eth, eth/downloader: moved peer selection to protocol handler

eth/downloader/downloader.go

@@ -89,7 +89,7 @@ func New(hasBlock hashCheckFn, insertChain chainInsertFn, currentTd currentTdFn)
 		blockCh:     make(chan blockPack, 1),
 		quit:        make(chan struct{}),
 	}
-	go downloader.peerHandler()
+	//go downloader.peerHandler()
 	go downloader.update()
 
 	return downloader
@@ -110,7 +110,6 @@ func (d *Downloader) RegisterPeer(id string, td *big.Int, hash common.Hash, getH
 	// add peer to our peer set
 	d.peers[id] = peer
 	// broadcast new peer
-	d.newPeerCh <- peer
 
 	return nil
 }
@@ -125,72 +124,78 @@ func (d *Downloader) UnregisterPeer(id string) {
 	delete(d.peers, id)
 }
 
-func (d *Downloader) peerHandler() {
-	// itimer is used to determine when to start ignoring `minDesiredPeerCount`
-	itimer := time.NewTimer(peerCountTimeout)
+func (d *Downloader) update() {
 out:
 	for {
 		select {
-		case <-d.newPeerCh:
-			// Meet the `minDesiredPeerCount` before we select our best peer
-			if len(d.peers) < minDesiredPeerCount {
+		case sync := <-d.syncCh:
+			var peer *peer = sync.peer
+			err := d.getFromPeer(peer, sync.hash, sync.ignoreInitial)
+			if err != nil {
+				glog.V(logger.Detail).Infoln(err)
 				break
 			}
-			itimer.Stop()
 
-			d.selectPeer(d.peers.bestPeer())
-		case <-itimer.C:
-			// The timer will make sure that the downloader keeps an active state
-			// in which it attempts to always check the network for highest td peers
-			// Either select the peer or restart the timer if no peers could
-			// be selected.
-			if peer := d.peers.bestPeer(); peer != nil {
-				d.selectPeer(d.peers.bestPeer())
-			} else {
-				itimer.Reset(5 * time.Second)
-			}
+			d.process()
 		case <-d.quit:
 			break out
 		}
 	}
 }
 
-func (d *Downloader) selectPeer(p *peer) {
+// SynchroniseWithPeer will select the peer and use it for synchronising. If an empty string is given
+// it will use the best peer possible and synchronise if it's TD is higher than our own. If any of the
+// checks fail an error will be returned. This method is synchronous
+func (d *Downloader) Synchronise(id string, hash common.Hash) (types.Blocks, error) {
 	// Make sure it's doing neither. Once done we can restart the
 	// downloading process if the TD is higher. For now just get on
 	// with whatever is going on. This prevents unecessary switching.
 	if d.isBusy() {
-		return
-	}
-	// selected peer must be better than our own
-	// XXX we also check the peer's recent hash to make sure we
-	// don't have it. Some peers report (i think) incorrect TD.
-	if p.td.Cmp(d.currentTd()) <= 0 || d.hasBlock(p.recentHash) {
-		return
+		return nil, errBusy
 	}
 
-	glog.V(logger.Detail).Infoln("New peer with highest TD =", p.td)
-	d.syncCh <- syncPack{p, p.recentHash, false}
-
+	// Fetch the peer using the id or throw an error if the peer couldn't be found
+	p := d.peers[id]
+	if p == nil {
+		return nil, errUnknownPeer
 	}
 
-func (d *Downloader) update() {
-out:
-	for {
-		select {
-		case sync := <-d.syncCh:
-			var peer *peer = sync.peer
-			err := d.getFromPeer(peer, sync.hash, sync.ignoreInitial)
+	// Get the hash from the peer and initiate the downloading progress.
+	err := d.getFromPeer(p, hash, false)
 	if err != nil {
-				glog.V(logger.Detail).Infoln(err)
-				break
+		return nil, err
 	}
 
-			d.process()
-		case <-d.quit:
-			break out
+	return d.queue.blocks, nil
+}
+
+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
+	// respectively.
+	if err := d.startFetchingHashes(p, hash, ignoreInitial); err != nil {
+		// handle error
+		glog.V(logger.Debug).Infoln("Error fetching hashes:", err)
+		// XXX Reset
+		return err
 	}
+
+	// Start fetching blocks in paralel. The strategy is simple
+	// take any available peers, seserve a chunk for each peer available,
+	// let the peer deliver the chunkn and periodically check if a peer
+	// has timedout. When done downloading, process blocks.
+	if err := d.startFetchingBlocks(p); err != nil {
+		glog.V(logger.Debug).Infoln("Error downloading blocks:", err)
+		// XXX reset
+		return err
 	}
+
+	glog.V(logger.Detail).Infoln("Sync completed")
+
+	return nil
 }
 
