eth/fetcher: fix premature queue cleanup, general polishes

eth/fetcher/fetcher.go

@@ -61,6 +61,10 @@ type Fetcher struct {
 	filter chan chan []*types.Block
 	quit   chan struct{}
 
+	// Announce states
+	announced map[common.Hash][]*announce // Announced blocks, scheduled for fetching
+	fetching  map[common.Hash]*announce   // Announced blocks, currently fetching
+
 	// Block cache
 	queue  *prque.Prque             // Queue containing the import operations (block number sorted)
 	queued map[common.Hash]struct{} // Presence set of already queued blocks (to dedup imports)
@@ -78,6 +82,8 @@ func New(hasBlock hashCheckFn, importBlock blockImporterFn, chainHeight chainHei
 		insert:      make(chan *inject),
 		filter:      make(chan chan []*types.Block),
 		quit:        make(chan struct{}),
+		announced:   make(map[common.Hash][]*announce),
+		fetching:    make(map[common.Hash]*announce),
 		queue:       prque.New(),
 		queued:      make(map[common.Hash]struct{}),
 		hasBlock:    hasBlock,
@@ -158,19 +164,16 @@ func (f *Fetcher) Filter(blocks types.Blocks) types.Blocks {
 // Loop is the main fetcher loop, checking and processing various notification
 // events.
 func (f *Fetcher) loop() {
-	announced := make(map[common.Hash][]*announce)
-	fetching := make(map[common.Hash]*announce)
-
 	// Iterate the block fetching until a quit is requested
 	fetch := time.NewTimer(0)
 	done := make(chan common.Hash)
 
 	for {
 		// Clean up any expired block fetches
-		for hash, announce := range fetching {
+		for hash, announce := range f.fetching {
 			if time.Since(announce.time) > fetchTimeout {
-				delete(announced, hash)
-				delete(fetching, hash)
+				delete(f.announced, hash)
+				delete(f.fetching, hash)
 			}
 		}
 		// Import any queued blocks that could potentially fit
@@ -184,17 +187,16 @@ func (f *Fetcher) loop() {
 			}
 			// Otherwise if not known yet, try and import
 			hash := op.block.Hash()
-			delete(f.queued, hash)
 			if f.hasBlock(hash) {
 				continue
 			}
 			// Block may just fit, try to import it
-			glog.V(logger.Debug).Infof("Peer %s: importing block %x", op.origin, hash.Bytes()[:4])
+			glog.V(logger.Debug).Infof("Peer %s: importing block #%d [%x]", op.origin, op.block.NumberU64(), hash.Bytes()[:4])
 			go func() {
 				defer func() { done <- hash }()
 
 				if err := f.importBlock(op.origin, op.block); err != nil {
-					glog.V(logger.Detail).Infof("Peer %s: block %x import failed: %v", op.origin, hash.Bytes()[:4], err)
+					glog.V(logger.Detail).Infof("Peer %s: block #%d [%x] import failed: %v", op.origin, op.block.NumberU64(), hash.Bytes()[:4], err)
 					return
 				}
 			}()
@@ -208,14 +210,13 @@ func (f *Fetcher) loop() {
 		case notification := <-f.notify:
 			// A block was announced, schedule if it's not yet downloading
 			glog.V(logger.Debug).Infof("Peer %s: scheduling %x", notification.origin, notification.hash[:4])
-			if _, ok := fetching[notification.hash]; ok {
+			if _, ok := f.fetching[notification.hash]; ok {
 				break
 			}
-			if len(announced) == 0 {
-				glog.V(logger.Detail).Infof("Scheduling fetch in %v, at %v", arriveTimeout-time.Since(notification.time), notification.time.Add(arriveTimeout))
-				fetch.Reset(arriveTimeout - time.Since(notification.time))
+			f.announced[notification.hash] = append(f.announced[notification.hash], notification)
+			if len(f.announced) == 1 {
+				f.reschedule(fetch)
 			}
-			announced[notification.hash] = append(announced[notification.hash], notification)
 
 		case op := <-f.insert:
 			// A direct block insertion was requested, try and fill any pending gaps
@@ -223,39 +224,31 @@ func (f *Fetcher) loop() {
 
 		case hash := <-done:
 			// A pending import finished, remove all traces of the notification
-			delete(announced, hash)
-			delete(fetching, hash)
+			delete(f.announced, hash)
+			delete(f.fetching, hash)
+			delete(f.queued, hash)
 
 		case <-fetch.C:
 			// At least one block's timer ran out, check for needing retrieval
 			request := make(map[string][]common.Hash)
 
