aboutsummaryrefslogtreecommitdiffstats
path: root/p2p
diff options
context:
space:
mode:
authorFelix Lange <fjl@twurst.com>2015-04-08 23:37:11 +0800
committerFelix Lange <fjl@twurst.com>2015-04-10 19:26:27 +0800
commitf1d710af006d7e9ed6046ab410976bd20c1e3c97 (patch)
treef7a6b948d41d1554bdf935d2854442c58b414d63 /p2p
parent22d1f0faf1fcb20063b719f8fc70534e268485b6 (diff)
downloadgo-tangerine-f1d710af006d7e9ed6046ab410976bd20c1e3c97.tar
go-tangerine-f1d710af006d7e9ed6046ab410976bd20c1e3c97.tar.gz
go-tangerine-f1d710af006d7e9ed6046ab410976bd20c1e3c97.tar.bz2
go-tangerine-f1d710af006d7e9ed6046ab410976bd20c1e3c97.tar.lz
go-tangerine-f1d710af006d7e9ed6046ab410976bd20c1e3c97.tar.xz
go-tangerine-f1d710af006d7e9ed6046ab410976bd20c1e3c97.tar.zst
go-tangerine-f1d710af006d7e9ed6046ab410976bd20c1e3c97.zip
p2p: fix Peer shutdown deadlocks
There were multiple synchronization issues in the disconnect handling, all caused by the odd special-casing of Peer.readLoop errors. Remove the special handling of read errors and make readLoop part of the Peer WaitGroup. Thanks to @Gustav-Simonsson for pointing at arrows in a diagram and playing rubber-duck.
Diffstat (limited to 'p2p')
-rw-r--r--p2p/handshake.go2
-rw-r--r--p2p/peer.go131
-rw-r--r--p2p/peer_error.go10
-rw-r--r--p2p/peer_test.go74
4 files changed, 139 insertions, 78 deletions
diff --git a/p2p/handshake.go b/p2p/handshake.go
index 031064407..5a259cd76 100644
--- a/p2p/handshake.go
+++ b/p2p/handshake.go
@@ -409,7 +409,7 @@ func readProtocolHandshake(r MsgReader, our *protoHandshake) (*protoHandshake, e
// spec and we send it ourself if Server.addPeer fails.
var reason DiscReason
rlp.Decode(msg.Payload, &reason)
- return nil, discRequestedError(reason)
+ return nil, reason
}
if msg.Code != handshakeMsg {
return nil, fmt.Errorf("expected handshake, got %x", msg.Code)
diff --git a/p2p/peer.go b/p2p/peer.go
index 6b97ea58d..a82ee4bca 100644
--- a/p2p/peer.go
+++ b/p2p/peer.go
@@ -44,7 +44,7 @@ type Peer struct {
rw *conn
running map[string]*protoRW
- protoWG sync.WaitGroup
+ wg sync.WaitGroup
protoErr chan error
closed chan struct{}
disc chan DiscReason
@@ -102,58 +102,50 @@ func (p *Peer) String() string {
func newPeer(fd net.Conn, conn *conn, protocols []Protocol) *Peer {
logtag := fmt.Sprintf("Peer %.8x %v", conn.ID[:], fd.RemoteAddr())
+ protomap := matchProtocols(protocols, conn.Caps, conn)
p := &Peer{
Logger: logger.NewLogger(logtag),
conn: fd,
rw: conn,
- running: matchProtocols(protocols, conn.Caps, conn),
+ running: protomap,
disc: make(chan DiscReason),
- protoErr: make(chan error),
+ protoErr: make(chan error, len(protomap)+1), // protocols + pingLoop
closed: make(chan struct{}),
}
return p
}
func (p *Peer) run() DiscReason {
- var readErr = make(chan error, 1)
- defer p.closeProtocols()
- defer close(p.closed)
+ readErr := make(chan error, 1)
+ p.wg.Add(2)
+ go p.readLoop(readErr)
+ go p.pingLoop()
p.startProtocols()
- go func() { readErr <- p.readLoop() }()
-
- ping := time.NewTicker(pingInterval)
- defer ping.Stop()
// Wait for an error or disconnect.
var reason DiscReason
-loop:
- for {
- select {
- case <-ping.C:
- go func() {
- if err := SendItems(p.rw, pingMsg); err != nil {
- p.protoErr <- err
- return
- }
- }()
- case err := <-readErr:
- // We rely on protocols to abort if there is a write error. It
- // might be more robust to handle them here as well.
