f\x2d\x88\xcf\x4c\x51\x70\xf2\xf1\x77\x52\xf0\xf3\x0f\x51\xf0\x0b\xf5\xf1\xd1\x01\xcb\x81\xd4\xe1\x90\x0a\x08\xf2\xf4\x75\x0c\x8a\x54\xf0\x76\x8d\x54\xd0\x80\x99\xa1\x03\xd3\xa1\xa9\xe0\xef\xa7\xe0\xec\xef\xe7\xe6\xe3\xe9\x1c\xa2\x10\xe4\x1a\xe0\xe3\xe8\xec\xca\xa5\x69\xcd\x05\x08\x00\x00\xff\xff\x67\x63\xbf\x36\x8c\x00\x00\x00")
+
+func _1565249278_initial_schemaUpSqlBytes() ([]byte, error) {
+	return bindataRead(
+		__1565249278_initial_schemaUpSql,
+		"1565249278_initial_schema.up.sql",
+	)
+}
+
+func _1565249278_initial_schemaUpSql() (*asset, error) {
+	bytes, err := _1565249278_initial_schemaUpSqlBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "1565249278_initial_schema.up.sql", size: 140, mode: os.FileMode(0644), modTime: time.Unix(1569335635, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0x8a, 0xbc, 0x3a, 0x87, 0x12, 0x93, 0xeb, 0xb4, 0xcc, 0x42, 0x6e, 0xb2, 0x7d, 0xfa, 0x9a, 0xa8, 0x3f, 0xb, 0x6b, 0xa8, 0x2d, 0x8b, 0xde, 0x67, 0x2a, 0xa8, 0xa5, 0x42, 0xad, 0x27, 0x15, 0x7e}}
+	return a, nil
+}
+
+var _docGo = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x84\x8f\xbb\x6e\xc3\x30\x0c\x45\x77\x7f\xc5\x45\x96\x2c\xb5\xb4\x74\xea\xd6\xb1\x7b\x7f\x80\x91\x68\x89\x88\x1e\xae\x48\xe7\xf1\xf7\x85\xd3\x02\xcd\xd6\xf5\x00\xe7\xf0\xd2\x7b\x7c\x66\x51\x2c\x52\x18\xa2\x68\x1c\x58\x95\xc6\x1d\x27\x0e\xb4\x29\xe3\x90\xc4\xf2\x76\x72\xa1\x57\xaf\x46\xb6\xe9\x2c\xd5\x57\x49\x83\x8c\xfd\xe5\xf5\x30\x79\x8f\x40\xed\x68\xc8\xd4\x62\xe1\x47\x4b\xa1\x46\xc3\xa4\x25\x5c\xc5\x32\x08\xeb\xe0\x45\x6e\x0e\xef\x86\xc2\xa4\x06\xcb\x64\x47\x85\x65\x46\x20\xe5\x3d\xb3\xf4\x81\xd4\xe7\x93\xb4\x48\x46\x6e\x47\x1f\xcb\x13\xd9\x17\x06\x2a\x85\x23\x96\xd1\xeb\xc3\x55\xaa\x8c\x28\x83\x83\xf5\x71\x7f\x01\xa9\xb2\xa1\x51\x65\xdd\xfd\x4c\x17\x46\xeb\xbf\xe7\x41\x2d\xfe\xff\x11\xae\x7d\x9c\x15\xa4\xe0\xdb\xca\xc1\x38\xba\x69\x5a\x29\x9c\x29\x31\xf4\xab\x88\xf1\x34\x79\x9f\xfa\x5b\xe2\xc6\xbb\xf5\xbc\x71\x5e\xcf\x09\x3f\x35\xe9\x4d\x31\x77\x38\xe7\xff\x80\x4b\x1d\x6e\xfa\x0e\x00\x00\xff\xff\x9d\x60\x3d\x88\x79\x01\x00\x00")
+
+func docGoBytes() ([]byte, error) {
+	return bindataRead(
+		_docGo,
+		"doc.go",
+	)
+}
+
+func docGo() (*asset, error) {
+	bytes, err := docGoBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "doc.go", size: 377, mode: os.FileMode(0644), modTime: time.Unix(1569335635, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0xef, 0xaf, 0xdf, 0xcf, 0x65, 0xae, 0x19, 0xfc, 0x9d, 0x29, 0xc1, 0x91, 0xaf, 0xb5, 0xd5, 0xb1, 0x56, 0xf3, 0xee, 0xa8, 0xba, 0x13, 0x65, 0xdb, 0xab, 0xcf, 0x4e, 0xac, 0x92, 0xe9, 0x60, 0xf1}}
+	return a, nil
+}
+
+// Asset loads and returns the asset for the given name.
+// It returns an error if the asset could not be found or
+// could not be loaded.
+func Asset(name string) ([]byte, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return nil, fmt.Errorf("Asset %s can't read by error: %v", name, err)
+		}
+		return a.bytes, nil
+	}
+	return nil, fmt.Errorf("Asset %s not found", name)
+}
+
+// AssetString returns the asset contents as a string (instead of a []byte).
+func AssetString(name string) (string, error) {
+	data, err := Asset(name)
+	return string(data), err
+}
+
+// MustAsset is like Asset but panics when Asset would return an error.
+// It simplifies safe initialization of global variables.
+func MustAsset(name string) []byte {
+	a, err := Asset(name)
+	if err != nil {
+		panic("asset: Asset(" + name + "): " + err.Error())
+	}
+
+	return a
+}
+
+// MustAssetString is like AssetString but panics when Asset would return an
+// error. It simplifies safe initialization of global variables.
+func MustAssetString(name string) string {
+	return string(MustAsset(name))
+}
+
+// AssetInfo loads and returns the asset info for the given name.
+// It returns an error if the asset could not be found or
+// could not be loaded.
+func AssetInfo(name string) (os.FileInfo, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return nil, fmt.Errorf("AssetInfo %s can't read by error: %v", name, err)
+		}
+		return a.info, nil
+	}
+	return nil, fmt.Errorf("AssetInfo %s not found", name)
+}
+
+// AssetDigest returns the digest of the file with the given name. It returns an
+// error if the asset could not be found or the digest could not be loaded.
+func AssetDigest(name string) ([sha256.Size]byte, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return [sha256.Size]byte{}, fmt.Errorf("AssetDigest %s can't read by error: %v", name, err)
+		}
+		return a.digest, nil
+	}
+	return [sha256.Size]byte{}, fmt.Errorf("AssetDigest %s not found", name)
+}
+
+// Digests returns a map of all known files and their checksums.
+func Digests() (map[string][sha256.Size]byte, error) {
+	mp := make(map[string][sha256.Size]byte, len(_bindata))
+	for name := range _bindata {
+		a, err := _bindata[name]()
+		if err != nil {
+			return nil, err
+		}
+		mp[name] = a.digest
+	}
+	return mp, nil
+}
+
+// AssetNames returns the names of the assets.
+func AssetNames() []string {
+	names := make([]string, 0, len(_bindata))
+	for name := range _bindata {
+		names = append(names, name)
+	}
+	return names
+}
+
+// _bindata is a table, holding each asset generator, mapped to its name.
+var _bindata = map[string]func() (*asset, error){
+	"1565249278_initial_schema.down.sql": _1565249278_initial_schemaDownSql,
+	"1565249278_initial_schema.up.sql":   _1565249278_initial_schemaUpSql,
+	"doc.go":                             docGo,
+}
+
+// AssetDir returns the file names below a certain
+// directory embedded in the file by go-bindata.
+// For example if you run go-bindata on data/... and data contains the
+// following hierarchy:
+//     data/
+//       foo.txt
+//       img/
+//         a.png
+//         b.png
+// then AssetDir("data") would return []string{"foo.txt", "img"},
+// AssetDir("data/img") would return []string{"a.png", "b.png"},
+// AssetDir("foo.txt") and AssetDir("notexist") would return an error, and
+// AssetDir("") will return []string{"data"}.
+func AssetDir(name string) ([]string, error) {
+	node := _bintree
+	if len(name) != 0 {
+		canonicalName := strings.Replace(name, "\\", "/", -1)
+		pathList := strings.Split(canonicalName, "/")
+		for _, p := range pathList {
+			node = node.Children[p]
+			if node == nil {
+				return nil, fmt.Errorf("Asset %s not found", name)
+			}
+		}
+	}
+	if node.Func != nil {
+		return nil, fmt.Errorf("Asset %s not found", name)
+	}
+	rv := make([]string, 0, len(node.Children))
+	for childName := range node.Children {
+		rv = append(rv, childName)
+	}
+	return rv, nil
+}
+
+type bintree struct {
+	Func     func() (*asset, error)
+	Children map[string]*bintree
+}
+
+var _bintree = &bintree{nil, map[string]*bintree{
+	"1565249278_initial_schema.down.sql": &bintree{_1565249278_initial_schemaDownSql, map[string]*bintree{}},
+	"1565249278_initial_schema.up.sql":   &bintree{_1565249278_initial_schemaUpSql, map[string]*bintree{}},
+	"doc.go":                             &bintree{docGo, map[string]*bintree{}},
+}}
+
+// RestoreAsset restores an asset under the given directory.
+func RestoreAsset(dir, name string) error {
+	data, err := Asset(name)
+	if err != nil {
+		return err
+	}
+	info, err := AssetInfo(name)
+	if err != nil {
+		return err
+	}
+	err = os.MkdirAll(_filePath(dir, filepath.Dir(name)), os.FileMode(0755))
+	if err != nil {
+		return err
+	}
+	err = ioutil.WriteFile(_filePath(dir, name), data, info.Mode())
+	if err != nil {
+		return err
+	}
+	return os.Chtimes(_filePath(dir, name), info.ModTime(), info.ModTime())
+}
+
+// RestoreAssets restores an asset under the given directory recursively.
+func RestoreAssets(dir, name string) error {
+	children, err := AssetDir(name)
+	// File
+	if err != nil {
+		return RestoreAsset(dir, name)
+	}
+	// Dir
+	for _, child := range children {
+		err = RestoreAssets(dir, filepath.Join(name, child))
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func _filePath(dir, name string) string {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	return filepath.Join(append([]string{dir}, strings.Split(canonicalName, "/")...)...)
+}

peers/migrations/sqlite/1565249278_initial_schema.down.sql

@@ -0,0 +1 @@
+DROP TABLE mvds_peers;

peers/migrations/sqlite/1565249278_initial_schema.up.sql

@@ -0,0 +1,5 @@
+CREATE TABLE mvds_peers (
+    group_id BLOB NOT NULL,
+    peer_id BLOB NOT NULL,
+    PRIMARY KEY (group_id, peer_id) ON CONFLICT REPLACE
+);

peers/migrations/sqlite/doc.go

@@ -0,0 +1,9 @@
+// This file is necessary because "github.com/status-im/migrate/v4"
+// can't handle files starting with a prefix. At least that's the case
+// for go-bindata.
+// If go-bindata is called from the same directory, asset names
+// have no prefix and "github.com/status-im/migrate/v4" works as expected.
+
+package sqlite
+
+//go:generate go-bindata -pkg migrations -o ../migrations.go .

peers/persistence.go

@@ -0,0 +1,11 @@
+package peers
+
+import (
+	"github.com/vacp2p/mvds/state"
+)
+
+type Persistence interface {
+	Add(state.GroupID, state.PeerID) error
+	GetByGroupID(group state.GroupID) ([]state.PeerID, error)
+	Exists(state.GroupID, state.PeerID) (bool, error)
+}

peers/persistence_memory.go

@@ -0,0 +1,32 @@
+package peers
+
+import "github.com/vacp2p/mvds/state"
+
+type memoryPersistence struct {
+	peers map[state.GroupID][]state.PeerID
+}
+
+func NewMemoryPersistence() *memoryPersistence {
+	return &memoryPersistence{
+		peers: make(map[state.GroupID][]state.PeerID),
+	}
+}
+
+func (p *memoryPersistence) Add(groupID state.GroupID, peerID state.PeerID) error {
+	p.peers[groupID] = append(p.peers[groupID], peerID)
+	return nil
+}
+
+func (p *memoryPersistence) Exists(groupID state.GroupID, peerID state.PeerID) (bool, error) {
+	for _, peer := range p.peers[groupID] {
+		if peer == peerID {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
+func (p *memoryPersistence) GetByGroupID(groupID state.GroupID) ([]state.PeerID, error) {
+	return p.peers[groupID], nil
+}
+

peers/persistence_sqlite.go

@@ -0,0 +1,63 @@
+package peers
+
+import (
+	"database/sql"
+	"errors"
+
+	"github.com/vacp2p/mvds/state"
+)
+
+var (
+	ErrPeerNotFound = errors.New("peer not found")
+)
+
+type sqlitePersistence struct {
+	db *sql.DB
+}
+
+func NewSQLitePersistence(db *sql.DB) sqlitePersistence {
+	return sqlitePersistence{db: db}
+}
+
+func (p sqlitePersistence) Add(groupID state.GroupID, peerID state.PeerID) error {
+	_, err := p.db.Exec(`INSERT INTO mvds_peers (group_id, peer_id) VALUES (?, ?)`, groupID[:], peerID[:])
+	return err
+}
+
+func (p sqlitePersistence) Exists(groupID state.GroupID, peerID state.PeerID) (bool, error) {
+	var result bool
+	err := p.db.QueryRow(
+		`SELECT EXISTS(SELECT 1 FROM mvds_peers WHERE group_id = ? AND peer_id = ?)`,
+		groupID[:],
+		peerID[:],
+	).Scan(&result)
+	switch err {
+	case sql.ErrNoRows:
+		return false, ErrPeerNotFound
+	case nil:
+		return result, nil
+	default:
+		return false, err
+	}
+}
+
+func (p sqlitePersistence) GetByGroupID(groupID state.GroupID) (result []state.PeerID, err error) {
+	rows, err := p.db.Query(`SELECT peer_id FROM mvds_peers WHERE group_id = ?`, groupID[:])
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var (
+			peerIDBytes []byte
+			peerID      state.PeerID
+		)
+		if err := rows.Scan(&peerIDBytes); err != nil {
+			return nil, err
+		}
+		copy(peerID[:], peerIDBytes)
+		result = append(result, peerID)
+	}
+	return
+}

peers/persistence_sqlite_test.go

@@ -0,0 +1,57 @@
+package peers
+
+import (
+	"io/ioutil"
+	"testing"
+
+	"github.com/vacp2p/mvds/peers/migrations"
+
+	"github.com/vacp2p/mvds/persistenceutil"
+	"github.com/vacp2p/mvds/state"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSQLitePersistence(t *testing.T) {
+	tmpFile, err := ioutil.TempFile("", "")
+	require.NoError(t, err)
+	db, err := persistenceutil.Open(tmpFile.Name(), "", persistenceutil.MigrationConfig{
+		AssetNames:  migrations.AssetNames(),
+		AssetGetter: migrations.Asset,
+	})
+	require.NoError(t, err)
+	p := NewSQLitePersistence(db)
+
+	err = p.Add(state.GroupID{0x01}, state.PeerID{0x01})
+	require.NoError(t, err)
+	// Add the same again.
+	err = p.Add(state.GroupID{0x01}, state.PeerID{0x01})
+	require.NoError(t, err)
+	// Add another peer to the same group.
+	err = p.Add(state.GroupID{0x01}, state.PeerID{0x02})
+	require.NoError(t, err)
+	// Create a new group.
+	err = p.Add(state.GroupID{0x02}, state.PeerID{0x01})
+	require.NoError(t, err)
+	err = p.Add(state.GroupID{0x02}, state.PeerID{0x02})
+	require.NoError(t, err)
+	err = p.Add(state.GroupID{0x02}, state.PeerID{0x03})
+	require.NoError(t, err)
+
+	// Validate group 0x01.
+	peers, err := p.GetByGroupID(state.GroupID{0x01})
+	require.NoError(t, err)
+	require.Equal(t, []state.PeerID{state.PeerID{0x01}, state.PeerID{0x02}}, peers)
+	// Validate group 0x02.
+	peers, err = p.GetByGroupID(state.GroupID{0x02})
+	require.NoError(t, err)
+	require.Equal(t, []state.PeerID{state.PeerID{0x01}, state.PeerID{0x02}, state.PeerID{0x03}}, peers)
+
+	// Validate existence method.
+	exists, err := p.Exists(state.GroupID{0x01}, state.PeerID{0x01})
+	require.NoError(t, err)
+	require.True(t, exists)
+	exists, err = p.Exists(state.GroupID{0x01}, state.PeerID{0xFF})
+	require.NoError(t, err)
+	require.False(t, exists)
+}

persistenceutil/migrations.go

@@ -0,0 +1,70 @@
+package persistenceutil
+
+import (
+	"github.com/pkg/errors"
+	"strings"
+
+	nodemigrations "github.com/vacp2p/mvds/node/migrations"
+	peersmigrations "github.com/vacp2p/mvds/peers/migrations"
+	statemigrations "github.com/vacp2p/mvds/state/migrations"
+	storemigrations "github.com/vacp2p/mvds/store/migrations"
+)
+
+type getter func(string) ([]byte, error)
+
+type Migration struct {
+	Names  []string
+	Getter func(name string) ([]byte, error)
+}
+
+func prepareMigrations(migrations []Migration) ([]string, getter, error) {
+	var allNames []string
+	nameToGetter := make(map[string]getter)
+
+	for _, m := range migrations {
+		for _, name := range m.Names {
+			if !validateName(name) {
+				continue
+			}
+
+			if _, ok := nameToGetter[name]; ok {
+				return nil, nil, errors.Errorf("migration with name %s already exists", name)
+			}
+			allNames = append(allNames, name)
+			nameToGetter[name] = m.Getter
+		}
+	}
+
+	return allNames, func(name string) ([]byte, error) {
+		getter, ok := nameToGetter[name]
+		if !ok {
+			return nil, errors.Errorf("no migration for name %s", name)
+		}
+		return getter(name)
+	}, nil
+}
+
+// DefaultMigrations is a collection of all mvds components migrations.
+var DefaultMigrations = []Migration{
+	{
+		Names:  nodemigrations.AssetNames(),
+		Getter: nodemigrations.Asset,
+	},
+	{
+		Names:  peersmigrations.AssetNames(),
+		Getter: peersmigrations.Asset,
+	},
+	{
+		Names:  statemigrations.AssetNames(),
+		Getter: statemigrations.Asset,
+	},
+	{
+		Names:  storemigrations.AssetNames(),
+		Getter: storemigrations.Asset,
+	},
+}
+
+// validateName verifies that only *.sql files are taken into consideration.
+func validateName(name string) bool {
+	return strings.HasSuffix(name, ".sql")
+}

persistenceutil/sqlite.go

@@ -0,0 +1,124 @@
+package persistenceutil
+
+import (
+	"database/sql"
+	"fmt"
+	"os"
+
+	"github.com/pkg/errors"
+	"github.com/status-im/migrate/v4"
+	"github.com/status-im/migrate/v4/database/sqlcipher"
+	bindata "github.com/status-im/migrate/v4/source/go_bindata"
+)
+
+// The reduced number of kdf iterations (for performance reasons) which is
+// currently used for derivation of the database key
+// https://github.com/status-im/status-go/pull/1343
+// https://notes.status.im/i8Y_l7ccTiOYq09HVgoFwA
+const reducedKdfIterationsNumber = 3200
+
+// MigrationConfig is a struct that allows to define bindata migrations.
+type MigrationConfig struct {
+	AssetNames  []string
+	AssetGetter func(name string) ([]byte, error)
+}
+
+// Migrate migrates a provided sqldb
+func Migrate(db *sql.DB) error {
+	assetNames, assetGetter, err := prepareMigrations(DefaultMigrations)
+	if err != nil {
+		return err
+	}
+	return ApplyMigrations(db, assetNames, assetGetter)
+
+}
+
+// Open opens or initializes a new database for a given file path.
+// MigrationConfig is optional but if provided migrations are applied automatically.
+func Open(path, key string, mc ...MigrationConfig) (*sql.DB, error) {
+	return open(path, key, reducedKdfIterationsNumber, mc)
+}
+
+// OpenWithIter allows to open a new database with a custom number of kdf iterations.
+// Higher kdf iterations number makes it slower to open the database.
+func OpenWithIter(path, key string, kdfIter int, mc ...MigrationConfig) (*sql.DB, error) {
+	return open(path, key, kdfIter, mc)
+}
+
+func open(path string, key string, kdfIter int, configs []MigrationConfig) (*sql.DB, error) {
+	_, err := os.OpenFile(path, os.O_CREATE, 0644)
+	if err != nil {
+		return nil, err
+	}
+
+	db, err := sql.Open("sqlite3", path)
+	if err != nil {
+		return nil, err
+	}
+
+	keyString := fmt.Sprintf("PRAGMA key = '%s'", key)
+
+	// Disable concurrent access as not supported by the driver
+	db.SetMaxOpenConns(1)
+
+	if _, err = db.Exec("PRAGMA foreign_keys=ON"); err != nil {
+		return nil, err
+	}
+
+	if _, err = db.Exec(keyString); err != nil {
+		return nil, err
+	}
+
+	kdfString := fmt.Sprintf("PRAGMA kdf_iter = '%d'", kdfIter)
+
+	if _, err = db.Exec(kdfString); err != nil {
+		return nil, err
+	}
+
+	// Apply all provided migrations.
+	for _, mc := range configs {
+		if err := ApplyMigrations(db, mc.AssetNames, mc.AssetGetter); err != nil {
+			return nil, err
+		}
+	}
+
+	return db, nil
+}
+
+// ApplyMigrations allows to apply bindata migrations on the current *sql.DB.
+// `assetNames` is a list of assets with migrations and `assetGetter` is responsible
+// for returning the content of the asset with a given name.
+func ApplyMigrations(db *sql.DB, assetNames []string, assetGetter func(name string) ([]byte, error)) error {
+	resources := bindata.Resource(
+		assetNames,
+		assetGetter,
+	)
+
+	source, err := bindata.WithInstance(resources)
+	if err != nil {
+		return errors.Wrap(err, "failed to create migration source")
+	}
+
+	driver, err := sqlcipher.WithInstance(db, &sqlcipher.Config{
+		MigrationsTable: "mvds_" + sqlcipher.DefaultMigrationsTable,
+	})
+	if err != nil {
+		return errors.Wrap(err, "failed to create driver")
+	}
+
+	m, err := migrate.NewWithInstance(
+		"go-bindata",
+		source,
+		"sqlcipher",
+		driver,
+	)
+	if err != nil {
+		return errors.Wrap(err, "failed to create migration instance")
+	}
+
+	if err = m.Up(); err != migrate.ErrNoChange {
+		return errors.Wrap(err, "failed to migrate")
+	}
+
+	return nil
+}

protobuf/messageid.go

@@ -4,7 +4,7 @@ import (
 	"crypto/sha256"
 	"encoding/binary"
 
-	"github.com/status-im/mvds/state"
+	"github.com/vacp2p/mvds/state"
 )
 
 // ID creates the MessageID for a Message

protobuf/payload.go

@@ -0,0 +1,7 @@
+package protobuf
+
+// IsValid checks whether there are any known field in the protobuf
+// message
+func (m *Payload) IsValid() bool {
+	return len(m.Messages)+len(m.Acks)+len(m.Offers)+len(m.Requests) != 0
+}

protobuf/sync.pb.go

@@ -83,10 +83,58 @@ func (m *Payload) GetMessages() []*Message {
 	return nil
 }
 
+type Metadata struct {
+	Parents              [][]byte `protobuf:"bytes,1,rep,name=parents,proto3" json:"parents,omitempty"`
+	Ephemeral            bool     `protobuf:"varint,2,opt,name=ephemeral,proto3" json:"ephemeral,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *Metadata) Reset()         { *m = Metadata{} }
+func (m *Metadata) String() string { return proto.CompactTextString(m) }
+func (*Metadata) ProtoMessage()    {}
+func (*Metadata) Descriptor() ([]byte, []int) {
+	return fileDescriptor_2dca527c092c79d7, []int{1}
+}
+
+func (m *Metadata) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_Metadata.Unmarshal(m, b)
+}
+func (m *Metadata) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_Metadata.Marshal(b, m, deterministic)
+}
+func (m *Metadata) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_Metadata.Merge(m, src)
+}
+func (m *Metadata) XXX_Size() int {
+	return xxx_messageInfo_Metadata.Size(m)
+}
+func (m *Metadata) XXX_DiscardUnknown() {
+	xxx_messageInfo_Metadata.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_Metadata proto.InternalMessageInfo
+
+func (m *Metadata) GetParents() [][]byte {
+	if m != nil {
+		return m.Parents
+	}
+	return nil
+}
+
+func (m *Metadata) GetEphemeral() bool {
+	if m != nil {
+		return m.Ephemeral
+	}
+	return false
+}
+
 type Message struct {
 	GroupId              []byte    `protobuf:"bytes,1,opt,name=group_id,json=groupId,proto3" json:"group_id,omitempty"`
 	Timestamp            int64     `protobuf:"varint,2,opt,name=timestamp,proto3" json:"timestamp,omitempty"`
 	Body                 []byte    `protobuf:"bytes,3,opt,name=body,proto3" json:"body,omitempty"`
+	Metadata             *Metadata `protobuf:"bytes,4,opt,name=metadata,proto3" json:"metadata,omitempty"`
 	XXX_NoUnkeyedLiteral struct{}  `json:"-"`
 	XXX_unrecognized     []byte    `json:"-"`
 	XXX_sizecache        int32     `json:"-"`
@@ -96,7 +144,7 @@ func (m *Message) Reset()         { *m = Message{} }
 func (m *Message) String() string { return proto.CompactTextString(m) }
 func (*Message) ProtoMessage()    {}
 func (*Message) Descriptor() ([]byte, []int) {
-	return fileDescriptor_2dca527c092c79d7, []int{1}
+	return fileDescriptor_2dca527c092c79d7, []int{2}
 }
 
 func (m *Message) XXX_Unmarshal(b []byte) error {
@@ -138,27 +186,38 @@ func (m *Message) GetBody() []byte {
 	return nil
 }
 
+func (m *Message) GetMetadata() *Metadata {
+	if m != nil {
+		return m.Metadata
+	}
+	return nil
+}
+
 func init() {
-	proto.RegisterType((*Payload)(nil), "mvds.Payload")
-	proto.RegisterType((*Message)(nil), "mvds.Message")
+	proto.RegisterType((*Payload)(nil), "vac.mvds.Payload")
+	proto.RegisterType((*Metadata)(nil), "vac.mvds.Metadata")
+	proto.RegisterType((*Message)(nil), "vac.mvds.Message")
 }
 
 func init() { proto.RegisterFile("protobuf/sync.proto", fileDescriptor_2dca527c092c79d7) }
 
 var fileDescriptor_2dca527c092c79d7 = []byte{
-	// 212 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x44, 0x8f, 0xb1, 0x4a, 0x04, 0x31,
-	0x10, 0x86, 0xd9, 0xcb, 0x72, 0x1b, 0xc7, 0xb3, 0x19, 0x41, 0xa2, 0x58, 0x84, 0xab, 0x62, 0xb3,
-	0x82, 0xbe, 0x81, 0x9d, 0x85, 0x20, 0x29, 0x2c, 0x6c, 0x24, 0x7b, 0xc9, 0x1e, 0x87, 0xc6, 0xac,
-	0x99, 0xac, 0xb0, 0xe0, 0xc3, 0xcb, 0x8d, 0xe7, 0x5e, 0xf7, 0x7f, 0xdf, 0xcf, 0x30, 0x33, 0x70,
-	0x3e, 0xe4, 0x54, 0x52, 0x37, 0xf6, 0xb7, 0x34, 0x7d, 0x6e, 0x5a, 0x26, 0xac, 0xe3, 0xb7, 0xa7,
-	0xf5, 0x0f, 0x34, 0xcf, 0x6e, 0xfa, 0x48, 0xce, 0x23, 0x42, 0xed, 0x36, 0xef, 0xa4, 0x2a, 0x2d,
-	0xcc, 0xca, 0x72, 0xc6, 0x0b, 0x58, 0xa6, 0xbe, 0x0f, 0x99, 0xd4, 0x82, 0xed, 0x81, 0xf0, 0x0a,
-	0x64, 0x0e, 0x5f, 0x63, 0xa0, 0x42, 0x4a, 0x70, 0x33, 0x33, 0xde, 0x80, 0x8c, 0x81, 0xc8, 0x6d,
-	0x03, 0xa9, 0x5a, 0x0b, 0x73, 0x7a, 0x77, 0xd6, 0xee, 0x77, 0xb5, 0x4f, 0x7f, 0xd6, 0xce, 0xf5,
-	0xfa, 0x05, 0x9a, 0x83, 0xc4, 0x4b, 0x90, 0xdb, 0x9c, 0xc6, 0xe1, 0x6d, 0xe7, 0x55, 0xa5, 0x2b,
-	0xb3, 0xb2, 0x0d, 0xf3, 0xa3, 0xc7, 0x6b, 0x38, 0x29, 0xbb, 0x18, 0xa8, 0xb8, 0x38, 0xa8, 0x85,
-	0xae, 0x8c, 0xb0, 0x47, 0xb1, 0x3f, 0xbb, 0x4b, 0x7e, 0x52, 0x82, 0x87, 0x38, 0x3f, 0xc0, 0xab,
-	0xfc, 0x7f, 0xb9, 0x5b, 0x72, 0xba, 0xff, 0x0d, 0x00, 0x00, 0xff, 0xff, 0x4c, 0x0a, 0x11, 0xee,
-	0x05, 0x01, 0x00, 0x00,
+	// 265 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x4c, 0x50, 0x3d, 0x4f, 0xc3, 0x30,
+	0x10, 0x95, 0x9b, 0xaa, 0x35, 0x57, 0x16, 0x0e, 0x09, 0x19, 0xc4, 0x10, 0x65, 0xca, 0x42, 0x90,
+	0xca, 0x3f, 0xe8, 0xc6, 0x50, 0x09, 0x65, 0x64, 0x41, 0x97, 0xf8, 0x52, 0x2a, 0x9a, 0x3a, 0xd8,
+	0x4e, 0xa5, 0x6c, 0x4c, 0xfc, 0x6e, 0x14, 0xa7, 0x49, 0xd9, 0xde, 0xc7, 0xf9, 0xf9, 0xde, 0xc1,
+	0x6d, 0x63, 0x8d, 0x37, 0x45, 0x5b, 0x3d, 0xbb, 0xee, 0x58, 0x66, 0x81, 0xa1, 0x3c, 0x51, 0x99,
+	0xd5, 0x27, 0xed, 0x92, 0x1f, 0x01, 0xcb, 0x37, 0xea, 0x0e, 0x86, 0x34, 0x22, 0xcc, 0xa9, 0xfc,
+	0x72, 0x4a, 0xc4, 0x51, 0x7a, 0x9d, 0x07, 0x8c, 0x77, 0xb0, 0x30, 0x55, 0xc5, 0xd6, 0xa9, 0x59,
+	0x50, 0xcf, 0x0c, 0x1f, 0x40, 0x5a, 0xfe, 0x6e, 0xd9, 0x79, 0xa7, 0xa2, 0xe0, 0x4c, 0x1c, 0x9f,
+	0x40, 0xd6, 0xec, 0x1c, 0xed, 0xd8, 0xa9, 0x79, 0x1c, 0xa5, 0xab, 0xf5, 0x4d, 0x36, 0x7e, 0x98,
+	0x6d, 0x07, 0x27, 0x9f, 0x46, 0x92, 0x0d, 0xc8, 0x2d, 0x7b, 0xd2, 0xe4, 0x09, 0x15, 0x2c, 0x1b,
+	0xb2, 0x7c, 0xf4, 0xe3, 0x16, 0x23, 0xc5, 0x47, 0xb8, 0xe2, 0xe6, 0x93, 0x6b, 0xb6, 0x74, 0x50,
+	0xb3, 0x58, 0xa4, 0x32, 0xbf, 0x08, 0xc9, 0xaf, 0x80, 0xe5, 0x39, 0x19, 0xef, 0x41, 0xee, 0xac,
+	0x69, 0x9b, 0x8f, 0xbd, 0x56, 0x22, 0x16, 0x7d, 0x48, 0xe0, 0xaf, 0xba, 0x0f, 0xf1, 0xfb, 0x9a,
+	0x9d, 0xa7, 0xba, 0x09, 0x21, 0x51, 0x7e, 0x11, 0xfa, 0xfe, 0x85, 0xd1, 0x9d, 0x8a, 0xc2, 0xa3,
+	0x80, 0x31, 0xeb, 0xbb, 0x0c, 0xcb, 0xa9, 0x79, 0x2c, 0xd2, 0xd5, 0x1a, 0xff, 0x77, 0x19, 0x9c,
+	0x7c, 0x9a, 0xd9, 0xc0, 0xbb, 0x1c, 0x0f, 0x5e, 0x2c, 0x02, 0x7a, 0xf9, 0x0b, 0x00, 0x00, 0xff,
+	0xff, 0x8f, 0x0f, 0x88, 0x6c, 0x83, 0x01, 0x00, 0x00,
 }

protobuf/sync.proto

@@ -1,6 +1,6 @@
 syntax = "proto3";
 
