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net: fix data races on deadline vars

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Fixes #4434.

This proposal replaces the previous CL 6855110. Due to issue 599, 64-bit atomic operations should probably be avoided, so use a sync.Mutex instead.

Benchmark comparisons against 025b9d070a85 on linux/386:

CL 6855110:

benchmark                        old ns/op    new ns/op    delta
BenchmarkTCPOneShot                 710024       727409   +2.45%
BenchmarkTCPOneShotTimeout          758178       768620   +1.38%
BenchmarkTCPPersistent              223464       228058   +2.06%
BenchmarkTCPPersistentTimeout       234494       242600   +3.46%

This proposal:

benchmark                        old ns/op    new ns/op    delta
BenchmarkTCPOneShot                 710024       718492   +1.19%
BenchmarkTCPOneShotTimeout          758178       748783   -1.24%
BenchmarkTCPPersistent              223464       227628   +1.86%
BenchmarkTCPPersistentTimeout       234494       238321   +1.63%

R=rsc, dvyukov, mikioh.mikioh, alex.brainman, bradfitz
CC=golang-dev, remyoudompheng
https://golang.org/cl/6866050
This commit is contained in:
Dave Cheney 2012-12-05 15:59:01 +11:00
parent 4855c1c145
commit 9fb96991e6
8 changed files with 147 additions and 83 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
src/pkg/net/fd_posix_test.go Normal file
View File

@ -0,0 +1,57 @@
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build darwin freebsd linux netbsd openbsd windows
package net
import (
"testing"
"time"
)
var deadlineSetTimeTests = []struct {
input time.Time
expected int64
}{
{time.Time{}, 0},
{time.Date(2009, 11, 10, 23, 00, 00, 00, time.UTC), 1257894000000000000}, // 2009-11-10 23:00:00 +0000 UTC
}
func TestDeadlineSetTime(t *testing.T) {
for _, tt := range deadlineSetTimeTests {
var d deadline
d.setTime(tt.input)
actual := d.value()
expected := int64(0)
if !tt.input.IsZero() {
expected = tt.input.UnixNano()
}
if actual != expected {
t.Errorf("set/value failed: expected %v, actual %v", expected, actual)
}
}
}
var deadlineExpiredTests = []struct {
deadline time.Time
expired bool
}{
// note, times are relative to the start of the test run, not
// the start of TestDeadlineExpired
{time.Now().Add(5 * time.Minute), false},
{time.Now().Add(-5 * time.Minute), true},
{time.Time{}, false}, // no deadline set
}
func TestDeadlineExpired(t *testing.T) {
for _, tt := range deadlineExpiredTests {
var d deadline
d.set(tt.deadline.UnixNano())
expired := d.expired()
if expired != tt.expired {
t.Errorf("expire failed: expected %v, actual %v", tt.expired, expired)
}
}
}

