core, light: send chain events using event.Feed (#14865)

eth/handler.go

@@ -45,6 +45,10 @@ import (
 const (
 	softResponseLimit = 2 * 1024 * 1024 // Target maximum size of returned blocks, headers or node data.
 	estHeaderRlpSize  = 500             // Approximate size of an RLP encoded block header
+
+	// txChanSize is the size of channel listening to TxPreEvent.
+	// The number is referenced from the size of tx pool.
+	txChanSize = 4096
 )
 
 var (
@@ -78,7 +82,8 @@ type ProtocolManager struct {
 	SubProtocols []p2p.Protocol
 
 	eventMux      *event.TypeMux
-	txSub         *event.TypeMuxSubscription
+	txCh          chan core.TxPreEvent
+	txSub         event.Subscription
 	minedBlockSub *event.TypeMuxSubscription
 
 	// channels for fetcher, syncer, txsyncLoop
@@ -200,7 +205,8 @@ func (pm *ProtocolManager) removePeer(id string) {
 
 func (pm *ProtocolManager) Start() {
 	// broadcast transactions
-	pm.txSub = pm.eventMux.Subscribe(core.TxPreEvent{})
+	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{})
@@ -724,10 +730,15 @@ func (self *ProtocolManager) minedBroadcastLoop() {
 }
 
 func (self *ProtocolManager) txBroadcastLoop() {
-	// automatically stops if unsubscribe
-	for obj := range self.txSub.Chan() {
-		event := obj.Data.(core.TxPreEvent)
-		self.BroadcastTx(event.Tx.Hash(), event.Tx)
+	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
+		}
 	}
 }