这篇跟上一篇的区别是同步数据完成之后，以太坊的工作流程是怎样的
初始化
eth/handler.go
func (pm *ProtocolManager) Start(maxPeers int) {
pm.maxPeers = maxPeers
// broadcast transactions
pm.txCh = make(chan core.TxPreEvent, txChanSize)
pm.txSub = pm.txpool.SubscribeTxPreEvent(pm.txCh)
go pm.txBroadcastLoop()
// broadcast mined blocks
pm.minedBlockSub = pm.eventMux.Subscribe(core.NewMinedBlockEvent{})
go pm.minedBroadcastLoop()
// start sync handlers
go pm.syncer()
go pm.txsyncLoop()
}
初始化Start的时候会新建4个goroutine：
txBroadcastLoop: 当收到新的tx时，会将它发送到连接的Peer
MinedBroadcastLoop：当挖出新的区块或者收到新的区块时，会将其发送到连接的Peer
syncer：有新的Peer连接时，会新建goroutine从td最高的Peer同步区块信息
txsyncLoop：当监听到txsyncCh有数据时（新连接peer时会把自身的txpool写到这个channel），新建goroutine发送tx记录到连接的Peer
广播交易
订阅tx消息
上面Start（）的时候订阅了txCh消息
func (pool *TxPool) SubscribeTxPreEvent(ch chan<- TxPreEvent) event.Subscription {
return pool.scope.Track(pool.txFeed.Subscribe(ch))
}
当自身节点收到了客户端的交易或者收到其他节点发来的交易加到txpool中时，Send订阅消息：core/tx_pool.go
func (pool *TxPool) add(tx *types.Transaction, local bool) (bool, error) {
// We've directly injected a replacement transaction, notify subsystems
go pool.txFeed.Send(TxPreEvent{tx})
}
这样txBroadcastLoop中就读到了tx：
func (self *ProtocolManager) txBroadcastLoop() {
for {
select {
case event := <-self.txCh:
self.BroadcastTx(event.Tx.Hash(), event.Tx)
// Err() channel will be closed when unsubscribing.
case <-self.txSub.Err():
return
}
}
}
然后BroadCastTx就是发送TxMsg到所有连接的Peer，对端Peer收到Tx后加入自己的Txpool中
这样就达到交易扩散的目的
广播区块
上面Start（）的时候订阅了NewMinedBlockEvent
pm.minedBlockSub = pm.eventMux.Subscribe(core.NewMinedBlockEvent{})
这是event.TypeMux自带的功能
当打包新区块成功时，会Post这个event：miner/worker.go
func (self *worker) wait() {
for {
mustCommitNewWork := true
for result := range self.recv {
atomic.AddInt32(&self.atWork, -1)
if result == nil {
continue
}
block := result.Block
work := result.Work
// Update the block hash in all logs since it is now available and not when the
// receipt/log of individual transactions were created.
for _, r := range work.receipts {
for _, l := range r.Logs {
l.BlockHash = block.Hash()
}
}
for _, log := range work.state.Logs() {
log.BlockHash = block.Hash()
}
stat, err := self.chain.WriteBlockWithState(block, work.receipts, work.state)
if err != nil {
log.Error("Failed writing block to chain", "err", err)
continue
}
// check if canon block and write transactions
if stat == core.CanonStatTy {
// implicit by posting ChainHeadEvent
mustCommitNewWork = false
}
// Broadcast the block and announce chain insertion event
self.mux.Post(core.NewMinedBlockEvent{Block: block})
var (
events []interface{}
logs = work.state.Logs()
)
events = append(events, core.ChainEvent{Block: block, Hash: block.Hash(), Logs: logs})
if stat == core.CanonStatTy {
events = append(events, core.ChainHeadEvent{Block: block})
}
self.chain.PostChainEvents(events, logs)
// Insert the block into the set of pending ones to wait for confirmations
self.unconfirmed.Insert(block.NumberU64(), block.Hash())
if mustCommitNewWork {
self.commitNewWork()
}
}
}
}
1 收到挖矿产生的block后WriteBlockWithState()写入本地leveldb
2 Post NewMinedBlockEvent
func (self *ProtocolManager) minedBroadcastLoop() {
// automatically stops if unsubscribe
for obj := range self.minedBlockSub.Chan() {
switch ev := obj.Data.(type) {
case core.NewMinedBlockEvent:
self.BroadcastBlock(ev.Block, true) // First propagate block to peers
self.BroadcastBlock(ev.Block, false) // Only then announce to the rest
}
}
}
这里收到新的区块后，调用BroadcastBlock广播区块，看代码是调用了两次，一次第二个参数为true，一次为fasle
func (pm *ProtocolManager) BroadcastBlock(block *types.Block, propagate bool) {
hash := block.Hash()
peers := pm.peers.PeersWithoutBlock(hash)
// If propagation is requested, send to a subset of the peer
if propagate {
// Calculate the TD of the block (it's not imported yet, so block.Td is not valid)
var td *big.Int
if parent := pm.blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1); parent != nil {
td = new(big.Int).Add(block.Difficulty(), pm.blockchain.GetTd(block.ParentHash(), block.NumberU64()-1))
} else {
log.Error("Propagating dangling block", "number", block.Number(), "hash", hash)
return
}
// Send the block to a subset of our peers
transfer := peers[:int(math.Sqrt(float64(len(peers))))]
for _, peer := range transfer {
peer.SendNewBlock(block, td)
}
log.Trace("Propagated block", "hash", hash, "recipients", len(transfer), "duration", common.PrettyDuration(time.Since(block.ReceivedAt)))
return
}
// Otherwise if the block is indeed in out own chain, announce it
if pm.blockchain.HasBlock(hash, block.NumberU64()) {
for _, peer := range peers {
peer.SendNewBlockHashes([]common.Hash{hash}, []uint64{block.NumberU64()})
}
log.Trace("Announced block", "hash", hash, "recipients", len(peers), "duration", common.PrettyDuration(time.Since(block.ReceivedAt)))
}
}
第二个参数：
true：从节点中找开平方根个节点广播整个区块
false：所有节点广播区块的hash；其他节点收到区块的hash，再发送消息获取区块
这么做的目的是减少本节点的瞬时网络负载，免得一次广播太多的block造成自己的网络拥堵
这样就实现了区块的扩散