- p.DebugDetailf("Read error: %v\n", err)
- p.conn.Close()
- return DiscNetworkError
- case err := <-p.protoErr:
- reason = discReasonForError(err)
- break loop
- case reason = <-p.disc:
- break loop
+ select {
+ case err := <-readErr:
+ if r, ok := err.(DiscReason); ok {
+ reason = r
+ break
}
+ // Note: We rely on protocols to abort if there is a write
+ // error. It might be more robust to handle them here as well.
+ p.DebugDetailf("Read error: %v\n", err)
+ p.conn.Close()
+ reason = DiscNetworkError
+ case err := <-p.protoErr:
+ reason = discReasonForError(err)
+ case reason = <-p.disc:
}
- p.politeDisconnect(reason)
- // Wait for readLoop. It will end because conn is now closed.
- <-readErr
+ close(p.closed)
+ p.wg.Wait()
+ if reason != DiscNetworkError {
+ p.politeDisconnect(reason)
+ }
p.Debugf("Disconnected: %v\n", reason)
return reason
}
@@ -174,18 +166,37 @@ func (p *Peer) politeDisconnect(reason DiscReason) {
p.conn.Close()
}
-func (p *Peer) readLoop() error {
+func (p *Peer) pingLoop() {
+ ping := time.NewTicker(pingInterval)
+ defer p.wg.Done()
+ defer ping.Stop()
+ for {
+ select {
+ case <-ping.C:
+ if err := SendItems(p.rw, pingMsg); err != nil {
+ p.protoErr <- err
+ return
+ }
+ case <-p.closed:
+ return
+ }
+ }
+}
+
+func (p *Peer) readLoop(errc chan<- error) {
+ defer p.wg.Done()
for {
p.conn.SetDeadline(time.Now().Add(frameReadTimeout))
msg, err := p.rw.ReadMsg()
if err != nil {
- return err
+ errc <- err
+ return
}
if err = p.handle(msg); err != nil {
- return err
+ errc <- err
+ return
}
}
- return nil
}
func (p *Peer) handle(msg Msg) error {
@@ -195,12 +206,11 @@ func (p *Peer) handle(msg Msg) error {
go SendItems(p.rw, pongMsg)
case msg.Code == discMsg:
var reason [1]DiscReason
- // no need to discard or for error checking, we'll close the
- // connection after this.
+ // This is the last message. We don't need to discard or
+ // check errors because, the connection will be closed after it.
rlp.Decode(msg.Payload, &reason)
p.Debugf("Disconnect requested: %v\n", reason[0])
- p.Disconnect(DiscRequested)
- return discRequestedError(reason[0])
+ return DiscRequested
case msg.Code < baseProtocolLength:
// ignore other base protocol messages
return msg.Discard()
@@ -210,7 +220,12 @@ func (p *Peer) handle(msg Msg) error {
if err != nil {
return fmt.Errorf("msg code out of range: %v", msg.Code)
}
- proto.in <- msg
+ select {
+ case proto.in <- msg:
+ return nil
+ case <-p.closed:
+ return io.EOF
+ }
}
return nil
}
@@ -234,10 +249,11 @@ outer:
}
func (p *Peer) startProtocols() {
+ p.wg.Add(len(p.running))
for _, proto := range p.running {
proto := proto
+ proto.closed = p.closed
p.DebugDetailf("Starting protocol %s/%d\n", proto.Name, proto.Version)
- p.protoWG.Add(1)
go func() {
err := proto.Run(p, proto)
if err == nil {
@@ -246,11 +262,8 @@ func (p *Peer) startProtocols() {
} else {
p.DebugDetailf("Protocol %s/%d error: %v\n", proto.Name, proto.Version, err)
}
- select {
- case p.protoErr <- err:
- case <-p.closed:
- }
- p.protoWG.Done()
+ p.protoErr <- err
+ p.wg.Done()
}()
}
}
@@ -266,13 +279,6 @@ func (p *Peer) getProto(code uint64) (*protoRW, error) {
return nil, newPeerError(errInvalidMsgCode, "%d", code)
}
-func (p *Peer) closeProtocols() {
- for _, p := range p.running {
- close(p.in)
- }
- p.protoWG.Wait()
-}
-
// writeProtoMsg sends the given message on behalf of the given named protocol.
