diff options
Diffstat (limited to 'p2p/server.go')
| -rw-r--r-- | p2p/server.go | 35 |
1 files changed, 28 insertions, 7 deletions
diff --git a/p2p/server.go b/p2p/server.go index 5e0c917fc..77f66f167 100644 --- a/p2p/server.go +++ b/p2p/server.go @@ -22,10 +22,11 @@ const ( refreshPeersInterval = 30 * time.Second staticPeerCheckInterval = 15 * time.Second - // This is the maximum number of inbound connection - // that are allowed to linger between 'accepted' and - // 'added as peer'. - maxAcceptConns = 50 + // Maximum number of concurrently handshaking inbound connections. + maxAcceptConns = 10 + + // Maximum number of concurrently dialing outbound connections. + maxDialingConns = 10 // total timeout for encryption handshake and protocol // handshake in both directions. @@ -52,6 +53,11 @@ type Server struct { // connected. It must be greater than zero. MaxPeers int + // MaxPendingPeers is the maximum number of peers that can be pending in the + // handshake phase, counted separately for inbound and outbound connections. + // Zero defaults to preset values. + MaxPendingPeers int + // Name sets the node name of this server. // Use common.MakeName to create a name that follows existing conventions. Name string @@ -331,8 +337,12 @@ func (srv *Server) listenLoop() { // This channel acts as a semaphore limiting // active inbound connections that are lingering pre-handshake. // If all slots are taken, no further connections are accepted. - slots := make(chan struct{}, maxAcceptConns) - for i := 0; i < maxAcceptConns; i++ { + tokens := maxAcceptConns + if srv.MaxPendingPeers > 0 { + tokens = srv.MaxPendingPeers + } + slots := make(chan struct{}, tokens) + for i := 0; i < tokens; i++ { slots <- struct{}{} } @@ -401,7 +411,15 @@ func (srv *Server) dialLoop() { defer srv.loopWG.Done() defer refresh.Stop() - // TODO: maybe limit number of active dials + // Limit the number of concurrent dials + tokens := maxAcceptConns + if srv.MaxPendingPeers > 0 { + tokens = srv.MaxPendingPeers + } + slots := make(chan struct{}, tokens) + for i := 0; i < tokens; i++ { + slots <- struct{}{} + } dial := func(dest *discover.Node) { // Don't dial nodes that would fail the checks in addPeer. // This is important because the connection handshake is a lot @@ -413,11 +431,14 @@ func (srv *Server) dialLoop() { if !ok || dialing[dest.ID] { return } + // Request a dial slot to prevent CPU exhaustion + <-slots dialing[dest.ID] = true srv.peerWG.Add(1) go func() { srv.dialNode(dest) + slots <- struct{}{} dialed <- dest }() } |