88
src/pkg/net/fd_unix.go
View File

@ -37,11 +37,11 @@ type netFD struct {
laddr Addr
raddr Addr
// owned by client
rdeadline int64
rio sync.Mutex
wdeadline int64
wio sync.Mutex
// serialize access to Read and Write methods
rio, wio sync.Mutex
// read and write deadlines
rdeadline, wdeadline deadline
// owned by fd wait server
ncr, ncw int
@ -82,11 +82,11 @@ func (s *pollServer) AddFD(fd *netFD, mode int) error {
key := intfd << 1
if mode == 'r' {
fd.ncr++
t = fd.rdeadline
t = fd.rdeadline.value()
} else {
fd.ncw++
key++
t = fd.wdeadline
t = fd.wdeadline.value()
}
s.pending[key] = fd
doWakeup := false
@ -153,12 +153,8 @@ func (s *pollServer) WakeFD(fd *netFD, mode int, err error) {
}
}
func (s *pollServer) Now() int64 {
return time.Now().UnixNano()
}
func (s *pollServer) CheckDeadlines() {
now := s.Now()
now := time.Now().UnixNano()
// TODO(rsc): This will need to be handled more efficiently,
// probably with a heap indexed by wakeup time.
@ -172,9 +168,9 @@ func (s *pollServer) CheckDeadlines() {
mode = 'w'
}
if mode == 'r' {
t = fd.rdeadline
t = fd.rdeadline.value()
} else {
t = fd.wdeadline
t = fd.wdeadline.value()
}
if t > 0 {
if t <= now {
@ -198,15 +194,15 @@ func (s *pollServer) Run() {
s.Lock()
defer s.Unlock()
for {
var t = s.deadline
if t > 0 {
t = t - s.Now()
if t <= 0 {
var timeout int64 // nsec to wait for or 0 for none
if s.deadline > 0 {
timeout = s.deadline - time.Now().UnixNano()
if timeout <= 0 {
s.CheckDeadlines()
continue
}
}
fd, mode, err := s.poll.WaitFD(s, t)
fd, mode, err := s.poll.WaitFD(s, timeout)
if err != nil {
print("pollServer WaitFD: ", err.Error(), "\n")
return
@ -418,11 +414,9 @@ func (fd *netFD) Read(p []byte) (n int, err error) {
}
defer fd.decref()
for {
if fd.rdeadline > 0 {
if time.Now().UnixNano() >= fd.rdeadline {
err = errTimeout
break
}
if fd.rdeadline.expired() {
err = errTimeout
break
}
n, err = syscall.Read(int(fd.sysfd), p)
if err != nil {
@ -450,11 +444,9 @@ func (fd *netFD) ReadFrom(p []byte) (n int, sa syscall.Sockaddr, err error) {
}
defer fd.decref()
for {
if fd.rdeadline > 0 {
if time.Now().UnixNano() >= fd.rdeadline {
err = errTimeout
break
}
if fd.rdeadline.expired() {
err = errTimeout
break
}
n, sa, err = syscall.Recvfrom(fd.sysfd, p, 0)
if err != nil {
@ -482,15 +474,13 @@ func (fd *netFD) ReadMsg(p []byte, oob []byte) (n, oobn, flags int, sa syscall.S
}
defer fd.decref()
for {
if fd.rdeadline > 0 {
if time.Now().UnixNano() >= fd.rdeadline {
err = errTimeout
break
}
if fd.rdeadline.expired() {
err = errTimeout
break
}
n, oobn, flags, sa, err = syscall.Recvmsg(fd.sysfd, p, oob, 0)
if err != nil {
// TODO(dfc) should n and oobn be set to nil
// TODO(dfc) should n and oobn be set to 0
if err == syscall.EAGAIN {
if err = fd.pollServer.WaitRead(fd); err == nil {
continue
@ -513,21 +503,17 @@ func chkReadErr(n int, err error, fd *netFD) error {
return err
}
func (fd *netFD) Write(p []byte) (int, error) {
func (fd *netFD) Write(p []byte) (nn int, err error) {
fd.wio.Lock()
defer fd.wio.Unlock()
if err := fd.incref(false); err != nil {
return 0, err
}
defer fd.decref()
var err error
nn := 0
for {
if fd.wdeadline > 0 {
if time.Now().UnixNano() >= fd.wdeadline {
err = errTimeout
break
}
if fd.wdeadline.expired() {
err = errTimeout
break
}
var n int
n, err = syscall.Write(int(fd.sysfd), p[nn:])
@ -565,11 +551,9 @@ func (fd *netFD) WriteTo(p []byte, sa syscall.Sockaddr) (n int, err error) {
}
defer fd.decref()
for {
if fd.wdeadline > 0 {
if time.Now().UnixNano() >= fd.wdeadline {
err = errTimeout
break
}
if fd.wdeadline.expired() {
err = errTimeout
break
}
err = syscall.Sendto(fd.sysfd, p, 0, sa)
if err == syscall.EAGAIN {
@ -595,11 +579,9 @@ func (fd *netFD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oob
}
defer fd.decref()
for {
if fd.wdeadline > 0 {
if time.Now().UnixNano() >= fd.wdeadline {
err = errTimeout
break
}
if fd.wdeadline.expired() {
err = errTimeout
break
}
err = syscall.Sendmsg(fd.sysfd, p, oob, sa, 0)
if err == syscall.EAGAIN {