-package mvds;
+package vac.mvds;
 option go_package = "protobuf";
 
 message Payload {
@@ -10,8 +10,14 @@ message Payload {
   repeated Message messages = 4;
 }
 
+message Metadata {
+  repeated bytes parents = 1;
+  bool ephemeral = 2;
+}
+
 message Message {
   bytes group_id = 1;
   int64 timestamp = 2;
   bytes body = 3;
+  Metadata metadata = 4;
 }

state/migrations/migrations.go

@@ -0,0 +1,317 @@
+// Code generated by go-bindata. DO NOT EDIT.
+// sources:
+// 1565341329_initial_schema.down.sql (24B)
+// 1565341329_initial_schema.up.sql (294B)
+// doc.go (377B)
+
+package migrations
+
+import (
+	"bytes"
+	"compress/gzip"
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+func bindataRead(data []byte, name string) ([]byte, error) {
+	gz, err := gzip.NewReader(bytes.NewBuffer(data))
+	if err != nil {
+		return nil, fmt.Errorf("read %q: %v", name, err)
+	}
+
+	var buf bytes.Buffer
+	_, err = io.Copy(&buf, gz)
+	clErr := gz.Close()
+
+	if err != nil {
+		return nil, fmt.Errorf("read %q: %v", name, err)
+	}
+	if clErr != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+type asset struct {
+	bytes  []byte
+	info   os.FileInfo
+	digest [sha256.Size]byte
+}
+
+type bindataFileInfo struct {
+	name    string
+	size    int64
+	mode    os.FileMode
+	modTime time.Time
+}
+
+func (fi bindataFileInfo) Name() string {
+	return fi.name
+}
+func (fi bindataFileInfo) Size() int64 {
+	return fi.size
+}
+func (fi bindataFileInfo) Mode() os.FileMode {
+	return fi.mode
+}
+func (fi bindataFileInfo) ModTime() time.Time {
+	return fi.modTime
+}
+func (fi bindataFileInfo) IsDir() bool {
+	return false
+}
+func (fi bindataFileInfo) Sys() interface{} {
+	return nil
+}
+
+var __1565341329_initial_schemaDownSql = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x72\x09\xf2\x0f\x50\x08\x71\x74\xf2\x71\x55\xc8\x2d\x4b\x29\x8e\x2f\x2e\x49\x2c\x49\x2d\xb6\xe6\x02\x04\x00\x00\xff\xff\xb7\x43\xc1\xc1\x18\x00\x00\x00")
+
+func _1565341329_initial_schemaDownSqlBytes() ([]byte, error) {
+	return bindataRead(
+		__1565341329_initial_schemaDownSql,
+		"1565341329_initial_schema.down.sql",
+	)
+}
+
+func _1565341329_initial_schemaDownSql() (*asset, error) {
+	bytes, err := _1565341329_initial_schemaDownSqlBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "1565341329_initial_schema.down.sql", size: 24, mode: os.FileMode(0644), modTime: time.Unix(1569335635, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0x20, 0x56, 0x1a, 0x0, 0xc5, 0x81, 0xb3, 0xeb, 0x2a, 0xae, 0xed, 0xbb, 0x68, 0x51, 0x68, 0xc7, 0xe3, 0x31, 0xe, 0x1, 0x3e, 0xd2, 0x85, 0x9e, 0x6d, 0x55, 0xad, 0x55, 0xd6, 0x2f, 0x29, 0xca}}
+	return a, nil
+}
+
+var __1565341329_initial_schemaUpSql = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x7c\x8f\xc1\x8a\x83\x30\x14\x45\xf7\xf9\x8a\xbb\x54\xf0\x0f\x5c\xe9\x4c\x18\x64\xd2\x58\x42\x0a\x75\x15\xc4\x3c\xac\x0b\x35\x98\x58\xda\xbf\x2f\xb4\x15\xa5\x60\xb7\xf7\x1c\x1e\xef\xfc\x28\x9e\x69\x0e\x9d\xe5\x82\xa3\xbf\x5a\x6f\x7c\xa8\x03\x79\x44\x0c\x00\xc2\xdd\x11\x0a\xa9\xf9\x1f\x57\x90\xa5\x86\x3c\x09\x91\x3c\x91\xa7\xc1\x9a\x66\x9c\x87\xf0\x4d\x20\x37\x36\x97\x1d\xa1\x9d\xc6\xd9\x99\xce\x22\x17\x65\xfe\x9a\x1c\xd1\xb4\x2c\x1f\x76\x4f\xde\xd7\x2d\xed\xd0\xa3\x2a\x0e\x99\xaa\xf0\xcf\x2b\x44\xab\x9a\x2c\x17\x63\x16\xa7\x8c\xbd\x6b\x0b\xf9\xcb\xcf\xe8\xec\xcd\x6c\x7e\x2c\xe5\xb6\x3f\x5a\x49\x9c\xb2\x47\x00\x00\x00\xff\xff\x5e\xe5\x72\x74\x26\x01\x00\x00")
+
+func _1565341329_initial_schemaUpSqlBytes() ([]byte, error) {
+	return bindataRead(
+		__1565341329_initial_schemaUpSql,
+		"1565341329_initial_schema.up.sql",
+	)
+}
+
+func _1565341329_initial_schemaUpSql() (*asset, error) {
+	bytes, err := _1565341329_initial_schemaUpSqlBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "1565341329_initial_schema.up.sql", size: 294, mode: os.FileMode(0644), modTime: time.Unix(1569335635, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0x3e, 0xa5, 0x37, 0x9d, 0x3f, 0xf3, 0xc9, 0xc8, 0x12, 0x74, 0x79, 0x74, 0xff, 0xfd, 0xb1, 0x5f, 0x13, 0xaf, 0xf2, 0x50, 0x14, 0x9f, 0xdf, 0xc8, 0xc5, 0xa7, 0xc3, 0xf5, 0xa4, 0x8e, 0x8a, 0xf6}}
+	return a, nil
+}
+
+var _docGo = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x84\x8f\xbb\x6e\xc3\x30\x0c\x45\x77\x7f\xc5\x45\x96\x2c\xb5\xb4\x74\xea\xd6\xb1\x7b\x7f\x80\x91\x68\x89\x88\x1e\xae\x48\xe7\xf1\xf7\x85\xd3\x02\xcd\xd6\xf5\x00\xe7\xf0\xd2\x7b\x7c\x66\x51\x2c\x52\x18\xa2\x68\x1c\x58\x95\xc6\x1d\x27\x0e\xb4\x29\xe3\x90\xc4\xf2\x76\x72\xa1\x57\xaf\x46\xb6\xe9\x2c\xd5\x57\x49\x83\x8c\xfd\xe5\xf5\x30\x79\x8f\x40\xed\x68\xc8\xd4\x62\xe1\x47\x4b\xa1\x46\xc3\xa4\x25\x5c\xc5\x32\x08\xeb\xe0\x45\x6e\x0e\xef\x86\xc2\xa4\x06\xcb\x64\x47\x85\x65\x46\x20\xe5\x3d\xb3\xf4\x81\xd4\xe7\x93\xb4\x48\x46\x6e\x47\x1f\xcb\x13\xd9\x17\x06\x2a\x85\x23\x96\xd1\xeb\xc3\x55\xaa\x8c\x28\x83\x83\xf5\x71\x7f\x01\xa9\xb2\xa1\x51\x65\xdd\xfd\x4c\x17\x46\xeb\xbf\xe7\x41\x2d\xfe\xff\x11\xae\x7d\x9c\x15\xa4\xe0\xdb\xca\xc1\x38\xba\x69\x5a\x29\x9c\x29\x31\xf4\xab\x88\xf1\x34\x79\x9f\xfa\x5b\xe2\xc6\xbb\xf5\xbc\x71\x5e\xcf\x09\x3f\x35\xe9\x4d\x31\x77\x38\xe7\xff\x80\x4b\x1d\x6e\xfa\x0e\x00\x00\xff\xff\x9d\x60\x3d\x88\x79\x01\x00\x00")
+
+func docGoBytes() ([]byte, error) {
+	return bindataRead(
+		_docGo,
+		"doc.go",
+	)
+}
+
+func docGo() (*asset, error) {
+	bytes, err := docGoBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "doc.go", size: 377, mode: os.FileMode(0644), modTime: time.Unix(1569335635, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0xef, 0xaf, 0xdf, 0xcf, 0x65, 0xae, 0x19, 0xfc, 0x9d, 0x29, 0xc1, 0x91, 0xaf, 0xb5, 0xd5, 0xb1, 0x56, 0xf3, 0xee, 0xa8, 0xba, 0x13, 0x65, 0xdb, 0xab, 0xcf, 0x4e, 0xac, 0x92, 0xe9, 0x60, 0xf1}}
+	return a, nil
+}
+
+// Asset loads and returns the asset for the given name.
+// It returns an error if the asset could not be found or
+// could not be loaded.
+func Asset(name string) ([]byte, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return nil, fmt.Errorf("Asset %s can't read by error: %v", name, err)
+		}
+		return a.bytes, nil
+	}
+	return nil, fmt.Errorf("Asset %s not found", name)
+}
+
+// AssetString returns the asset contents as a string (instead of a []byte).
+func AssetString(name string) (string, error) {
+	data, err := Asset(name)
+	return string(data), err
+}
+
+// MustAsset is like Asset but panics when Asset would return an error.
+// It simplifies safe initialization of global variables.
+func MustAsset(name string) []byte {
+	a, err := Asset(name)
+	if err != nil {
+		panic("asset: Asset(" + name + "): " + err.Error())
+	}
+
+	return a
+}
+
+// MustAssetString is like AssetString but panics when Asset would return an
+// error. It simplifies safe initialization of global variables.
+func MustAssetString(name string) string {
+	return string(MustAsset(name))
+}
+
+// AssetInfo loads and returns the asset info for the given name.
+// It returns an error if the asset could not be found or
+// could not be loaded.
+func AssetInfo(name string) (os.FileInfo, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return nil, fmt.Errorf("AssetInfo %s can't read by error: %v", name, err)
+		}
+		return a.info, nil
+	}
+	return nil, fmt.Errorf("AssetInfo %s not found", name)
+}
+
+// AssetDigest returns the digest of the file with the given name. It returns an
+// error if the asset could not be found or the digest could not be loaded.
+func AssetDigest(name string) ([sha256.Size]byte, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return [sha256.Size]byte{}, fmt.Errorf("AssetDigest %s can't read by error: %v", name, err)
+		}
+		return a.digest, nil
+	}
+	return [sha256.Size]byte{}, fmt.Errorf("AssetDigest %s not found", name)
+}
+
+// Digests returns a map of all known files and their checksums.
+func Digests() (map[string][sha256.Size]byte, error) {
+	mp := make(map[string][sha256.Size]byte, len(_bindata))
+	for name := range _bindata {
+		a, err := _bindata[name]()
+		if err != nil {
+			return nil, err
+		}
+		mp[name] = a.digest
+	}
+	return mp, nil
+}
+
+// AssetNames returns the names of the assets.
+func AssetNames() []string {
+	names := make([]string, 0, len(_bindata))
+	for name := range _bindata {
+		names = append(names, name)
+	}
+	return names
+}
+
+// _bindata is a table, holding each asset generator, mapped to its name.
+var _bindata = map[string]func() (*asset, error){
+	"1565341329_initial_schema.down.sql": _1565341329_initial_schemaDownSql,
+	"1565341329_initial_schema.up.sql":   _1565341329_initial_schemaUpSql,
+	"doc.go":                             docGo,
+}
+
+// AssetDir returns the file names below a certain
+// directory embedded in the file by go-bindata.
+// For example if you run go-bindata on data/... and data contains the
+// following hierarchy:
+//     data/
+//       foo.txt
+//       img/
+//         a.png
+//         b.png
+// then AssetDir("data") would return []string{"foo.txt", "img"},
+// AssetDir("data/img") would return []string{"a.png", "b.png"},
+// AssetDir("foo.txt") and AssetDir("notexist") would return an error, and
+// AssetDir("") will return []string{"data"}.
+func AssetDir(name string) ([]string, error) {
+	node := _bintree
+	if len(name) != 0 {
+		canonicalName := strings.Replace(name, "\\", "/", -1)
+		pathList := strings.Split(canonicalName, "/")
+		for _, p := range pathList {
+			node = node.Children[p]
+			if node == nil {
+				return nil, fmt.Errorf("Asset %s not found", name)
+			}
+		}
+	}
+	if node.Func != nil {
+		return nil, fmt.Errorf("Asset %s not found", name)
+	}
+	rv := make([]string, 0, len(node.Children))
+	for childName := range node.Children {
+		rv = append(rv, childName)
+	}
+	return rv, nil
+}
+
+type bintree struct {
+	Func     func() (*asset, error)
+	Children map[string]*bintree
+}
+
+var _bintree = &bintree{nil, map[string]*bintree{
+	"1565341329_initial_schema.down.sql": &bintree{_1565341329_initial_schemaDownSql, map[string]*bintree{}},
+	"1565341329_initial_schema.up.sql":   &bintree{_1565341329_initial_schemaUpSql, map[string]*bintree{}},
+	"doc.go":                             &bintree{docGo, map[string]*bintree{}},
+}}
+
+// RestoreAsset restores an asset under the given directory.
+func RestoreAsset(dir, name string) error {
+	data, err := Asset(name)
+	if err != nil {
+		return err
+	}
+	info, err := AssetInfo(name)
+	if err != nil {
+		return err
+	}
+	err = os.MkdirAll(_filePath(dir, filepath.Dir(name)), os.FileMode(0755))
+	if err != nil {
+		return err
+	}
+	err = ioutil.WriteFile(_filePath(dir, name), data, info.Mode())
+	if err != nil {
+		return err
+	}
+	return os.Chtimes(_filePath(dir, name), info.ModTime(), info.ModTime())
+}
+
+// RestoreAssets restores an asset under the given directory recursively.
+func RestoreAssets(dir, name string) error {
+	children, err := AssetDir(name)
+	// File
+	if err != nil {
+		return RestoreAsset(dir, name)
+	}
+	// Dir
+	for _, child := range children {
+		err = RestoreAssets(dir, filepath.Join(name, child))
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func _filePath(dir, name string) string {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	return filepath.Join(append([]string{dir}, strings.Split(canonicalName, "/")...)...)
+}

state/migrations/sqlite/1565341329_initial_schema.down.sql

@@ -0,0 +1 @@
+DROP TABLE mvds_states;

state/migrations/sqlite/1565341329_initial_schema.up.sql

@@ -0,0 +1,11 @@
+CREATE TABLE mvds_states (
+    type INTEGER NOT NULL,
+    send_count INTEGER NOT NULL,
+    send_epoch INTEGER NOT NULL,
+    group_id BLOB,
+    peer_id BLOB NOT NULL,
+    message_id BLOB NOT NULL,
+    PRIMARY KEY (message_id, peer_id)
+);
+
+CREATE INDEX idx_send_epoch ON mvds_states(send_epoch);

state/migrations/sqlite/doc.go

@@ -0,0 +1,9 @@
+// This file is necessary because "github.com/status-im/migrate/v4"
+// can't handle files starting with a prefix. At least that's the case
+// for go-bindata.
+// If go-bindata is called from the same directory, asset names
+// have no prefix and "github.com/status-im/migrate/v4" works as expected.
+
+package sqlite
+
+//go:generate go-bindata -pkg migrations -o ../migrations.go .

state/peerid.go

@@ -1,3 +1,4 @@
 package state
 
+// PeerID is the ID for a specific peer.
 type PeerID [65]byte

state/state.go

@@ -1,6 +1,7 @@
 // Package state contains everything related to the synchronization state for MVDS.
 package state
 
+// RecordType is the type for a specific record, either `OFFER`, `REQUEST` or `MESSAGE`.
 type RecordType int
 
 const (
@@ -9,15 +10,20 @@ const (
 	MESSAGE
 )
 
+// State is a struct used to store a records [state](https://github.com/status-im/bigbrother-specs/blob/master/data_sync/mvds.md#state).
 type State struct {
 	Type      RecordType
 	SendCount uint64
 	SendEpoch int64
+	// GroupID is optional, thus nullable
+	GroupID   *GroupID
+	PeerID    PeerID
+	MessageID MessageID
 }
 
 type SyncState interface {
-	Get(group GroupID, id MessageID, peer PeerID) (State, error)
-	Set(group GroupID, id MessageID, peer PeerID, newState State) error
-	Remove(group GroupID, id MessageID, peer PeerID) error
-	Map(epoch int64, process func(GroupID, MessageID, PeerID, State) State) error
+	Add(newState State) error
+	Remove(id MessageID, peer PeerID) error
+	All(epoch int64) ([]State, error)
+	Map(epoch int64, process func(State) State) error
 }

state/state_memory.go

@@ -7,61 +7,54 @@ import (
 type memorySyncState struct {
 	sync.Mutex
 
-	state map[GroupID]map[MessageID]map[PeerID]State
+	state []State
 }
 
-func NewSyncState() *memorySyncState {
-	return &memorySyncState{
-		state: make(map[GroupID]map[MessageID]map[PeerID]State),
-	}
+func NewMemorySyncState() *memorySyncState {
+	return &memorySyncState{}
 }
 
-func (s *memorySyncState) Get(group GroupID, id MessageID, peer PeerID) (State, error) {
+func (s *memorySyncState) Add(newState State) error {
 	s.Lock()
 	defer s.Unlock()
 
-	state, _ := s.state[group][id][peer]
-	return state, nil
-}
+	s.state = append(s.state, newState)
 
-func (s *memorySyncState) Set(group GroupID, id MessageID, peer PeerID, newState State) error {
-	s.Lock()
-	defer s.Unlock()
-
-	if _, ok := s.state[group]; !ok {
-		s.state[group] = make(map[MessageID]map[PeerID]State)
-	}
-
-	if _, ok := s.state[group][id]; !ok {
-		s.state[group][id] = make(map[PeerID]State)
-	}
-
-	s.state[group][id][peer] = newState
 	return nil
 }
 
-func (s *memorySyncState) Remove(group GroupID, id MessageID, peer PeerID) error {
+func (s *memorySyncState) Remove(id MessageID, peer PeerID) error {
 	s.Lock()
 	defer s.Unlock()
+	var newState []State
+
+	for _, state := range s.state {
+		if state.MessageID != id || state.PeerID != peer {
+			newState = append(newState, state)
+		}
+	}
+
+	s.state = newState
 
-	delete(s.state[group][id], peer)
 	return nil
 }
 
-func (s *memorySyncState) Map(epoch int64, process func(GroupID, MessageID, PeerID, State) State) error {
+func (s *memorySyncState) All(_ int64) ([]State, error) {
+	s.Lock()
+	defer s.Unlock()
+	return s.state, nil
+}
+
+func (s *memorySyncState) Map(epoch int64, process func(State) State) error {
 	s.Lock()
 	defer s.Unlock()
 
-	for group, syncstate := range s.state {
-		for id, peers := range syncstate {
-			for peer, state := range peers {
-				if state.SendEpoch < epoch {
+	for i, state := range s.state {
+		if state.SendEpoch > epoch {
 			continue
 		}
 
-				s.state[group][id][peer] = process(group, id, peer, state)
-			}
-		}
+		s.state[i] = process(state)
 	}
 
 	return nil

state/state_sqlite.go

@@ -0,0 +1,166 @@
+package state
+
+import (
+	"database/sql"
+	"errors"
+	"log"
+)
+
+var (
+	ErrStateNotFound = errors.New("state not found")
+)
+
+// Verify that SyncState interface is implemented.
+var _ SyncState = (*sqliteSyncState)(nil)
+
+type sqliteSyncState struct {
+	db *sql.DB
+}
+
+func NewPersistentSyncState(db *sql.DB) *sqliteSyncState {
+	return &sqliteSyncState{db: db}
+}
+
+func (p *sqliteSyncState) Add(newState State) error {
+	var groupIDBytes []byte
+	if newState.GroupID != nil {
+		groupIDBytes = newState.GroupID[:]
+	}
+
+	_, err := p.db.Exec(`
+		INSERT INTO mvds_states 
+			(type, send_count, send_epoch, group_id, peer_id, message_id) 
+		VALUES 
+			(?, ?, ?, ?, ?, ?)`,
+		newState.Type,
+		newState.SendCount,
+		newState.SendEpoch,
+		groupIDBytes,
+		newState.PeerID[:],
+		newState.MessageID[:],
+	)
+	return err
+}
+
+func (p *sqliteSyncState) Remove(messageID MessageID, peerID PeerID) error {
+	result, err := p.db.Exec(
+		`DELETE FROM mvds_states WHERE message_id = ? AND peer_id = ?`,
+		messageID[:],
+		peerID[:],
+	)
+	if err != nil {
+		return err
+	}
+	if n, err := result.RowsAffected(); err != nil {
+		return err
+	} else if n == 0 {
+		return ErrStateNotFound
+	}
+	return nil
+}
+
+func (p *sqliteSyncState) All(epoch int64) ([]State, error) {
+	var result []State
+
+	rows, err := p.db.Query(`
+		SELECT 
+			type, send_count, send_epoch, group_id, peer_id, message_id 
+		FROM
+			mvds_states
+		WHERE
+			send_epoch <= ?
+	`, epoch)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var (
+			state                      State
+			groupID, peerID, messageID []byte
+		)
+		err := rows.Scan(
+			&state.Type,
+			&state.SendCount,
+			&state.SendEpoch,
+			&groupID,
+			&peerID,
+			&messageID,
+		)
+		if err != nil {
+			return nil, err
+		}
+		if len(groupID) > 0 {
+			val := GroupID{}
+			copy(val[:], groupID)
+			state.GroupID = &val
+		}
+		copy(state.PeerID[:], peerID)
+		copy(state.MessageID[:], messageID)
+
+		result = append(result, state)
+	}
+
+	return result, nil
+}
+
+func (p *sqliteSyncState) Map(epoch int64, process func(State) State) error {
+	states, err := p.All(epoch)
+	if err != nil {
+		return err
+	}
+
+	var updated []State
+
+	for _, state := range states {
+		if err := invariant(state.SendEpoch <= epoch, "invalid state provided to process"); err != nil {
+			log.Printf("%v", err)
+			continue
+		}
+		newState := process(state)
+		if newState != state {
+			updated = append(updated, newState)
+		}
+	}
+
+	if len(updated) == 0 {
+		return nil
+	}
+
+	tx, err := p.db.Begin()
+	if err != nil {
+		return err
+	}
+	for _, state := range updated {
+		if err := updateInTx(tx, state); err != nil {
+			_ = tx.Rollback()
+			return err
+		}
+	}
+	return tx.Commit()
+}
+
+func updateInTx(tx *sql.Tx, state State) error {
+	_, err := tx.Exec(`
+		UPDATE mvds_states
+		SET 
+			 send_count = ?,
+			 send_epoch = ?
+		WHERE
+			message_id = ? AND 
+			peer_id = ?
+		`,
+		state.SendCount,
+		state.SendEpoch,
+		state.MessageID[:],
+		state.PeerID[:],
+	)
+	return err
+}
+
+func invariant(cond bool, message string) error {
+	if !cond {
+		return errors.New(message)
+	}
+	return nil
+}

state/state_sqlite_test.go

@@ -0,0 +1,56 @@
+package state
+
+import (
+	"io/ioutil"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/vacp2p/mvds/persistenceutil"
+	"github.com/vacp2p/mvds/state/migrations"
+)
+
+func TestPersistentSyncState(t *testing.T) {
+	tmpFile, err := ioutil.TempFile("", "")
+	require.NoError(t, err)
+	db, err := persistenceutil.Open(tmpFile.Name(), "", persistenceutil.MigrationConfig{
+		AssetNames:  migrations.AssetNames(),
+		AssetGetter: migrations.Asset,
+	})
+	require.NoError(t, err)
+	p := NewPersistentSyncState(db)
+
+	stateWithoutGroupID := State{
+		Type:      OFFER,
+		SendCount: 1,
+		SendEpoch: 1,
+		GroupID:   nil,
+		PeerID:    PeerID{0x01},
+		MessageID: MessageID{0xaa},
+	}
+	err = p.Add(stateWithoutGroupID)
+	require.NoError(t, err)
+
+	stateWithGroupID := stateWithoutGroupID
+	stateWithGroupID.GroupID = &GroupID{0x01}
+	stateWithGroupID.MessageID = MessageID{0xbb}
+	err = p.Add(stateWithGroupID)
+	require.NoError(t, err)
+
+	// Getting states for the old epoch.
+	allStates, err := p.All(0)
+	require.NoError(t, err)
+	require.Nil(t, allStates)
+
+	// Getting states for the current epoch.
+	allStates, err = p.All(1)
+	require.NoError(t, err)
+	require.Equal(t, []State{stateWithoutGroupID, stateWithGroupID}, allStates)
+	require.Nil(t, allStates[0].GroupID)
+	require.EqualValues(t, &GroupID{0x01}, allStates[1].GroupID)
+
+	err = p.Remove(stateWithoutGroupID.MessageID, stateWithoutGroupID.PeerID)
+	require.NoError(t, err)
+	// remove non-existing row
+	err = p.Remove(MessageID{0xff}, PeerID{0xff})
+	require.EqualError(t, err, "state not found")
+}

state/sync_types.go

@@ -2,3 +2,17 @@ package state
 
 type MessageID [32]byte
 type GroupID [32]byte
+
+// ToMessageID converts a byte array to a MessageID.
+func ToMessageID(b []byte) MessageID {
+	var id MessageID
+	copy(id[:], b)
+	return id
+}
+
+// ToGroupID converts a byte array to a GroupID.
+func ToGroupID(b []byte) GroupID {
+	var id GroupID
+	copy(id[:], b)
+	return id
+}

store/messagestore.go

@@ -2,12 +2,13 @@
 package store
 
 import (
-	"github.com/status-im/mvds/protobuf"
-	"github.com/status-im/mvds/state"
+	"github.com/vacp2p/mvds/protobuf"
+	"github.com/vacp2p/mvds/state"
 )
 
 type MessageStore interface {
-	Has(id state.MessageID) bool
-	Get(id state.MessageID) (protobuf.Message, error)
-	Add(message protobuf.Message) error
+	Has(id state.MessageID) (bool, error)
+	Get(id state.MessageID) (*protobuf.Message, error)
+	Add(message *protobuf.Message) error
+	GetMessagesWithoutChildren(id state.GroupID) ([]state.MessageID, error)
 }

store/messagestore_dummy.go

@@ -1,44 +0,0 @@
-package store
-
-import (
-	"errors"
-	"sync"
-
-	"github.com/status-im/mvds/protobuf"
-	"github.com/status-im/mvds/state"
-)
-
-type DummyStore struct {
-	sync.Mutex
-	ms map[state.MessageID]protobuf.Message
-}
-
-func NewDummyStore() DummyStore {
-	return DummyStore{ms: make(map[state.MessageID]protobuf.Message)}
-}
-
-func (ds *DummyStore) Has(id state.MessageID) bool {
-	ds.Lock()
-	defer ds.Unlock()
-
-	_, ok := ds.ms[id]; return ok
-}
-
-func (ds *DummyStore) Get(id state.MessageID) (protobuf.Message, error) {
-	ds.Lock()
-	defer ds.Unlock()
-
-	m, ok := ds.ms[id]
-	if !ok {
-		return protobuf.Message{}, errors.New("message does not exist")
-	}
-
-	return m, nil
-}
-
-func (ds *DummyStore) Add(message protobuf.Message) error {
-	ds.Lock()
-	defer ds.Unlock()
-	ds.ms[message.ID()] = message
-	return nil
-}

