mirror of https://go.googlesource.com/go
180 lines
4.6 KiB
Go
180 lines
4.6 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build darwin || dragonfly || freebsd || netbsd || openbsd
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package runtime
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// Integrated network poller (kqueue-based implementation).
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import (
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"internal/goarch"
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"internal/runtime/atomic"
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"unsafe"
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)
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var (
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kq int32 = -1
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netpollWakeSig atomic.Uint32 // used to avoid duplicate calls of netpollBreak
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)
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func netpollinit() {
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kq = kqueue()
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if kq < 0 {
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println("runtime: kqueue failed with", -kq)
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throw("runtime: netpollinit failed")
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}
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closeonexec(kq)
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addWakeupEvent(kq)
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}
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func netpollopen(fd uintptr, pd *pollDesc) int32 {
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// Arm both EVFILT_READ and EVFILT_WRITE in edge-triggered mode (EV_CLEAR)
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// for the whole fd lifetime. The notifications are automatically unregistered
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// when fd is closed.
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var ev [2]keventt
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*(*uintptr)(unsafe.Pointer(&ev[0].ident)) = fd
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ev[0].filter = _EVFILT_READ
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ev[0].flags = _EV_ADD | _EV_CLEAR
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ev[0].fflags = 0
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ev[0].data = 0
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if goarch.PtrSize == 4 {
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// We only have a pointer-sized field to store into,
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// so on a 32-bit system we get no sequence protection.
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// TODO(iant): If we notice any problems we could at least
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// steal the low-order 2 bits for a tiny sequence number.
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ev[0].udata = (*byte)(unsafe.Pointer(pd))
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} else {
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tp := taggedPointerPack(unsafe.Pointer(pd), pd.fdseq.Load())
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ev[0].udata = (*byte)(unsafe.Pointer(uintptr(tp)))
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}
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ev[1] = ev[0]
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ev[1].filter = _EVFILT_WRITE
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n := kevent(kq, &ev[0], 2, nil, 0, nil)
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if n < 0 {
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return -n
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}
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return 0
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}
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func netpollclose(fd uintptr) int32 {
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// Don't need to unregister because calling close()
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// on fd will remove any kevents that reference the descriptor.
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return 0
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}
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func netpollarm(pd *pollDesc, mode int) {
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throw("runtime: unused")
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}
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// netpollBreak interrupts a kevent.
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func netpollBreak() {
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// Failing to cas indicates there is an in-flight wakeup, so we're done here.
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if !netpollWakeSig.CompareAndSwap(0, 1) {
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return
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}
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wakeNetpoll(kq)
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}
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// netpoll checks for ready network connections.
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// Returns list of goroutines that become runnable.
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// delay < 0: blocks indefinitely
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// delay == 0: does not block, just polls
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// delay > 0: block for up to that many nanoseconds
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func netpoll(delay int64) (gList, int32) {
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if kq == -1 {
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return gList{}, 0
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}
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var tp *timespec
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var ts timespec
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if delay < 0 {
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tp = nil
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} else if delay == 0 {
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tp = &ts
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} else {
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ts.setNsec(delay)
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if ts.tv_sec > 1e6 {
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// Darwin returns EINVAL if the sleep time is too long.
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ts.tv_sec = 1e6
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}
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tp = &ts
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}
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var events [64]keventt
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retry:
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n := kevent(kq, nil, 0, &events[0], int32(len(events)), tp)
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if n < 0 {
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// Ignore the ETIMEDOUT error for now, but try to dive deep and
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// figure out what really happened with n == ETIMEOUT,
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// see https://go.dev/issue/59679 for details.
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if n != -_EINTR && n != -_ETIMEDOUT {
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println("runtime: kevent on fd", kq, "failed with", -n)
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throw("runtime: netpoll failed")
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}
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// If a timed sleep was interrupted, just return to
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// recalculate how long we should sleep now.
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if delay > 0 {
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return gList{}, 0
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}
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goto retry
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}
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var toRun gList
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delta := int32(0)
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for i := 0; i < int(n); i++ {
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ev := &events[i]
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if isWakeup(ev) {
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if delay != 0 {
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// netpollBreak could be picked up by a nonblocking poll.
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// Only call drainWakeupEvent and reset the netpollWakeSig if blocking.
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drainWakeupEvent(kq)
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netpollWakeSig.Store(0)
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}
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continue
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}
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var mode int32
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switch ev.filter {
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case _EVFILT_READ:
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mode += 'r'
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// On some systems when the read end of a pipe
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// is closed the write end will not get a
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// _EVFILT_WRITE event, but will get a
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// _EVFILT_READ event with EV_EOF set.
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// Note that setting 'w' here just means that we
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// will wake up a goroutine waiting to write;
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// that goroutine will try the write again,
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// and the appropriate thing will happen based
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// on what that write returns (success, EPIPE, EAGAIN).
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if ev.flags&_EV_EOF != 0 {
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mode += 'w'
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}
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case _EVFILT_WRITE:
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mode += 'w'
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}
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if mode != 0 {
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var pd *pollDesc
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var tag uintptr
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if goarch.PtrSize == 4 {
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// No sequence protection on 32-bit systems.
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// See netpollopen for details.
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pd = (*pollDesc)(unsafe.Pointer(ev.udata))
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tag = 0
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} else {
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tp := taggedPointer(uintptr(unsafe.Pointer(ev.udata)))
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pd = (*pollDesc)(tp.pointer())
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tag = tp.tag()
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if pd.fdseq.Load() != tag {
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continue
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}
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}
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pd.setEventErr(ev.flags == _EV_ERROR, tag)
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delta += netpollready(&toRun, pd, mode)
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}
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}
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return toRun, delta
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}
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