eth: adapted to new synchronous api of downloader's AddBlock

eth/downloader/downloader.go

@@ -173,8 +173,6 @@ out:
 		select {
 		case sync := <-d.syncCh:
 			var peer *peer = sync.peer
-			d.activePeer = peer.id
-
 			err := d.getFromPeer(peer, sync.hash, sync.ignoreInitial)
 			if err != nil {
 				break

eth/downloader/synchronous.go

@@ -50,6 +50,8 @@ func (d *Downloader) Synchronise() (types.Blocks, error) {
 }
 
 func (d *Downloader) getFromPeer(p *peer, hash common.Hash, ignoreInitial bool) error {
+	d.activePeer = p.id
+
 	glog.V(logger.Detail).Infoln("Synchronising with the network using:", p.id)
 	// Start the fetcher. This will block the update entirely
 	// interupts need to be send to the appropriate channels

eth/handler.go

@@ -265,10 +265,12 @@ func (self *ProtocolManager) handleMsg(p *peer) error {
 		if self.chainman.HasBlock(hash) {
 			break
 		}
-		if self.chainman.Td().Cmp(request.TD) > 0 {
+		/* XXX unsure about this
+		if self.chainman.Td().Cmp(request.TD) > 0 && new(big.Int).Add(request.Block.Number(), big.NewInt(7)).Cmp(self.chainman.CurrentBlock().Number()) < 0 {
 			glog.V(logger.Debug).Infoln("dropped block", request.Block.Number(), "due to low TD", request.TD)
 			break
 		}
+		*/
 
 		// Attempt to insert the newly received by checking if the parent exists.
 		// if the parent exists we process the block and propagate to our peers
@@ -281,7 +283,15 @@ func (self *ProtocolManager) handleMsg(p *peer) error {
 			}
 			self.BroadcastBlock(hash, request.Block)
 		} else {
-			self.downloader.AddBlock(p.id, request.Block, request.TD)
+			// adding blocks is synchronous
+			go func() {
+				err := self.downloader.AddBlock(p.id, request.Block, request.TD)
+				if err != nil {
+					glog.V(logger.Detail).Infoln("downloader err:", err)
+					return
+				}
+				self.BroadcastBlock(hash, request.Block)
+			}()
 		}
 	default:
 		return errResp(ErrInvalidMsgCode, "%v", msg.Code)