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

light/lightchain.go

@@ -44,11 +44,14 @@ var (
 // headers, downloading block bodies and receipts on demand through an ODR
 // interface. It only does header validation during chain insertion.
 type LightChain struct {
-	hc           *core.HeaderChain
-	chainDb      ethdb.Database
-	odr          OdrBackend
-	eventMux     *event.TypeMux
-	genesisBlock *types.Block
+	hc            *core.HeaderChain
+	chainDb       ethdb.Database
+	odr           OdrBackend
+	chainFeed     event.Feed
+	chainSideFeed event.Feed
+	chainHeadFeed event.Feed
+	scope         event.SubscriptionScope
+	genesisBlock  *types.Block
 
 	mu      sync.RWMutex
 	chainmu sync.RWMutex
@@ -69,7 +72,7 @@ type LightChain struct {
 // NewLightChain returns a fully initialised light chain using information
 // available in the database. It initialises the default Ethereum header
 // validator.
-func NewLightChain(odr OdrBackend, config *params.ChainConfig, engine consensus.Engine, mux *event.TypeMux) (*LightChain, error) {
+func NewLightChain(odr OdrBackend, config *params.ChainConfig, engine consensus.Engine) (*LightChain, error) {
 	bodyCache, _ := lru.New(bodyCacheLimit)
 	bodyRLPCache, _ := lru.New(bodyCacheLimit)
 	blockCache, _ := lru.New(blockCacheLimit)
@@ -77,7 +80,6 @@ func NewLightChain(odr OdrBackend, config *params.ChainConfig, engine consensus.
 	bc := &LightChain{
 		chainDb:      odr.Database(),
 		odr:          odr,
-		eventMux:     mux,
 		quit:         make(chan struct{}),
 		bodyCache:    bodyCache,
 		bodyRLPCache: bodyRLPCache,
@@ -316,16 +318,18 @@ func (self *LightChain) Rollback(chain []common.Hash) {
 }
 
 // postChainEvents iterates over the events generated by a chain insertion and
-// posts them into the event mux.
+// posts them into the event feed.
 func (self *LightChain) postChainEvents(events []interface{}) {
 	for _, event := range events {
-		if event, ok := event.(core.ChainEvent); ok {
-			if self.LastBlockHash() == event.Hash {
-				self.eventMux.Post(core.ChainHeadEvent{Block: event.Block})
+		switch ev := event.(type) {
+		case core.ChainEvent:
+			if self.LastBlockHash() == ev.Hash {
+				self.chainHeadFeed.Send(core.ChainHeadEvent{Block: ev.Block})
 			}
+			self.chainFeed.Send(ev)
+		case core.ChainSideEvent:
+			self.chainSideFeed.Send(ev)
 		}
-		// Fire the insertion events individually too
-		self.eventMux.Post(event)
 	}
 }
 
@@ -467,3 +471,30 @@ func (self *LightChain) LockChain() {
 func (self *LightChain) UnlockChain() {
 	self.chainmu.RUnlock()
 }
+
+// SubscribeChainEvent registers a subscription of ChainEvent.
+func (self *LightChain) SubscribeChainEvent(ch chan<- core.ChainEvent) event.Subscription {
+	return self.scope.Track(self.chainFeed.Subscribe(ch))
+}
+
+// SubscribeChainHeadEvent registers a subscription of ChainHeadEvent.
+func (self *LightChain) SubscribeChainHeadEvent(ch chan<- core.ChainHeadEvent) event.Subscription {
+	return self.scope.Track(self.chainHeadFeed.Subscribe(ch))
+}
+
+// SubscribeChainSideEvent registers a subscription of ChainSideEvent.
+func (self *LightChain) SubscribeChainSideEvent(ch chan<- core.ChainSideEvent) event.Subscription {
+	return self.scope.Track(self.chainSideFeed.Subscribe(ch))
+}
+
+// SubscribeLogsEvent implements the interface of filters.Backend
+// LightChain does not send logs events, so return an empty subscription.
+func (self *LightChain) SubscribeLogsEvent(ch chan<- []*types.Log) event.Subscription {
+	return self.scope.Track(new(event.Feed).Subscribe(ch))
+}
+
+// SubscribeRemovedLogsEvent implements the interface of filters.Backend
+// LightChain does not send core.RemovedLogsEvent, so return an empty subscription.
+func (self *LightChain) SubscribeRemovedLogsEvent(ch chan<- core.RemovedLogsEvent) event.Subscription {
+	return self.scope.Track(new(event.Feed).Subscribe(ch))
+}