mirror of
https://github.com/golang/go
synced 2024-11-19 13:04:45 -07:00
23aad448b1
On systems that use kqueue, we always register descriptors for both EVFILT_READ and EVFILT_WRITE. On at least FreeBSD and OpenBSD, when the write end of a pipe is registered for EVFILT_READ and EVFILT_WRITE events, and the read end of the pipe is closed, kqueue reports an EVFILT_READ event with EV_EOF set, but does not report an EVFILT_WRITE event. Since the write to the pipe is waiting for an EVFILT_WRITE event, closing the read end of a pipe can cause the write end to hang rather than attempt another write which will fail with EPIPE. Fix this by treating EVFILT_READ with EV_EOF set as making both reads and writes ready to proceed. The real test for this is in CL 71770, which tests using various timeouts with pipes. Updates #22114 Change-Id: Ib23fbaaddbccd8eee77bdf18f27a7f0aa50e2742 Reviewed-on: https://go-review.googlesource.com/71973 Reviewed-by: Matthew Dempsky <mdempsky@google.com>
119 lines
2.7 KiB
Go
119 lines
2.7 KiB
Go
// Copyright 2013 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 dragonfly freebsd netbsd openbsd
|
|
|
|
package runtime
|
|
|
|
// Integrated network poller (kqueue-based implementation).
|
|
|
|
import "unsafe"
|
|
|
|
func kqueue() int32
|
|
|
|
//go:noescape
|
|
func kevent(kq int32, ch *keventt, nch int32, ev *keventt, nev int32, ts *timespec) int32
|
|
func closeonexec(fd int32)
|
|
|
|
var (
|
|
kq int32 = -1
|
|
)
|
|
|
|
func netpollinit() {
|
|
kq = kqueue()
|
|
if kq < 0 {
|
|
println("runtime: kqueue failed with", -kq)
|
|
throw("runtime: netpollinit failed")
|
|
}
|
|
closeonexec(kq)
|
|
}
|
|
|
|
func netpolldescriptor() uintptr {
|
|
return uintptr(kq)
|
|
}
|
|
|
|
func netpollopen(fd uintptr, pd *pollDesc) int32 {
|
|
// Arm both EVFILT_READ and EVFILT_WRITE in edge-triggered mode (EV_CLEAR)
|
|
// for the whole fd lifetime. The notifications are automatically unregistered
|
|
// when fd is closed.
|
|
var ev [2]keventt
|
|
*(*uintptr)(unsafe.Pointer(&ev[0].ident)) = fd
|
|
ev[0].filter = _EVFILT_READ
|
|
ev[0].flags = _EV_ADD | _EV_CLEAR
|
|
ev[0].fflags = 0
|
|
ev[0].data = 0
|
|
ev[0].udata = (*byte)(unsafe.Pointer(pd))
|
|
ev[1] = ev[0]
|
|
ev[1].filter = _EVFILT_WRITE
|
|
n := kevent(kq, &ev[0], 2, nil, 0, nil)
|
|
if n < 0 {
|
|
return -n
|
|
}
|
|
return 0
|
|
}
|
|
|
|
func netpollclose(fd uintptr) int32 {
|
|
// Don't need to unregister because calling close()
|
|
// on fd will remove any kevents that reference the descriptor.
|
|
return 0
|
|
}
|
|
|
|
func netpollarm(pd *pollDesc, mode int) {
|
|
throw("runtime: unused")
|
|
}
|
|
|
|
// Polls for ready network connections.
|
|
// Returns list of goroutines that become runnable.
|
|
func netpoll(block bool) *g {
|
|
if kq == -1 {
|
|
return nil
|
|
}
|
|
var tp *timespec
|
|
var ts timespec
|
|
if !block {
|
|
tp = &ts
|
|
}
|
|
var events [64]keventt
|
|
retry:
|
|
n := kevent(kq, nil, 0, &events[0], int32(len(events)), tp)
|
|
if n < 0 {
|
|
if n != -_EINTR {
|
|
println("runtime: kevent on fd", kq, "failed with", -n)
|
|
throw("runtime: netpoll failed")
|
|
}
|
|
goto retry
|
|
}
|
|
var gp guintptr
|
|
for i := 0; i < int(n); i++ {
|
|
ev := &events[i]
|
|
var mode int32
|
|
switch ev.filter {
|
|
case _EVFILT_READ:
|
|
mode += 'r'
|
|
|
|
// On some systems when the read end of a pipe
|
|
// is closed the write end will not get a
|
|
// _EVFILT_WRITE event, but will get a
|
|
// _EVFILT_READ event with EV_EOF set.
|
|
// Note that setting 'w' here just means that we
|
|
// will wake up a goroutine waiting to write;
|
|
// that goroutine will try the write again,
|
|
// and the appropriate thing will happen based
|
|
// on what that write returns (success, EPIPE, EAGAIN).
|
|
if ev.flags&_EV_EOF != 0 {
|
|
mode += 'w'
|
|
}
|
|
case _EVFILT_WRITE:
|
|
mode += 'w'
|
|
}
|
|
if mode != 0 {
|
|
netpollready(&gp, (*pollDesc)(unsafe.Pointer(ev.udata)), mode)
|
|
}
|
|
}
|
|
if block && gp == 0 {
|
|
goto retry
|
|
}
|
|
return gp.ptr()
|
|
}
|