// this exists because of Server.Broadcast.
func (p *Peer) writeProtoMsg(protoName string, msg Msg) error {
@@ -289,8 +295,8 @@ func (p *Peer) writeProtoMsg(protoName string, msg Msg) error {
type protoRW struct {
Protocol
-
in chan Msg
+ closed <-chan struct{}
offset uint64
w MsgWriter
}
@@ -304,10 +310,11 @@ func (rw *protoRW) WriteMsg(msg Msg) error {
}
func (rw *protoRW) ReadMsg() (Msg, error) {
- msg, ok := <-rw.in
- if !ok {
- return msg, io.EOF
+ select {
+ case msg := <-rw.in:
+ msg.Code -= rw.offset
+ return msg, nil
+ case <-rw.closed:
+ return Msg{}, io.EOF
}
- msg.Code -= rw.offset
- return msg, nil
}
diff --git a/p2p/peer_error.go b/p2p/peer_error.go
index 0ff4f4b43..402131630 100644
--- a/p2p/peer_error.go
+++ b/p2p/peer_error.go
@@ -98,15 +98,13 @@ func (d DiscReason) String() string {
return discReasonToString[d]
}
-type discRequestedError DiscReason
-
-func (err discRequestedError) Error() string {
- return fmt.Sprintf("disconnect requested: %v", DiscReason(err))
+func (d DiscReason) Error() string {
+ return d.String()
}
func discReasonForError(err error) DiscReason {
- if reason, ok := err.(discRequestedError); ok {
- return DiscReason(reason)
+ if reason, ok := err.(DiscReason); ok {
+ return reason
}
peerError, ok := err.(*peerError)
if !ok {
diff --git a/p2p/peer_test.go b/p2p/peer_test.go
index 3c4c71c0c..fb76818a0 100644
--- a/p2p/peer_test.go
+++ b/p2p/peer_test.go
@@ -2,8 +2,9 @@ package p2p
import (
"bytes"
+ "errors"
"fmt"
- "io"
+ "math/rand"
"net"
"reflect"
"testing"
@@ -27,7 +28,7 @@ var discard = Protocol{
},
}
-func testPeer(protos []Protocol) (io.Closer, *conn, *Peer, <-chan DiscReason) {
+func testPeer(protos []Protocol) (func(), *conn, *Peer, <-chan DiscReason) {
fd1, _ := net.Pipe()
hs1 := &protoHandshake{ID: randomID(), Version: baseProtocolVersion}
hs2 := &protoHandshake{ID: randomID(), Version: baseProtocolVersion}
@@ -41,7 +42,11 @@ func testPeer(protos []Protocol) (io.Closer, *conn, *Peer, <-chan DiscReason) {
errc := make(chan DiscReason, 1)
go func() { errc <- peer.run() }()
- return p1, &conn{p2, hs2}, peer, errc
+ closer := func() {
+ p1.Close()
+ fd1.Close()
+ }
+ return closer, &conn{p2, hs2}, peer, errc
}
func TestPeerProtoReadMsg(t *testing.T) {
@@ -67,7 +72,7 @@ func TestPeerProtoReadMsg(t *testing.T) {
}
closer, rw, _, errc := testPeer([]Protocol{proto})
- defer closer.Close()
+ defer closer()
Send(rw, baseProtocolLength+2, []uint{1})
Send(rw, baseProtocolLength+3, []uint{2})
@@ -99,7 +104,7 @@ func TestPeerProtoEncodeMsg(t *testing.T) {
},
}
closer, rw, _, _ := testPeer([]Protocol{proto})
- defer closer.Close()
+ defer closer()
if err := ExpectMsg(rw, 17, []string{"foo", "bar"}); err != nil {