store/messagestore_memory.go

@@ -0,0 +1,81 @@
+package store
+
+import (
+	"errors"
+	"sync"
+
+	"github.com/vacp2p/mvds/protobuf"
+	"github.com/vacp2p/mvds/state"
+)
+
+type memoryMessageStore struct {
+	sync.Mutex
+	ms map[state.MessageID]*protobuf.Message
+}
+
+func NewMemoryMessageStore() *memoryMessageStore {
+	return &memoryMessageStore{ms: make(map[state.MessageID]*protobuf.Message)}
+}
+
+func (ds *memoryMessageStore) Has(id state.MessageID) (bool, error) {
+	ds.Lock()
+	defer ds.Unlock()
+
+	_, ok := ds.ms[id]
+	return ok, nil
+}
+
+func (ds *memoryMessageStore) Get(id state.MessageID) (*protobuf.Message, error) {
+	ds.Lock()
+	defer ds.Unlock()
+
+	m, ok := ds.ms[id]
+	if !ok {
+		return nil, errors.New("message does not exist")
+	}
+
+	return m, nil
+}
+
+func (ds *memoryMessageStore) Add(message *protobuf.Message) error {
+	ds.Lock()
+	defer ds.Unlock()
+	ds.ms[message.ID()] = message
+	return nil
+}
+
+func (ds *memoryMessageStore) GetMessagesWithoutChildren(group state.GroupID) ([]state.MessageID, error) {
+	ds.Lock()
+	defer ds.Unlock()
+
+	hasChildren := make(map[state.MessageID]bool)
+
+	for id, msg := range ds.ms {
+		if state.ToGroupID(msg.GroupId) != group {
+			continue
+		}
+
+		if msg.Metadata != nil {
+			for _, parent := range msg.Metadata.Parents {
+				hasChildren[state.ToMessageID(parent)] = true
+			}
+		}
+
+		if hasChildren[id] {
+			continue
+		}
+
+		hasChildren[id] = false
+	}
+
+	msgs := make([]state.MessageID, 0)
+	for id, hasChildren := range hasChildren {
+		if hasChildren {
+			continue
+		}
+
+		msgs = append(msgs, id)
+	}
+
+	return msgs, nil
+}

store/messagestore_sqlite.go

@@ -0,0 +1,160 @@
+package store
+
+import (
+	"database/sql"
+	"errors"
+	"strings"
+
+	"github.com/vacp2p/mvds/state"
+
+	"github.com/vacp2p/mvds/protobuf"
+)
+
+var (
+	ErrMessageNotFound = errors.New("message not found")
+)
+
+type persistentMessageStore struct {
+	db *sql.DB
+}
+
+func NewPersistentMessageStore(db *sql.DB) *persistentMessageStore {
+	return &persistentMessageStore{db: db}
+}
+
+func (p *persistentMessageStore) Add(message *protobuf.Message) error {
+	id := message.ID()
+
+	tx, err := p.db.Begin()
+	if err != nil {
+		return err
+	}
+
+	_, err = tx.Exec(
+		`INSERT INTO mvds_messages (id, group_id, timestamp, body)
+		VALUES (?, ?, ?, ?)`,
+		id[:],
+		message.GroupId,
+		message.Timestamp,
+		message.Body,
+	)
+
+	if err != nil {
+		_ = tx.Rollback()
+		return err
+	}
+
+	if message.Metadata != nil && len(message.Metadata.Parents) > 0 {
+		var sb strings.Builder
+		sb.WriteString("INSERT INTO mvds_parents(message_id, parent_id) VALUES ")
+		var vals []interface{}
+
+		for _, row := range message.Metadata.Parents {
+			sb.WriteString("(?, ?),")
+			vals = append(vals, id[:], row[:])
+		}
+
+		query := sb.String()
+		stmt, err := tx.Prepare(query[0:len(query)-1])
+		if err != nil {
+			_ = tx.Rollback()
+			return err
+		}
+
+		_, err = stmt.Exec(vals...)
+		if err != nil {
+			_ = tx.Rollback()
+			return err
+		}
+	}
+
+	return tx.Commit()
+}
+
+func (p *persistentMessageStore) Get(id state.MessageID) (*protobuf.Message, error) {
+	var message protobuf.Message
+	row := p.db.QueryRow(
+		`SELECT group_id, timestamp, body FROM mvds_messages WHERE id = ?`,
+		id[:],
+	)
+	if err := row.Scan(
+		&message.GroupId,
+		&message.Timestamp,
+		&message.Body,
+	); err != nil {
+		return nil, err
+	}
+
+	message.Metadata = &protobuf.Metadata{Ephemeral: false}
+
+	rows, err := p.db.Query(`SELECT parent_id FROM mvds_parents WHERE message_id = ?`, id[:])
+	if err != nil {
+		return nil, err
+	}
+
+	defer rows.Close()
+
+	for rows.Next() {
+		var parent []byte
+		err := rows.Scan(&parent)
+		if err != nil {
+			return nil, err
+		}
+
+		message.Metadata.Parents = append(message.Metadata.Parents, parent)
+	}
+
+	err = rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
+	return &message, nil
+}
+
+func (p *persistentMessageStore) Has(id state.MessageID) (bool, error) {
+	var result bool
+	err := p.db.QueryRow(
+		`SELECT EXISTS(SELECT 1 FROM mvds_messages WHERE id = ?)`,
+		id[:],
+	).Scan(&result)
+	switch err {
+	case sql.ErrNoRows:
+		return false, ErrMessageNotFound
+	case nil:
+		return result, nil
+	default:
+		return false, err
+	}
+}
+
+func (p *persistentMessageStore) GetMessagesWithoutChildren(id state.GroupID) ([]state.MessageID, error) {
+	var result []state.MessageID
+	rows, err := p.db.Query(
+		`SELECT id FROM mvds_messages WHERE group_id = ? AND id NOT IN (SELECT parent_id FROM mvds_parents)`,
+		id[:],
+	)
+
+	if err != nil {
+		return nil, err
+	}
+
+	defer rows.Close()
+
+	for rows.Next() {
+		var parent []byte
+		err := rows.Scan(&parent)
+		if err != nil {
+			return nil, err
+		}
+
+		result = append(result, state.ToMessageID(parent))
+	}
+
+	err = rows.Err()
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}

store/messagestore_sqlite_test.go

@@ -0,0 +1,104 @@
+package store
+
+import (
+	"io/ioutil"
+	"math/rand"
+	"testing"
+	"time"
+
+	"github.com/vacp2p/mvds/state"
+
+	"github.com/stretchr/testify/require"
+	"github.com/vacp2p/mvds/persistenceutil"
+	"github.com/vacp2p/mvds/protobuf"
+	"github.com/vacp2p/mvds/store/migrations"
+)
+
+func TestPersistentMessageStore(t *testing.T) {
+	tmpFile, err := ioutil.TempFile("", "")
+	require.NoError(t, err)
+	db, err := persistenceutil.Open(tmpFile.Name(), "", persistenceutil.MigrationConfig{
+		AssetNames:  migrations.AssetNames(),
+		AssetGetter: migrations.Asset,
+	})
+	require.NoError(t, err)
+	p := NewPersistentMessageStore(db)
+
+	now := time.Now().Unix()
+	message := protobuf.Message{
+		GroupId:   []byte{0x01},
+		Timestamp: now,
+		Body:      []byte{0xaa, 0xbb, 0xcc},
+		Metadata: &protobuf.Metadata{Ephemeral: false, Parents: [][]byte{{0xaa, 0xbb, 0xcc}}},
+	}
+
+	err = p.Add(&message)
+	require.NoError(t, err)
+	// Adding the same message twice is not allowed.
+	err = p.Add(&message)
+	require.EqualError(t, err, "UNIQUE constraint failed: mvds_messages.id")
+	// Verify if saved.
+	exists, err := p.Has(message.ID())
+	require.NoError(t, err)
+	require.True(t, exists)
+	recvMessage, err := p.Get(message.ID())
+	require.NoError(t, err)
+	require.Equal(t, message, *recvMessage)
+
+	// Verify methods against non existing message.
+	recvMessage, err = p.Get(state.MessageID{0xff})
+	require.EqualError(t, err, "sql: no rows in result set")
+	require.Nil(t, recvMessage)
+	exists, err = p.Has(state.MessageID{0xff})
+	require.NoError(t, err)
+	require.False(t, exists)
+}
+
+func TestPersistentMessageStore_GetMessagesWithoutChildren(t *testing.T) {
+	tmpFile, err := ioutil.TempFile("", "")
+	require.NoError(t, err)
+	db, err := persistenceutil.Open(tmpFile.Name(), "", persistenceutil.MigrationConfig{
+		AssetNames:  migrations.AssetNames(),
+		AssetGetter: migrations.Asset,
+	})
+
+	require.NoError(t, err)
+	p := NewPersistentMessageStore(db)
+
+	group := groupId()
+
+	now := time.Now().Unix()
+	msg := &protobuf.Message{
+		GroupId:   group[:],
+		Timestamp: now,
+		Body:      []byte{0xaa, 0xbb, 0xcc},
+		Metadata: &protobuf.Metadata{Ephemeral: false, Parents: [][]byte{}},
+	}
+
+	err = p.Add(msg)
+	require.NoError(t, err)
+
+	id := msg.ID()
+
+	child := &protobuf.Message{
+		GroupId:   group[:],
+		Timestamp: now,
+		Body:      []byte{0xaa, 0xcc},
+		Metadata: &protobuf.Metadata{Ephemeral: false, Parents: [][]byte{id[:]}},
+	}
+
+	err = p.Add(child)
+	require.NoError(t, err)
+
+	msgs, err := p.GetMessagesWithoutChildren(group)
+	require.NoError(t, err)
+
+	if msgs[0] != child.ID() {
+		t.Errorf("not same \n expected %v \n actual: %v", msgs[0], child.ID())
+	}
+}
+
+func groupId() (id state.GroupID) {
+	_, _ = rand.Read(id[:])
+	return id
+}

store/migrations/migrations.go

@@ -0,0 +1,317 @@
+// Code generated by go-bindata. DO NOT EDIT.
+// sources:
+// 1572372377_initial_schema.down.sql (55B)
+// 1572372377_initial_schema.up.sql (365B)
+// doc.go (377B)
+
+package migrations
+
+import (
+	"bytes"
+	"compress/gzip"
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+func bindataRead(data []byte, name string) ([]byte, error) {
+	gz, err := gzip.NewReader(bytes.NewBuffer(data))
+	if err != nil {
+		return nil, fmt.Errorf("read %q: %v", name, err)
+	}
+
+	var buf bytes.Buffer
+	_, err = io.Copy(&buf, gz)
+	clErr := gz.Close()
+
+	if err != nil {
+		return nil, fmt.Errorf("read %q: %v", name, err)
+	}
+	if clErr != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+type asset struct {
+	bytes  []byte
+	info   os.FileInfo
+	digest [sha256.Size]byte
+}
+
+type bindataFileInfo struct {
+	name    string
+	size    int64
+	mode    os.FileMode
+	modTime time.Time
+}
+
+func (fi bindataFileInfo) Name() string {
+	return fi.name
+}
+func (fi bindataFileInfo) Size() int64 {
+	return fi.size
+}
+func (fi bindataFileInfo) Mode() os.FileMode {
+	return fi.mode
+}
+func (fi bindataFileInfo) ModTime() time.Time {
+	return fi.modTime
+}
+func (fi bindataFileInfo) IsDir() bool {
+	return false
+}
+func (fi bindataFileInfo) Sys() interface{} {
+	return nil
+}
+
+var __1572372377_initial_schemaDownSql = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x72\x71\xf5\x71\x0d\x71\x55\x08\x71\x74\xf2\x71\x55\xc8\x2d\x4b\x29\x8e\xcf\x4d\x2d\x2e\x4e\x4c\x4f\x2d\xb6\xe6\xc2\x94\x2b\x48\x2c\x4a\xcd\x2b\x29\xb6\xe6\x02\x04\x00\x00\xff\xff\xa9\xdd\x32\x20\x37\x00\x00\x00")
+
+func _1572372377_initial_schemaDownSqlBytes() ([]byte, error) {
+	return bindataRead(
+		__1572372377_initial_schemaDownSql,
+		"1572372377_initial_schema.down.sql",
+	)
+}
+
+func _1572372377_initial_schemaDownSql() (*asset, error) {
+	bytes, err := _1572372377_initial_schemaDownSqlBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "1572372377_initial_schema.down.sql", size: 55, mode: os.FileMode(0644), modTime: time.Unix(1572706379, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0xc1, 0x69, 0x72, 0x9f, 0x13, 0xdd, 0x23, 0x1b, 0xef, 0x2e, 0x95, 0x19, 0x42, 0xa3, 0x57, 0x8d, 0x77, 0x4, 0x73, 0xf6, 0x8a, 0xab, 0xad, 0xc1, 0xe6, 0xc7, 0x59, 0xbc, 0xee, 0x86, 0xce, 0x2f}}
+	return a, nil
+}
+
+var __1572372377_initial_schemaUpSql = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x64\x90\xbd\x4e\xc4\x30\x10\x84\x7b\x3f\xc5\x94\xb1\xc4\x1b\x50\x25\xc7\xde\xc9\xc2\xd8\xc8\x18\x89\xab\xa2\x20\x5b\x27\x17\x26\x51\x1c\x10\xbc\x3d\x72\x7e\xc8\x0f\xdb\x7e\x3b\xb3\x33\x7b\x32\x54\x5a\x82\x2d\x2b\x49\x88\x5f\x2e\xd5\xd1\xa7\xd4\xdc\x7c\x42\xc1\x00\x20\x38\xcc\x53\x49\x5d\xe1\xd9\x88\xa7\xd2\x5c\xf1\x48\xd7\xbb\x91\xdf\xfa\xf6\xb3\xab\xf3\xd6\xc8\x01\x28\x6d\xa1\x5e\xa5\x9c\xf8\x10\xa2\x4f\x43\x13\x3b\x08\x65\xe9\x42\xe6\xc0\xdf\x5b\xf7\xb3\xf1\xdf\xe8\x19\xbf\x67\x6c\xce\x27\xd4\x03\xbd\x21\xb8\xef\xfa\xef\x9e\x56\xfb\xbc\xc5\x42\xb2\x8c\xfd\xef\xd5\x35\xbd\xff\x18\x96\x5a\xb3\x2a\x1b\x8d\x77\xf7\xa1\xa6\xdd\xb5\xd5\x9e\x9e\xb5\x21\x71\x51\xf9\x07\x28\x56\x23\x0e\x43\x67\x32\xa4\x4e\xf4\x72\x7c\x65\x70\x9c\x71\xf6\x1b\x00\x00\xff\xff\xed\x46\xeb\x1a\x6d\x01\x00\x00")
+
+func _1572372377_initial_schemaUpSqlBytes() ([]byte, error) {
+	return bindataRead(
+		__1572372377_initial_schemaUpSql,
+		"1572372377_initial_schema.up.sql",
+	)
+}
+
+func _1572372377_initial_schemaUpSql() (*asset, error) {
+	bytes, err := _1572372377_initial_schemaUpSqlBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "1572372377_initial_schema.up.sql", size: 365, mode: os.FileMode(0644), modTime: time.Unix(1572895921, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0x9b, 0xb2, 0x13, 0xf6, 0x6c, 0xa8, 0xdb, 0xfb, 0xb5, 0x8d, 0xe3, 0xa9, 0x50, 0x67, 0xb, 0xe2, 0x53, 0x6b, 0x24, 0xde, 0x18, 0x19, 0xac, 0x39, 0x3f, 0x52, 0x3a, 0xe1, 0xb8, 0x91, 0x8d, 0xd0}}
+	return a, nil
+}
+
+var _docGo = []byte("\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\xff\x84\x8f\xbb\x6e\xc3\x30\x0c\x45\x77\x7f\xc5\x45\x96\x2c\xb5\xb4\x74\xea\xd6\xb1\x7b\x7f\x80\x91\x68\x89\x88\x1e\xae\x48\xe7\xf1\xf7\x85\xd3\x02\xcd\xd6\xf5\x00\xe7\xf0\xd2\x7b\x7c\x66\x51\x2c\x52\x18\xa2\x68\x1c\x58\x95\xc6\x1d\x27\x0e\xb4\x29\xe3\x90\xc4\xf2\x76\x72\xa1\x57\xaf\x46\xb6\xe9\x2c\xd5\x57\x49\x83\x8c\xfd\xe5\xf5\x30\x79\x8f\x40\xed\x68\xc8\xd4\x62\xe1\x47\x4b\xa1\x46\xc3\xa4\x25\x5c\xc5\x32\x08\xeb\xe0\x45\x6e\x0e\xef\x86\xc2\xa4\x06\xcb\x64\x47\x85\x65\x46\x20\xe5\x3d\xb3\xf4\x81\xd4\xe7\x93\xb4\x48\x46\x6e\x47\x1f\xcb\x13\xd9\x17\x06\x2a\x85\x23\x96\xd1\xeb\xc3\x55\xaa\x8c\x28\x83\x83\xf5\x71\x7f\x01\xa9\xb2\xa1\x51\x65\xdd\xfd\x4c\x17\x46\xeb\xbf\xe7\x41\x2d\xfe\xff\x11\xae\x7d\x9c\x15\xa4\xe0\xdb\xca\xc1\x38\xba\x69\x5a\x29\x9c\x29\x31\xf4\xab\x88\xf1\x34\x79\x9f\xfa\x5b\xe2\xc6\xbb\xf5\xbc\x71\x5e\xcf\x09\x3f\x35\xe9\x4d\x31\x77\x38\xe7\xff\x80\x4b\x1d\x6e\xfa\x0e\x00\x00\xff\xff\x9d\x60\x3d\x88\x79\x01\x00\x00")
+
+func docGoBytes() ([]byte, error) {
+	return bindataRead(
+		_docGo,
+		"doc.go",
+	)
+}
+
+func docGo() (*asset, error) {
+	bytes, err := docGoBytes()
+	if err != nil {
+		return nil, err
+	}
+
+	info := bindataFileInfo{name: "doc.go", size: 377, mode: os.FileMode(0644), modTime: time.Unix(1569335635, 0)}
+	a := &asset{bytes: bytes, info: info, digest: [32]uint8{0xef, 0xaf, 0xdf, 0xcf, 0x65, 0xae, 0x19, 0xfc, 0x9d, 0x29, 0xc1, 0x91, 0xaf, 0xb5, 0xd5, 0xb1, 0x56, 0xf3, 0xee, 0xa8, 0xba, 0x13, 0x65, 0xdb, 0xab, 0xcf, 0x4e, 0xac, 0x92, 0xe9, 0x60, 0xf1}}
+	return a, nil
+}
+
+// Asset loads and returns the asset for the given name.
+// It returns an error if the asset could not be found or
+// could not be loaded.
+func Asset(name string) ([]byte, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return nil, fmt.Errorf("Asset %s can't read by error: %v", name, err)
+		}
+		return a.bytes, nil
+	}
+	return nil, fmt.Errorf("Asset %s not found", name)
+}
+
+// AssetString returns the asset contents as a string (instead of a []byte).
+func AssetString(name string) (string, error) {
+	data, err := Asset(name)
+	return string(data), err
+}
+
+// MustAsset is like Asset but panics when Asset would return an error.
+// It simplifies safe initialization of global variables.
+func MustAsset(name string) []byte {
+	a, err := Asset(name)
+	if err != nil {
+		panic("asset: Asset(" + name + "): " + err.Error())
+	}
+
+	return a
+}
+
+// MustAssetString is like AssetString but panics when Asset would return an
+// error. It simplifies safe initialization of global variables.
+func MustAssetString(name string) string {
+	return string(MustAsset(name))
+}
+
+// AssetInfo loads and returns the asset info for the given name.
+// It returns an error if the asset could not be found or
+// could not be loaded.
+func AssetInfo(name string) (os.FileInfo, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return nil, fmt.Errorf("AssetInfo %s can't read by error: %v", name, err)
+		}
+		return a.info, nil
+	}
+	return nil, fmt.Errorf("AssetInfo %s not found", name)
+}
+
+// AssetDigest returns the digest of the file with the given name. It returns an
+// error if the asset could not be found or the digest could not be loaded.
+func AssetDigest(name string) ([sha256.Size]byte, error) {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	if f, ok := _bindata[canonicalName]; ok {
+		a, err := f()
+		if err != nil {
+			return [sha256.Size]byte{}, fmt.Errorf("AssetDigest %s can't read by error: %v", name, err)
+		}
+		return a.digest, nil
+	}
+	return [sha256.Size]byte{}, fmt.Errorf("AssetDigest %s not found", name)
+}
+
+// Digests returns a map of all known files and their checksums.
+func Digests() (map[string][sha256.Size]byte, error) {
+	mp := make(map[string][sha256.Size]byte, len(_bindata))
+	for name := range _bindata {
+		a, err := _bindata[name]()
+		if err != nil {
+			return nil, err
+		}
+		mp[name] = a.digest
+	}
+	return mp, nil
+}
+
+// AssetNames returns the names of the assets.
+func AssetNames() []string {
+	names := make([]string, 0, len(_bindata))
+	for name := range _bindata {
+		names = append(names, name)
+	}
+	return names
+}
+
+// _bindata is a table, holding each asset generator, mapped to its name.
+var _bindata = map[string]func() (*asset, error){
+	"1572372377_initial_schema.down.sql": _1572372377_initial_schemaDownSql,
+	"1572372377_initial_schema.up.sql":   _1572372377_initial_schemaUpSql,
+	"doc.go":                             docGo,
+}
+
+// AssetDir returns the file names below a certain
+// directory embedded in the file by go-bindata.
+// For example if you run go-bindata on data/... and data contains the
+// following hierarchy:
+//     data/
+//       foo.txt
+//       img/
+//         a.png
+//         b.png
+// then AssetDir("data") would return []string{"foo.txt", "img"},
+// AssetDir("data/img") would return []string{"a.png", "b.png"},
+// AssetDir("foo.txt") and AssetDir("notexist") would return an error, and
+// AssetDir("") will return []string{"data"}.
+func AssetDir(name string) ([]string, error) {
+	node := _bintree
+	if len(name) != 0 {
+		canonicalName := strings.Replace(name, "\\", "/", -1)
+		pathList := strings.Split(canonicalName, "/")
+		for _, p := range pathList {
+			node = node.Children[p]
+			if node == nil {
+				return nil, fmt.Errorf("Asset %s not found", name)
+			}
+		}
+	}
+	if node.Func != nil {
+		return nil, fmt.Errorf("Asset %s not found", name)
+	}
+	rv := make([]string, 0, len(node.Children))
+	for childName := range node.Children {
+		rv = append(rv, childName)
+	}
+	return rv, nil
+}
+
+type bintree struct {
+	Func     func() (*asset, error)
+	Children map[string]*bintree
+}
+
+var _bintree = &bintree{nil, map[string]*bintree{
+	"1572372377_initial_schema.down.sql": &bintree{_1572372377_initial_schemaDownSql, map[string]*bintree{}},
+	"1572372377_initial_schema.up.sql":   &bintree{_1572372377_initial_schemaUpSql, map[string]*bintree{}},
+	"doc.go":                             &bintree{docGo, map[string]*bintree{}},
+}}
+
+// RestoreAsset restores an asset under the given directory.
+func RestoreAsset(dir, name string) error {
+	data, err := Asset(name)
+	if err != nil {
+		return err
+	}
+	info, err := AssetInfo(name)
+	if err != nil {
+		return err
+	}
+	err = os.MkdirAll(_filePath(dir, filepath.Dir(name)), os.FileMode(0755))
+	if err != nil {
+		return err
+	}
+	err = ioutil.WriteFile(_filePath(dir, name), data, info.Mode())
+	if err != nil {
+		return err
+	}
+	return os.Chtimes(_filePath(dir, name), info.ModTime(), info.ModTime())
+}
+
+// RestoreAssets restores an asset under the given directory recursively.
+func RestoreAssets(dir, name string) error {
+	children, err := AssetDir(name)
+	// File
+	if err != nil {
+		return RestoreAsset(dir, name)
+	}
+	// Dir
+	for _, child := range children {
+		err = RestoreAssets(dir, filepath.Join(name, child))
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func _filePath(dir, name string) string {
+	canonicalName := strings.Replace(name, "\\", "/", -1)
+	return filepath.Join(append([]string{dir}, strings.Split(canonicalName, "/")...)...)
+}

store/migrations/sqlite/1572372377_initial_schema.down.sql

@@ -0,0 +1,2 @@
+DELETE TABLE mvds_messages;
+DELETE TABLE mvds_parents;

store/migrations/sqlite/1572372377_initial_schema.up.sql

@@ -0,0 +1,15 @@
+CREATE TABLE mvds_messages (
+    id        BLOB PRIMARY KEY,
+    group_id  BLOB    NOT NULL,
+    timestamp INTEGER NOT NULL,
+    body      BLOB    NOT NULL
+);
+
+CREATE INDEX idx_group_id ON mvds_messages(group_id);
+
+
+CREATE TABLE mvds_parents (
+    message_id BLOB NOT NULL,
+    parent_id  BLOB NOT NULL,
+    FOREIGN KEY (message_id) REFERENCES mvds_messages (id)
+)

store/migrations/sqlite/doc.go

@@ -0,0 +1,9 @@
+// This file is necessary because "github.com/status-im/migrate/v4"
+// can't handle files starting with a prefix. At least that's the case
+// for go-bindata.
+// If go-bindata is called from the same directory, asset names
+// have no prefix and "github.com/status-im/migrate/v4" works as expected.
+
+package sqlite
+
+//go:generate go-bindata -pkg migrations -o ../migrations.go .

transport/channel_transport.go

@@ -6,8 +6,8 @@ import (
 	"sync"
 	"time"
 
-	"github.com/status-im/mvds/protobuf"
-	"github.com/status-im/mvds/state"
+	"github.com/vacp2p/mvds/protobuf"
+	"github.com/vacp2p/mvds/state"
 )
 
 // ChannelTransport implements a basic MVDS transport using channels for basic testing purposes.
@@ -28,7 +28,7 @@ func NewChannelTransport(offline int, in <-chan Packet) *ChannelTransport {
 	}
 }
 
-func (t *ChannelTransport) AddOutput(id state.PeerID, c chan<-Packet) {
+func (t *ChannelTransport) AddOutput(id state.PeerID, c chan<- Packet) {
 	t.out[id] = c
 }
 
@@ -36,7 +36,7 @@ func (t *ChannelTransport) Watch() Packet {
 	return <-t.in
 }
 
-func (t *ChannelTransport) Send(group state.GroupID, sender state.PeerID, peer state.PeerID, payload protobuf.Payload) error {
+func (t *ChannelTransport) Send(sender state.PeerID, peer state.PeerID, payload protobuf.Payload) error {
 	// @todo we can do this better, we put node onlineness into a goroutine where we just stop the nodes for x seconds
 	// outside of this class
 	math.Seed(time.Now().UnixNano())
@@ -49,6 +49,6 @@ func (t *ChannelTransport) Send(group state.GroupID, sender state.PeerID, peer s
 		return errors.New("peer unknown")
 	}
 
