core: use ChainHeadEvent subscription in the chain indexer (#17826)

core/chain_indexer.go

@@ -53,14 +53,14 @@ type ChainIndexerChain interface {
 	// CurrentHeader retrieves the latest locally known header.
 	CurrentHeader() *types.Header
 
-	// SubscribeChainEvent subscribes to new head header notifications.
-	SubscribeChainEvent(ch chan<- ChainEvent) event.Subscription
+	// SubscribeChainHeadEvent subscribes to new head header notifications.
+	SubscribeChainHeadEvent(ch chan<- ChainHeadEvent) event.Subscription
 }
 
 // ChainIndexer does a post-processing job for equally sized sections of the
 // canonical chain (like BlooomBits and CHT structures). A ChainIndexer is
 // connected to the blockchain through the event system by starting a
-// ChainEventLoop in a goroutine.
+// ChainHeadEventLoop in a goroutine.
 //
 // Further child ChainIndexers can be added which use the output of the parent
 // section indexer. These child indexers receive new head notifications only
@@ -142,8 +142,8 @@ func (c *ChainIndexer) AddCheckpoint(section uint64, shead common.Hash) {
 // cascading background processing. Children do not need to be started, they
 // are notified about new events by their parents.
 func (c *ChainIndexer) Start(chain ChainIndexerChain) {
-	events := make(chan ChainEvent, 10)
-	sub := chain.SubscribeChainEvent(events)
+	events := make(chan ChainHeadEvent, 10)
+	sub := chain.SubscribeChainHeadEvent(events)
 
 	go c.eventLoop(chain.CurrentHeader(), events, sub)
 }
@@ -190,7 +190,7 @@ func (c *ChainIndexer) Close() error {
 // eventLoop is a secondary - optional - event loop of the indexer which is only
 // started for the outermost indexer to push chain head events into a processing
 // queue.
-func (c *ChainIndexer) eventLoop(currentHeader *types.Header, events chan ChainEvent, sub event.Subscription) {
+func (c *ChainIndexer) eventLoop(currentHeader *types.Header, events chan ChainHeadEvent, sub event.Subscription) {
 	// Mark the chain indexer as active, requiring an additional teardown
 	atomic.StoreUint32(&c.active, 1)