 // XXX Make synchronous

eth/downloader/synchronous.go

-package downloader
-
-import (
-	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/core/types"
-	"github.com/ethereum/go-ethereum/logger"
-	"github.com/ethereum/go-ethereum/logger/glog"
-)
-
-// THIS IS PENDING AND TO DO CHANGES FOR MAKING THE DOWNLOADER SYNCHRONOUS
-
-// SynchroniseWithPeer will select the peer and use it for synchronising. If an empty string is given
-// it will use the best peer possible and synchronise if it's TD is higher than our own. If any of the
-// checks fail an error will be returned. This method is synchronous
-func (d *Downloader) SynchroniseWithPeer(id string) (types.Blocks, error) {
-	// Check if we're busy
-	if d.isBusy() {
-		return nil, errBusy
-	}
-
-	// Attempt to select a peer. This can either be nothing, which returns, best peer
-	// or selected peer. If no peer could be found an error will be returned
-	var p *peer
-	if len(id) == 0 {
-		p = d.peers[id]
-		if p == nil {
-			return nil, errUnknownPeer
-		}
-	} else {
-		p = d.peers.bestPeer()
-	}
-
-	// Make sure our td is lower than the peer's td
-	if p.td.Cmp(d.currentTd()) <= 0 || d.hasBlock(p.recentHash) {
-		return nil, errLowTd
-	}
-
-	// Get the hash from the peer and initiate the downloading progress.
-	err := d.getFromPeer(p, p.recentHash, false)
-	if err != nil {
-		return nil, err
-	}
-
-	return d.queue.blocks, nil
-}
-
-// Synchronise will synchronise using the best peer.
-func (d *Downloader) Synchronise() (types.Blocks, error) {
-	return d.SynchroniseWithPeer("")
-}
-
-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
-	// respectively.
-	if err := d.startFetchingHashes(p, hash, ignoreInitial); err != nil {
-		// handle error
-		glog.V(logger.Debug).Infoln("Error fetching hashes:", err)
-		// XXX Reset
-		return err
-	}
-
-	// Start fetching blocks in paralel. The strategy is simple
-	// take any available peers, seserve a chunk for each peer available,
-	// let the peer deliver the chunkn and periodically check if a peer
-	// has timedout. When done downloading, process blocks.
-	if err := d.startFetchingBlocks(p); err != nil {
-		glog.V(logger.Debug).Infoln("Error downloading blocks:", err)
-		// XXX reset
-		return err
-	}
-
-	glog.V(logger.Detail).Infoln("Sync completed")
-
-	return nil
-}

eth/handler.go

@@ -39,6 +39,7 @@ import (
 	"math"
 	"math/big"
 	"sync"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
@@ -51,6 +52,11 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
+const (
+	peerCountTimeout    = 12 * time.Second // Amount of time it takes for the peer handler to ignore minDesiredPeerCount
+	minDesiredPeerCount = 5                // Amount of peers desired to start syncing
+)
+
 func errResp(code errCode, format string, v ...interface{}) error {
 	return fmt.Errorf("%v - %v", code, fmt.Sprintf(format, v...))
 }
@@ -82,6 +88,9 @@ type ProtocolManager struct {
 	eventMux      *event.TypeMux
 	txSub         event.Subscription
 	minedBlockSub event.Subscription
+
+	newPeerCh chan *peer
+	quit      chan struct{}
 }
 
 // NewProtocolManager returns a new ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
@@ -93,7 +102,10 @@ func NewProtocolManager(protocolVersion, networkId int, mux *event.TypeMux, txpo
 		chainman:   chainman,
 		downloader: downloader,
 		peers:      make(map[string]*peer),
+		newPeerCh:  make(chan *peer, 1),
+		quit:       make(chan struct{}),
 	}
+	go manager.peerHandler()
 
 	manager.SubProtocol = p2p.Protocol{
 		Name:    "eth",
@@ -101,16 +113,61 @@ func NewProtocolManager(protocolVersion, networkId int, mux *event.TypeMux, txpo
 		Length:  ProtocolLength,
 		Run: func(p *p2p.Peer, rw p2p.MsgReadWriter) error {
 			peer := manager.newPeer(protocolVersion, networkId, p, rw)
-			err := manager.handle(peer)
-			//glog.V(logger.Detail).Infof("[%s]: %v\n", peer.id, err)
 