-	c <- Packet{Group: group, Sender: sender, Payload: payload}
+	c <- Packet{Sender: sender, Payload: payload}
 	return nil
 }

transport/transport.go

@@ -2,12 +2,11 @@
 package transport
 
 import (
-	"github.com/status-im/mvds/protobuf"
-	"github.com/status-im/mvds/state"
+	"github.com/vacp2p/mvds/protobuf"
+	"github.com/vacp2p/mvds/state"
 )
 
 type Packet struct {
-	Group   state.GroupID
 	Sender  state.PeerID
 	Payload protobuf.Payload
 }
@@ -15,5 +14,5 @@ type Packet struct {
 // Transport defines an interface allowing for agnostic transport implementations.
 type Transport interface {
 	Watch() Packet
-	Send(group state.GroupID, sender state.PeerID, peer state.PeerID, payload protobuf.Payload) error
+	Send(sender state.PeerID, peer state.PeerID, payload protobuf.Payload) error
 }

vendor/github.com/davecgh/go-spew/LICENSE

@@ -0,0 +1,15 @@
+ISC License
+
+Copyright (c) 2012-2016 Dave Collins <dave@davec.name>
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

vendor/github.com/davecgh/go-spew/spew/bypass.go

@@ -0,0 +1,145 @@
+// Copyright (c) 2015-2016 Dave Collins <dave@davec.name>
+//
+// Permission to use, copy, modify, and distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+// NOTE: Due to the following build constraints, this file will only be compiled
+// when the code is not running on Google App Engine, compiled by GopherJS, and
+// "-tags safe" is not added to the go build command line.  The "disableunsafe"
+// tag is deprecated and thus should not be used.
+// Go versions prior to 1.4 are disabled because they use a different layout
+// for interfaces which make the implementation of unsafeReflectValue more complex.
+// +build !js,!appengine,!safe,!disableunsafe,go1.4
+
+package spew
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+const (
+	// UnsafeDisabled is a build-time constant which specifies whether or
+	// not access to the unsafe package is available.
+	UnsafeDisabled = false
+
+	// ptrSize is the size of a pointer on the current arch.
+	ptrSize = unsafe.Sizeof((*byte)(nil))
+)
+
+type flag uintptr
+
+var (
+	// flagRO indicates whether the value field of a reflect.Value
+	// is read-only.
+	flagRO flag
+
+	// flagAddr indicates whether the address of the reflect.Value's
+	// value may be taken.
+	flagAddr flag
+)
+
+// flagKindMask holds the bits that make up the kind
+// part of the flags field. In all the supported versions,
+// it is in the lower 5 bits.
+const flagKindMask = flag(0x1f)
+
+// Different versions of Go have used different
+// bit layouts for the flags type. This table
+// records the known combinations.
+var okFlags = []struct {
+	ro, addr flag
+}{{
+	// From Go 1.4 to 1.5
+	ro:   1 << 5,
+	addr: 1 << 7,
+}, {
+	// Up to Go tip.
+	ro:   1<<5 | 1<<6,
+	addr: 1 << 8,
+}}
+
+var flagValOffset = func() uintptr {
+	field, ok := reflect.TypeOf(reflect.Value{}).FieldByName("flag")
+	if !ok {
+		panic("reflect.Value has no flag field")
+	}
+	return field.Offset
+}()
+
+// flagField returns a pointer to the flag field of a reflect.Value.
+func flagField(v *reflect.Value) *flag {
+	return (*flag)(unsafe.Pointer(uintptr(unsafe.Pointer(v)) + flagValOffset))
+}
+
+// unsafeReflectValue converts the passed reflect.Value into a one that bypasses
+// the typical safety restrictions preventing access to unaddressable and
+// unexported data.  It works by digging the raw pointer to the underlying
+// value out of the protected value and generating a new unprotected (unsafe)
+// reflect.Value to it.
+//
+// This allows us to check for implementations of the Stringer and error
+// interfaces to be used for pretty printing ordinarily unaddressable and
+// inaccessible values such as unexported struct fields.
+func unsafeReflectValue(v reflect.Value) reflect.Value {
+	if !v.IsValid() || (v.CanInterface() && v.CanAddr()) {
+		return v
+	}
+	flagFieldPtr := flagField(&v)
+	*flagFieldPtr &^= flagRO
+	*flagFieldPtr |= flagAddr
+	return v
+}
+
+// Sanity checks against future reflect package changes
+// to the type or semantics of the Value.flag field.
+func init() {
+	field, ok := reflect.TypeOf(reflect.Value{}).FieldByName("flag")
+	if !ok {
+		panic("reflect.Value has no flag field")
+	}
+	if field.Type.Kind() != reflect.TypeOf(flag(0)).Kind() {
+		panic("reflect.Value flag field has changed kind")
+	}
+	type t0 int
+	var t struct {
+		A t0
+		// t0 will have flagEmbedRO set.
+		t0
+		// a will have flagStickyRO set
+		a t0
+	}
+	vA := reflect.ValueOf(t).FieldByName("A")
+	va := reflect.ValueOf(t).FieldByName("a")
+	vt0 := reflect.ValueOf(t).FieldByName("t0")
+
+	// Infer flagRO from the difference between the flags
+	// for the (otherwise identical) fields in t.
+	flagPublic := *flagField(&vA)
+	flagWithRO := *flagField(&va) | *flagField(&vt0)
+	flagRO = flagPublic ^ flagWithRO
+
+	// Infer flagAddr from the difference between a value
+	// taken from a pointer and not.
+	vPtrA := reflect.ValueOf(&t).Elem().FieldByName("A")
+	flagNoPtr := *flagField(&vA)
+	flagPtr := *flagField(&vPtrA)
+	flagAddr = flagNoPtr ^ flagPtr
+
+	// Check that the inferred flags tally with one of the known versions.
+	for _, f := range okFlags {
+		if flagRO == f.ro && flagAddr == f.addr {
+			return
+		}
+	}
+	panic("reflect.Value read-only flag has changed semantics")
+}

vendor/github.com/davecgh/go-spew/spew/bypasssafe.go

@@ -0,0 +1,38 @@
+// Copyright (c) 2015-2016 Dave Collins <dave@davec.name>
+//
+// Permission to use, copy, modify, and distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+// NOTE: Due to the following build constraints, this file will only be compiled
+// when the code is running on Google App Engine, compiled by GopherJS, or
+// "-tags safe" is added to the go build command line.  The "disableunsafe"
+// tag is deprecated and thus should not be used.
+// +build js appengine safe disableunsafe !go1.4
+
+package spew
+
+import "reflect"
+
+const (
+	// UnsafeDisabled is a build-time constant which specifies whether or
+	// not access to the unsafe package is available.
+	UnsafeDisabled = true
+)
+
+// unsafeReflectValue typically converts the passed reflect.Value into a one
+// that bypasses the typical safety restrictions preventing access to
+// unaddressable and unexported data.  However, doing this relies on access to
+// the unsafe package.  This is a stub version which simply returns the passed
+// reflect.Value when the unsafe package is not available.
+func unsafeReflectValue(v reflect.Value) reflect.Value {
+	return v
+}

vendor/github.com/davecgh/go-spew/spew/common.go

@@ -0,0 +1,341 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package spew
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"reflect"
+	"sort"
+	"strconv"
+)
+
+// Some constants in the form of bytes to avoid string overhead.  This mirrors
+// the technique used in the fmt package.
+var (
+	panicBytes            = []byte("(PANIC=")
+	plusBytes             = []byte("+")
+	iBytes                = []byte("i")
+	trueBytes             = []byte("true")
+	falseBytes            = []byte("false")
+	interfaceBytes        = []byte("(interface {})")
+	commaNewlineBytes     = []byte(",\n")
+	newlineBytes          = []byte("\n")
+	openBraceBytes        = []byte("{")
+	openBraceNewlineBytes = []byte("{\n")
+	closeBraceBytes       = []byte("}")
+	asteriskBytes         = []byte("*")
+	colonBytes            = []byte(":")
+	colonSpaceBytes       = []byte(": ")
+	openParenBytes        = []byte("(")
+	closeParenBytes       = []byte(")")
+	spaceBytes            = []byte(" ")
+	pointerChainBytes     = []byte("->")
+	nilAngleBytes         = []byte("<nil>")
+	maxNewlineBytes       = []byte("<max depth reached>\n")
+	maxShortBytes         = []byte("<max>")
+	circularBytes         = []byte("<already shown>")
+	circularShortBytes    = []byte("<shown>")
+	invalidAngleBytes     = []byte("<invalid>")
+	openBracketBytes      = []byte("[")
+	closeBracketBytes     = []byte("]")
+	percentBytes          = []byte("%")
+	precisionBytes        = []byte(".")
+	openAngleBytes        = []byte("<")
+	closeAngleBytes       = []byte(">")
+	openMapBytes          = []byte("map[")
+	closeMapBytes         = []byte("]")
+	lenEqualsBytes        = []byte("len=")
+	capEqualsBytes        = []byte("cap=")
+)
+
+// hexDigits is used to map a decimal value to a hex digit.
+var hexDigits = "0123456789abcdef"
+
+// catchPanic handles any panics that might occur during the handleMethods
+// calls.
+func catchPanic(w io.Writer, v reflect.Value) {
+	if err := recover(); err != nil {
+		w.Write(panicBytes)
+		fmt.Fprintf(w, "%v", err)
+		w.Write(closeParenBytes)
+	}
+}
+
+// handleMethods attempts to call the Error and String methods on the underlying
+// type the passed reflect.Value represents and outputes the result to Writer w.
+//
+// It handles panics in any called methods by catching and displaying the error
+// as the formatted value.
+func handleMethods(cs *ConfigState, w io.Writer, v reflect.Value) (handled bool) {
+	// We need an interface to check if the type implements the error or
+	// Stringer interface.  However, the reflect package won't give us an
+	// interface on certain things like unexported struct fields in order
+	// to enforce visibility rules.  We use unsafe, when it's available,
+	// to bypass these restrictions since this package does not mutate the
+	// values.
+	if !v.CanInterface() {
+		if UnsafeDisabled {
+			return false
+		}
+
+		v = unsafeReflectValue(v)
+	}
+
+	// Choose whether or not to do error and Stringer interface lookups against
+	// the base type or a pointer to the base type depending on settings.
+	// Technically calling one of these methods with a pointer receiver can
+	// mutate the value, however, types which choose to satisify an error or
+	// Stringer interface with a pointer receiver should not be mutating their
+	// state inside these interface methods.
+	if !cs.DisablePointerMethods && !UnsafeDisabled && !v.CanAddr() {
+		v = unsafeReflectValue(v)
+	}
+	if v.CanAddr() {
+		v = v.Addr()
+	}
+
+	// Is it an error or Stringer?
+	switch iface := v.Interface().(type) {
+	case error:
+		defer catchPanic(w, v)
+		if cs.ContinueOnMethod {
+			w.Write(openParenBytes)
+			w.Write([]byte(iface.Error()))
+			w.Write(closeParenBytes)
+			w.Write(spaceBytes)
+			return false
+		}
+
+		w.Write([]byte(iface.Error()))
+		return true
+
+	case fmt.Stringer:
+		defer catchPanic(w, v)
+		if cs.ContinueOnMethod {
+			w.Write(openParenBytes)
+			w.Write([]byte(iface.String()))
+			w.Write(closeParenBytes)
+			w.Write(spaceBytes)
+			return false
+		}
+		w.Write([]byte(iface.String()))
+		return true
+	}
+	return false
+}
+
+// printBool outputs a boolean value as true or false to Writer w.
+func printBool(w io.Writer, val bool) {
+	if val {
+		w.Write(trueBytes)
+	} else {
+		w.Write(falseBytes)
+	}
+}
+
+// printInt outputs a signed integer value to Writer w.
+func printInt(w io.Writer, val int64, base int) {
+	w.Write([]byte(strconv.FormatInt(val, base)))
+}
+
+// printUint outputs an unsigned integer value to Writer w.
+func printUint(w io.Writer, val uint64, base int) {
+	w.Write([]byte(strconv.FormatUint(val, base)))
+}
+
+// printFloat outputs a floating point value using the specified precision,
+// which is expected to be 32 or 64bit, to Writer w.
+func printFloat(w io.Writer, val float64, precision int) {
+	w.Write([]byte(strconv.FormatFloat(val, 'g', -1, precision)))
+}
+
+// printComplex outputs a complex value using the specified float precision
+// for the real and imaginary parts to Writer w.
+func printComplex(w io.Writer, c complex128, floatPrecision int) {
+	r := real(c)
+	w.Write(openParenBytes)
+	w.Write([]byte(strconv.FormatFloat(r, 'g', -1, floatPrecision)))
+	i := imag(c)
+	if i >= 0 {
+		w.Write(plusBytes)
+	}
+	w.Write([]byte(strconv.FormatFloat(i, 'g', -1, floatPrecision)))
+	w.Write(iBytes)
+	w.Write(closeParenBytes)
+}
+
+// printHexPtr outputs a uintptr formatted as hexadecimal with a leading '0x'
+// prefix to Writer w.
+func printHexPtr(w io.Writer, p uintptr) {
+	// Null pointer.
+	num := uint64(p)
+	if num == 0 {
+		w.Write(nilAngleBytes)
+		return
+	}
+
+	// Max uint64 is 16 bytes in hex + 2 bytes for '0x' prefix
+	buf := make([]byte, 18)
+
+	// It's simpler to construct the hex string right to left.
+	base := uint64(16)
+	i := len(buf) - 1
+	for num >= base {
+		buf[i] = hexDigits[num%base]
+		num /= base
+		i--
+	}
+	buf[i] = hexDigits[num]
+
+	// Add '0x' prefix.
+	i--
+	buf[i] = 'x'
+	i--
+	buf[i] = '0'
+
+	// Strip unused leading bytes.
+	buf = buf[i:]
+	w.Write(buf)
+}
+
+// valuesSorter implements sort.Interface to allow a slice of reflect.Value
+// elements to be sorted.
+type valuesSorter struct {
+	values  []reflect.Value
+	strings []string // either nil or same len and values
+	cs      *ConfigState
+}
+
+// newValuesSorter initializes a valuesSorter instance, which holds a set of
+// surrogate keys on which the data should be sorted.  It uses flags in
+// ConfigState to decide if and how to populate those surrogate keys.
+func newValuesSorter(values []reflect.Value, cs *ConfigState) sort.Interface {
+	vs := &valuesSorter{values: values, cs: cs}
+	if canSortSimply(vs.values[0].Kind()) {
+		return vs
+	}
+	if !cs.DisableMethods {
+		vs.strings = make([]string, len(values))
+		for i := range vs.values {
+			b := bytes.Buffer{}
+			if !handleMethods(cs, &b, vs.values[i]) {
+				vs.strings = nil
+				break
+			}
+			vs.strings[i] = b.String()
+		}
+	}
+	if vs.strings == nil && cs.SpewKeys {
+		vs.strings = make([]string, len(values))
+		for i := range vs.values {
+			vs.strings[i] = Sprintf("%#v", vs.values[i].Interface())
+		}
+	}
+	return vs
+}
+
+// canSortSimply tests whether a reflect.Kind is a primitive that can be sorted
+// directly, or whether it should be considered for sorting by surrogate keys
+// (if the ConfigState allows it).
+func canSortSimply(kind reflect.Kind) bool {
+	// This switch parallels valueSortLess, except for the default case.
+	switch kind {
+	case reflect.Bool:
+		return true
+	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
+		return true
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
+		return true
+	case reflect.Float32, reflect.Float64:
+		return true
+	case reflect.String:
+		return true
+	case reflect.Uintptr:
+		return true
+	case reflect.Array:
+		return true
+	}
+	return false
+}
+
+// Len returns the number of values in the slice.  It is part of the
+// sort.Interface implementation.
+func (s *valuesSorter) Len() int {
+	return len(s.values)
+}
+
+// Swap swaps the values at the passed indices.  It is part of the
+// sort.Interface implementation.
+func (s *valuesSorter) Swap(i, j int) {
+	s.values[i], s.values[j] = s.values[j], s.values[i]
+	if s.strings != nil {
+		s.strings[i], s.strings[j] = s.strings[j], s.strings[i]
+	}
+}
+
+// valueSortLess returns whether the first value should sort before the second
+// value.  It is used by valueSorter.Less as part of the sort.Interface
+// implementation.
+func valueSortLess(a, b reflect.Value) bool {
+	switch a.Kind() {
+	case reflect.Bool:
+		return !a.Bool() && b.Bool()
+	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
+		return a.Int() < b.Int()
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
+		return a.Uint() < b.Uint()
+	case reflect.Float32, reflect.Float64:
+		return a.Float() < b.Float()
+	case reflect.String:
+		return a.String() < b.String()
+	case reflect.Uintptr:
+		return a.Uint() < b.Uint()
+	case reflect.Array:
+		// Compare the contents of both arrays.
+		l := a.Len()
+		for i := 0; i < l; i++ {
+			av := a.Index(i)
+			bv := b.Index(i)
+			if av.Interface() == bv.Interface() {
+				continue
+			}
+			return valueSortLess(av, bv)
+		}
+	}
+	return a.String() < b.String()
+}
+
+// Less returns whether the value at index i should sort before the
+// value at index j.  It is part of the sort.Interface implementation.
+func (s *valuesSorter) Less(i, j int) bool {
+	if s.strings == nil {
+		return valueSortLess(s.values[i], s.values[j])
+	}
+	return s.strings[i] < s.strings[j]
+}
+
+// sortValues is a sort function that handles both native types and any type that
+// can be converted to error or Stringer.  Other inputs are sorted according to
+// their Value.String() value to ensure display stability.
+func sortValues(values []reflect.Value, cs *ConfigState) {
+	if len(values) == 0 {
+		return
+	}
+	sort.Sort(newValuesSorter(values, cs))
+}

vendor/github.com/davecgh/go-spew/spew/config.go

@@ -0,0 +1,306 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package spew
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+)
+
+// ConfigState houses the configuration options used by spew to format and
+// display values.  There is a global instance, Config, that is used to control
+// all top-level Formatter and Dump functionality.  Each ConfigState instance
+// provides methods equivalent to the top-level functions.
+//
+// The zero value for ConfigState provides no indentation.  You would typically
+// want to set it to a space or a tab.
+//
+// Alternatively, you can use NewDefaultConfig to get a ConfigState instance
+// with default settings.  See the documentation of NewDefaultConfig for default
+// values.
+type ConfigState struct {
+	// Indent specifies the string to use for each indentation level.  The
+	// global config instance that all top-level functions use set this to a
+	// single space by default.  If you would like more indentation, you might
+	// set this to a tab with "\t" or perhaps two spaces with "  ".
+	Indent string
+
+	// MaxDepth controls the maximum number of levels to descend into nested
+	// data structures.  The default, 0, means there is no limit.
+	//
+	// NOTE: Circular data structures are properly detected, so it is not
+	// necessary to set this value unless you specifically want to limit deeply
+	// nested data structures.
+	MaxDepth int
+
+	// DisableMethods specifies whether or not error and Stringer interfaces are
+	// invoked for types that implement them.
+	DisableMethods bool
+
+	// DisablePointerMethods specifies whether or not to check for and invoke
+	// error and Stringer interfaces on types which only accept a pointer
+	// receiver when the current type is not a pointer.
+	//
+	// NOTE: This might be an unsafe action since calling one of these methods
+	// with a pointer receiver could technically mutate the value, however,
+	// in practice, types which choose to satisify an error or Stringer
+	// interface with a pointer receiver should not be mutating their state
+	// inside these interface methods.  As a result, this option relies on
+	// access to the unsafe package, so it will not have any effect when
+	// running in environments without access to the unsafe package such as
+	// Google App Engine or with the "safe" build tag specified.
+	DisablePointerMethods bool
+
+	// DisablePointerAddresses specifies whether to disable the printing of
+	// pointer addresses. This is useful when diffing data structures in tests.
+	DisablePointerAddresses bool
+
+	// DisableCapacities specifies whether to disable the printing of capacities
+	// for arrays, slices, maps and channels. This is useful when diffing
+	// data structures in tests.
+	DisableCapacities bool
+
+	// ContinueOnMethod specifies whether or not recursion should continue once
+	// a custom error or Stringer interface is invoked.  The default, false,
+	// means it will print the results of invoking the custom error or Stringer
+	// interface and return immediately instead of continuing to recurse into
+	// the internals of the data type.
+	//
+	// NOTE: This flag does not have any effect if method invocation is disabled
+	// via the DisableMethods or DisablePointerMethods options.
+	ContinueOnMethod bool
+
+	// SortKeys specifies map keys should be sorted before being printed. Use
+	// this to have a more deterministic, diffable output.  Note that only
+	// native types (bool, int, uint, floats, uintptr and string) and types
+	// that support the error or Stringer interfaces (if methods are
+	// enabled) are supported, with other types sorted according to the
+	// reflect.Value.String() output which guarantees display stability.
+	SortKeys bool
+
+	// SpewKeys specifies that, as a last resort attempt, map keys should
+	// be spewed to strings and sorted by those strings.  This is only
+	// considered if SortKeys is true.
+	SpewKeys bool
+}
+
+// Config is the active configuration of the top-level functions.
+// The configuration can be changed by modifying the contents of spew.Config.
+var Config = ConfigState{Indent: " "}
+
+// Errorf is a wrapper for fmt.Errorf that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the formatted string as a value that satisfies error.  See NewFormatter
+// for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Errorf(format, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Errorf(format string, a ...interface{}) (err error) {
+	return fmt.Errorf(format, c.convertArgs(a)...)
+}
+
+// Fprint is a wrapper for fmt.Fprint that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprint(w, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Fprint(w io.Writer, a ...interface{}) (n int, err error) {
+	return fmt.Fprint(w, c.convertArgs(a)...)
+}
+
+// Fprintf is a wrapper for fmt.Fprintf that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprintf(w, format, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Fprintf(w io.Writer, format string, a ...interface{}) (n int, err error) {
+	return fmt.Fprintf(w, format, c.convertArgs(a)...)
+}
+
+// Fprintln is a wrapper for fmt.Fprintln that treats each argument as if it
+// passed with a Formatter interface returned by c.NewFormatter.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprintln(w, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Fprintln(w io.Writer, a ...interface{}) (n int, err error) {
+	return fmt.Fprintln(w, c.convertArgs(a)...)
+}
+
+// Print is a wrapper for fmt.Print that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Print(c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Print(a ...interface{}) (n int, err error) {
+	return fmt.Print(c.convertArgs(a)...)
+}
+
+// Printf is a wrapper for fmt.Printf that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Printf(format, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Printf(format string, a ...interface{}) (n int, err error) {
+	return fmt.Printf(format, c.convertArgs(a)...)
+}
+
+// Println is a wrapper for fmt.Println that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Println(c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Println(a ...interface{}) (n int, err error) {
+	return fmt.Println(c.convertArgs(a)...)
+}
+
+// Sprint is a wrapper for fmt.Sprint that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprint(c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Sprint(a ...interface{}) string {
+	return fmt.Sprint(c.convertArgs(a)...)
+}
+
+// Sprintf is a wrapper for fmt.Sprintf that treats each argument as if it were
+// passed with a Formatter interface returned by c.NewFormatter.  It returns
+// the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprintf(format, c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Sprintf(format string, a ...interface{}) string {
+	return fmt.Sprintf(format, c.convertArgs(a)...)
+}
+
+// Sprintln is a wrapper for fmt.Sprintln that treats each argument as if it
+// were passed with a Formatter interface returned by c.NewFormatter.  It
+// returns the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprintln(c.NewFormatter(a), c.NewFormatter(b))
+func (c *ConfigState) Sprintln(a ...interface{}) string {
+	return fmt.Sprintln(c.convertArgs(a)...)
+}
+
+/*
+NewFormatter returns a custom formatter that satisfies the fmt.Formatter
+interface.  As a result, it integrates cleanly with standard fmt package
+printing functions.  The formatter is useful for inline printing of smaller data
+types similar to the standard %v format specifier.
+
+The custom formatter only responds to the %v (most compact), %+v (adds pointer
+addresses), %#v (adds types), and %#+v (adds types and pointer addresses) verb
+combinations.  Any other verbs such as %x and %q will be sent to the the
+standard fmt package for formatting.  In addition, the custom formatter ignores
+the width and precision arguments (however they will still work on the format
+specifiers not handled by the custom formatter).
+
+Typically this function shouldn't be called directly.  It is much easier to make
+use of the custom formatter by calling one of the convenience functions such as
+c.Printf, c.Println, or c.Printf.
+*/
+func (c *ConfigState) NewFormatter(v interface{}) fmt.Formatter {
+	return newFormatter(c, v)
+}
+
+// Fdump formats and displays the passed arguments to io.Writer w.  It formats
+// exactly the same as Dump.
+func (c *ConfigState) Fdump(w io.Writer, a ...interface{}) {
+	fdump(c, w, a...)
+}
+
+/*
+Dump displays the passed parameters to standard out with newlines, customizable
+indentation, and additional debug information such as complete types and all
+pointer addresses used to indirect to the final value.  It provides the
+following features over the built-in printing facilities provided by the fmt
+package:
+
+	* Pointers are dereferenced and followed
+	* Circular data structures are detected and handled properly
+	* Custom Stringer/error interfaces are optionally invoked, including
+	  on unexported types
+	* Custom types which only implement the Stringer/error interfaces via
+	  a pointer receiver are optionally invoked when passing non-pointer
+	  variables
+	* Byte arrays and slices are dumped like the hexdump -C command which
+	  includes offsets, byte values in hex, and ASCII output
+
+The configuration options are controlled by modifying the public members
+of c.  See ConfigState for options documentation.
+
+See Fdump if you would prefer dumping to an arbitrary io.Writer or Sdump to
+get the formatted result as a string.
+*/
+func (c *ConfigState) Dump(a ...interface{}) {
+	fdump(c, os.Stdout, a...)
+}
+
+// Sdump returns a string with the passed arguments formatted exactly the same
+// as Dump.
+func (c *ConfigState) Sdump(a ...interface{}) string {
+	var buf bytes.Buffer
+	fdump(c, &buf, a...)
+	return buf.String()
+}
+
+// convertArgs accepts a slice of arguments and returns a slice of the same
+// length with each argument converted to a spew Formatter interface using
+// the ConfigState associated with s.
+func (c *ConfigState) convertArgs(args []interface{}) (formatters []interface{}) {
+	formatters = make([]interface{}, len(args))
+	for index, arg := range args {
+		formatters[index] = newFormatter(c, arg)
+	}
+	return formatters
+}
+
+// NewDefaultConfig returns a ConfigState with the following default settings.
+//
+// 	Indent: " "
+// 	MaxDepth: 0
+// 	DisableMethods: false
+// 	DisablePointerMethods: false
+// 	ContinueOnMethod: false
+// 	SortKeys: false
+func NewDefaultConfig() *ConfigState {
+	return &ConfigState{Indent: " "}
+}

vendor/github.com/davecgh/go-spew/spew/doc.go

@@ -0,0 +1,211 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+Package spew implements a deep pretty printer for Go data structures to aid in
+debugging.
+
+A quick overview of the additional features spew provides over the built-in
+printing facilities for Go data types are as follows:
+
+	* Pointers are dereferenced and followed
+	* Circular data structures are detected and handled properly
+	* Custom Stringer/error interfaces are optionally invoked, including
+	  on unexported types
+	* Custom types which only implement the Stringer/error interfaces via
+	  a pointer receiver are optionally invoked when passing non-pointer
+	  variables
+	* Byte arrays and slices are dumped like the hexdump -C command which
+	  includes offsets, byte values in hex, and ASCII output (only when using
+	  Dump style)
+
+There are two different approaches spew allows for dumping Go data structures:
+
+	* Dump style which prints with newlines, customizable indentation,
+	  and additional debug information such as types and all pointer addresses
+	  used to indirect to the final value
+	* A custom Formatter interface that integrates cleanly with the standard fmt
+	  package and replaces %v, %+v, %#v, and %#+v to provide inline printing
+	  similar to the default %v while providing the additional functionality
+	  outlined above and passing unsupported format verbs such as %x and %q
+	  along to fmt
+
+Quick Start
+
+This section demonstrates how to quickly get started with spew.  See the
+sections below for further details on formatting and configuration options.
+
+To dump a variable with full newlines, indentation, type, and pointer
+information use Dump, Fdump, or Sdump:
+	spew.Dump(myVar1, myVar2, ...)
+	spew.Fdump(someWriter, myVar1, myVar2, ...)
+	str := spew.Sdump(myVar1, myVar2, ...)
+
+Alternatively, if you would prefer to use format strings with a compacted inline
+printing style, use the convenience wrappers Printf, Fprintf, etc with
+%v (most compact), %+v (adds pointer addresses), %#v (adds types), or
+%#+v (adds types and pointer addresses):
+	spew.Printf("myVar1: %v -- myVar2: %+v", myVar1, myVar2)
+	spew.Printf("myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
+	spew.Fprintf(someWriter, "myVar1: %v -- myVar2: %+v", myVar1, myVar2)
+	spew.Fprintf(someWriter, "myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
+
+Configuration Options
+
+Configuration of spew is handled by fields in the ConfigState type.  For
+convenience, all of the top-level functions use a global state available
+via the spew.Config global.
+
+It is also possible to create a ConfigState instance that provides methods
+equivalent to the top-level functions.  This allows concurrent configuration
+options.  See the ConfigState documentation for more details.
+
+The following configuration options are available:
+	* Indent
+		String to use for each indentation level for Dump functions.
+		It is a single space by default.  A popular alternative is "\t".
+
+	* MaxDepth
+		Maximum number of levels to descend into nested data structures.
+		There is no limit by default.
+
+	* DisableMethods
+		Disables invocation of error and Stringer interface methods.
+		Method invocation is enabled by default.
+
+	* DisablePointerMethods
+		Disables invocation of error and Stringer interface methods on types
+		which only accept pointer receivers from non-pointer variables.
+		Pointer method invocation is enabled by default.
+
+	* DisablePointerAddresses
+		DisablePointerAddresses specifies whether to disable the printing of
+		pointer addresses. This is useful when diffing data structures in tests.
+
+	* DisableCapacities
+		DisableCapacities specifies whether to disable the printing of
+		capacities for arrays, slices, maps and channels. This is useful when
+		diffing data structures in tests.
+
+	* ContinueOnMethod
+		Enables recursion into types after invoking error and Stringer interface
+		methods. Recursion after method invocation is disabled by default.
+
+	* SortKeys
+		Specifies map keys should be sorted before being printed. Use
+		this to have a more deterministic, diffable output.  Note that
+		only native types (bool, int, uint, floats, uintptr and string)
+		and types which implement error or Stringer interfaces are
+		supported with other types sorted according to the
+		reflect.Value.String() output which guarantees display
+		stability.  Natural map order is used by default.
+
+	* SpewKeys
+		Specifies that, as a last resort attempt, map keys should be
+		spewed to strings and sorted by those strings.  This is only
+		considered if SortKeys is true.
+
+Dump Usage
+
+Simply call spew.Dump with a list of variables you want to dump:
+
+	spew.Dump(myVar1, myVar2, ...)
+
+You may also call spew.Fdump if you would prefer to output to an arbitrary
+io.Writer.  For example, to dump to standard error:
+
+	spew.Fdump(os.Stderr, myVar1, myVar2, ...)
+
+A third option is to call spew.Sdump to get the formatted output as a string:
+
+	str := spew.Sdump(myVar1, myVar2, ...)
+
+Sample Dump Output
+
+See the Dump example for details on the setup of the types and variables being
+shown here.
+
+	(main.Foo) {
+	 unexportedField: (*main.Bar)(0xf84002e210)({
+	  flag: (main.Flag) flagTwo,
+	  data: (uintptr) <nil>
+	 }),
+	 ExportedField: (map[interface {}]interface {}) (len=1) {
+	  (string) (len=3) "one": (bool) true
+	 }
+	}
+
+Byte (and uint8) arrays and slices are displayed uniquely like the hexdump -C
+command as shown.
+	([]uint8) (len=32 cap=32) {
+	 00000000  11 12 13 14 15 16 17 18  19 1a 1b 1c 1d 1e 1f 20  |............... |
+	 00000010  21 22 23 24 25 26 27 28  29 2a 2b 2c 2d 2e 2f 30  |!"#$%&'()*+,-./0|
+	 00000020  31 32                                             |12|
+	}
+
+Custom Formatter
+
+Spew provides a custom formatter that implements the fmt.Formatter interface
+so that it integrates cleanly with standard fmt package printing functions. The
+formatter is useful for inline printing of smaller data types similar to the
+standard %v format specifier.
+
+The custom formatter only responds to the %v (most compact), %+v (adds pointer
+addresses), %#v (adds types), or %#+v (adds types and pointer addresses) verb
+combinations.  Any other verbs such as %x and %q will be sent to the the
+standard fmt package for formatting.  In addition, the custom formatter ignores
+the width and precision arguments (however they will still work on the format
+specifiers not handled by the custom formatter).
+
+Custom Formatter Usage
+
+The simplest way to make use of the spew custom formatter is to call one of the
+convenience functions such as spew.Printf, spew.Println, or spew.Printf.  The
+functions have syntax you are most likely already familiar with:
+
+	spew.Printf("myVar1: %v -- myVar2: %+v", myVar1, myVar2)
+	spew.Printf("myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
+	spew.Println(myVar, myVar2)
+	spew.Fprintf(os.Stderr, "myVar1: %v -- myVar2: %+v", myVar1, myVar2)
+	spew.Fprintf(os.Stderr, "myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
+
+See the Index for the full list convenience functions.
+
+Sample Formatter Output
+
+Double pointer to a uint8:
+	  %v: <**>5
+	 %+v: <**>(0xf8400420d0->0xf8400420c8)5
+	 %#v: (**uint8)5
+	%#+v: (**uint8)(0xf8400420d0->0xf8400420c8)5
+
+Pointer to circular struct with a uint8 field and a pointer to itself:
+	  %v: <*>{1 <*><shown>}
+	 %+v: <*>(0xf84003e260){ui8:1 c:<*>(0xf84003e260)<shown>}
+	 %#v: (*main.circular){ui8:(uint8)1 c:(*main.circular)<shown>}
+	%#+v: (*main.circular)(0xf84003e260){ui8:(uint8)1 c:(*main.circular)(0xf84003e260)<shown>}
+
+See the Printf example for details on the setup of variables being shown
+here.
+
+Errors
+
+Since it is possible for custom Stringer/error interfaces to panic, spew
+detects them and handles them internally by printing the panic information
+inline with the output.  Since spew is intended to provide deep pretty printing
+capabilities on structures, it intentionally does not return any errors.
+*/
+package spew