t.Error(err)
@@ -110,7 +115,7 @@ func TestPeerWriteForBroadcast(t *testing.T) {
defer testlog(t).detach()
closer, rw, peer, peerErr := testPeer([]Protocol{discard})
- defer closer.Close()
+ defer closer()
emptymsg := func(code uint64) Msg {
return Msg{Code: code, Size: 0, Payload: bytes.NewReader(nil)}
@@ -150,7 +155,7 @@ func TestPeerPing(t *testing.T) {
defer testlog(t).detach()
closer, rw, _, _ := testPeer(nil)
- defer closer.Close()
+ defer closer()
if err := SendItems(rw, pingMsg); err != nil {
t.Fatal(err)
}
@@ -163,19 +168,70 @@ func TestPeerDisconnect(t *testing.T) {
defer testlog(t).detach()
closer, rw, _, disc := testPeer(nil)
- defer closer.Close()
+ defer closer()
if err := SendItems(rw, discMsg, DiscQuitting); err != nil {
t.Fatal(err)
}
if err := ExpectMsg(rw, discMsg, []interface{}{DiscRequested}); err != nil {
t.Error(err)
}
- closer.Close() // make test end faster
+ closer()
if reason := <-disc; reason != DiscRequested {
t.Errorf("run returned wrong reason: got %v, want %v", reason, DiscRequested)
}
}
+// This test is supposed to verify that Peer can reliably handle
+// multiple causes of disconnection occurring at the same time.
+func TestPeerDisconnectRace(t *testing.T) {
+ defer testlog(t).detach()
+ maybe := func() bool { return rand.Intn(1) == 1 }
+
+ for i := 0; i < 1000; i++ {
+ protoclose := make(chan error)
+ protodisc := make(chan DiscReason)
+ closer, rw, p, disc := testPeer([]Protocol{
+ {
+ Name: "closereq",
+ Run: func(p *Peer, rw MsgReadWriter) error { return <-protoclose },
+ Length: 1,
+ },
+ {
+ Name: "disconnect",
+ Run: func(p *Peer, rw MsgReadWriter) error { p.Disconnect(<-protodisc); return nil },
+ Length: 1,
+ },
+ })
+
+ // Simulate incoming messages.
+ go SendItems(rw, baseProtocolLength+1)
+ go SendItems(rw, baseProtocolLength+2)
+ // Close the network connection.
+ go closer()
+ // Make protocol "closereq" return.
+ protoclose <- errors.New("protocol closed")
+ // Make protocol "disconnect" call peer.Disconnect
+ protodisc <- DiscAlreadyConnected
+ // In some cases, simulate something else calling peer.Disconnect.
+ if maybe() {
+ go p.Disconnect(DiscInvalidIdentity)
+ }
+ // In some cases, simulate remote requesting a disconnect.
+ if maybe() {
+ go SendItems(rw, discMsg, DiscQuitting)
+ }
+
+ select {
+ case <-disc:
+ case <-time.After(2 * time.Second):
+ // Peer.run should return quickly. If it doesn't the Peer
+ // goroutines are probably deadlocked. Call panic in order to
+ // show the stacks.
+ panic("Peer.run took to long to return.")
+ }
+ }
+}
+
func TestNewPeer(t *testing.T) {
name := "nodename"
caps := []Cap{{"foo", 2}, {"bar", 3}}