// 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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// +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 "unsafe"
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var (
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kq int32 = -1
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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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}
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func netpolldescriptor() uintptr {
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return uintptr(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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ev[0].udata = (*byte)(unsafe.Pointer(pd))
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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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// Polls for ready network connections.
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// Returns list of goroutines that become runnable.
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func netpoll(block bool) gList {
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if kq == -1 {
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return gList{}
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}
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var tp *timespec
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var ts timespec
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if !block {
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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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if n != -_EINTR {
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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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goto retry
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}
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var toRun gList
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for i := 0; i < int(n); i++ {
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ev := &events[i]
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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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netpollready(&toRun, (*pollDesc)(unsafe.Pointer(ev.udata)), mode)
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}
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}
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if block && toRun.empty() {
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goto retry
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}
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return toRun
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}
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