vendor/github.com/davecgh/go-spew/spew/dump.go

@@ -0,0 +1,509 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package spew
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"reflect"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var (
+	// uint8Type is a reflect.Type representing a uint8.  It is used to
+	// convert cgo types to uint8 slices for hexdumping.
+	uint8Type = reflect.TypeOf(uint8(0))
+
+	// cCharRE is a regular expression that matches a cgo char.
+	// It is used to detect character arrays to hexdump them.
+	cCharRE = regexp.MustCompile(`^.*\._Ctype_char$`)
+
+	// cUnsignedCharRE is a regular expression that matches a cgo unsigned
+	// char.  It is used to detect unsigned character arrays to hexdump
+	// them.
+	cUnsignedCharRE = regexp.MustCompile(`^.*\._Ctype_unsignedchar$`)
+
+	// cUint8tCharRE is a regular expression that matches a cgo uint8_t.
+	// It is used to detect uint8_t arrays to hexdump them.
+	cUint8tCharRE = regexp.MustCompile(`^.*\._Ctype_uint8_t$`)
+)
+
+// dumpState contains information about the state of a dump operation.
+type dumpState struct {
+	w                io.Writer
+	depth            int
+	pointers         map[uintptr]int
+	ignoreNextType   bool
+	ignoreNextIndent bool
+	cs               *ConfigState
+}
+
+// indent performs indentation according to the depth level and cs.Indent
+// option.
+func (d *dumpState) indent() {
+	if d.ignoreNextIndent {
+		d.ignoreNextIndent = false
+		return
+	}
+	d.w.Write(bytes.Repeat([]byte(d.cs.Indent), d.depth))
+}
+
+// unpackValue returns values inside of non-nil interfaces when possible.
+// This is useful for data types like structs, arrays, slices, and maps which
+// can contain varying types packed inside an interface.
+func (d *dumpState) unpackValue(v reflect.Value) reflect.Value {
+	if v.Kind() == reflect.Interface && !v.IsNil() {
+		v = v.Elem()
+	}
+	return v
+}
+
+// dumpPtr handles formatting of pointers by indirecting them as necessary.
+func (d *dumpState) dumpPtr(v reflect.Value) {
+	// Remove pointers at or below the current depth from map used to detect
+	// circular refs.
+	for k, depth := range d.pointers {
+		if depth >= d.depth {
+			delete(d.pointers, k)
+		}
+	}
+
+	// Keep list of all dereferenced pointers to show later.
+	pointerChain := make([]uintptr, 0)
+
+	// Figure out how many levels of indirection there are by dereferencing
+	// pointers and unpacking interfaces down the chain while detecting circular
+	// references.
+	nilFound := false
+	cycleFound := false
+	indirects := 0
+	ve := v
+	for ve.Kind() == reflect.Ptr {
+		if ve.IsNil() {
+			nilFound = true
+			break
+		}
+		indirects++
+		addr := ve.Pointer()
+		pointerChain = append(pointerChain, addr)
+		if pd, ok := d.pointers[addr]; ok && pd < d.depth {
+			cycleFound = true
+			indirects--
+			break
+		}
+		d.pointers[addr] = d.depth
+
+		ve = ve.Elem()
+		if ve.Kind() == reflect.Interface {
+			if ve.IsNil() {
+				nilFound = true
+				break
+			}
+			ve = ve.Elem()
+		}
+	}
+
+	// Display type information.
+	d.w.Write(openParenBytes)
+	d.w.Write(bytes.Repeat(asteriskBytes, indirects))
+	d.w.Write([]byte(ve.Type().String()))
+	d.w.Write(closeParenBytes)
+
+	// Display pointer information.
+	if !d.cs.DisablePointerAddresses && len(pointerChain) > 0 {
+		d.w.Write(openParenBytes)
+		for i, addr := range pointerChain {
+			if i > 0 {
+				d.w.Write(pointerChainBytes)
+			}
+			printHexPtr(d.w, addr)
+		}
+		d.w.Write(closeParenBytes)
+	}
+
+	// Display dereferenced value.
+	d.w.Write(openParenBytes)
+	switch {
+	case nilFound:
+		d.w.Write(nilAngleBytes)
+
+	case cycleFound:
+		d.w.Write(circularBytes)
+
+	default:
+		d.ignoreNextType = true
+		d.dump(ve)
+	}
+	d.w.Write(closeParenBytes)
+}
+
+// dumpSlice handles formatting of arrays and slices.  Byte (uint8 under
+// reflection) arrays and slices are dumped in hexdump -C fashion.
+func (d *dumpState) dumpSlice(v reflect.Value) {
+	// Determine whether this type should be hex dumped or not.  Also,
+	// for types which should be hexdumped, try to use the underlying data
+	// first, then fall back to trying to convert them to a uint8 slice.
+	var buf []uint8
+	doConvert := false
+	doHexDump := false
+	numEntries := v.Len()
+	if numEntries > 0 {
+		vt := v.Index(0).Type()
+		vts := vt.String()
+		switch {
+		// C types that need to be converted.
+		case cCharRE.MatchString(vts):
+			fallthrough
+		case cUnsignedCharRE.MatchString(vts):
+			fallthrough
+		case cUint8tCharRE.MatchString(vts):
+			doConvert = true
+
+		// Try to use existing uint8 slices and fall back to converting
+		// and copying if that fails.
+		case vt.Kind() == reflect.Uint8:
+			// We need an addressable interface to convert the type
+			// to a byte slice.  However, the reflect package won't
+			// give us an interface on certain things like
+			// unexported struct fields in order to enforce
+			// visibility rules.  We use unsafe, when available, to
+			// bypass these restrictions since this package does not
+			// mutate the values.
+			vs := v
+			if !vs.CanInterface() || !vs.CanAddr() {
+				vs = unsafeReflectValue(vs)
+			}
+			if !UnsafeDisabled {
+				vs = vs.Slice(0, numEntries)
+
+				// Use the existing uint8 slice if it can be
+				// type asserted.
+				iface := vs.Interface()
+				if slice, ok := iface.([]uint8); ok {
+					buf = slice
+					doHexDump = true
+					break
+				}
+			}
+
+			// The underlying data needs to be converted if it can't
+			// be type asserted to a uint8 slice.
+			doConvert = true
+		}
+
+		// Copy and convert the underlying type if needed.
+		if doConvert && vt.ConvertibleTo(uint8Type) {
+			// Convert and copy each element into a uint8 byte
+			// slice.
+			buf = make([]uint8, numEntries)
+			for i := 0; i < numEntries; i++ {
+				vv := v.Index(i)
+				buf[i] = uint8(vv.Convert(uint8Type).Uint())
+			}
+			doHexDump = true
+		}
+	}
+
+	// Hexdump the entire slice as needed.
+	if doHexDump {
+		indent := strings.Repeat(d.cs.Indent, d.depth)
+		str := indent + hex.Dump(buf)
+		str = strings.Replace(str, "\n", "\n"+indent, -1)
+		str = strings.TrimRight(str, d.cs.Indent)
+		d.w.Write([]byte(str))
+		return
+	}
+
+	// Recursively call dump for each item.
+	for i := 0; i < numEntries; i++ {
+		d.dump(d.unpackValue(v.Index(i)))
+		if i < (numEntries - 1) {
+			d.w.Write(commaNewlineBytes)
+		} else {
+			d.w.Write(newlineBytes)
+		}
+	}
+}
+
+// dump is the main workhorse for dumping a value.  It uses the passed reflect
+// value to figure out what kind of object we are dealing with and formats it
+// appropriately.  It is a recursive function, however circular data structures
+// are detected and handled properly.
+func (d *dumpState) dump(v reflect.Value) {
+	// Handle invalid reflect values immediately.
+	kind := v.Kind()
+	if kind == reflect.Invalid {
+		d.w.Write(invalidAngleBytes)
+		return
+	}
+
+	// Handle pointers specially.
+	if kind == reflect.Ptr {
+		d.indent()
+		d.dumpPtr(v)
+		return
+	}
+
+	// Print type information unless already handled elsewhere.
+	if !d.ignoreNextType {
+		d.indent()
+		d.w.Write(openParenBytes)
+		d.w.Write([]byte(v.Type().String()))
+		d.w.Write(closeParenBytes)
+		d.w.Write(spaceBytes)
+	}
+	d.ignoreNextType = false
+
+	// Display length and capacity if the built-in len and cap functions
+	// work with the value's kind and the len/cap itself is non-zero.
+	valueLen, valueCap := 0, 0
+	switch v.Kind() {
+	case reflect.Array, reflect.Slice, reflect.Chan:
+		valueLen, valueCap = v.Len(), v.Cap()
+	case reflect.Map, reflect.String:
+		valueLen = v.Len()
+	}
+	if valueLen != 0 || !d.cs.DisableCapacities && valueCap != 0 {
+		d.w.Write(openParenBytes)
+		if valueLen != 0 {
+			d.w.Write(lenEqualsBytes)
+			printInt(d.w, int64(valueLen), 10)
+		}
+		if !d.cs.DisableCapacities && valueCap != 0 {
+			if valueLen != 0 {
+				d.w.Write(spaceBytes)
+			}
+			d.w.Write(capEqualsBytes)
+			printInt(d.w, int64(valueCap), 10)
+		}
+		d.w.Write(closeParenBytes)
+		d.w.Write(spaceBytes)
+	}
+
+	// Call Stringer/error interfaces if they exist and the handle methods flag
+	// is enabled
+	if !d.cs.DisableMethods {
+		if (kind != reflect.Invalid) && (kind != reflect.Interface) {
+			if handled := handleMethods(d.cs, d.w, v); handled {
+				return
+			}
+		}
+	}
+
+	switch kind {
+	case reflect.Invalid:
+		// Do nothing.  We should never get here since invalid has already
+		// been handled above.
+
+	case reflect.Bool:
+		printBool(d.w, v.Bool())
+
+	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
+		printInt(d.w, v.Int(), 10)
+
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
+		printUint(d.w, v.Uint(), 10)
+
+	case reflect.Float32:
+		printFloat(d.w, v.Float(), 32)
+
+	case reflect.Float64:
+		printFloat(d.w, v.Float(), 64)
+
+	case reflect.Complex64:
+		printComplex(d.w, v.Complex(), 32)
+
+	case reflect.Complex128:
+		printComplex(d.w, v.Complex(), 64)
+
+	case reflect.Slice:
+		if v.IsNil() {
+			d.w.Write(nilAngleBytes)
+			break
+		}
+		fallthrough
+
+	case reflect.Array:
+		d.w.Write(openBraceNewlineBytes)
+		d.depth++
+		if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) {
+			d.indent()
+			d.w.Write(maxNewlineBytes)
+		} else {
+			d.dumpSlice(v)
+		}
+		d.depth--
+		d.indent()
+		d.w.Write(closeBraceBytes)
+
+	case reflect.String:
+		d.w.Write([]byte(strconv.Quote(v.String())))
+
+	case reflect.Interface:
+		// The only time we should get here is for nil interfaces due to
+		// unpackValue calls.
+		if v.IsNil() {
+			d.w.Write(nilAngleBytes)
+		}
+
+	case reflect.Ptr:
+		// Do nothing.  We should never get here since pointers have already
+		// been handled above.
+
+	case reflect.Map:
+		// nil maps should be indicated as different than empty maps
+		if v.IsNil() {
+			d.w.Write(nilAngleBytes)
+			break
+		}
+
+		d.w.Write(openBraceNewlineBytes)
+		d.depth++
+		if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) {
+			d.indent()
+			d.w.Write(maxNewlineBytes)
+		} else {
+			numEntries := v.Len()
+			keys := v.MapKeys()
+			if d.cs.SortKeys {
+				sortValues(keys, d.cs)
+			}
+			for i, key := range keys {
+				d.dump(d.unpackValue(key))
+				d.w.Write(colonSpaceBytes)
+				d.ignoreNextIndent = true
+				d.dump(d.unpackValue(v.MapIndex(key)))
+				if i < (numEntries - 1) {
+					d.w.Write(commaNewlineBytes)
+				} else {
+					d.w.Write(newlineBytes)
+				}
+			}
+		}
+		d.depth--
+		d.indent()
+		d.w.Write(closeBraceBytes)
+
+	case reflect.Struct:
+		d.w.Write(openBraceNewlineBytes)
+		d.depth++
+		if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) {
+			d.indent()
+			d.w.Write(maxNewlineBytes)
+		} else {
+			vt := v.Type()
+			numFields := v.NumField()
+			for i := 0; i < numFields; i++ {
+				d.indent()
+				vtf := vt.Field(i)
+				d.w.Write([]byte(vtf.Name))
+				d.w.Write(colonSpaceBytes)
+				d.ignoreNextIndent = true
+				d.dump(d.unpackValue(v.Field(i)))
+				if i < (numFields - 1) {
+					d.w.Write(commaNewlineBytes)
+				} else {
+					d.w.Write(newlineBytes)
+				}
+			}
+		}
+		d.depth--
+		d.indent()
+		d.w.Write(closeBraceBytes)
+
+	case reflect.Uintptr:
+		printHexPtr(d.w, uintptr(v.Uint()))
+
+	case reflect.UnsafePointer, reflect.Chan, reflect.Func:
+		printHexPtr(d.w, v.Pointer())
+
+	// There were not any other types at the time this code was written, but
+	// fall back to letting the default fmt package handle it in case any new
+	// types are added.
+	default:
+		if v.CanInterface() {
+			fmt.Fprintf(d.w, "%v", v.Interface())
+		} else {
+			fmt.Fprintf(d.w, "%v", v.String())
+		}
+	}
+}
+
+// fdump is a helper function to consolidate the logic from the various public
+// methods which take varying writers and config states.
+func fdump(cs *ConfigState, w io.Writer, a ...interface{}) {
+	for _, arg := range a {
+		if arg == nil {
+			w.Write(interfaceBytes)
+			w.Write(spaceBytes)
+			w.Write(nilAngleBytes)
+			w.Write(newlineBytes)
+			continue
+		}
+
+		d := dumpState{w: w, cs: cs}
+		d.pointers = make(map[uintptr]int)
+		d.dump(reflect.ValueOf(arg))
+		d.w.Write(newlineBytes)
+	}
+}
+
+// Fdump formats and displays the passed arguments to io.Writer w.  It formats
+// exactly the same as Dump.
+func Fdump(w io.Writer, a ...interface{}) {
+	fdump(&Config, w, a...)
+}
+
+// Sdump returns a string with the passed arguments formatted exactly the same
+// as Dump.
+func Sdump(a ...interface{}) string {
+	var buf bytes.Buffer
+	fdump(&Config, &buf, a...)
+	return buf.String()
+}
+
+/*
+Dump displays the passed parameters to standard out with newlines, customizable
+indentation, and additional debug information such as complete types and all
+pointer addresses used to indirect to the final value.  It provides the
+following features over the built-in printing facilities provided by the fmt
+package:
+
+	* Pointers are dereferenced and followed
+	* Circular data structures are detected and handled properly
+	* Custom Stringer/error interfaces are optionally invoked, including
+	  on unexported types
+	* Custom types which only implement the Stringer/error interfaces via
+	  a pointer receiver are optionally invoked when passing non-pointer
+	  variables
+	* Byte arrays and slices are dumped like the hexdump -C command which
+	  includes offsets, byte values in hex, and ASCII output
+
+The configuration options are controlled by an exported package global,
+spew.Config.  See ConfigState for options documentation.
+
+See Fdump if you would prefer dumping to an arbitrary io.Writer or Sdump to
+get the formatted result as a string.
+*/
+func Dump(a ...interface{}) {
+	fdump(&Config, os.Stdout, a...)
+}

vendor/github.com/davecgh/go-spew/spew/format.go

@@ -0,0 +1,419 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package spew
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+// supportedFlags is a list of all the character flags supported by fmt package.
+const supportedFlags = "0-+# "
+
+// formatState implements the fmt.Formatter interface and contains information
+// about the state of a formatting operation.  The NewFormatter function can
+// be used to get a new Formatter which can be used directly as arguments
+// in standard fmt package printing calls.
+type formatState struct {
+	value          interface{}
+	fs             fmt.State
+	depth          int
+	pointers       map[uintptr]int
+	ignoreNextType bool
+	cs             *ConfigState
+}
+
+// buildDefaultFormat recreates the original format string without precision
+// and width information to pass in to fmt.Sprintf in the case of an
+// unrecognized type.  Unless new types are added to the language, this
+// function won't ever be called.
+func (f *formatState) buildDefaultFormat() (format string) {
+	buf := bytes.NewBuffer(percentBytes)
+
+	for _, flag := range supportedFlags {
+		if f.fs.Flag(int(flag)) {
+			buf.WriteRune(flag)
+		}
+	}
+
+	buf.WriteRune('v')
+
+	format = buf.String()
+	return format
+}
+
+// constructOrigFormat recreates the original format string including precision
+// and width information to pass along to the standard fmt package.  This allows
+// automatic deferral of all format strings this package doesn't support.
+func (f *formatState) constructOrigFormat(verb rune) (format string) {
+	buf := bytes.NewBuffer(percentBytes)
+
+	for _, flag := range supportedFlags {
+		if f.fs.Flag(int(flag)) {
+			buf.WriteRune(flag)
+		}
+	}
+
+	if width, ok := f.fs.Width(); ok {
+		buf.WriteString(strconv.Itoa(width))
+	}
+
+	if precision, ok := f.fs.Precision(); ok {
+		buf.Write(precisionBytes)
+		buf.WriteString(strconv.Itoa(precision))
+	}
+
+	buf.WriteRune(verb)
+
+	format = buf.String()
+	return format
+}
+
+// unpackValue returns values inside of non-nil interfaces when possible and
+// ensures that types for values which have been unpacked from an interface
+// are displayed when the show types flag is also set.
+// This is useful for data types like structs, arrays, slices, and maps which
+// can contain varying types packed inside an interface.
+func (f *formatState) unpackValue(v reflect.Value) reflect.Value {
+	if v.Kind() == reflect.Interface {
+		f.ignoreNextType = false
+		if !v.IsNil() {
+			v = v.Elem()
+		}
+	}
+	return v
+}
+
+// formatPtr handles formatting of pointers by indirecting them as necessary.
+func (f *formatState) formatPtr(v reflect.Value) {
+	// Display nil if top level pointer is nil.
+	showTypes := f.fs.Flag('#')
+	if v.IsNil() && (!showTypes || f.ignoreNextType) {
+		f.fs.Write(nilAngleBytes)
+		return
+	}
+
+	// Remove pointers at or below the current depth from map used to detect
+	// circular refs.
+	for k, depth := range f.pointers {
+		if depth >= f.depth {
+			delete(f.pointers, k)
+		}
+	}
+
+	// Keep list of all dereferenced pointers to possibly show later.
+	pointerChain := make([]uintptr, 0)
+
+	// Figure out how many levels of indirection there are by derferencing
+	// pointers and unpacking interfaces down the chain while detecting circular
+	// references.
+	nilFound := false
+	cycleFound := false
+	indirects := 0
+	ve := v
+	for ve.Kind() == reflect.Ptr {
+		if ve.IsNil() {
+			nilFound = true
+			break
+		}
+		indirects++
+		addr := ve.Pointer()
+		pointerChain = append(pointerChain, addr)
+		if pd, ok := f.pointers[addr]; ok && pd < f.depth {
+			cycleFound = true
+			indirects--
+			break
+		}
+		f.pointers[addr] = f.depth
+
+		ve = ve.Elem()
+		if ve.Kind() == reflect.Interface {
+			if ve.IsNil() {
+				nilFound = true
+				break
+			}
+			ve = ve.Elem()
+		}
+	}
+
+	// Display type or indirection level depending on flags.
+	if showTypes && !f.ignoreNextType {
+		f.fs.Write(openParenBytes)
+		f.fs.Write(bytes.Repeat(asteriskBytes, indirects))
+		f.fs.Write([]byte(ve.Type().String()))
+		f.fs.Write(closeParenBytes)
+	} else {
+		if nilFound || cycleFound {
+			indirects += strings.Count(ve.Type().String(), "*")
+		}
+		f.fs.Write(openAngleBytes)
+		f.fs.Write([]byte(strings.Repeat("*", indirects)))
+		f.fs.Write(closeAngleBytes)
+	}
+
+	// Display pointer information depending on flags.
+	if f.fs.Flag('+') && (len(pointerChain) > 0) {
+		f.fs.Write(openParenBytes)
+		for i, addr := range pointerChain {
+			if i > 0 {
+				f.fs.Write(pointerChainBytes)
+			}
+			printHexPtr(f.fs, addr)
+		}
+		f.fs.Write(closeParenBytes)
+	}
+
+	// Display dereferenced value.
+	switch {
+	case nilFound:
+		f.fs.Write(nilAngleBytes)
+
+	case cycleFound:
+		f.fs.Write(circularShortBytes)
+
+	default:
+		f.ignoreNextType = true
+		f.format(ve)
+	}
+}
+
+// format is the main workhorse for providing the Formatter interface.  It
+// uses the passed reflect value to figure out what kind of object we are
+// dealing with and formats it appropriately.  It is a recursive function,
+// however circular data structures are detected and handled properly.
+func (f *formatState) format(v reflect.Value) {
+	// Handle invalid reflect values immediately.
+	kind := v.Kind()
+	if kind == reflect.Invalid {
+		f.fs.Write(invalidAngleBytes)
+		return
+	}
+
+	// Handle pointers specially.
+	if kind == reflect.Ptr {
+		f.formatPtr(v)
+		return
+	}
+
+	// Print type information unless already handled elsewhere.
+	if !f.ignoreNextType && f.fs.Flag('#') {
+		f.fs.Write(openParenBytes)
+		f.fs.Write([]byte(v.Type().String()))
+		f.fs.Write(closeParenBytes)
+	}
+	f.ignoreNextType = false
+
+	// Call Stringer/error interfaces if they exist and the handle methods
+	// flag is enabled.
+	if !f.cs.DisableMethods {
+		if (kind != reflect.Invalid) && (kind != reflect.Interface) {
+			if handled := handleMethods(f.cs, f.fs, v); handled {
+				return
+			}
+		}
+	}
+
+	switch kind {
+	case reflect.Invalid:
+		// Do nothing.  We should never get here since invalid has already
+		// been handled above.
+
+	case reflect.Bool:
+		printBool(f.fs, v.Bool())
+
+	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
+		printInt(f.fs, v.Int(), 10)
+
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
+		printUint(f.fs, v.Uint(), 10)
+
+	case reflect.Float32:
+		printFloat(f.fs, v.Float(), 32)
+
+	case reflect.Float64:
+		printFloat(f.fs, v.Float(), 64)
+
+	case reflect.Complex64:
+		printComplex(f.fs, v.Complex(), 32)
+
+	case reflect.Complex128:
+		printComplex(f.fs, v.Complex(), 64)
+
+	case reflect.Slice:
+		if v.IsNil() {
+			f.fs.Write(nilAngleBytes)
+			break
+		}
+		fallthrough
+
+	case reflect.Array:
+		f.fs.Write(openBracketBytes)
+		f.depth++
+		if (f.cs.MaxDepth != 0) && (f.depth > f.cs.MaxDepth) {
+			f.fs.Write(maxShortBytes)
+		} else {
+			numEntries := v.Len()
+			for i := 0; i < numEntries; i++ {
+				if i > 0 {
+					f.fs.Write(spaceBytes)
+				}
+				f.ignoreNextType = true
+				f.format(f.unpackValue(v.Index(i)))
+			}
+		}
+		f.depth--
+		f.fs.Write(closeBracketBytes)
+
+	case reflect.String:
+		f.fs.Write([]byte(v.String()))
+
+	case reflect.Interface:
+		// The only time we should get here is for nil interfaces due to
+		// unpackValue calls.
+		if v.IsNil() {
+			f.fs.Write(nilAngleBytes)
+		}
+
+	case reflect.Ptr:
+		// Do nothing.  We should never get here since pointers have already
+		// been handled above.
+
+	case reflect.Map:
+		// nil maps should be indicated as different than empty maps
+		if v.IsNil() {
+			f.fs.Write(nilAngleBytes)
+			break
+		}
+
+		f.fs.Write(openMapBytes)
+		f.depth++
+		if (f.cs.MaxDepth != 0) && (f.depth > f.cs.MaxDepth) {
+			f.fs.Write(maxShortBytes)
+		} else {
+			keys := v.MapKeys()
+			if f.cs.SortKeys {
+				sortValues(keys, f.cs)
+			}
+			for i, key := range keys {
+				if i > 0 {
+					f.fs.Write(spaceBytes)
+				}
+				f.ignoreNextType = true
+				f.format(f.unpackValue(key))
+				f.fs.Write(colonBytes)
+				f.ignoreNextType = true
+				f.format(f.unpackValue(v.MapIndex(key)))
+			}
+		}
+		f.depth--
+		f.fs.Write(closeMapBytes)
+
+	case reflect.Struct:
+		numFields := v.NumField()
+		f.fs.Write(openBraceBytes)
+		f.depth++
+		if (f.cs.MaxDepth != 0) && (f.depth > f.cs.MaxDepth) {
+			f.fs.Write(maxShortBytes)
+		} else {
+			vt := v.Type()
+			for i := 0; i < numFields; i++ {
+				if i > 0 {
+					f.fs.Write(spaceBytes)
+				}
+				vtf := vt.Field(i)
+				if f.fs.Flag('+') || f.fs.Flag('#') {
+					f.fs.Write([]byte(vtf.Name))
+					f.fs.Write(colonBytes)
+				}
+				f.format(f.unpackValue(v.Field(i)))
+			}
+		}
+		f.depth--
+		f.fs.Write(closeBraceBytes)
+
+	case reflect.Uintptr:
+		printHexPtr(f.fs, uintptr(v.Uint()))
+
+	case reflect.UnsafePointer, reflect.Chan, reflect.Func:
+		printHexPtr(f.fs, v.Pointer())
+
+	// There were not any other types at the time this code was written, but
+	// fall back to letting the default fmt package handle it if any get added.
+	default:
+		format := f.buildDefaultFormat()
+		if v.CanInterface() {
+			fmt.Fprintf(f.fs, format, v.Interface())
+		} else {
+			fmt.Fprintf(f.fs, format, v.String())
+		}
+	}
+}
+
+// Format satisfies the fmt.Formatter interface. See NewFormatter for usage
+// details.
+func (f *formatState) Format(fs fmt.State, verb rune) {
+	f.fs = fs
+
+	// Use standard formatting for verbs that are not v.
+	if verb != 'v' {
+		format := f.constructOrigFormat(verb)
+		fmt.Fprintf(fs, format, f.value)
+		return
+	}
+
+	if f.value == nil {
+		if fs.Flag('#') {
+			fs.Write(interfaceBytes)
+		}
+		fs.Write(nilAngleBytes)
+		return
+	}
+
+	f.format(reflect.ValueOf(f.value))
+}
+
+// newFormatter is a helper function to consolidate the logic from the various
+// public methods which take varying config states.
+func newFormatter(cs *ConfigState, v interface{}) fmt.Formatter {
+	fs := &formatState{value: v, cs: cs}
+	fs.pointers = make(map[uintptr]int)
+	return fs
+}
+
+/*
+NewFormatter returns a custom formatter that satisfies the fmt.Formatter
+interface.  As a result, it integrates cleanly with standard fmt package
+printing functions.  The formatter is useful for inline printing of smaller data
+types similar to the standard %v format specifier.
+
+The custom formatter only responds to the %v (most compact), %+v (adds pointer
+addresses), %#v (adds types), or %#+v (adds types and pointer addresses) verb
+combinations.  Any other verbs such as %x and %q will be sent to the the
+standard fmt package for formatting.  In addition, the custom formatter ignores
+the width and precision arguments (however they will still work on the format
+specifiers not handled by the custom formatter).
+
+Typically this function shouldn't be called directly.  It is much easier to make
+use of the custom formatter by calling one of the convenience functions such as
+Printf, Println, or Fprintf.
+*/
+func NewFormatter(v interface{}) fmt.Formatter {
+	return newFormatter(&Config, v)
+}

vendor/github.com/davecgh/go-spew/spew/spew.go

@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+package spew
+
+import (
+	"fmt"
+	"io"
+)
+
+// Errorf is a wrapper for fmt.Errorf that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the formatted string as a value that satisfies error.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Errorf(format, spew.NewFormatter(a), spew.NewFormatter(b))
+func Errorf(format string, a ...interface{}) (err error) {
+	return fmt.Errorf(format, convertArgs(a)...)
+}
+
+// Fprint is a wrapper for fmt.Fprint that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprint(w, spew.NewFormatter(a), spew.NewFormatter(b))
+func Fprint(w io.Writer, a ...interface{}) (n int, err error) {
+	return fmt.Fprint(w, convertArgs(a)...)
+}
+
+// Fprintf is a wrapper for fmt.Fprintf that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprintf(w, format, spew.NewFormatter(a), spew.NewFormatter(b))
+func Fprintf(w io.Writer, format string, a ...interface{}) (n int, err error) {
+	return fmt.Fprintf(w, format, convertArgs(a)...)
+}
+
+// Fprintln is a wrapper for fmt.Fprintln that treats each argument as if it
+// passed with a default Formatter interface returned by NewFormatter.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Fprintln(w, spew.NewFormatter(a), spew.NewFormatter(b))
+func Fprintln(w io.Writer, a ...interface{}) (n int, err error) {
+	return fmt.Fprintln(w, convertArgs(a)...)
+}
+
+// Print is a wrapper for fmt.Print that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Print(spew.NewFormatter(a), spew.NewFormatter(b))
+func Print(a ...interface{}) (n int, err error) {
+	return fmt.Print(convertArgs(a)...)
+}
+
+// Printf is a wrapper for fmt.Printf that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Printf(format, spew.NewFormatter(a), spew.NewFormatter(b))
+func Printf(format string, a ...interface{}) (n int, err error) {
+	return fmt.Printf(format, convertArgs(a)...)
+}
+
+// Println is a wrapper for fmt.Println that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the number of bytes written and any write error encountered.  See
+// NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Println(spew.NewFormatter(a), spew.NewFormatter(b))
+func Println(a ...interface{}) (n int, err error) {
+	return fmt.Println(convertArgs(a)...)
+}
+
+// Sprint is a wrapper for fmt.Sprint that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprint(spew.NewFormatter(a), spew.NewFormatter(b))
+func Sprint(a ...interface{}) string {
+	return fmt.Sprint(convertArgs(a)...)
+}
+
+// Sprintf is a wrapper for fmt.Sprintf that treats each argument as if it were
+// passed with a default Formatter interface returned by NewFormatter.  It
+// returns the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprintf(format, spew.NewFormatter(a), spew.NewFormatter(b))
+func Sprintf(format string, a ...interface{}) string {
+	return fmt.Sprintf(format, convertArgs(a)...)
+}
+
+// Sprintln is a wrapper for fmt.Sprintln that treats each argument as if it
+// were passed with a default Formatter interface returned by NewFormatter.  It
+// returns the resulting string.  See NewFormatter for formatting details.
+//
+// This function is shorthand for the following syntax:
+//
+//	fmt.Sprintln(spew.NewFormatter(a), spew.NewFormatter(b))
+func Sprintln(a ...interface{}) string {
+	return fmt.Sprintln(convertArgs(a)...)
+}
+
+// convertArgs accepts a slice of arguments and returns a slice of the same
+// length with each argument converted to a default spew Formatter interface.
+func convertArgs(args []interface{}) (formatters []interface{}) {
+	formatters = make([]interface{}, len(args))
+	for index, arg := range args {
+		formatters[index] = NewFormatter(arg)
+	}
+	return formatters
+}

