From 22d1f0faf1fcb20063b719f8fc70534e268485b6 Mon Sep 17 00:00:00 2001 From: Felix Lange Date: Fri, 3 Apr 2015 03:56:17 +0200 Subject: p2p: improve peer selection logic This commit introduces a new (temporary) peer selection strategy based on random lookups. While we're here, also implement the TODOs in dialLoop. --- p2p/server.go | 117 ++++++++++++++++++++++++++++++---------------------------- 1 file changed, 61 insertions(+), 56 deletions(-) (limited to 'p2p/server.go') diff --git a/p2p/server.go b/p2p/server.go index 0a2621aa8..b21b83252 100644 --- a/p2p/server.go +++ b/p2p/server.go @@ -3,6 +3,7 @@ package p2p import ( "bytes" "crypto/ecdsa" + "crypto/rand" "errors" "fmt" "net" @@ -276,46 +277,58 @@ func (srv *Server) listenLoop() { } func (srv *Server) dialLoop() { + var ( + dialed = make(chan *discover.Node) + dialing = make(map[discover.NodeID]bool) + findresults = make(chan []*discover.Node) + refresh = time.NewTimer(0) + ) defer srv.loopWG.Done() - refresh := time.NewTicker(refreshPeersInterval) defer refresh.Stop() - srv.ntab.Bootstrap(srv.BootstrapNodes) - go srv.findPeers() - - dialed := make(chan *discover.Node) - dialing := make(map[discover.NodeID]bool) - - // TODO: limit number of active dials - // TODO: ensure only one findPeers goroutine is running - // TODO: pause findPeers when we're at capacity + // TODO: maybe limit number of active dials + dial := func(dest *discover.Node) { + srv.lock.Lock() + ok, _ := srv.checkPeer(dest.ID) + srv.lock.Unlock() + // Don't dial nodes that would fail the checks in addPeer. + // This is important because the connection handshake is a lot + // of work and we'd rather avoid doing that work for peers + // that can't be added. + if !ok || dialing[dest.ID] { + return + } + dialing[dest.ID] = true + srv.peerWG.Add(1) + go func() { + srv.dialNode(dest) + dialed <- dest + }() + } + srv.ntab.Bootstrap(srv.BootstrapNodes) for { select { case <-refresh.C: - - go srv.findPeers() - - case dest := <-srv.peerConnect: - // avoid dialing nodes that are already connected. - // there is another check for this in addPeer, - // which runs after the handshake. srv.lock.Lock() - _, isconnected := srv.peers[dest.ID] + needpeers := len(srv.peers) < srv.MaxPeers srv.lock.Unlock() - if isconnected || dialing[dest.ID] || dest.ID == srv.Self().ID { - continue + if needpeers { + go func() { + var target discover.NodeID + rand.Read(target[:]) + findresults <- srv.ntab.Lookup(target) + }() + refresh.Stop() } - dialing[dest.ID] = true - srv.peerWG.Add(1) - go func() { - srv.dialNode(dest) - // at this point, the peer has been added - // or discarded. either way, we're not dialing it anymore. - dialed <- dest - }() - + case dest := <-srv.peerConnect: + dial(dest) + case dests := <-findresults: + for _, dest := range dests { + dial(dest) + } + refresh.Reset(refreshPeersInterval) case dest := <-dialed: delete(dialing, dest.ID) @@ -341,24 +354,6 @@ func (srv *Server) Self() *discover.Node { return srv.ntab.Self() } -func (srv *Server) findPeers() { - far := srv.Self().ID - for i := range far { - far[i] = ^far[i] - } - closeToSelf := srv.ntab.Lookup(srv.Self().ID) - farFromSelf := srv.ntab.Lookup(far) - - for i := 0; i < len(closeToSelf) || i < len(farFromSelf); i++ { - if i < len(closeToSelf) { - srv.peerConnect <- closeToSelf[i] - } - if i < len(farFromSelf) { - srv.peerConnect <- farFromSelf[i] - } - } -} - func (srv *Server) startPeer(fd net.Conn, dest *discover.Node) { // TODO: handle/store session token fd.SetDeadline(time.Now().Add(handshakeTimeout)) @@ -368,7 +363,6 @@ func (srv *Server) startPeer(fd net.Conn, dest *discover.Node) { glog.V(logger.Debug).Infof("Handshake with %v failed: %v", fd.RemoteAddr(), err) return } - conn.MsgReadWriter = &netWrapper{ wrapped: conn.MsgReadWriter, conn: fd, rtimeout: frameReadTimeout, wtimeout: frameWriteTimeout, @@ -379,24 +373,27 @@ func (srv *Server) startPeer(fd net.Conn, dest *discover.Node) { p.politeDisconnect(reason) return } + // The handshakes are done and it passed all checks. + // Spawn the Peer loops. + go srv.runPeer(p) +} +func (srv *Server) runPeer(p *Peer) { glog.V(logger.Debug).Infof("Added %v\n", p) srvjslog.LogJson(&logger.P2PConnected{ - RemoteId: fmt.Sprintf("%x", conn.ID[:]), - RemoteAddress: fd.RemoteAddr().String(), - RemoteVersionString: conn.Name, + RemoteId: p.ID().String(), + RemoteAddress: p.RemoteAddr().String(), + RemoteVersionString: p.Name(), NumConnections: srv.PeerCount(), }) - if srv.newPeerHook != nil { srv.newPeerHook(p) } discreason := p.run() srv.removePeer(p) - glog.V(logger.Debug).Infof("Removed %v (%v)\n", p, discreason) srvjslog.LogJson(&logger.P2PDisconnected{ - RemoteId: fmt.Sprintf("%x", conn.ID[:]), + RemoteId: p.ID().String(), NumConnections: srv.PeerCount(), }) } @@ -404,6 +401,14 @@ func (srv *Server) startPeer(fd net.Conn, dest *discover.Node) { func (srv *Server) addPeer(id discover.NodeID, p *Peer) (bool, DiscReason) { srv.lock.Lock() defer srv.lock.Unlock() + if ok, reason := srv.checkPeer(id); !ok { + return false, reason + } + srv.peers[id] = p + return true, 0 +} + +func (srv *Server) checkPeer(id discover.NodeID) (bool, DiscReason) { switch { case !srv.running: return false, DiscQuitting @@ -413,9 +418,9 @@ func (srv *Server) addPeer(id discover.NodeID, p *Peer) (bool, DiscReason) { return false, DiscAlreadyConnected case id == srv.Self().ID: return false, DiscSelf + default: + return true, 0 } - srv.peers[id] = p - return true, 0 } func (srv *Server) removePeer(p *Peer) { -- cgit v1.2.3