-			return err
+			manager.newPeerCh <- peer
+
+			return manager.handle(peer)
 		},
 	}
 
 	return manager
 }
 
+func (pm *ProtocolManager) peerHandler() {
+	// itimer is used to determine when to start ignoring `minDesiredPeerCount`
+	itimer := time.NewTimer(peerCountTimeout)
+out:
+	for {
+		select {
+		case <-pm.newPeerCh:
+			// Meet the `minDesiredPeerCount` before we select our best peer
+			if len(pm.peers) < minDesiredPeerCount {
+				break
+			}
+			itimer.Stop()
+
+			// Find the best peer
+			peer := getBestPeer(pm.peers)
+			if peer == nil {
+				glog.V(logger.Debug).Infoln("Sync attempt cancelled. No peers available")
+				return
+			}
+			go pm.synchronise(peer)
+		case <-itimer.C:
+			// The timer will make sure that the downloader keeps an active state
+			// in which it attempts to always check the network for highest td peers
+			// Either select the peer or restart the timer if no peers could
+			// be selected.
+			if peer := getBestPeer(pm.peers); peer != nil {
+				go pm.synchronise(peer)
+			} else {
+				itimer.Reset(5 * time.Second)
+			}
+		case <-pm.quit:
+			break out
+		}
+	}
+}
+
+func (pm *ProtocolManager) synchronise(peer *peer) {
+	// Get the hashes from the peer (synchronously)
+	_, err := pm.downloader.Synchronise(peer.id, peer.recentHash)
+	if err != nil {
+		// handle error
+		glog.V(logger.Debug).Infoln("error downloading:", err)
+	}
+}
+
 func (pm *ProtocolManager) Start() {
 	// broadcast transactions
 	pm.txSub = pm.eventMux.Subscribe(core.TxPreEvent{})
@@ -141,7 +198,7 @@ func (pm *ProtocolManager) handle(p *peer) error {
 	pm.peers[p.id] = p
 	pm.pmu.Unlock()
 
-	pm.downloader.RegisterPeer(p.id, p.td, p.currentHash, p.requestHashes, p.requestBlocks)
+	pm.downloader.RegisterPeer(p.id, p.td, p.recentHash, p.requestHashes, p.requestBlocks)
 	defer func() {
 		pm.pmu.Lock()
 		defer pm.pmu.Unlock()

eth/peer.go

@@ -25,6 +25,16 @@ type getBlockHashesMsgData struct {
 	Amount uint64
 }
 
+func getBestPeer(peers map[string]*peer) *peer {
+	var peer *peer
+	for _, cp := range peers {
+		if peer == nil || cp.td.Cmp(peer.td) > 0 {
+			peer = cp
+		}
+	}
+	return peer
+}
+
 type peer struct {
 	*p2p.Peer
 
@@ -32,7 +42,7 @@ type peer struct {
 
 	protv, netid int
 
-	currentHash common.Hash
+	recentHash common.Hash
 	id         string
 	td         *big.Int
 
@@ -43,14 +53,14 @@ type peer struct {
 	blockHashes *set.Set
 }
 
-func newPeer(protv, netid int, genesis, currentHash common.Hash, td *big.Int, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
+func newPeer(protv, netid int, genesis, recentHash common.Hash, td *big.Int, p *p2p.Peer, rw p2p.MsgReadWriter) *peer {
 	id := p.ID()
 
 	return &peer{
 		Peer:        p,
 		rw:          rw,
 		genesis:     genesis,
-		ourHash:     currentHash,
+		ourHash:     recentHash,
 		ourTd:       td,
 		protv:       protv,
 		netid:       netid,
@@ -145,7 +155,7 @@ func (p *peer) handleStatus() error {
 	// Set the total difficulty of the peer
 	p.td = status.TD
 	// set the best hash of the peer
-	p.currentHash = status.CurrentBlock
+	p.recentHash = status.CurrentBlock
 
 	return <-errc
 }