vendor/github.com/golang-migrate/migrate/v4/.dockerignore

@@ -0,0 +1,13 @@
+# Project
+FAQ.md
+README.md
+LICENSE
+Makefile
+.gitignore
+.travis.yml
+CONTRIBUTING.md
+MIGRATIONS.md
+docker-deploy.sh
+
+# Golang
+testing

vendor/github.com/golang-migrate/migrate/v4/.gitignore

@@ -0,0 +1,8 @@
+.DS_Store
+cli/build
+cli/cli
+cli/migrate
+.coverage
+.godoc.pid
+vendor/
+.vscode/

vendor/github.com/golang-migrate/migrate/v4/.golangci.yml

@@ -0,0 +1,27 @@
+run:
+  # timeout for analysis, e.g. 30s, 5m, default is 1m
+  deadline: 2m
+linters:
+  enable:
+    #- golint
+    - interfacer
+    - unconvert
+    #- dupl
+    - goconst
+    - gofmt
+    - misspell
+    - maligned
+    - unparam
+    - nakedret
+    - prealloc
+    #- gosec
+linters-settings:
+  misspell:
+    locale: US
+issues:
+  max-same: 0
+  max-per-linter: 0
+  exclude-use-default: false
+  exclude:
+    # gosec: Duplicated errcheck checks
+    - G104

vendor/github.com/golang-migrate/migrate/v4/.travis.yml

@@ -0,0 +1,135 @@
+language: go
+sudo: required
+
+matrix:
+  allow_failures:
+    - go: master
+  include:
+    # Supported versions of Go: https://golang.org/dl/
+    - go: "1.11.x"
+    - go: "1.12.x"
+    - go: master
+
+go_import_path: github.com/golang-migrate/migrate
+
+env:
+  global:
+    - GO111MODULE=on
+    - MIGRATE_TEST_CONTAINER_BOOT_TIMEOUT=60
+    - DOCKER_USERNAME=golangmigrate
+    -   secure: "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"
+
+services:
+  - docker
+
+cache:
+  directories:
+    - $GOPATH/pkg
+
+
+before_install:
+  # Update docker to latest version: https://docs.travis-ci.com/user/docker/#installing-a-newer-docker-version
+  - curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
+  - sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
+  - sudo apt-get update
+  - sudo apt-get -y -o Dpkg::Options::="--force-confnew" install docker-ce
+  # Install golangci-lint
+  - curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(go env GOPATH)/bin v1.17.1
+  - echo "TRAVIS_GO_VERSION=${TRAVIS_GO_VERSION}"
+
+install:
+  - go get github.com/mattn/goveralls
+
+script:
+  - golangci-lint run
+  - make test COVERAGE_DIR=/tmp/coverage
+
+after_success:
+  - goveralls -service=travis-ci -coverprofile /tmp/coverage/combined.txt
+  - make list-external-deps > dependency_tree.txt && cat dependency_tree.txt
+  - make build-cli
+  - gem install --no-document fpm
+  - fpm -s dir -t deb -n migrate -v "$(git describe --tags 2>/dev/null | cut -c 2-)" --license MIT -m dhui@users.noreply.github.com --url https://github.com/golang-migrate/migrate --description='Database migrations' -a amd64 -p migrate.$(git describe --tags 2>/dev/null | cut -c 2-).deb --deb-no-default-config-files -f -C cli/build migrate.linux-amd64=/usr/local/bin/migrate
+
+deploy:
+  - provider: releases
+    api_key:
+      secure: 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
+    skip_cleanup: true
+    on:
+      go: "1.12.x"
+      repo: golang-migrate/migrate
+      tags: true
+    file:
+      - cli/build/migrate.linux-amd64.tar.gz
+      - cli/build/migrate.darwin-amd64.tar.gz
+      - cli/build/migrate.windows-amd64.exe.tar.gz
+      - cli/build/sha256sum.txt
+      - dependency_tree.txt
+  - provider: packagecloud
+    repository: migrate
+    username: golang-migrate
+    token:
+      secure: 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
+    dist: ubuntu/xenial
+    package_glob: '*.deb'
+    skip_cleanup: true
+    on:
+      go: "1.12.x"
+      repo: golang-migrate/migrate
+      tags: true
+  - provider: packagecloud
+    repository: migrate
+    username: golang-migrate
+    token:
+      secure: aICwu3gJ1sJ1QVCD3elpg+Jxzt4P+Zj1uoh5f0sOwnjDNIZ4FwUT1cMrWloP8P2KD0iyCOawuZER27o/kQ21oX2OxHvQbYPReA2znLm7lHzCmypAAOHPxpgnQ4rMGHHJXd+OsxtdclGs67c+EbdBfoRRbK400Qz/vjPJEDeH4mh02ZHC2nw4Nk/wV4jjBIkIt9dGEx6NgOA17FCMa3MaPHlHeFIzU7IfTlDHbS0mCCYbg/wafWBWcbGqtZLWAYtJDmfjrAStmDLdAX5J5PsB7taGSGPZHmPmpGoVgrKt/tb9Xz1rFBGslTpGROOiO4CiMAvkEKFn8mxrBGjfSBqp7Dp3eeSalKXB1DJAbEXx2sEbMcvmnoR9o43meaAn+ZRts8lRL8S/skBloe6Nk8bx3NlJCGB9WPK1G56b7c/fZnJxQbrCw6hxDfbZwm8S2YPviFTo/z1BfZDhRsL74reKsN2kgnGo2W/k38vvzIpsssQ9DHN1b0TLCxolCNPtQ7oHcQ1ohcjP2UgYXk0FhqDoL+9LQva/DU4N9sKH0UbAaqsMVSErLeG8A4aauuFcVrWRBaDYyTag4dQqzTulEy7iru2kDDIBgSQ1gMW/yoBOIPK4oi6MtbTf1X39fzXFLS1cDd3LW61yAu3YrbjAetpfx2frIvrRAiL9TxWA1gnrs5o=
+    dist: ubuntu/bionic
+    package_glob: '*.deb'
+    skip_cleanup: true
+    on:
+      go: "1.12.x"
+      repo: golang-migrate/migrate
+      tags: true
+  - provider: packagecloud
+    repository: migrate
+    username: golang-migrate
+    token:
+      secure: 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
+    dist: ubuntu/cosmic
+    package_glob: '*.deb'
+    skip_cleanup: true
+    on:
+      go: "1.12.x"
+      repo: golang-migrate/migrate
+      tags: true
+  - provider: packagecloud
+    repository: migrate
+    username: golang-migrate
+    token:
+      secure: aICwu3gJ1sJ1QVCD3elpg+Jxzt4P+Zj1uoh5f0sOwnjDNIZ4FwUT1cMrWloP8P2KD0iyCOawuZER27o/kQ21oX2OxHvQbYPReA2znLm7lHzCmypAAOHPxpgnQ4rMGHHJXd+OsxtdclGs67c+EbdBfoRRbK400Qz/vjPJEDeH4mh02ZHC2nw4Nk/wV4jjBIkIt9dGEx6NgOA17FCMa3MaPHlHeFIzU7IfTlDHbS0mCCYbg/wafWBWcbGqtZLWAYtJDmfjrAStmDLdAX5J5PsB7taGSGPZHmPmpGoVgrKt/tb9Xz1rFBGslTpGROOiO4CiMAvkEKFn8mxrBGjfSBqp7Dp3eeSalKXB1DJAbEXx2sEbMcvmnoR9o43meaAn+ZRts8lRL8S/skBloe6Nk8bx3NlJCGB9WPK1G56b7c/fZnJxQbrCw6hxDfbZwm8S2YPviFTo/z1BfZDhRsL74reKsN2kgnGo2W/k38vvzIpsssQ9DHN1b0TLCxolCNPtQ7oHcQ1ohcjP2UgYXk0FhqDoL+9LQva/DU4N9sKH0UbAaqsMVSErLeG8A4aauuFcVrWRBaDYyTag4dQqzTulEy7iru2kDDIBgSQ1gMW/yoBOIPK4oi6MtbTf1X39fzXFLS1cDd3LW61yAu3YrbjAetpfx2frIvrRAiL9TxWA1gnrs5o=
+    dist: debian/stretch
+    package_glob: '*.deb'
+    skip_cleanup: true
+    on:
+      go: "1.12.x"
+      repo: golang-migrate/migrate
+      tags: true
+  - provider: packagecloud
+    repository: migrate
+    username: golang-migrate
+    token:
+      secure: aICwu3gJ1sJ1QVCD3elpg+Jxzt4P+Zj1uoh5f0sOwnjDNIZ4FwUT1cMrWloP8P2KD0iyCOawuZER27o/kQ21oX2OxHvQbYPReA2znLm7lHzCmypAAOHPxpgnQ4rMGHHJXd+OsxtdclGs67c+EbdBfoRRbK400Qz/vjPJEDeH4mh02ZHC2nw4Nk/wV4jjBIkIt9dGEx6NgOA17FCMa3MaPHlHeFIzU7IfTlDHbS0mCCYbg/wafWBWcbGqtZLWAYtJDmfjrAStmDLdAX5J5PsB7taGSGPZHmPmpGoVgrKt/tb9Xz1rFBGslTpGROOiO4CiMAvkEKFn8mxrBGjfSBqp7Dp3eeSalKXB1DJAbEXx2sEbMcvmnoR9o43meaAn+ZRts8lRL8S/skBloe6Nk8bx3NlJCGB9WPK1G56b7c/fZnJxQbrCw6hxDfbZwm8S2YPviFTo/z1BfZDhRsL74reKsN2kgnGo2W/k38vvzIpsssQ9DHN1b0TLCxolCNPtQ7oHcQ1ohcjP2UgYXk0FhqDoL+9LQva/DU4N9sKH0UbAaqsMVSErLeG8A4aauuFcVrWRBaDYyTag4dQqzTulEy7iru2kDDIBgSQ1gMW/yoBOIPK4oi6MtbTf1X39fzXFLS1cDd3LW61yAu3YrbjAetpfx2frIvrRAiL9TxWA1gnrs5o=
+    dist: debian/buster
+    package_glob: '*.deb'
+    skip_cleanup: true
+    on:
+      go: "1.12.x"
+      repo: golang-migrate/migrate
+      tags: true
+  - provider: script
+    script: ./docker-deploy.sh
+    skip_cleanup: true
+    on:
+      go: "1.12.x"
+      repo: golang-migrate/migrate
+      tags: true

vendor/github.com/golang-migrate/migrate/v4/CONTRIBUTING.md

@@ -0,0 +1,24 @@
+# Development, Testing and Contributing
+
+  1. Make sure you have a running Docker daemon
+     (Install for [MacOS](https://docs.docker.com/docker-for-mac/))
+  1. Use a version of Go that supports [modules](https://golang.org/cmd/go/#hdr-Modules__module_versions__and_more) (e.g. Go 1.11+)
+  1. Fork this repo and `git clone` somewhere to `$GOPATH/src/github.com/golang-migrate/migrate`
+      * Ensure that [Go modules are enabled](https://golang.org/cmd/go/#hdr-Preliminary_module_support) (e.g. your repo path or the `GO111MODULE` environment variable are set correctly)
+  1. Install [golangci-lint](https://github.com/golangci/golangci-lint#install)
+  1. Run the linter: `golangci-lint run`
+  1. Confirm tests are working: `make test-short`
+  1. Write awesome code ...
+  1. `make test` to run all tests against all database versions
+  1. Push code and open Pull Request
+ 
+Some more helpful commands:
+
+  * You can specify which database/ source tests to run:
+    `make test-short SOURCE='file go_bindata' DATABASE='postgres cassandra'`
+  * After `make test`, run `make html-coverage` which opens a shiny test coverage overview.
+  * `make build-cli` builds the CLI in directory `cli/build/`.
+  * `make list-external-deps` lists all external dependencies for each package
+  * `make docs && make open-docs` opens godoc in your browser, `make kill-docs` kills the godoc server.
+    Repeatedly call `make docs` to refresh the server.
+  * Set the `DOCKER_API_VERSION` environment variable to the latest supported version if you get errors regarding the docker client API version being too new.

vendor/github.com/golang-migrate/migrate/v4/Dockerfile

@@ -0,0 +1,23 @@
+FROM golang:1.12-alpine3.10 AS downloader
+ARG VERSION
+
+RUN apk add --no-cache git gcc musl-dev
+
+WORKDIR /go/src/github.com/golang-migrate/migrate
+
+COPY . ./
+
+ENV GO111MODULE=on
+ENV DATABASES="postgres mysql redshift cassandra spanner cockroachdb clickhouse mongodb sqlserver"
+ENV SOURCES="file go_bindata github github_ee aws_s3 google_cloud_storage godoc_vfs gitlab"
+
+RUN go build -a -o build/migrate.linux-386 -ldflags="-s -w -X main.Version=${VERSION}" -tags "$DATABASES $SOURCES" ./cmd/migrate
+
+FROM alpine:3.10
+
+RUN apk add --no-cache ca-certificates
+
+COPY --from=downloader /go/src/github.com/golang-migrate/migrate/build/migrate.linux-386 /migrate
+
+ENTRYPOINT ["/migrate"]
+CMD ["--help"]

vendor/github.com/golang-migrate/migrate/v4/FAQ.md

@@ -0,0 +1,76 @@
+# FAQ
+
+#### How is the code base structured?
+  ```
+  /          package migrate (the heart of everything)
+  /cli       the CLI wrapper
+  /database  database driver and sub directories have the actual driver implementations
+  /source    source driver and sub directories have the actual driver implementations
+  ```
+
+#### Why is there no `source/driver.go:Last()`?
+  It's not needed. And unless the source has a "native" way to read a directory in reversed order,
+  it might be expensive to do a full directory scan in order to get the last element.
+
+#### What is a NilMigration? NilVersion?
+  NilMigration defines a migration without a body. NilVersion is defined as const -1.
+
+#### What is the difference between uint(version) and int(targetVersion)?
+  version refers to an existing migration version coming from a source and therefor can never be negative.
+  targetVersion can either be a version OR represent a NilVersion, which equals -1.
+
+#### What's the difference between Next/Previous and Up/Down?
+  ```
+  1_first_migration.up.extension           next ->  2_second_migration.up.extension      ...
+  1_first_migration.down.extension  <- previous     2_second_migration.down.extension    ...
+  ```
+
+#### Why two separate files (up and down) for a migration?
+  It makes all of our lives easier. No new markup/syntax to learn for users
+  and existing database utility tools continue to work as expected.
+
+#### How many migrations can migrate handle?
+  Whatever the maximum positive signed integer value is for your platform.
+  For 32bit it would be 2,147,483,647 migrations. Migrate only keeps references to
+  the currently run and pre-fetched migrations in memory. Please note that some
+  source drivers need to do build a full "directory" tree first, which puts some
+  heat on the memory consumption.
+
+#### Are the table tests in migrate_test.go bloated?
+  Yes and no. There are duplicate test cases for sure but they don't hurt here. In fact
+  the tests are very visual now and might help new users understand expected behaviors quickly.
+  Migrate from version x to y and y is the last migration? Just check out the test for
+  that particular case and know what's going on instantly.
+
+#### What is Docker being used for?
+  Only for testing. See [testing/docker.go](testing/docker.go)
+
+#### Why not just use docker-compose?
+  It doesn't give us enough runtime control for testing. We want to be able to bring up containers fast
+  and whenever we want, not just once at the beginning of all tests.
+
+#### Can I maintain my driver in my own repository?
+  Yes, technically thats possible. We want to encourage you to contribute your driver to this respository though.
+  The driver's functionality is dictated by migrate's interfaces. That means there should really
+  just be one driver for a database/ source. We want to prevent a future where several drivers doing the exact same thing,
+  just implemented a bit differently, co-exist somewhere on Github. If users have to do research first to find the
+  "best" available driver for a database in order to get started, we would have failed as an open source community.
+
+#### Can I mix multiple sources during a batch of migrations?
+  No.
+
+#### What does "dirty" database mean?
+  Before a migration runs, each database sets a dirty flag. Execution stops if a migration fails and the dirty state persists,
+  which prevents attempts to run more migrations on top of a failed migration. You need to manually fix the error
+  and then "force" the expected version.
+
+#### What happens if two programs try and update the database at the same time?
+Database-specific locking features are used by *some* database drivers to prevent multiple instances of migrate from running migrations at the same time
+  the same database at the same time. For example, the MySQL driver uses the `GET_LOCK` function, while the Postgres driver uses
+  the `pg_advisory_lock` function.
+
+#### Do I need to create a table for tracking migration version used?
+No, it is done automatically.
+
+#### Can I use migrate with a non-Go project?
+Yes, you can use the migrate CLI in a non-Go project, but there are probably other libraries/frameworks available that offer better test and deploy integrations in that language/framework.

vendor/github.com/golang-migrate/migrate/v4/GETTING_STARTED.md

@@ -0,0 +1,43 @@
+# Getting started
+Before you start, you should understand the concept of forward/up and reverse/down database migrations.
+
+Configure a database for your application. Make sure that your database driver is supported [here](README.md#databases)
+
+## Create migrations
+Create some migrations using migrate CLI. Here is an example:
+```
+migrate create -ext sql -dir db/migrations -seq create_users_table
+```
+Once you create your files, you should fill them.
+
+**IMPORTANT:** In a project developed by more than one person there is a chance of migrations inconsistency - e.g. two developers can create conflicting migrations, and the developer that created his migration later gets it merged to the repository first.
+Developers and Teams should keep an eye on such cases (especially during code review).
+[Here](https://github.com/golang-migrate/migrate/issues/179#issuecomment-475821264) is the issue summary if you would like to read more.
+
+Consider making your migrations idempotent - we can run the same sql code twice in a row with the same result. This makes our migrations more robust. On the other hand, it causes slightly less control over database schema - e.g. let's say you forgot to drop the table in down migration. You run down migration - the table is still there. When you run up migration again - `CREATE TABLE` would return an error, helping you find an issue in down migration, while `CREATE TABLE IF NOT EXISTS` would not. Use those conditions wisely.
+
+In case you would like to run several commands/queries in one migration, you should wrap them in a transaction (if your database supports it).
+This way if one of commands fails, our database will remain unchanged.
+
+## Run migrations
+Run your migrations through the CLI or your app and check if they applied expected changes.
+Just to give you an idea:
+```
+migrate -database YOUR_DATBASE_URL -path PATH_TO_YOUR_MIGRATIONS up
+```
+
+Just add the code to your app and you're ready to go!
+
+Before commiting your migrations you should run your migrations up, down, and then up again to see if migrations are working properly both ways.
+(e.g. if you created a table in a migration but reverse migration did not delete it, you will encounter an error when running the forward migration again)
+It's also worth checking your migrations in a separate, containerized environment. You can find some tools in the end of this document.
+
+**IMPORTANT:** If you would like to run multiple instances of your app on different machines be sure to use a database that supports locking when running migrations. Otherwise you may encounter issues.
+
+## Further reading:
+- [PostgreSQL tutorial](database/postgres/TUTORIAL.md)
+- [Best practices](MIGRATIONS.md)
+- [FAQ](FAQ.md)
+- Tools for testing your migrations in a container:
+	- https://github.com/dhui/dktest
+	- https://github.com/ory/dockertest

vendor/github.com/golang-migrate/migrate/v4/LICENSE

@@ -0,0 +1,28 @@
+The MIT License (MIT)
+
+Original Work
+Copyright (c) 2016 Matthias Kadenbach
+https://github.com/mattes/migrate
+
+Modified Work
+Copyright (c) 2018 Dale Hui
+https://github.com/golang-migrate/migrate
+
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

vendor/github.com/golang-migrate/migrate/v4/MIGRATIONS.md

@@ -0,0 +1,86 @@
+# Migrations
+
+## Migration Filename Format
+
+A single logical migration is represented as two separate migration files, one
+to migrate "up" to the specified version from the previous version, and a second
+to migrate back "down" to the previous version.  These migrations can be provided
+by any one of the supported [migration sources](./README.md#migration-sources).
+
+The ordering and direction of the migration files is determined by the filenames
+used for them.  `migrate` expects the filenames of migrations to have the format:
+
+    {version}_{title}.up.{extension}
+    {version}_{title}.down.{extension}
+
+The `title` of each migration is unused, and is only for readability.  Similarly,
+the `extension` of the migration files is not checked by the library, and should
+be an appropriate format for the database in use (`.sql` for SQL variants, for
+instance).
+
+Versions of migrations may be represented as any 64 bit unsigned integer.
+All migrations are applied upward in order of increasing version number, and
+downward by decreasing version number.
+
+Common versioning schemes include incrementing integers:
+
+    1_initialize_schema.down.sql
+    1_initialize_schema.up.sql
+    2_add_table.down.sql
+    2_add_table.up.sql
+    ...
+
+Or timestamps at an appropriate resolution:
+
+    1500360784_initialize_schema.down.sql
+    1500360784_initialize_schema.up.sql
+    1500445949_add_table.down.sql
+    1500445949_add_table.up.sql
+    ...
+
+But any scheme resulting in distinct, incrementing integers as versions is valid.
+
+It is suggested that the version number of corresponding `up` and `down` migration
+files be equivalent for clarity, but they are allowed to differ so long as the
+relative ordering of the migrations is preserved.
+
+The migration files are permitted to be "empty", in the event that a migration
+is a no-op or is irreversible. It is recommended to still include both migration
+files by making the whole migration file consist of a comment.
+If your database does not support comments, then deleting the migration file will also work.
+Note, an actual empty file (e.g. a 0 byte file) may cause issues with your database since migrate
+will attempt to run an empty query. In this case, deleting the migration file will also work.
+For the rational of this behavior see:
+[#244 (comment)](https://github.com/golang-migrate/migrate/issues/244#issuecomment-510758270)
+
+## Migration Content Format
+
+The format of the migration files themselves varies between database systems.
+Different databases have different semantics around schema changes and when and
+how they are allowed to occur
+(for instance, [if schema changes can occur within a transaction](https://wiki.postgresql.org/wiki/Transactional_DDL_in_PostgreSQL:_A_Competitive_Analysis)).
+
+As such, the `migrate` library has little to no checking around the format of
+migration sources.  The migration files are generally processed directly by the
+drivers as raw operations.
+
+## Reversibility of Migrations
+
+Best practice for writing schema migration is that all migrations should be
+reversible.  It should in theory be possible for run migrations down and back up
+through any and all versions with the state being fully cleaned and recreated
+by doing so.
+
+By adhering to this recommended practice, development and deployment of new code
+is cleaner and easier (cleaning database state for a new feature should be as
+easy as migrating down to a prior version, and back up to the latest).
+
+As opposed to some other migration libraries, `migrate` represents up and down
+migrations as separate files.  This prevents any non-standard file syntax from
+being introduced which may result in unintended behavior or errors, depending
+on what database is processing the file.
+
+While it is technically possible for an up or down migration to exist on its own
+without an equivalently versioned counterpart, it is strongly recommended to
+always include a down migration which cleans up the state of the corresponding
+up migration.

vendor/github.com/golang-migrate/migrate/v4/Makefile

@@ -0,0 +1,105 @@
+SOURCE ?= file go_bindata github github_ee aws_s3 google_cloud_storage godoc_vfs gitlab
+DATABASE ?= postgres mysql redshift cassandra spanner cockroachdb clickhouse mongodb sqlserver
+VERSION ?= $(shell git describe --tags 2>/dev/null | cut -c 2-)
+TEST_FLAGS ?=
+REPO_OWNER ?= $(shell cd .. && basename "$$(pwd)")
+COVERAGE_DIR ?= .coverage
+
+
+build-cli: clean
+	-mkdir ./cli/build
+	cd ./cmd/migrate && CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -o ../../cli/build/migrate.linux-amd64 -ldflags='-X main.Version=$(VERSION) -extldflags "-static"' -tags '$(DATABASE) $(SOURCE)' .
+	cd ./cmd/migrate && CGO_ENABLED=0 GOOS=darwin GOARCH=amd64 go build -a -o ../../cli/build/migrate.darwin-amd64 -ldflags='-X main.Version=$(VERSION) -extldflags "-static"' -tags '$(DATABASE) $(SOURCE)' .
+	cd ./cmd/migrate && CGO_ENABLED=0 GOOS=windows GOARCH=amd64 go build -a -o ../../cli/build/migrate.windows-amd64.exe -ldflags='-X main.Version=$(VERSION) -extldflags "-static"' -tags '$(DATABASE) $(SOURCE)' .
+	cd ./cli/build && find . -name 'migrate*' | xargs -I{} tar czf {}.tar.gz {}
+	cd ./cli/build && shasum -a 256 * > sha256sum.txt
+	cat ./cli/build/sha256sum.txt
+
+
+clean:
+	-rm -r ./cli/build
+
+
+test-short:
+	make test-with-flags --ignore-errors TEST_FLAGS='-short'
+
+
+test:
+	@-rm -r $(COVERAGE_DIR)
+	@mkdir $(COVERAGE_DIR)
+	make test-with-flags TEST_FLAGS='-v -race -covermode atomic -coverprofile $$(COVERAGE_DIR)/combined.txt -bench=. -benchmem -timeout 20m'
+
+
+test-with-flags:
+	@echo SOURCE: $(SOURCE)
+	@echo DATABASE: $(DATABASE)
+
+	@go test $(TEST_FLAGS) ./...
+
+
+kill-orphaned-docker-containers:
+	docker rm -f $(shell docker ps -aq --filter label=migrate_test)
+
+
+html-coverage:
+	go tool cover -html=$(COVERAGE_DIR)/combined.txt
+
+
+list-external-deps:
+	$(call external_deps,'.')
+	$(call external_deps,'./cli/...')
+	$(call external_deps,'./testing/...')
+
+	$(foreach v, $(SOURCE), $(call external_deps,'./source/$(v)/...'))
+	$(call external_deps,'./source/testing/...')
+	$(call external_deps,'./source/stub/...')
+
+	$(foreach v, $(DATABASE), $(call external_deps,'./database/$(v)/...'))
+	$(call external_deps,'./database/testing/...')
+	$(call external_deps,'./database/stub/...')
+
+
+restore-import-paths:
+	find . -name '*.go' -type f -execdir sed -i '' s%\"github.com/$(REPO_OWNER)/migrate%\"github.com/mattes/migrate%g '{}' \;
+
+
+rewrite-import-paths:
+	find . -name '*.go' -type f -execdir sed -i '' s%\"github.com/mattes/migrate%\"github.com/$(REPO_OWNER)/migrate%g '{}' \;
+
+
+# example: fswatch -0 --exclude .godoc.pid --event Updated . | xargs -0 -n1 -I{} make docs
+docs:
+	-make kill-docs
+	nohup godoc -play -http=127.0.0.1:6064 </dev/null >/dev/null 2>&1 & echo $$! > .godoc.pid
+	cat .godoc.pid
+
+
+kill-docs:
+	@cat .godoc.pid
+	kill -9 $$(cat .godoc.pid)
+	rm .godoc.pid
+
+
+open-docs:
+	open http://localhost:6064/pkg/github.com/$(REPO_OWNER)/migrate
+
+
+# example: make release V=0.0.0
+release:
+	git tag v$(V)
+	@read -p "Press enter to confirm and push to origin ..." && git push origin v$(V)
+
+
+define external_deps
+	@echo '-- $(1)';  go list -f '{{join .Deps "\n"}}' $(1) | grep -v github.com/$(REPO_OWNER)/migrate | xargs go list -f '{{if not .Standard}}{{.ImportPath}}{{end}}'
+
+endef
+
+
+.PHONY: build-cli clean test-short test test-with-flags html-coverage \
+        restore-import-paths rewrite-import-paths list-external-deps release \
+        docs kill-docs open-docs kill-orphaned-docker-containers
+
+SHELL = /bin/bash
+RAND = $(shell echo $$RANDOM)
+

