eth, eth/fetcher: separate notification sync mechanism

eth/sync.go

@@ -12,11 +12,8 @@ import (
 )
 
 const (
-	forceSyncCycle      = 10 * time.Second       // Time interval to force syncs, even if few peers are available
-	notifyCheckCycle    = 100 * time.Millisecond // Time interval to allow hash notifies to fulfill before hard fetching
-	notifyArriveTimeout = 500 * time.Millisecond // Time allowance before an announced block is explicitly requested
-	notifyFetchTimeout  = 5 * time.Second        // Maximum alloted time to return an explicitly requested block
-	minDesiredPeerCount = 5                      // Amount of peers desired to start syncing
+	forceSyncCycle      = 10 * time.Second // Time interval to force syncs, even if few peers are available
+	minDesiredPeerCount = 5                // Amount of peers desired to start syncing
 
 	// This is the target size for the packs of transactions sent by txsyncLoop.
 	// A pack can get larger than this if a single transactions exceeds this size.
@@ -119,140 +116,15 @@ func (pm *ProtocolManager) txsyncLoop() {
 	}
 }
 
-// fetcher is responsible for collecting hash notifications, and periodically
-// checking all unknown ones and individually fetching them.
-func (pm *ProtocolManager) fetcher() {
-	announces := make(map[common.Hash][]*blockAnnounce)
-	request := make(map[*peer][]common.Hash)
-	pending := make(map[common.Hash]*blockAnnounce)
-	cycle := time.Tick(notifyCheckCycle)
-	done := make(chan common.Hash)
-
-	// Iterate the block fetching until a quit is requested
-	for {
-		select {
-		case notifications := <-pm.newHashCh:
-			// A batch of hashes the notified, schedule them for retrieval
-			glog.V(logger.Debug).Infof("Scheduling %d hash announcements from %s", len(notifications), notifications[0].peer.id)
-			for _, announce := range notifications {
-				// Skip if it's already pending fetch
-				if _, ok := pending[announce.hash]; ok {
-					continue
-				}
-				// Otherwise queue up the peer as a potential source
-				announces[announce.hash] = append(announces[announce.hash], announce)
-			}
-
-		case hash := <-done:
-			// A pending import finished, remove all traces
-			delete(pending, hash)
-
-		case <-cycle:
-			// Clean up any expired block fetches
-			for hash, announce := range pending {
-				if time.Since(announce.time) > notifyFetchTimeout {
-					delete(pending, hash)
-				}
-			}
-			// Check if any notified blocks failed to arrive
-			for hash, all := range announces {
-				if time.Since(all[0].time) > notifyArriveTimeout {
-					announce := all[rand.Intn(len(all))]
-					if !pm.chainman.HasBlock(hash) {
-						request[announce.peer] = append(request[announce.peer], hash)
-						pending[hash] = announce
-					}
-					delete(announces, hash)
-				}
-			}
-			if len(request) == 0 {
-				break
-			}
-			// Send out all block requests
-			for peer, hashes := range request {
-				glog.V(logger.Debug).Infof("Explicitly fetching %d blocks from %s", len(hashes), peer.id)
-				go peer.requestBlocks(hashes)
-			}
-			request = make(map[*peer][]common.Hash)
-
-		case filter := <-pm.newBlockCh:
-			// Blocks arrived, extract any explicit fetches, return all else
-			var blocks types.Blocks
-			select {
-			case blocks = <-filter:
-			case <-pm.quitSync:
-				return
-			}
-
-			explicit, download := []*types.Block{}, []*types.Block{}
-			for _, block := range blocks {
-				hash := block.Hash()
-
-				// Filter explicitly requested blocks from hash announcements
-				if _, ok := pending[hash]; ok {
-					// Discard if already imported by other means
-					if !pm.chainman.HasBlock(hash) {
-						explicit = append(explicit, block)
-					} else {
-						delete(pending, hash)
-					}
-				} else {
-					download = append(download, block)
-				}
-			}
-
-			select {
-			case filter <- download:
-			case <-pm.quitSync:
-				return
-			}
-			// Create a closure with the retrieved blocks and origin peers
-			peers := make([]*peer, 0, len(explicit))
-			blocks = make([]*types.Block, 0, len(explicit))
-			for _, block := range explicit {
-				hash := block.Hash()
-				if announce := pending[hash]; announce != nil {
-					// Drop the block if it surely cannot fit
-					if pm.chainman.HasBlock(hash) || !pm.chainman.HasBlock(block.ParentHash()) {
-						// delete(pending, hash) // if we drop, it will re-fetch it, wait for timeout?
-						continue
-					}
-					// Otherwise accumulate for import
-					peers = append(peers, announce.peer)
-					blocks = append(blocks, block)
-				}
-			}
-			// If any explicit fetches were replied to, import them
-			if count := len(blocks); count > 0 {
-				glog.V(logger.Debug).Infof("Importing %d explicitly fetched blocks", len(blocks))
-				go func() {
-					// Make sure all hashes are cleaned up
-					for _, block := range blocks {
-						hash := block.Hash()
-						defer func() { done <- hash }()
-					}
-					// Try and actually import the blocks
-					for i := 0; i < len(blocks); i++ {
-						if err := pm.importBlock(peers[i], blocks[i], nil); err != nil {
-							glog.V(logger.Detail).Infof("Failed to import explicitly fetched block: %v", err)
-							return
-						}
-					}
-				}()
-			}
-
-		case <-pm.quitSync:
-			return
-		}
-	}
-}
-
 // syncer is responsible for periodically synchronising with the network, both
-// downloading hashes and blocks as well as retrieving cached ones.
+// downloading hashes and blocks as well as handling the announcement handler.
 func (pm *ProtocolManager) syncer() {
-	// Abort any pending syncs if we terminate
+	// Start and ensure cleanup of sync mechanisms
+	pm.fetcher.Start()
+	defer pm.fetcher.Stop()
 	defer pm.downloader.Terminate()
 
+	// Wait for different events to fire synchronisation operations
 	forceSync := time.Tick(forceSyncCycle)
 	for {
 		select {
@@ -273,8 +145,7 @@ func (pm *ProtocolManager) syncer() {
 	}
 }
 
-// synchronise tries to sync up our local block chain with a remote peer, both
-// adding various sanity checks as well as wrapping it with various log entries.
+// synchronise tries to sync up our local block chain with a remote peer.
 func (pm *ProtocolManager) synchronise(peer *peer) {
 	// Short circuit if no peers are available
 	if peer == nil {