-			for hash, announces := range announced {
+			for hash, announces := range f.announced {
 				if time.Since(announces[0].time) > arriveTimeout {
 					announce := announces[rand.Intn(len(announces))]
 					if !f.hasBlock(hash) {
 						request[announce.origin] = append(request[announce.origin], hash)
-						fetching[hash] = announce
+						f.fetching[hash] = announce
 					}
-					delete(announced, hash)
+					delete(f.announced, hash)
 				}
 			}
 			// Send out all block requests
 			for peer, hashes := range request {
 				glog.V(logger.Debug).Infof("Peer %s: explicitly fetching %d blocks", peer, len(hashes))
-				go fetching[hashes[0]].fetch(hashes)
+				go f.fetching[hashes[0]].fetch(hashes)
 			}
 			// Schedule the next fetch if blocks are still pending
-			if len(announced) > 0 {
-				nearest := time.Now()
-				for _, announces := range announced {
-					if nearest.After(announces[0].time) {
-						nearest = announces[0].time
-					}
-				}
-				glog.V(logger.Detail).Infof("Rescheduling fetch in %v, at %v", arriveTimeout-time.Since(nearest), nearest.Add(arriveTimeout))
-				fetch.Reset(arriveTimeout - time.Since(nearest))
-			}
+			f.reschedule(fetch)
 
 		case filter := <-f.filter:
 			// Blocks arrived, extract any explicit fetches, return all else
@@ -271,12 +264,12 @@ func (f *Fetcher) loop() {
 				hash := block.Hash()
 
 				// Filter explicitly requested blocks from hash announcements
-				if _, ok := fetching[hash]; ok {
+				if _, ok := f.fetching[hash]; ok {
 					// Discard if already imported by other means
 					if !f.hasBlock(hash) {
 						explicit = append(explicit, block)
 					} else {
-						delete(fetching, hash)
+						delete(f.fetching, hash)
 					}
 				} else {
 					download = append(download, block)
@@ -290,7 +283,7 @@ func (f *Fetcher) loop() {
 			}
 			// Schedule the retrieved blocks for ordered import
 			for _, block := range explicit {
-				if announce := fetching[block.Hash()]; announce != nil {
+				if announce := f.fetching[block.Hash()]; announce != nil {
 					f.enqueue(announce.origin, block)
 				}
 			}
@@ -298,21 +291,40 @@ func (f *Fetcher) loop() {
 	}
 }
 
+// reschedule resets the specified fetch timer to the next announce timeout.
+func (f *Fetcher) reschedule(fetch *time.Timer) {
+	// Short circuit if no blocks are announced
+	if len(f.announced) == 0 {
+		return
+	}
+	// Otherwise find the earliest expiring announcement
+	earliest := time.Now()
+	for _, announces := range f.announced {
+		if earliest.After(announces[0].time) {
+			earliest = announces[0].time
+		}
+	}
+	glog.V(logger.Detail).Infof("Scheduling next fetch in %v", arriveTimeout-time.Since(earliest))
+	fetch.Reset(arriveTimeout - time.Since(earliest))
+}
+
 // enqueue schedules a new future import operation, if the block to be imported
 // has not yet been seen.
 func (f *Fetcher) enqueue(peer string, block *types.Block) {
+	hash := block.Hash()
+
 	// Make sure the block isn't in some weird place
 	if math.Abs(float64(f.chainHeight())-float64(block.NumberU64())) > maxQueueDist {
+		glog.Infof("Peer %s: discarded block #%d [%x] too far from head", peer, block.NumberU64(), hash.Bytes()[:4])
 		return
 	}
 	// Schedule the block for future importing
-	hash := block.Hash()
 	if _, ok := f.queued[hash]; !ok {
 		f.queued[hash] = struct{}{}
 		f.queue.Push(&inject{origin: peer, block: block}, -float32(block.NumberU64()))
 
 		if glog.V(logger.Detail) {
-			glog.Infof("Peer %s: queued block %x, total %v", peer, hash.Bytes()[:4], f.queue.Size())
+			glog.Infof("Peer %s: queued block #%d [%x], total %v", peer, block.NumberU64(), hash.Bytes()[:4], f.queue.Size())
 		}
 	}
 }