20
src/pkg/net/fd_windows.go
View File

@ -285,11 +285,11 @@ type netFD struct {
errnoc [2]chan error // read/write submit or cancel operation errors
closec chan bool // used by Close to cancel pending IO
// owned by client
rdeadline int64
rio sync.Mutex
wdeadline int64
wio sync.Mutex
// serialize access to Read and Write methods
rio, wio sync.Mutex
// read and write deadlines
rdeadline, wdeadline deadline
}
func allocFD(fd syscall.Handle, family, sotype int, net string) *netFD {
@ -426,7 +426,7 @@ func (fd *netFD) Read(buf []byte) (int, error) {
defer fd.rio.Unlock()
var o readOp
o.Init(fd, buf, 'r')
n, err := iosrv.ExecIO(&o, fd.rdeadline)
n, err := iosrv.ExecIO(&o, fd.rdeadline.value())
if err == nil && n == 0 {
err = io.EOF
}
@ -463,7 +463,7 @@ func (fd *netFD) ReadFrom(buf []byte) (n int, sa syscall.Sockaddr, err error) {
var o readFromOp
o.Init(fd, buf, 'r')
o.rsan = int32(unsafe.Sizeof(o.rsa))
n, err = iosrv.ExecIO(&o, fd.rdeadline)
n, err = iosrv.ExecIO(&o, fd.rdeadline.value())
if err != nil {
return 0, nil, err
}
@ -495,7 +495,7 @@ func (fd *netFD) Write(buf []byte) (int, error) {
defer fd.wio.Unlock()
var o writeOp
o.Init(fd, buf, 'w')
return iosrv.ExecIO(&o, fd.wdeadline)
return iosrv.ExecIO(&o, fd.wdeadline.value())
}
// WriteTo to network.
@ -527,7 +527,7 @@ func (fd *netFD) WriteTo(buf []byte, sa syscall.Sockaddr) (int, error) {
var o writeToOp
o.Init(fd, buf, 'w')
o.sa = sa
return iosrv.ExecIO(&o, fd.wdeadline)
return iosrv.ExecIO(&o, fd.wdeadline.value())
}
// Accept new network connections.
@ -577,7 +577,7 @@ func (fd *netFD) accept(toAddr func(syscall.Sockaddr) Addr) (*netFD, error) {
var o acceptOp
o.Init(fd, 'r')
o.newsock = s
_, err = iosrv.ExecIO(&o, fd.rdeadline)
_, err = iosrv.ExecIO(&o, fd.rdeadline.value())
if err != nil {
closesocket(s)
return nil, err

34
src/pkg/net/net.go
View File

@ -46,6 +46,7 @@ import (
"errors"
"io"
"os"
"sync"
"syscall"
"time"
)
@ -375,3 +376,36 @@ func genericReadFrom(w io.Writer, r io.Reader) (n int64, err error) {
// Use wrapper to hide existing r.ReadFrom from io.Copy.
return io.Copy(writerOnly{w}, r)
}
// deadline is an atomically-accessed number of nanoseconds since 1970
// or 0, if no deadline is set.
type deadline struct {
sync.Mutex
val int64
}
func (d *deadline) expired() bool {
t := d.value()
return t > 0 && time.Now().UnixNano() >= t
}
func (d *deadline) value() (v int64) {
d.Lock()
v = d.val
d.Unlock()
return
}
func (d *deadline) set(v int64) {
d.Lock()
d.val = v
d.Unlock()
}
func (d *deadline) setTime(t time.Time) {
if t.IsZero() {
d.set(0)
} else {
d.set(t.UnixNano())
}
}

2
src/pkg/net/sendfile_freebsd.go
View File

@ -82,7 +82,7 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
if n == 0 && err1 == nil {
break
}
if err1 == syscall.EAGAIN && c.wdeadline >= 0 {
if err1 == syscall.EAGAIN {
if err1 = c.pollServer.WaitWrite(c); err1 == nil {
continue
}

2
src/pkg/net/sendfile_linux.go
View File

@ -58,7 +58,7 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
if n == 0 && err1 == nil {
break
}
if err1 == syscall.EAGAIN && c.wdeadline >= 0 {
if err1 == syscall.EAGAIN {
if err1 = c.pollServer.WaitWrite(c); err1 == nil {
continue
}

6
src/pkg/net/sock_posix.go
View File

@ -56,15 +56,13 @@ func socket(net string, f, t, p int, ipv6only bool, ulsa, ursa syscall.Sockaddr,
}
if ursa != nil {
if !deadline.IsZero() {
fd.wdeadline = deadline.UnixNano()
}
fd.wdeadline.setTime(deadline)
if err = fd.connect(ursa); err != nil {
closesocket(s)
return nil, err
}
fd.isConnected = true
fd.wdeadline = 0
fd.wdeadline.set(0)
}
lsa, _ := syscall.Getsockname(s)

21
src/pkg/net/sockopt_posix.go
View File

@ -119,29 +119,22 @@ func setWriteBuffer(fd *netFD, bytes int) error {
return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd.sysfd, syscall.SOL_SOCKET, syscall.SO_SNDBUF, bytes))
}
// TODO(dfc) these unused error returns could be removed
func setReadDeadline(fd *netFD, t time.Time) error {
if t.IsZero() {
fd.rdeadline = 0
} else {
fd.rdeadline = t.UnixNano()
}
fd.rdeadline.setTime(t)
return nil
}
func setWriteDeadline(fd *netFD, t time.Time) error {
if t.IsZero() {
fd.wdeadline = 0
} else {
fd.wdeadline = t.UnixNano()
}
fd.wdeadline.setTime(t)
return nil
}
func setDeadline(fd *netFD, t time.Time) error {
if err := setReadDeadline(fd, t); err != nil {
return err
}
return setWriteDeadline(fd, t)
setReadDeadline(fd, t)
setWriteDeadline(fd, t)
return nil
}
func setKeepAlive(fd *netFD, keepalive bool) error {