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https://github.com/OffchainLabs/prysm.git
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a9afdd90ef
Former-commit-id: 0a23d54aa3006d103bb7123bcfe0ac2ca3a2b027 [formerly 7266cc53ca4d6826b4a54d30391f9c5e5b0b7d10] Former-commit-id: 6b33ca471ede8696fc83285ae426645308a4c6fe
107 lines
3.3 KiB
Go
107 lines
3.3 KiB
Go
package sharding
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import (
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"context"
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"fmt"
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"github.com/ethereum/go-ethereum/accounts/abi/bind"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/ethereum/go-ethereum/log"
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"math/big"
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)
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// subscribeBlockHeaders checks incoming block headers and determines if
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// we are an eligible proposer for collations. Then, it finds the pending tx's
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// from the running geth node and sorts them by descending order of gas price,
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// eliminates those that ask for too much gas, and routes them over
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// to the VMC to create a collation
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func subscribeBlockHeaders(c *Client) error {
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headerChan := make(chan *types.Header, 16)
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_, err := c.client.SubscribeNewHead(context.Background(), headerChan)
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if err != nil {
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return fmt.Errorf("unable to subscribe to incoming headers. %v", err)
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}
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log.Info("listening for new headers...")
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for {
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select {
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case head := <-headerChan:
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// Query the current state to see if we are an eligible proposer
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log.Info(fmt.Sprintf("received new header %v", head.Number.String()))
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// TODO: Only run this code on certain periods?
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err := watchShards(c, head)
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if err != nil {
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return fmt.Errorf("unable to watch shards. %v", err)
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}
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}
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}
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}
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// watchShards checks if we are an eligible proposer for collation for
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// the available shards in the VMC. The function calls getEligibleProposer from
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// the VMC and proposes a collation if conditions are met
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func watchShards(c *Client, head *types.Header) error {
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accounts := c.keystore.Accounts()
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if len(accounts) == 0 {
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return fmt.Errorf("no accounts found")
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}
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if err := c.unlockAccount(accounts[0]); err != nil {
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return fmt.Errorf("cannot unlock account. %v", err)
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}
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log.Info(fmt.Sprint("watching shards..."))
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s := 0
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for s < shardCount {
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// Checks if we are an eligible proposer according to the VMC
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ops := bind.CallOpts{}
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period := head.Number.Div(head.Number, big.NewInt(int64(periodLength)))
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addr, err := c.vmc.VMCCaller.GetEligibleProposer(&ops, big.NewInt(int64(s)), period)
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// If output is non-empty and the addr == coinbase
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if err == nil && addr == accounts[0].Address {
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log.Info(fmt.Sprintf("selected as collator on shard %d", s))
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err := proposeCollation(s)
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if err != nil {
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return fmt.Errorf("could not propose collation. %v", err)
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}
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}
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s++
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}
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return nil
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}
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// proposeCollation interacts with the VMC directly to add a collation header
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func proposeCollation(shardID int) error {
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// TODO: Adds a collation header to the VMC with the following fields:
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// [
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// shard_id: uint256,
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// expected_period_number: uint256,
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// period_start_prevhash: bytes32,
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// parent_hash: bytes32,
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// transactions_root: bytes32,
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// coinbase: address,
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// state_root: bytes32,
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// receipts_root: bytes32,
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// number: uint256,
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// sig: bytes
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// ]
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//
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// Before calling this, we would need to have access to the state of
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// the period_start_prevhash. Refer to the comments in:
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// https://github.com/ethereum/py-evm/issues/258#issuecomment-359879350
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//
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// This function will call FetchCandidateHead() of the VMC to obtain
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// more necessary information.
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//
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// This functions will fetch the transactions in the txpool and and apply
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// them to finish up the collation. It will then need to broadcast the
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// collation to the main chain using JSON-RPC.
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log.Info(fmt.Sprint("propose collation called"))
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return nil
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}
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