vendor/github.com/golang-migrate/migrate/v4/README.md

@@ -0,0 +1,181 @@
+[![Build Status](https://img.shields.io/travis/com/golang-migrate/migrate/master.svg)](https://travis-ci.com/golang-migrate/migrate)
+[![GoDoc](https://godoc.org/github.com/golang-migrate/migrate?status.svg)](https://godoc.org/github.com/golang-migrate/migrate)
+[![Coverage Status](https://img.shields.io/coveralls/github/golang-migrate/migrate/master.svg)](https://coveralls.io/github/golang-migrate/migrate?branch=master)
+[![packagecloud.io](https://img.shields.io/badge/deb-packagecloud.io-844fec.svg)](https://packagecloud.io/golang-migrate/migrate?filter=debs)
+[![Docker Pulls](https://img.shields.io/docker/pulls/migrate/migrate.svg)](https://hub.docker.com/r/migrate/migrate/)
+![Supported Go Versions](https://img.shields.io/badge/Go-1.11%2C%201.12-lightgrey.svg)
+[![GitHub Release](https://img.shields.io/github/release/golang-migrate/migrate.svg)](https://github.com/golang-migrate/migrate/releases)
+[![Go Report Card](https://goreportcard.com/badge/github.com/golang-migrate/migrate)](https://goreportcard.com/report/github.com/golang-migrate/migrate) 
+
+# migrate
+
+__Database migrations written in Go. Use as [CLI](#cli-usage) or import as [library](#use-in-your-go-project).__
+
+* Migrate reads migrations from [sources](#migration-sources)
+   and applies them in correct order to a [database](#databases).
+* Drivers are "dumb", migrate glues everything together and makes sure the logic is bulletproof.
+   (Keeps the drivers lightweight, too.)
+* Database drivers don't assume things or try to correct user input. When in doubt, fail.
+
+Forked from [mattes/migrate](https://github.com/mattes/migrate)
+
+## Databases
+
+Database drivers run migrations. [Add a new database?](database/driver.go)
+
+* [PostgreSQL](database/postgres)
+* [Redshift](database/redshift)
+* [Ql](database/ql)
+* [Cassandra](database/cassandra)
+* [SQLite](database/sqlite3) ([todo #165](https://github.com/mattes/migrate/issues/165))
+* [MySQL/ MariaDB](database/mysql)
+* [Neo4j](database/neo4j) ([todo #167](https://github.com/mattes/migrate/issues/167))
+* [MongoDB](database/mongodb)
+* [CrateDB](database/crate) ([todo #170](https://github.com/mattes/migrate/issues/170))
+* [Shell](database/shell) ([todo #171](https://github.com/mattes/migrate/issues/171))
+* [Google Cloud Spanner](database/spanner)
+* [CockroachDB](database/cockroachdb)
+* [ClickHouse](database/clickhouse)
+* [Firebird](database/firebird) ([todo #49](https://github.com/golang-migrate/migrate/issues/49))
+* [MS SQL Server](database/sqlserver)
+
+### Database URLs
+
+Database connection strings are specified via URLs. The URL format is driver dependent but generally has the form: `dbdriver://username:password@host:port/dbname?option1=true&option2=false`
+
+Any [reserved URL characters](https://en.wikipedia.org/wiki/Percent-encoding#Percent-encoding_reserved_characters) need to be escaped. Note, the `%` character also [needs to be escaped](https://en.wikipedia.org/wiki/Percent-encoding#Percent-encoding_the_percent_character)
+
+Explicitly, the following characters need to be escaped:
+`!`, `#`, `$`, `%`, `&`, `'`, `(`, `)`, `*`, `+`, `,`, `/`, `:`, `;`, `=`, `?`, `@`, `[`, `]`
+
+It's easiest to always run the URL parts of your DB connection URL (e.g. username, password, etc) through an URL encoder. See the example Python snippets below:
+
+```bash
+$ python3 -c 'import urllib.parse; print(urllib.parse.quote(input("String to encode: "), ""))'
+String to encode: FAKEpassword!#$%&'()*+,/:;=?@[]
+FAKEpassword%21%23%24%25%26%27%28%29%2A%2B%2C%2F%3A%3B%3D%3F%40%5B%5D
+$ python2 -c 'import urllib; print urllib.quote(raw_input("String to encode: "), "")'
+String to encode: FAKEpassword!#$%&'()*+,/:;=?@[]
+FAKEpassword%21%23%24%25%26%27%28%29%2A%2B%2C%2F%3A%3B%3D%3F%40%5B%5D
+$
+```
+
+## Migration Sources
+
+Source drivers read migrations from local or remote sources. [Add a new source?](source/driver.go)
+
+* [Filesystem](source/file) - read from filesystem
+* [Go-Bindata](source/go_bindata) - read from embedded binary data ([jteeuwen/go-bindata](https://github.com/jteeuwen/go-bindata))
+* [Github](source/github) - read from remote Github repositories
+* [Github Enterprise](source/github_ee) - read from remote Github Enterprise repositories
+* [Gitlab](source/gitlab) - read from remote Gitlab repositories
+* [AWS S3](source/aws_s3) - read from Amazon Web Services S3
+* [Google Cloud Storage](source/google_cloud_storage) - read from Google Cloud Platform Storage
+
+## CLI usage
+
+* Simple wrapper around this library.
+* Handles ctrl+c (SIGINT) gracefully.
+* No config search paths, no config files, no magic ENV var injections.
+
+__[CLI Documentation](cmd/migrate)__
+
+### Basic usage
+
+```bash
+$ migrate -source file://path/to/migrations -database postgres://localhost:5432/database up 2
+```
+
+### Docker usage
+
+```bash
+$ docker run -v {{ migration dir }}:/migrations --network host migrate/migrate
+    -path=/migrations/ -database postgres://localhost:5432/database up 2
+```
+
+## Use in your Go project
+
+* API is stable and frozen for this release (v3 & v4).
+* Uses [Go modules](https://golang.org/cmd/go/#hdr-Modules__module_versions__and_more) to manage dependencies.
+* To help prevent database corruptions, it supports graceful stops via `GracefulStop chan bool`.
+* Bring your own logger.
+* Uses `io.Reader` streams internally for low memory overhead.
+* Thread-safe and no goroutine leaks.
+
+__[Go Documentation](https://godoc.org/github.com/golang-migrate/migrate)__
+
+```go
+import (
+    "github.com/golang-migrate/migrate/v4"
+    _ "github.com/golang-migrate/migrate/v4/database/postgres"
+    _ "github.com/golang-migrate/migrate/v4/source/github"
+)
+
+func main() {
+    m, err := migrate.New(
+        "github://mattes:personal-access-token@mattes/migrate_test",
+        "postgres://localhost:5432/database?sslmode=enable")
+    m.Steps(2)
+}
+```
+
+Want to use an existing database client?
+
+```go
+import (
+    "database/sql"
+    _ "github.com/lib/pq"
+    "github.com/golang-migrate/migrate/v4"
+    "github.com/golang-migrate/migrate/v4/database/postgres"
+    _ "github.com/golang-migrate/migrate/v4/source/file"
+)
+
+func main() {
+    db, err := sql.Open("postgres", "postgres://localhost:5432/database?sslmode=enable")
+    driver, err := postgres.WithInstance(db, &postgres.Config{})
+    m, err := migrate.NewWithDatabaseInstance(
+        "file:///migrations",
+        "postgres", driver)
+    m.Steps(2)
+}
+```
+
+## Getting started
+
+Go to [getting started](GETTING_STARTED.md)
+
+## Tutorials
+
+- [PostgreSQL](database/postgres/TUTORIAL.md)
+
+(more tutorials to come)
+
+## Migration files
+
+Each migration has an up and down migration. [Why?](FAQ.md#why-two-separate-files-up-and-down-for-a-migration)
+
+```bash
+1481574547_create_users_table.up.sql
+1481574547_create_users_table.down.sql
+```
+
+[Best practices: How to write migrations.](MIGRATIONS.md)
+
+## Versions
+
+Version | Supported? | Import | Notes
+--------|------------|--------|------
+**master** | :white_check_mark: | `import "github.com/golang-migrate/migrate/v4"` | New features and bug fixes arrive here first |
+**v4** | :white_check_mark: | `import "github.com/golang-migrate/migrate/v4"` | Used for stable releases |
+**v3** | :x: | `import "github.com/golang-migrate/migrate"` (with package manager) or `import "gopkg.in/golang-migrate/migrate.v3"` (not recommended) | **DO NOT USE** - No longer supported |
+
+## Development and Contributing
+
+Yes, please! [`Makefile`](Makefile) is your friend,
+read the [development guide](CONTRIBUTING.md).
+
+Also have a look at the [FAQ](FAQ.md).
+
+---
+
+Looking for alternatives? [https://awesome-go.com/#database](https://awesome-go.com/#database).

vendor/github.com/golang-migrate/migrate/v4/database/driver.go

@@ -0,0 +1,122 @@
+// Package database provides the Database interface.
+// All database drivers must implement this interface, register themselves,
+// optionally provide a `WithInstance` function and pass the tests
+// in package database/testing.
+package database
+
+import (
+	"fmt"
+	"io"
+	"sync"
+
+	iurl "github.com/golang-migrate/migrate/v4/internal/url"
+)
+
+var (
+	ErrLocked = fmt.Errorf("can't acquire lock")
+)
+
+const NilVersion int = -1
+
+var driversMu sync.RWMutex
+var drivers = make(map[string]Driver)
+
+// Driver is the interface every database driver must implement.
+//
+// How to implement a database driver?
+//   1. Implement this interface.
+//   2. Optionally, add a function named `WithInstance`.
+//      This function should accept an existing DB instance and a Config{} struct
+//      and return a driver instance.
+//   3. Add a test that calls database/testing.go:Test()
+//   4. Add own tests for Open(), WithInstance() (when provided) and Close().
+//      All other functions are tested by tests in database/testing.
+//      Saves you some time and makes sure all database drivers behave the same way.
+//   5. Call Register in init().
+//   6. Create a migrate/cli/build_<driver-name>.go file
+//   7. Add driver name in 'DATABASE' variable in Makefile
+//
+// Guidelines:
+//   * Don't try to correct user input. Don't assume things.
+//     When in doubt, return an error and explain the situation to the user.
+//   * All configuration input must come from the URL string in func Open()
+//     or the Config{} struct in WithInstance. Don't os.Getenv().
+type Driver interface {
+	// Open returns a new driver instance configured with parameters
+	// coming from the URL string. Migrate will call this function
+	// only once per instance.
+	Open(url string) (Driver, error)
+
+	// Close closes the underlying database instance managed by the driver.
+	// Migrate will call this function only once per instance.
+	Close() error
+
+	// Lock should acquire a database lock so that only one migration process
+	// can run at a time. Migrate will call this function before Run is called.
+	// If the implementation can't provide this functionality, return nil.
+	// Return database.ErrLocked if database is already locked.
+	Lock() error
+
+	// Unlock should release the lock. Migrate will call this function after
+	// all migrations have been run.
+	Unlock() error
+
+	// Run applies a migration to the database. migration is garantueed to be not nil.
+	Run(migration io.Reader) error
+
+	// SetVersion saves version and dirty state.
+	// Migrate will call this function before and after each call to Run.
+	// version must be >= -1. -1 means NilVersion.
+	SetVersion(version int, dirty bool) error
+
+	// Version returns the currently active version and if the database is dirty.
+	// When no migration has been applied, it must return version -1.
+	// Dirty means, a previous migration failed and user interaction is required.
+	Version() (version int, dirty bool, err error)
+
+	// Drop deletes everything in the database.
+	// Note that this is a breaking action, a new call to Open() is necessary to
+	// ensure subsequent calls work as expected.
+	Drop() error
+}
+
+// Open returns a new driver instance.
+func Open(url string) (Driver, error) {
+	scheme, err := iurl.SchemeFromURL(url)
+	if err != nil {
+		return nil, err
+	}
+
+	driversMu.RLock()
+	d, ok := drivers[scheme]
+	driversMu.RUnlock()
+	if !ok {
+		return nil, fmt.Errorf("database driver: unknown driver %v (forgotten import?)", scheme)
+	}
+
+	return d.Open(url)
+}
+
+// Register globally registers a driver.
+func Register(name string, driver Driver) {
+	driversMu.Lock()
+	defer driversMu.Unlock()
+	if driver == nil {
+		panic("Register driver is nil")
+	}
+	if _, dup := drivers[name]; dup {
+		panic("Register called twice for driver " + name)
+	}
+	drivers[name] = driver
+}
+
+// List lists the registered drivers
+func List() []string {
+	driversMu.RLock()
+	defer driversMu.RUnlock()
+	names := make([]string, 0, len(drivers))
+	for n := range drivers {
+		names = append(names, n)
+	}
+	return names
+}

vendor/github.com/golang-migrate/migrate/v4/database/error.go

@@ -0,0 +1,27 @@
+package database
+
+import (
+	"fmt"
+)
+
+// Error should be used for errors involving queries ran against the database
+type Error struct {
+	// Optional: the line number
+	Line uint
+
+	// Query is a query excerpt
+	Query []byte
+
+	// Err is a useful/helping error message for humans
+	Err string
+
+	// OrigErr is the underlying error
+	OrigErr error
+}
+
+func (e Error) Error() string {
+	if len(e.Err) == 0 {
+		return fmt.Sprintf("%v in line %v: %s", e.OrigErr, e.Line, e.Query)
+	}
+	return fmt.Sprintf("%v in line %v: %s (details: %v)", e.Err, e.Line, e.Query, e.OrigErr)
+}

vendor/github.com/golang-migrate/migrate/v4/database/util.go

@@ -0,0 +1,19 @@
+package database
+
+import (
+	"fmt"
+	"hash/crc32"
+	"strings"
+)
+
+const advisoryLockIDSalt uint = 1486364155
+
+// GenerateAdvisoryLockId inspired by rails migrations, see https://goo.gl/8o9bCT
+func GenerateAdvisoryLockId(databaseName string, additionalNames ...string) (string, error) { // nolint: golint
+	if len(additionalNames) > 0 {
+		databaseName = strings.Join(append(additionalNames, databaseName), "\x00")
+	}
+	sum := crc32.ChecksumIEEE([]byte(databaseName))
+	sum = sum * uint32(advisoryLockIDSalt)
+	return fmt.Sprint(sum), nil
+}

vendor/github.com/golang-migrate/migrate/v4/docker-deploy.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin && \
+docker build --build-arg VERSION="$TRAVIS_TAG" . -t migrate/migrate -t migrate/migrate:"$TRAVIS_TAG" && \
+docker push migrate/migrate:"$TRAVIS_TAG" && docker push migrate/migrate

vendor/github.com/golang-migrate/migrate/v4/go.mod

@@ -0,0 +1,56 @@
+module github.com/golang-migrate/migrate/v4
+
+require (
+	cloud.google.com/go v0.37.4
+	github.com/aws/aws-sdk-go v1.17.7
+	github.com/bitly/go-hostpool v0.0.0-20171023180738-a3a6125de932 // indirect
+	github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869 // indirect
+	github.com/cockroachdb/apd v1.1.0 // indirect
+	github.com/cockroachdb/cockroach-go v0.0.0-20181001143604-e0a95dfd547c
+	github.com/containerd/containerd v1.2.7 // indirect
+	github.com/cznic/ql v1.2.0
+	github.com/denisenkom/go-mssqldb v0.0.0-20190515213511-eb9f6a1743f3
+	github.com/dhui/dktest v0.3.0
+	github.com/docker/docker v0.7.3-0.20190817195342-4760db040282
+	github.com/fsouza/fake-gcs-server v1.7.0
+	github.com/go-sql-driver/mysql v1.4.1
+	github.com/gocql/gocql v0.0.0-20190301043612-f6df8288f9b4
+	github.com/gogo/protobuf v1.2.1 // indirect
+	github.com/golang/protobuf v1.3.1 // indirect
+	github.com/golang/snappy v0.0.1 // indirect
+	github.com/google/go-github v17.0.0+incompatible
+	github.com/hashicorp/go-multierror v1.0.0
+	github.com/hashicorp/golang-lru v0.5.1 // indirect
+	github.com/jackc/fake v0.0.0-20150926172116-812a484cc733 // indirect
+	github.com/jackc/pgx v3.2.0+incompatible // indirect
+	github.com/kardianos/osext v0.0.0-20190222173326-2bc1f35cddc0 // indirect
+	github.com/konsorten/go-windows-terminal-sequences v1.0.2 // indirect
+	github.com/kr/pretty v0.1.0 // indirect
+	github.com/kshvakov/clickhouse v1.3.5
+	github.com/lib/pq v1.0.0
+	github.com/mattn/go-sqlite3 v1.10.0
+	github.com/morikuni/aec v0.0.0-20170113033406-39771216ff4c // indirect
+	github.com/nakagami/firebirdsql v0.0.0-20190310045651-3c02a58cfed8
+	github.com/pkg/errors v0.8.1 // indirect
+	github.com/satori/go.uuid v1.2.0 // indirect
+	github.com/shopspring/decimal v0.0.0-20180709203117-cd690d0c9e24 // indirect
+	github.com/sirupsen/logrus v1.4.1 // indirect
+	github.com/stretchr/testify v1.3.0
+	github.com/tidwall/pretty v0.0.0-20180105212114-65a9db5fad51 // indirect
+	github.com/xanzy/go-gitlab v0.15.0
+	github.com/xdg/scram v0.0.0-20180814205039-7eeb5667e42c // indirect
+	github.com/xdg/stringprep v1.0.0 // indirect
+	gitlab.com/nyarla/go-crypt v0.0.0-20160106005555-d9a5dc2b789b // indirect
+	go.mongodb.org/mongo-driver v1.1.0
+	golang.org/x/crypto v0.0.0-20190426145343-a29dc8fdc734 // indirect
+	golang.org/x/net v0.0.0-20190424112056-4829fb13d2c6
+	golang.org/x/oauth2 v0.0.0-20190402181905-9f3314589c9a // indirect
+	golang.org/x/sys v0.0.0-20190426135247-a129542de9ae // indirect
+	golang.org/x/text v0.3.2 // indirect
+	golang.org/x/time v0.0.0-20190308202827-9d24e82272b4 // indirect
+	golang.org/x/tools v0.0.0-20190425222832-ad9eeb80039a
+	google.golang.org/api v0.4.0
+	google.golang.org/appengine v1.5.0 // indirect
+	google.golang.org/genproto v0.0.0-20190425155659-357c62f0e4bb
+	google.golang.org/grpc v1.20.1 // indirect
+)

vendor/github.com/golang-migrate/migrate/v4/go.sum

@@ -0,0 +1,308 @@
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vendor/github.com/golang-migrate/migrate/v4/internal/url/url.go

@@ -0,0 +1,25 @@
+package url
+
+import (
+	"errors"
+	"strings"
+)
+
+var errNoScheme = errors.New("no scheme")
+var errEmptyURL = errors.New("URL cannot be empty")
+
+// schemeFromURL returns the scheme from a URL string
+func SchemeFromURL(url string) (string, error) {
+	if url == "" {
+		return "", errEmptyURL
+	}
+
+	i := strings.Index(url, ":")
+
+	// No : or : is the first character.
+	if i < 1 {
+		return "", errNoScheme
+	}
+
+	return url[0:i], nil
+}

vendor/github.com/golang-migrate/migrate/v4/log.go

@@ -0,0 +1,12 @@
+package migrate
+
+// Logger is an interface so you can pass in your own
+// logging implementation.
+type Logger interface {
+
+	// Printf is like fmt.Printf
+	Printf(format string, v ...interface{})
+
+	// Verbose should return true when verbose logging output is wanted
+	Verbose() bool
+}

