downloader: updated downloader and fixed issues with catch up

Properly ignore blocks coming from peers not in our peer list (blocked)
and do never request anything from bad peers. Added some checks to
account for blocks known when requesting hashes (missing parents).

eth/downloader/downloader.go

@@ -54,8 +54,9 @@ type blockPack struct {
 }
 
 type syncPack struct {
-	peer *peer
-	hash common.Hash
+	peer          *peer
+	hash          common.Hash
+	ignoreInitial bool
 }
 
 func New(hasBlock hashCheckFn, insertChain chainInsertFn, currentTd currentTdFn) *Downloader {
@@ -104,11 +105,13 @@ func (d *Downloader) UnregisterPeer(id string) {
 
 func (d *Downloader) peerHandler() {
 	// itimer is used to determine when to start ignoring `minDesiredPeerCount`
-	itimer := time.NewTicker(5 * time.Second)
+	//itimer := time.NewTicker(5 * time.Second)
+	itimer := time.NewTimer(5 * time.Second)
 out:
 	for {
 		select {
 		case <-d.newPeerCh:
+			itimer.Stop()
 			// Meet the `minDesiredPeerCount` before we select our best peer
 			if len(d.peers) < minDesiredPeerCount {
 				break
@@ -137,7 +140,7 @@ func (d *Downloader) selectPeer(p *peer) {
 		}
 
 		glog.V(logger.Detail).Infoln("New peer with highest TD =", p.td)
-		d.syncCh <- syncPack{p, p.recentHash}
+		d.syncCh <- syncPack{p, p.recentHash, false}
 	}
 }
 
@@ -147,11 +150,11 @@ out:
 		select {
 		case sync := <-d.syncCh:
 			selectedPeer := sync.peer
-			glog.V(logger.Detail).Infoln("Synchronising with network using:", selectedPeer.id)
+			glog.V(logger.Detail).Infoln("Synchronising with the network using:", selectedPeer.id)
 			// Start the fetcher. This will block the update entirely
 			// interupts need to be send to the appropriate channels
 			// respectively.
-			if err := d.startFetchingHashes(selectedPeer, sync.hash); err != nil {
+			if err := d.startFetchingHashes(selectedPeer, sync.hash, sync.ignoreInitial); err != nil {
 				// handle error
 				glog.V(logger.Debug).Infoln("Error fetching hashes:", err)
 				// XXX Reset
@@ -178,11 +181,18 @@ out:
 }
 
 // XXX Make synchronous
-func (d *Downloader) startFetchingHashes(p *peer, hash common.Hash) error {
-	glog.V(logger.Debug).Infoln("Downloading hashes")
+func (d *Downloader) startFetchingHashes(p *peer, hash common.Hash, ignoreInitial bool) error {
+	glog.V(logger.Debug).Infof("Downloading hashes (%x) from %s", hash.Bytes()[:4], p.id)
 
 	start := time.Now()
 
+	// We ignore the initial hash in some cases (e.g. we received a block without it's parent)
+	// In such circumstances we don't need to download the block so don't add it to the queue.
+	if !ignoreInitial {
+		// Add the hash to the queue first
+		d.queue.hashPool.Add(hash)
+	}
+
 	// Get the first batch of hashes
 	p.getHashes(hash)
 	atomic.StoreInt32(&d.fetchingHashes, 1)
@@ -195,7 +205,7 @@ out:
 			hashSet := set.New()
 			for _, hash := range hashes {
 				if d.hasBlock(hash) {
-					glog.V(logger.Debug).Infof("Found common hash %x\n", hash)
+					glog.V(logger.Debug).Infof("Found common hash %x\n", hash[:4])
 
 					done = true
 					break
@@ -207,7 +217,7 @@ out:
 
 			// Add hashes to the chunk set
 			// Check if we're done fetching
-			if !done {
+			if !done && len(hashes) > 0 {
 				//fmt.Println("re-fetch. current =", d.queue.hashPool.Size())
 				// Get the next set of hashes
 				p.getHashes(hashes[len(hashes)-1])
@@ -218,7 +228,7 @@ out:
 			}
 		}
 	}
-	glog.V(logger.Detail).Infoln("Download hashes: done. Took", time.Since(start))
+	glog.V(logger.Detail).Infof("Downloaded hashes (%d). Took %v\n", d.queue.hashPool.Size(), time.Since(start))
 
 	return nil
 }
@@ -242,6 +252,10 @@ out:
 			// from the available peers.
 			if d.queue.hashPool.Size() > 0 {
 				availablePeers := d.peers.get(idleState)
+				if len(availablePeers) == 0 {
+					glog.V(logger.Detail).Infoln("No peers available out of", len(d.peers))
+				}
+
 				for _, peer := range availablePeers {
 					// Get a possible chunk. If nil is returned no chunk
 					// could be returned due to no hashes available.
@@ -317,21 +331,33 @@ func (d *Downloader) AddBlock(id string, block *types.Block, td *big.Int) {
 		return
 	}
 
+	peer := d.peers.getPeer(id)
+	// if the peer is in our healthy list of peers; update the td
+	// and add the block. Otherwise just ignore it
+	if peer == nil {
+		glog.V(logger.Detail).Infof("Ignored block from bad peer %s\n", id)
+		return
+	}
+
+	peer.mu.Lock()
+	peer.td = td
+	peer.recentHash = block.Hash()
+	peer.mu.Unlock()
+
 	glog.V(logger.Detail).Infoln("Inserting new block from:", id)
 	d.queue.addBlock(id, block, td)
 
-	// if the peer is in our healthy list of peers; update the td
-	// here is a good chance to add the peer back to the list
-	if peer := d.peers.getPeer(id); peer != nil {
-		peer.mu.Lock()
-		peer.td = td
-		peer.recentHash = block.Hash()
-		peer.mu.Unlock()
-	}
-
 	// if neither go ahead to process
 	if !(d.isFetchingHashes() || d.isDownloadingBlocks()) {
-		d.process()
+		// Check if the parent of the received block is known.
+		// If the block is not know, request it otherwise, request.
+		phash := block.ParentHash()
+		if !d.hasBlock(phash) {
+			glog.V(logger.Detail).Infof("Missing parent %x, requires fetching\n", phash.Bytes()[:4])
+			d.syncCh <- syncPack{peer, peer.recentHash, true}
+		} else {
+			d.process()
+		}
 	}
 }
 
@@ -369,7 +395,7 @@ func (d *Downloader) process() error {
 			// TODO change this. This shite
 			for i, block := range blocks[:max] {
 				if !d.hasBlock(block.ParentHash()) {
-					d.syncCh <- syncPack{d.peers.bestPeer(), block.Hash()}
+					d.syncCh <- syncPack{d.peers.bestPeer(), block.Hash(), true}
 					// remove processed blocks
 					blocks = blocks[i:]