enhancement/node-stopping (#46)

* made node stoppable

* updated

* added todo

* comments

* remove/ecsda (#50)

main.go

@@ -1,8 +1,6 @@
 package main
 
 import (
-	"crypto/ecdsa"
-	"crypto/elliptic"
 	"crypto/rand"
 	"flag"
 	"fmt"
@@ -78,7 +76,7 @@ func main() {
 	}
 
 	for _, n := range nodes {
-		n.Run()
+		n.Start()
 	}
 
 	chat(group, nodes[:communicating-1]...)
@@ -138,8 +136,13 @@ func Calc(count uint64, epoch int64) int64 {
 }
 
 func peerID() state.PeerID {
-	key, _ := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
-	return state.PublicKeyToPeerID(key.PublicKey)
+	bytes := make([]byte, 65)
+	rand.Read(bytes)
+
+	id := state.PeerID{}
+	copy(id[:], bytes)
+
+	return id
 }
 
 func groupId() state.GroupID {

node/node.go

@@ -5,6 +5,7 @@ package node
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"log"
 	"sync/atomic"
@@ -28,6 +29,9 @@ 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 {
+	ctx    context.Context
+	cancel context.CancelFunc
+
 	store     store.MessageStore
 	transport transport.Transport
 
@@ -55,7 +59,11 @@ func NewNode(
 	id state.PeerID,
 	mode Mode,
 ) *Node {
+	ctx, cancel := context.WithCancel(context.Background())
+
 	return &Node{
+		ctx:       ctx,
+		cancel:    cancel,
 		store:     ms,
 		transport: st,
 		syncState: ss,
@@ -68,26 +76,43 @@ func NewNode(
 	}
 }
 
-// Run listens for new messages received by the node and sends out those required every epoch.
-func (n *Node) Run() {
+// Start listens for new messages received by the node and sends out those required every epoch.
+func (n *Node) Start() {
 	go func() {
 		for {
+			select {
+			case <-n.ctx.Done():
+				log.Print("Watch stopped")
+				return
+			default:
 				p := n.transport.Watch()
 				go n.onPayload(p.Group, p.Sender, p.Payload)
 			}
+		}
 	}()
 
 	go func() {
 		for {
+			select {
+			case <-n.ctx.Done():
+				log.Print("Epoch processing stopped")
+				return
+			default:
 				log.Printf("Node: %x Epoch: %d", n.ID[:4], n.epoch)
 				time.Sleep(1 * time.Second)
 
 				n.sendMessages()
 				atomic.AddInt64(&n.epoch, 1)
 			}
+		}
 	}()
 }
 
+// Stop message reading and epoch processing
+func (n *Node) Stop() {
+	n.cancel()
+}
+
 // AppendMessage sends a message to a given group.
 func (n *Node) AppendMessage(group state.GroupID, data []byte) (state.MessageID, error) {
 	m := protobuf.Message{

state/peerid.go

@@ -1,16 +1,3 @@
 package state
 
-import (
-	"crypto/ecdsa"
-
-	"github.com/ethereum/go-ethereum/crypto"
-)
-
 type PeerID [65]byte
-
-// Turns an ECSDA PublicKey to a PeerID
-func PublicKeyToPeerID(k ecdsa.PublicKey) PeerID {
-	var p PeerID
-	copy(p[:], crypto.FromECDSAPub(&k))
-	return p
-}

transport/channel_transport.go

@@ -37,6 +37,8 @@ func (t *ChannelTransport) Watch() Packet {
 }
 
 func (t *ChannelTransport) Send(group state.GroupID, 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())
 	if math.Intn(100) < t.offline {
 		return nil