vendor/github.com/golang-migrate/migrate/v4/migrate.go

@@ -0,0 +1,980 @@
+// Package migrate reads migrations from sources and runs them against databases.
+// Sources are defined by the `source.Driver` and databases by the `database.Driver`
+// interface. The driver interfaces are kept "dump", all migration logic is kept
+// in this package.
+package migrate
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"sync"
+	"time"
+
+	"github.com/hashicorp/go-multierror"
+
+	"github.com/golang-migrate/migrate/v4/database"
+	iurl "github.com/golang-migrate/migrate/v4/internal/url"
+	"github.com/golang-migrate/migrate/v4/source"
+)
+
+// DefaultPrefetchMigrations sets the number of migrations to pre-read
+// from the source. This is helpful if the source is remote, but has little
+// effect for a local source (i.e. file system).
+// Please note that this setting has a major impact on the memory usage,
+// since each pre-read migration is buffered in memory. See DefaultBufferSize.
+var DefaultPrefetchMigrations = uint(10)
+
+// DefaultLockTimeout sets the max time a database driver has to acquire a lock.
+var DefaultLockTimeout = 15 * time.Second
+
+var (
+	ErrNoChange       = errors.New("no change")
+	ErrNilVersion     = errors.New("no migration")
+	ErrInvalidVersion = errors.New("version must be >= -1")
+	ErrLocked         = errors.New("database locked")
+	ErrLockTimeout    = errors.New("timeout: can't acquire database lock")
+)
+
+// ErrShortLimit is an error returned when not enough migrations
+// can be returned by a source for a given limit.
+type ErrShortLimit struct {
+	Short uint
+}
+
+// Error implements the error interface.
+func (e ErrShortLimit) Error() string {
+	return fmt.Sprintf("limit %v short", e.Short)
+}
+
+type ErrDirty struct {
+	Version int
+}
+
+func (e ErrDirty) Error() string {
+	return fmt.Sprintf("Dirty database version %v. Fix and force version.", e.Version)
+}
+
+type Migrate struct {
+	sourceName   string
+	sourceDrv    source.Driver
+	databaseName string
+	databaseDrv  database.Driver
+
+	// Log accepts a Logger interface
+	Log Logger
+
+	// GracefulStop accepts `true` and will stop executing migrations
+	// as soon as possible at a safe break point, so that the database
+	// is not corrupted.
+	GracefulStop chan bool
+	isLockedMu   *sync.Mutex
+
+	isGracefulStop bool
+	isLocked       bool
+
+	// PrefetchMigrations defaults to DefaultPrefetchMigrations,
+	// but can be set per Migrate instance.
+	PrefetchMigrations uint
+
+	// LockTimeout defaults to DefaultLockTimeout,
+	// but can be set per Migrate instance.
+	LockTimeout time.Duration
+}
+
+// New returns a new Migrate instance from a source URL and a database URL.
+// The URL scheme is defined by each driver.
+func New(sourceURL, databaseURL string) (*Migrate, error) {
+	m := newCommon()
+
+	sourceName, err := iurl.SchemeFromURL(sourceURL)
+	if err != nil {
+		return nil, err
+	}
+	m.sourceName = sourceName
+
+	databaseName, err := iurl.SchemeFromURL(databaseURL)
+	if err != nil {
+		return nil, err
+	}
+	m.databaseName = databaseName
+
+	sourceDrv, err := source.Open(sourceURL)
+	if err != nil {
+		return nil, err
+	}
+	m.sourceDrv = sourceDrv
+
+	databaseDrv, err := database.Open(databaseURL)
+	if err != nil {
+		return nil, err
+	}
+	m.databaseDrv = databaseDrv
+
+	return m, nil
+}
+
+// NewWithDatabaseInstance returns a new Migrate instance from a source URL
+// and an existing database instance. The source URL scheme is defined by each driver.
+// Use any string that can serve as an identifier during logging as databaseName.
+// You are responsible for closing the underlying database client if necessary.
+func NewWithDatabaseInstance(sourceURL string, databaseName string, databaseInstance database.Driver) (*Migrate, error) {
+	m := newCommon()
+
+	sourceName, err := iurl.SchemeFromURL(sourceURL)
+	if err != nil {
+		return nil, err
+	}
+	m.sourceName = sourceName
+
+	m.databaseName = databaseName
+
+	sourceDrv, err := source.Open(sourceURL)
+	if err != nil {
+		return nil, err
+	}
+	m.sourceDrv = sourceDrv
+
+	m.databaseDrv = databaseInstance
+
+	return m, nil
+}
+
+// NewWithSourceInstance returns a new Migrate instance from an existing source instance
+// and a database URL. The database URL scheme is defined by each driver.
+// Use any string that can serve as an identifier during logging as sourceName.
+// You are responsible for closing the underlying source client if necessary.
+func NewWithSourceInstance(sourceName string, sourceInstance source.Driver, databaseURL string) (*Migrate, error) {
+	m := newCommon()
+
+	databaseName, err := iurl.SchemeFromURL(databaseURL)
+	if err != nil {
+		return nil, err
+	}
+	m.databaseName = databaseName
+
+	m.sourceName = sourceName
+
+	databaseDrv, err := database.Open(databaseURL)
+	if err != nil {
+		return nil, err
+	}
+	m.databaseDrv = databaseDrv
+
+	m.sourceDrv = sourceInstance
+
+	return m, nil
+}
+
+// NewWithInstance returns a new Migrate instance from an existing source and
+// database instance. Use any string that can serve as an identifier during logging
+// as sourceName and databaseName. You are responsible for closing down
+// the underlying source and database client if necessary.
+func NewWithInstance(sourceName string, sourceInstance source.Driver, databaseName string, databaseInstance database.Driver) (*Migrate, error) {
+	m := newCommon()
+
+	m.sourceName = sourceName
+	m.databaseName = databaseName
+
+	m.sourceDrv = sourceInstance
+	m.databaseDrv = databaseInstance
+
+	return m, nil
+}
+
+func newCommon() *Migrate {
+	return &Migrate{
+		GracefulStop:       make(chan bool, 1),
+		PrefetchMigrations: DefaultPrefetchMigrations,
+		LockTimeout:        DefaultLockTimeout,
+		isLockedMu:         &sync.Mutex{},
+	}
+}
+
+// Close closes the source and the database.
+func (m *Migrate) Close() (source error, database error) {
+	databaseSrvClose := make(chan error)
+	sourceSrvClose := make(chan error)
+
+	m.logVerbosePrintf("Closing source and database\n")
+
+	go func() {
+		databaseSrvClose <- m.databaseDrv.Close()
+	}()
+
+	go func() {
+		sourceSrvClose <- m.sourceDrv.Close()
+	}()
+
+	return <-sourceSrvClose, <-databaseSrvClose
+}
+
+// Migrate looks at the currently active migration version,
+// then migrates either up or down to the specified version.
+func (m *Migrate) Migrate(version uint) error {
+	if err := m.lock(); err != nil {
+		return err
+	}
+
+	curVersion, dirty, err := m.databaseDrv.Version()
+	if err != nil {
+		return m.unlockErr(err)
+	}
+
+	if dirty {
+		return m.unlockErr(ErrDirty{curVersion})
+	}
+
+	ret := make(chan interface{}, m.PrefetchMigrations)
+	go m.read(curVersion, int(version), ret)
+
+	return m.unlockErr(m.runMigrations(ret))
+}
+
+// Steps looks at the currently active migration version.
+// It will migrate up if n > 0, and down if n < 0.
+func (m *Migrate) Steps(n int) error {
+	if n == 0 {
+		return ErrNoChange
+	}
+
+	if err := m.lock(); err != nil {
+		return err
+	}
+
+	curVersion, dirty, err := m.databaseDrv.Version()
+	if err != nil {
+		return m.unlockErr(err)
+	}
+
+	if dirty {
+		return m.unlockErr(ErrDirty{curVersion})
+	}
+
+	ret := make(chan interface{}, m.PrefetchMigrations)
+
+	if n > 0 {
+		go m.readUp(curVersion, n, ret)
+	} else {
+		go m.readDown(curVersion, -n, ret)
+	}
+
+	return m.unlockErr(m.runMigrations(ret))
+}
+
+// Up looks at the currently active migration version
+// and will migrate all the way up (applying all up migrations).
+func (m *Migrate) Up() error {
+	if err := m.lock(); err != nil {
+		return err
+	}
+
+	curVersion, dirty, err := m.databaseDrv.Version()
+	if err != nil {
+		return m.unlockErr(err)
+	}
+
+	if dirty {
+		return m.unlockErr(ErrDirty{curVersion})
+	}
+
+	ret := make(chan interface{}, m.PrefetchMigrations)
+
+	go m.readUp(curVersion, -1, ret)
+	return m.unlockErr(m.runMigrations(ret))
+}
+
+// Down looks at the currently active migration version
+// and will migrate all the way down (applying all down migrations).
+func (m *Migrate) Down() error {
+	if err := m.lock(); err != nil {
+		return err
+	}
+
+	curVersion, dirty, err := m.databaseDrv.Version()
+	if err != nil {
+		return m.unlockErr(err)
+	}
+
+	if dirty {
+		return m.unlockErr(ErrDirty{curVersion})
+	}
+
+	ret := make(chan interface{}, m.PrefetchMigrations)
+	go m.readDown(curVersion, -1, ret)
+	return m.unlockErr(m.runMigrations(ret))
+}
+
+// Drop deletes everything in the database.
+func (m *Migrate) Drop() error {
+	if err := m.lock(); err != nil {
+		return err
+	}
+	if err := m.databaseDrv.Drop(); err != nil {
+		return m.unlockErr(err)
+	}
+	return m.unlock()
+}
+
+// Run runs any migration provided by you against the database.
+// It does not check any currently active version in database.
+// Usually you don't need this function at all. Use Migrate,
+// Steps, Up or Down instead.
+func (m *Migrate) Run(migration ...*Migration) error {
+	if len(migration) == 0 {
+		return ErrNoChange
+	}
+
+	if err := m.lock(); err != nil {
+		return err
+	}
+
+	curVersion, dirty, err := m.databaseDrv.Version()
+	if err != nil {
+		return m.unlockErr(err)
+	}
+
+	if dirty {
+		return m.unlockErr(ErrDirty{curVersion})
+	}
+
+	ret := make(chan interface{}, m.PrefetchMigrations)
+
+	go func() {
+		defer close(ret)
+		for _, migr := range migration {
+			if m.PrefetchMigrations > 0 && migr.Body != nil {
+				m.logVerbosePrintf("Start buffering %v\n", migr.LogString())
+			} else {
+				m.logVerbosePrintf("Scheduled %v\n", migr.LogString())
+			}
+
+			ret <- migr
+			go func(migr *Migration) {
+				if err := migr.Buffer(); err != nil {
+					m.logErr(err)
+				}
+			}(migr)
+		}
+	}()
+
+	return m.unlockErr(m.runMigrations(ret))
+}
+
+// Force sets a migration version.
+// It does not check any currently active version in database.
+// It resets the dirty state to false.
+func (m *Migrate) Force(version int) error {
+	if version < -1 {
+		return ErrInvalidVersion
+	}
+
+	if err := m.lock(); err != nil {
+		return err
+	}
+
+	if err := m.databaseDrv.SetVersion(version, false); err != nil {
+		return m.unlockErr(err)
+	}
+
+	return m.unlock()
+}
+
+// Version returns the currently active migration version.
+// If no migration has been applied, yet, it will return ErrNilVersion.
+func (m *Migrate) Version() (version uint, dirty bool, err error) {
+	v, d, err := m.databaseDrv.Version()
+	if err != nil {
+		return 0, false, err
+	}
+
+	if v == database.NilVersion {
+		return 0, false, ErrNilVersion
+	}
+
+	return suint(v), d, nil
+}
+
+// read reads either up or down migrations from source `from` to `to`.
+// Each migration is then written to the ret channel.
+// If an error occurs during reading, that error is written to the ret channel, too.
+// Once read is done reading it will close the ret channel.
+func (m *Migrate) read(from int, to int, ret chan<- interface{}) {
+	defer close(ret)
+
+	// check if from version exists
+	if from >= 0 {
+		if err := m.versionExists(suint(from)); err != nil {
+			ret <- err
+			return
+		}
+	}
+
+	// check if to version exists
+	if to >= 0 {
+		if err := m.versionExists(suint(to)); err != nil {
+			ret <- err
+			return
+		}
+	}
+
+	// no change?
+	if from == to {
+		ret <- ErrNoChange
+		return
+	}
+
+	if from < to {
+		// it's going up
+		// apply first migration if from is nil version
+		if from == -1 {
+			firstVersion, err := m.sourceDrv.First()
+			if err != nil {
+				ret <- err
+				return
+			}
+
+			migr, err := m.newMigration(firstVersion, int(firstVersion))
+			if err != nil {
+				ret <- err
+				return
+			}
+
+			ret <- migr
+			go func() {
+				if err := migr.Buffer(); err != nil {
+					m.logErr(err)
+				}
+			}()
+
+			from = int(firstVersion)
+		}
+
+		// run until we reach target ...
+		for from < to {
+			if m.stop() {
+				return
+			}
+
+			next, err := m.sourceDrv.Next(suint(from))
+			if err != nil {
+				ret <- err
+				return
+			}
+
+			migr, err := m.newMigration(next, int(next))
+			if err != nil {
+				ret <- err
+				return
+			}
+
+			ret <- migr
+			go func() {
+				if err := migr.Buffer(); err != nil {
+					m.logErr(err)
+				}
+			}()
+
+			from = int(next)
+		}
+
+	} else {
+		// it's going down
+		// run until we reach target ...
+		for from > to && from >= 0 {
+			if m.stop() {
+				return
+			}
+
+			prev, err := m.sourceDrv.Prev(suint(from))
+			if os.IsNotExist(err) && to == -1 {
+				// apply nil migration
+				migr, err := m.newMigration(suint(from), -1)
+				if err != nil {
+					ret <- err
+					return
+				}
+				ret <- migr
+				go func() {
+					if err := migr.Buffer(); err != nil {
+						m.logErr(err)
+					}
+				}()
+
+				return
+
+			} else if err != nil {
+				ret <- err
+				return
+			}
+
+			migr, err := m.newMigration(suint(from), int(prev))
+			if err != nil {
+				ret <- err
+				return
+			}
+
+			ret <- migr
+			go func() {
+				if err := migr.Buffer(); err != nil {
+					m.logErr(err)
+				}
+			}()
+
+			from = int(prev)
+		}
+	}
+}
+
+// readUp reads up migrations from `from` limitted by `limit`.
+// limit can be -1, implying no limit and reading until there are no more migrations.
+// Each migration is then written to the ret channel.
+// If an error occurs during reading, that error is written to the ret channel, too.
+// Once readUp is done reading it will close the ret channel.
+func (m *Migrate) readUp(from int, limit int, ret chan<- interface{}) {
+	defer close(ret)
+
+	// check if from version exists
+	if from >= 0 {
+		if err := m.versionExists(suint(from)); err != nil {
+			ret <- err
+			return
+		}
+	}
+
+	if limit == 0 {
+		ret <- ErrNoChange
+		return
+	}
+
+	count := 0
+	for count < limit || limit == -1 {
+		if m.stop() {
+			return
+		}
+
+		// apply first migration if from is nil version
+		if from == -1 {
+			firstVersion, err := m.sourceDrv.First()
+			if err != nil {
+				ret <- err
+				return
+			}
+
+			migr, err := m.newMigration(firstVersion, int(firstVersion))
+			if err != nil {
+				ret <- err
+				return
+			}
+
+			ret <- migr
+			go func() {
+				if err := migr.Buffer(); err != nil {
+					m.logErr(err)
+				}
+			}()
+			from = int(firstVersion)
+			count++
+			continue
+		}
+
+		// apply next migration
+		next, err := m.sourceDrv.Next(suint(from))
+		if os.IsNotExist(err) {
+			// no limit, but no migrations applied?
+			if limit == -1 && count == 0 {
+				ret <- ErrNoChange
+				return
+			}
+
+			// no limit, reached end
+			if limit == -1 {
+				return
+			}
+
+			// reached end, and didn't apply any migrations
+			if limit > 0 && count == 0 {
+				ret <- os.ErrNotExist
+				return
+			}
+
+			// applied less migrations than limit?
+			if count < limit {
+				ret <- ErrShortLimit{suint(limit - count)}
+				return
+			}
+		}
+		if err != nil {
+			ret <- err
+			return
+		}
+
+		migr, err := m.newMigration(next, int(next))
+		if err != nil {
+			ret <- err
+			return
+		}
+
+		ret <- migr
+		go func() {
+			if err := migr.Buffer(); err != nil {
+				m.logErr(err)
+			}
+		}()
+		from = int(next)
+		count++
+	}
+}
+
+// readDown reads down migrations from `from` limitted by `limit`.
+// limit can be -1, implying no limit and reading until there are no more migrations.
+// Each migration is then written to the ret channel.
+// If an error occurs during reading, that error is written to the ret channel, too.
+// Once readDown is done reading it will close the ret channel.
+func (m *Migrate) readDown(from int, limit int, ret chan<- interface{}) {
+	defer close(ret)
+
+	// check if from version exists
+	if from >= 0 {
+		if err := m.versionExists(suint(from)); err != nil {
+			ret <- err
+			return
+		}
+	}
+
+	if limit == 0 {
+		ret <- ErrNoChange
+		return
+	}
+
+	// no change if already at nil version
+	if from == -1 && limit == -1 {
+		ret <- ErrNoChange
+		return
+	}
+
+	// can't go over limit if already at nil version
+	if from == -1 && limit > 0 {
+		ret <- os.ErrNotExist
+		return
+	}
+
+	count := 0
+	for count < limit || limit == -1 {
+		if m.stop() {
+			return
+		}
+
+		prev, err := m.sourceDrv.Prev(suint(from))
+		if os.IsNotExist(err) {
+			// no limit or haven't reached limit, apply "first" migration
+			if limit == -1 || limit-count > 0 {
+				firstVersion, err := m.sourceDrv.First()
+				if err != nil {
+					ret <- err
+					return
+				}
+
+				migr, err := m.newMigration(firstVersion, -1)
+				if err != nil {
+					ret <- err
+					return
+				}
+				ret <- migr
+				go func() {
+					if err := migr.Buffer(); err != nil {
+						m.logErr(err)
+					}
+				}()
+				count++
+			}
+
+			if count < limit {
+				ret <- ErrShortLimit{suint(limit - count)}
+			}
+			return
+		}
+		if err != nil {
+			ret <- err
+			return
+		}
+
+		migr, err := m.newMigration(suint(from), int(prev))
+		if err != nil {
+			ret <- err
+			return
+		}
+
+		ret <- migr
+		go func() {
+			if err := migr.Buffer(); err != nil {
+				m.logErr(err)
+			}
+		}()
+		from = int(prev)
+		count++
+	}
+}
+
+// runMigrations reads *Migration and error from a channel. Any other type
+// sent on this channel will result in a panic. Each migration is then
+// proxied to the database driver and run against the database.
+// Before running a newly received migration it will check if it's supposed
+// to stop execution because it might have received a stop signal on the
+// GracefulStop channel.
+func (m *Migrate) runMigrations(ret <-chan interface{}) error {
+	for r := range ret {
+
+		if m.stop() {
+			return nil
+		}
+
+		switch r := r.(type) {
+		case error:
+			return r
+
+		case *Migration:
+			migr := r
+
+			// set version with dirty state
+			if err := m.databaseDrv.SetVersion(migr.TargetVersion, true); err != nil {
+				return err
+			}
+
+			if migr.Body != nil {
+				m.logVerbosePrintf("Read and execute %v\n", migr.LogString())
+				if err := m.databaseDrv.Run(migr.BufferedBody); err != nil {
+					return err
+				}
+			}
+
+			// set clean state
+			if err := m.databaseDrv.SetVersion(migr.TargetVersion, false); err != nil {
+				return err
+			}
+
+			endTime := time.Now()
+			readTime := migr.FinishedReading.Sub(migr.StartedBuffering)
+			runTime := endTime.Sub(migr.FinishedReading)
+
+			// log either verbose or normal
+			if m.Log != nil {
+				if m.Log.Verbose() {
+					m.logPrintf("Finished %v (read %v, ran %v)\n", migr.LogString(), readTime, runTime)
+				} else {
+					m.logPrintf("%v (%v)\n", migr.LogString(), readTime+runTime)
+				}
+			}
+
+		default:
+			return fmt.Errorf("unknown type: %T with value: %+v", r, r)
+		}
+	}
+	return nil
+}
+
+// versionExists checks the source if either the up or down migration for
+// the specified migration version exists.
+func (m *Migrate) versionExists(version uint) (result error) {
+	// try up migration first
+	up, _, err := m.sourceDrv.ReadUp(version)
+	if err == nil {
+		defer func() {
+			if errClose := up.Close(); errClose != nil {
+				result = multierror.Append(result, errClose)
+			}
+		}()
+	}
+	if os.IsExist(err) {
+		return nil
+	} else if !os.IsNotExist(err) {
+		return err
+	}
+
+	// then try down migration
+	down, _, err := m.sourceDrv.ReadDown(version)
+	if err == nil {
+		defer func() {
+			if errClose := down.Close(); errClose != nil {
+				result = multierror.Append(result, errClose)
+			}
+		}()
+	}
+	if os.IsExist(err) {
+		return nil
+	} else if !os.IsNotExist(err) {
+		return err
+	}
+
+	m.logErr(fmt.Errorf("no migration found for version %d", version))
+	return os.ErrNotExist
+}
+
+// stop returns true if no more migrations should be run against the database
+// because a stop signal was received on the GracefulStop channel.
+// Calls are cheap and this function is not blocking.
+func (m *Migrate) stop() bool {
+	if m.isGracefulStop {
+		return true
+	}
+
+	select {
+	case <-m.GracefulStop:
+		m.isGracefulStop = true
+		return true
+
+	default:
+		return false
+	}
+}
+
+// newMigration is a helper func that returns a *Migration for the
+// specified version and targetVersion.
+func (m *Migrate) newMigration(version uint, targetVersion int) (*Migration, error) {
+	var migr *Migration
+
+	if targetVersion >= int(version) {
+		r, identifier, err := m.sourceDrv.ReadUp(version)
+		if os.IsNotExist(err) {
+			// create "empty" migration
+			migr, err = NewMigration(nil, "", version, targetVersion)
+			if err != nil {
+				return nil, err
+			}
+
+		} else if err != nil {
+			return nil, err
+
+		} else {
+			// create migration from up source
+			migr, err = NewMigration(r, identifier, version, targetVersion)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+	} else {
+		r, identifier, err := m.sourceDrv.ReadDown(version)
+		if os.IsNotExist(err) {
+			// create "empty" migration
+			migr, err = NewMigration(nil, "", version, targetVersion)
+			if err != nil {
+				return nil, err
+			}
+
+		} else if err != nil {
+			return nil, err
+
+		} else {
+			// create migration from down source
+			migr, err = NewMigration(r, identifier, version, targetVersion)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	if m.PrefetchMigrations > 0 && migr.Body != nil {
+		m.logVerbosePrintf("Start buffering %v\n", migr.LogString())
+	} else {
+		m.logVerbosePrintf("Scheduled %v\n", migr.LogString())
+	}
+
+	return migr, nil
+}
+
+// lock is a thread safe helper function to lock the database.
+// It should be called as late as possible when running migrations.
+func (m *Migrate) lock() error {
+	m.isLockedMu.Lock()
+	defer m.isLockedMu.Unlock()
+
+	if m.isLocked {
+		return ErrLocked
+	}
+
+	// create done channel, used in the timeout goroutine
+	done := make(chan bool, 1)
+	defer func() {
+		done <- true
+	}()
+
+	// use errchan to signal error back to this context
+	errchan := make(chan error, 2)
+
+	// start timeout goroutine
+	timeout := time.After(m.LockTimeout)
+	go func() {
+		for {
+			select {
+			case <-done:
+				return
+			case <-timeout:
+				errchan <- ErrLockTimeout
+				return
+			}
+		}
+	}()
+
+	// now try to acquire the lock
+	go func() {
+		if err := m.databaseDrv.Lock(); err != nil {
+			errchan <- err
+		} else {
+			errchan <- nil
+		}
+	}()
+
+	// wait until we either receive ErrLockTimeout or error from Lock operation
+	err := <-errchan
+	if err == nil {
+		m.isLocked = true
+	}
+	return err
+}
+
+// unlock is a thread safe helper function to unlock the database.
+// It should be called as early as possible when no more migrations are
+// expected to be executed.
+func (m *Migrate) unlock() error {
+	m.isLockedMu.Lock()
+	defer m.isLockedMu.Unlock()
+
+	if err := m.databaseDrv.Unlock(); err != nil {
+		// BUG: Can potentially create a deadlock. Add a timeout.
+		return err
+	}
+
+	m.isLocked = false
+	return nil
+}
+
+// unlockErr calls unlock and returns a combined error
+// if a prevErr is not nil.
+func (m *Migrate) unlockErr(prevErr error) error {
+	if err := m.unlock(); err != nil {
+		return multierror.Append(prevErr, err)
+	}
+	return prevErr
+}
+
+// logPrintf writes to m.Log if not nil
+func (m *Migrate) logPrintf(format string, v ...interface{}) {
+	if m.Log != nil {
+		m.Log.Printf(format, v...)
+	}
+}
+
+// logVerbosePrintf writes to m.Log if not nil. Use for verbose logging output.
+func (m *Migrate) logVerbosePrintf(format string, v ...interface{}) {
+	if m.Log != nil && m.Log.Verbose() {
+		m.Log.Printf(format, v...)
+	}
+}
+
+// logErr writes error to m.Log if not nil
+func (m *Migrate) logErr(err error) {
+	if m.Log != nil {
+		m.Log.Printf("error: %v", err)
+	}
+}

vendor/github.com/golang-migrate/migrate/v4/migration.go

@@ -0,0 +1,160 @@
+package migrate
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"time"
+)
+
+// DefaultBufferSize sets the in memory buffer size (in Bytes) for every
+// pre-read migration (see DefaultPrefetchMigrations).
+var DefaultBufferSize = uint(100000)
+
+// Migration holds information about a migration.
+// It is initially created from data coming from the source and then
+// used when run against the database.
+type Migration struct {
+	// Identifier can be any string to help identifying
+	// the migration in the source.
+	Identifier string
+
+	// Version is the version of this migration.
+	Version uint
+
+	// TargetVersion is the migration version after this migration
+	// has been applied to the database.
+	// Can be -1, implying that this is a NilVersion.
+	TargetVersion int
+
+	// Body holds an io.ReadCloser to the source.
+	Body io.ReadCloser
+
+	// BufferedBody holds an buffered io.Reader to the underlying Body.
+	BufferedBody io.Reader
+
+	// BufferSize defaults to DefaultBufferSize
+	BufferSize uint
+
+	// bufferWriter holds an io.WriteCloser and pipes to BufferBody.
+	// It's an *Closer for flow control.
+	bufferWriter io.WriteCloser
+
+	// Scheduled is the time when the migration was scheduled/ queued.
+	Scheduled time.Time
+
+	// StartedBuffering is the time when buffering of the migration source started.
+	StartedBuffering time.Time
+
+	// FinishedBuffering is the time when buffering of the migration source finished.
+	FinishedBuffering time.Time
+
+	// FinishedReading is the time when the migration source is fully read.
+	FinishedReading time.Time
+
+	// BytesRead holds the number of Bytes read from the migration source.
+	BytesRead int64
+}
+
+// NewMigration returns a new Migration and sets the body, identifier,
+// version and targetVersion. Body can be nil, which turns this migration
+// into a "NilMigration". If no identifier is provided, it will default to "<empty>".
+// targetVersion can be -1, implying it is a NilVersion.
+//
+// What is a NilMigration?
+// Usually each migration version coming from source is expected to have an
+// Up and Down migration. This is not a hard requirement though, leading to
+// a situation where only the Up or Down migration is present. So let's say
+// the user wants to migrate up to a version that doesn't have the actual Up
+// migration, in that case we still want to apply the version, but with an empty
+// body. We are calling that a NilMigration, a migration with an empty body.
+//
+// What is a NilVersion?
+// NilVersion is a const(-1). When running down migrations and we are at the
+// last down migration, there is no next down migration, the targetVersion should
+// be nil. Nil in this case is represented by -1 (because type int).
+func NewMigration(body io.ReadCloser, identifier string,
+	version uint, targetVersion int) (*Migration, error) {
+	tnow := time.Now()
+	m := &Migration{
+		Identifier:    identifier,
+		Version:       version,
+		TargetVersion: targetVersion,
+		Scheduled:     tnow,
+	}
+
+	if body == nil {
+		if len(identifier) == 0 {
+			m.Identifier = "<empty>"
+		}
+
+		m.StartedBuffering = tnow
+		m.FinishedBuffering = tnow
+		m.FinishedReading = tnow
+		return m, nil
+	}
+
+	br, bw := io.Pipe()
+	m.Body = body // want to simulate low latency? newSlowReader(body)
+	m.BufferSize = DefaultBufferSize
+	m.BufferedBody = br
+	m.bufferWriter = bw
+	return m, nil
+}
+
+// String implements string.Stringer and is used in tests.
+func (m *Migration) String() string {
+	return fmt.Sprintf("%v [%v=>%v]", m.Identifier, m.Version, m.TargetVersion)
+}
+
+// LogString returns a string describing this migration to humans.
+func (m *Migration) LogString() string {
+	directionStr := "u"
+	if m.TargetVersion < int(m.Version) {
+		directionStr = "d"
+	}
+	return fmt.Sprintf("%v/%v %v", m.Version, directionStr, m.Identifier)
+}
+
+// Buffer buffers Body up to BufferSize.
+// Calling this function blocks. Call with goroutine.
+func (m *Migration) Buffer() error {
+	if m.Body == nil {
+		return nil
+	}
+
+	m.StartedBuffering = time.Now()
+
+	b := bufio.NewReaderSize(m.Body, int(m.BufferSize))
+
+	// start reading from body, peek won't move the read pointer though
+	// poor man's solution?
+	if _, err := b.Peek(int(m.BufferSize)); err != nil && err != io.EOF {
+		return err
+	}
+
+	m.FinishedBuffering = time.Now()
+
+	// write to bufferWriter, this will block until
+	// something starts reading from m.Buffer
+	n, err := b.WriteTo(m.bufferWriter)
+	if err != nil {
+		return err
+	}
+
+	m.FinishedReading = time.Now()
+	m.BytesRead = n
+
+	// close bufferWriter so Buffer knows that there is no
+	// more data coming
+	if err := m.bufferWriter.Close(); err != nil {
+		return err
+	}
+
+	// it's safe to close the Body too
+	if err := m.Body.Close(); err != nil {
+		return err
+	}
+
+	return nil
+}

vendor/github.com/golang-migrate/migrate/v4/source/driver.go

@@ -0,0 +1,118 @@
+// Package source provides the Source interface.
+// All source drivers must implement this interface, register themselves,
+// optionally provide a `WithInstance` function and pass the tests
+// in package source/testing.
+package source
+
+import (
+	"fmt"
+	"io"
+	nurl "net/url"
+	"sync"
+)
+
+var driversMu sync.RWMutex
+var drivers = make(map[string]Driver)
+
+// Driver is the interface every source driver must implement.
+//
+// How to implement a source driver?
+//   1. Implement this interface.
+//   2. Optionally, add a function named `WithInstance`.
+//      This function should accept an existing source instance and a Config{} struct
+//      and return a driver instance.
+//   3. Add a test that calls source/testing.go:Test()
+//   4. Add own tests for Open(), WithInstance() (when provided) and Close().
+//      All other functions are tested by tests in source/testing.
+//      Saves you some time and makes sure all source drivers behave the same way.
+//   5. Call Register in init().
+//
+// Guidelines:
+//   * All configuration input must come from the URL string in func Open()
+//     or the Config{} struct in WithInstance. Don't os.Getenv().
+//   * Drivers are supposed to be read only.
+//   * Ideally don't load any contents (into memory) in Open or WithInstance.
+type Driver interface {
+	// Open returns a a new driver instance configured with parameters
+	// coming from the URL string. Migrate will call this function
+	// only once per instance.
+	Open(url string) (Driver, error)
+
+	// Close closes the underlying source instance managed by the driver.
+	// Migrate will call this function only once per instance.
+	Close() error
+
+	// First returns the very first migration version available to the driver.
+	// Migrate will call this function multiple times.
+	// If there is no version available, it must return os.ErrNotExist.
+	First() (version uint, err error)
+
+	// Prev returns the previous version for a given version available to the driver.
+	// Migrate will call this function multiple times.
+	// If there is no previous version available, it must return os.ErrNotExist.
+	Prev(version uint) (prevVersion uint, err error)
+
+	// Next returns the next version for a given version available to the driver.
+	// Migrate will call this function multiple times.
+	// If there is no next version available, it must return os.ErrNotExist.
+	Next(version uint) (nextVersion uint, err error)
+
+	// ReadUp returns the UP migration body and an identifier that helps
+	// finding this migration in the source for a given version.
+	// If there is no up migration available for this version,
+	// it must return os.ErrNotExist.
+	// Do not start reading, just return the ReadCloser!
+	ReadUp(version uint) (r io.ReadCloser, identifier string, err error)
+
+	// ReadDown returns the DOWN migration body and an identifier that helps
+	// finding this migration in the source for a given version.
+	// If there is no down migration available for this version,
+	// it must return os.ErrNotExist.
+	// Do not start reading, just return the ReadCloser!
+	ReadDown(version uint) (r io.ReadCloser, identifier string, err error)
+}
+
+// Open returns a new driver instance.
+func Open(url string) (Driver, error) {
+	u, err := nurl.Parse(url)
+	if err != nil {
+		return nil, err
+	}
+
+	if u.Scheme == "" {
+		return nil, fmt.Errorf("source driver: invalid URL scheme")
+	}
+
+	driversMu.RLock()
+	d, ok := drivers[u.Scheme]
+	driversMu.RUnlock()
+	if !ok {
+		return nil, fmt.Errorf("source driver: unknown driver %v (forgotten import?)", u.Scheme)
+	}
+
+	return d.Open(url)
+}
+
+// Register globally registers a driver.
+func Register(name string, driver Driver) {
+	driversMu.Lock()
+	defer driversMu.Unlock()
+	if driver == nil {
+		panic("Register driver is nil")
+	}
+	if _, dup := drivers[name]; dup {
+		panic("Register called twice for driver " + name)
+	}
+	drivers[name] = driver
+}
+
+// List lists the registered drivers
+func List() []string {
+	driversMu.RLock()
+	defer driversMu.RUnlock()
+	names := make([]string, 0, len(drivers))
+	for n := range drivers {
+		names = append(names, n)
+	}
+	return names
+}

vendor/github.com/golang-migrate/migrate/v4/source/migration.go

@@ -0,0 +1,143 @@
+package source
+
+import (
+	"sort"
+)
+
+// Direction is either up or down.
+type Direction string
+
+const (
+	Down Direction = "down"
+	Up   Direction = "up"
+)
+
+// Migration is a helper struct for source drivers that need to
+// build the full directory tree in memory.
+// Migration is fully independent from migrate.Migration.
+type Migration struct {
+	// Version is the version of this migration.
+	Version uint
+
+	// Identifier can be any string that helps identifying
+	// this migration in the source.
+	Identifier string
+
+	// Direction is either Up or Down.
+	Direction Direction
+
+	// Raw holds the raw location path to this migration in source.
+	// ReadUp and ReadDown will use this.
+	Raw string
+}
+
+// Migrations wraps Migration and has an internal index
+// to keep track of Migration order.
+type Migrations struct {
+	index      uintSlice
+	migrations map[uint]map[Direction]*Migration
+}
+
+func NewMigrations() *Migrations {
+	return &Migrations{
+		index:      make(uintSlice, 0),
+		migrations: make(map[uint]map[Direction]*Migration),
+	}
+}
+
+func (i *Migrations) Append(m *Migration) (ok bool) {
+	if m == nil {
+		return false
+	}
+
+	if i.migrations[m.Version] == nil {
+		i.migrations[m.Version] = make(map[Direction]*Migration)
+	}
+
+	// reject duplicate versions
+	if _, dup := i.migrations[m.Version][m.Direction]; dup {
+		return false
+	}
+
+	i.migrations[m.Version][m.Direction] = m
+	i.buildIndex()
+
+	return true
+}
+
+func (i *Migrations) buildIndex() {
+	i.index = make(uintSlice, 0)
+	for version := range i.migrations {
+		i.index = append(i.index, version)
+	}
+	sort.Sort(i.index)
+}
+
+func (i *Migrations) First() (version uint, ok bool) {
+	if len(i.index) == 0 {
+		return 0, false
+	}
+	return i.index[0], true
+}
+
+func (i *Migrations) Prev(version uint) (prevVersion uint, ok bool) {
+	pos := i.findPos(version)
+	if pos >= 1 && len(i.index) > pos-1 {
+		return i.index[pos-1], true
+	}
+	return 0, false
+}
+
+func (i *Migrations) Next(version uint) (nextVersion uint, ok bool) {
+	pos := i.findPos(version)
+	if pos >= 0 && len(i.index) > pos+1 {
+		return i.index[pos+1], true
+	}
+	return 0, false
+}
+
+func (i *Migrations) Up(version uint) (m *Migration, ok bool) {
+	if _, ok := i.migrations[version]; ok {
+		if mx, ok := i.migrations[version][Up]; ok {
+			return mx, true
+		}
+	}
+	return nil, false
+}
+
+func (i *Migrations) Down(version uint) (m *Migration, ok bool) {
+	if _, ok := i.migrations[version]; ok {
+		if mx, ok := i.migrations[version][Down]; ok {
+			return mx, true
+		}
+	}
+	return nil, false
+}
+
+func (i *Migrations) findPos(version uint) int {
+	if len(i.index) > 0 {
+		ix := i.index.Search(version)
+		if ix < len(i.index) && i.index[ix] == version {
+			return ix
+		}
+	}
+	return -1
+}
+
+type uintSlice []uint
+
+func (s uintSlice) Len() int {
+	return len(s)
+}
+
+func (s uintSlice) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func (s uintSlice) Less(i, j int) bool {
+	return s[i] < s[j]
+}
+
+func (s uintSlice) Search(x uint) int {
+	return sort.Search(len(s), func(i int) bool { return s[i] >= x })
+}

vendor/github.com/golang-migrate/migrate/v4/source/parse.go

@@ -0,0 +1,39 @@
+package source
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+)
+
+var (
+	ErrParse = fmt.Errorf("no match")
+)
+
+var (
+	DefaultParse = Parse
+	DefaultRegex = Regex
+)
+
+// Regex matches the following pattern:
+//  123_name.up.ext
+//  123_name.down.ext
+var Regex = regexp.MustCompile(`^([0-9]+)_(.*)\.(` + string(Down) + `|` + string(Up) + `)\.(.*)$`)
+
+// Parse returns Migration for matching Regex pattern.
+func Parse(raw string) (*Migration, error) {
+	m := Regex.FindStringSubmatch(raw)
+	if len(m) == 5 {
+		versionUint64, err := strconv.ParseUint(m[1], 10, 64)
+		if err != nil {
+			return nil, err
+		}
+		return &Migration{
+			Version:    uint(versionUint64),
+			Identifier: m[2],
+			Direction:  Direction(m[3]),
+			Raw:        raw,
+		}, nil
+	}
+	return nil, ErrParse
+}

vendor/github.com/golang-migrate/migrate/v4/util.go

@@ -0,0 +1,62 @@
+package migrate
+
+import (
+	"fmt"
+	nurl "net/url"
+	"strings"
+)
+
+// MultiError holds multiple errors.
+//
+// Deprecated: Use github.com/hashicorp/go-multierror instead
+type MultiError struct {
+	Errs []error
+}
+
+// NewMultiError returns an error type holding multiple errors.
+//
+// Deprecated: Use github.com/hashicorp/go-multierror instead
+//
+func NewMultiError(errs ...error) MultiError {
+	compactErrs := make([]error, 0)
+	for _, e := range errs {
+		if e != nil {
+			compactErrs = append(compactErrs, e)
+		}
+	}
+	return MultiError{compactErrs}
+}
+
+// Error implements error. Multiple errors are concatenated with 'and's.
+func (m MultiError) Error() string {
+	var strs = make([]string, 0)
+	for _, e := range m.Errs {
+		if len(e.Error()) > 0 {
+			strs = append(strs, e.Error())
+		}
+	}
+	return strings.Join(strs, " and ")
+}
+
+// suint safely converts int to uint
+// see https://goo.gl/wEcqof
+// see https://goo.gl/pai7Dr
+func suint(n int) uint {
+	if n < 0 {
+		panic(fmt.Sprintf("suint(%v) expects input >= 0", n))
+	}
+	return uint(n)
+}
+
+// FilterCustomQuery filters all query values starting with `x-`
+func FilterCustomQuery(u *nurl.URL) *nurl.URL {
+	ux := *u
+	vx := make(nurl.Values)
+	for k, v := range ux.Query() {
+		if len(k) <= 1 || (len(k) > 1 && k[0:2] != "x-") {
+			vx[k] = v
+		}
+	}
+	ux.RawQuery = vx.Encode()
+	return &ux
+}

vendor/github.com/golang/mock/AUTHORS

@@ -0,0 +1,12 @@
+# This is the official list of GoMock authors for copyright purposes.
+# This file is distinct from the CONTRIBUTORS files.
+# See the latter for an explanation.
+
+# Names should be added to this file as
+#	Name or Organization <email address>
+# The email address is not required for organizations.
+
+# Please keep the list sorted.
+
+Alex Reece <awreece@gmail.com>
+Google Inc.

vendor/github.com/golang/mock/CONTRIBUTORS

@@ -0,0 +1,37 @@
+# This is the official list of people who can contribute (and typically
+# have contributed) code to the gomock repository.
+# The AUTHORS file lists the copyright holders; this file
+# lists people.  For example, Google employees are listed here
+# but not in AUTHORS, because Google holds the copyright.
+#
+# The submission process automatically checks to make sure
+# that people submitting code are listed in this file (by email address).
+#
+# Names should be added to this file only after verifying that
+# the individual or the individual's organization has agreed to
+# the appropriate Contributor License Agreement, found here:
+#
+#     http://code.google.com/legal/individual-cla-v1.0.html
+#     http://code.google.com/legal/corporate-cla-v1.0.html
+#
+# The agreement for individuals can be filled out on the web.
+#
+# When adding J Random Contributor's name to this file,
+# either J's name or J's organization's name should be
+# added to the AUTHORS file, depending on whether the
+# individual or corporate CLA was used.
+
+# Names should be added to this file like so:
+#     Name <email address>
+#
+# An entry with two email addresses specifies that the
+# first address should be used in the submit logs and
+# that the second address should be recognized as the
+# same person when interacting with Rietveld.
+
+# Please keep the list sorted.
+
+Aaron Jacobs <jacobsa@google.com> <aaronjjacobs@gmail.com>
+Alex Reece <awreece@gmail.com>
+David Symonds <dsymonds@golang.org>
+Ryan Barrett <ryanb@google.com>