fdtrack: temporary hack for tracking file descriptor usage

Package fdtrack logs statistics about open file descriptors.
This should help identify the source of #1549.

p2p/dial.go

@@ -23,6 +23,7 @@ import (
 	"net"
 	"time"
 
+	"github.com/ethereum/go-ethereum/fdtrack"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/p2p/discover"
@@ -212,6 +213,7 @@ func (t *dialTask) Do(srv *Server) {
 		glog.V(logger.Detail).Infof("dial error: %v", err)
 		return
 	}
+	fd = fdtrack.WrapConn("p2p", fd)
 	mfd := newMeteredConn(fd, false)
 
 	srv.setupConn(mfd, t.flags, t.dest)

p2p/discover/udp.go

@@ -25,6 +25,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/fdtrack"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/p2p/nat"
@@ -197,6 +198,7 @@ func ListenUDP(priv *ecdsa.PrivateKey, laddr string, natm nat.Interface, nodeDBP
 	if err != nil {
 		return nil, err
 	}
+	fdtrack.Open("p2p")
 	conn, err := net.ListenUDP("udp", addr)
 	if err != nil {
 		return nil, err
@@ -234,6 +236,7 @@ func newUDP(priv *ecdsa.PrivateKey, c conn, natm nat.Interface, nodeDBPath strin
 
 func (t *udp) close() {
 	close(t.closing)
+	fdtrack.Close("p2p")
 	t.conn.Close()
 	// TODO: wait for the loops to end.
 }

p2p/metrics.go

@@ -34,7 +34,7 @@ var (
 // meteredConn is a wrapper around a network TCP connection that meters both the
 // inbound and outbound network traffic.
 type meteredConn struct {
-	*net.TCPConn // Network connection to wrap with metering
+	net.Conn
 }
 
 // newMeteredConn creates a new metered connection, also bumping the ingress or
@@ -45,13 +45,13 @@ func newMeteredConn(conn net.Conn, ingress bool) net.Conn {
 	} else {
 		egressConnectMeter.Mark(1)
 	}
-	return &meteredConn{conn.(*net.TCPConn)}
+	return &meteredConn{conn}
 }
 
 // Read delegates a network read to the underlying connection, bumping the ingress
 // traffic meter along the way.
 func (c *meteredConn) Read(b []byte) (n int, err error) {
-	n, err = c.TCPConn.Read(b)
+	n, err = c.Conn.Read(b)
 	ingressTrafficMeter.Mark(int64(n))
 	return
 }
@@ -59,7 +59,7 @@ func (c *meteredConn) Read(b []byte) (n int, err error) {
 // Write delegates a network write to the underlying connection, bumping the
 // egress traffic meter along the way.
 func (c *meteredConn) Write(b []byte) (n int, err error) {
-	n, err = c.TCPConn.Write(b)
+	n, err = c.Conn.Write(b)
 	egressTrafficMeter.Mark(int64(n))
 	return
 }

p2p/server.go

@@ -25,6 +25,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/ethereum/go-ethereum/fdtrack"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/p2p/discover"
@@ -372,7 +373,7 @@ func (srv *Server) startListening() error {
 	}
 	laddr := listener.Addr().(*net.TCPAddr)
 	srv.ListenAddr = laddr.String()
-	srv.listener = listener
+	srv.listener = fdtrack.WrapListener("p2p", listener)
 	srv.loopWG.Add(1)
 	go srv.listenLoop()
 	// Map the TCP listening port if NAT is configured.