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// Copyright 2009 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.
// Waiting for FDs via kqueue/kevent.
package net
import (
"os"
"syscall"
)
type pollster struct {
kq int
eventbuf [10]syscall.Kevent_t
events []syscall.Kevent_t
// An event buffer for AddFD/DelFD.
// Must hold pollServer lock.
kbuf [1]syscall.Kevent_t
}
func newpollster() (p *pollster, err error) {
p = new(pollster)
if p.kq, err = syscall.Kqueue(); err != nil {
return nil, os.NewSyscallError("kqueue", err)
}
p.events = p.eventbuf[0:0]
return p, nil
}
func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, error) {
// pollServer is locked.
var kmode int
if mode == 'r' {
kmode = syscall.EVFILT_READ
} else {
kmode = syscall.EVFILT_WRITE
}
ev := &p.kbuf[0]
// EV_ADD - add event to kqueue list
// EV_ONESHOT - delete the event the first time it triggers
flags := syscall.EV_ADD
if !repeat {
flags |= syscall.EV_ONESHOT
}
syscall.SetKevent(ev, fd, kmode, flags)
n, e := syscall.Kevent(p.kq, p.kbuf[:], nil, nil)
if e != nil {
return false, os.NewSyscallError("kevent", e)
}
if n != 1 || (ev.Flags&syscall.EV_ERROR) == 0 || int(ev.Ident) != fd || int(ev.Filter) != kmode {
return false, os.NewSyscallError("kqueue phase error", e)
}
if ev.Data != 0 {
return false, syscall.Errno(int(ev.Data))
}
return false, nil
}
func (p *pollster) DelFD(fd int, mode int) {
// pollServer is locked.
var kmode int
if mode == 'r' {
kmode = syscall.EVFILT_READ
} else {
kmode = syscall.EVFILT_WRITE
}
ev := &p.kbuf[0]
// EV_DELETE - delete event from kqueue list
syscall.SetKevent(ev, fd, kmode, syscall.EV_DELETE)
syscall.Kevent(p.kq, p.kbuf[:], nil, nil)
}
func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err error) {
var t *syscall.Timespec
for len(p.events) == 0 {
if nsec > 0 {
if t == nil {
t = new(syscall.Timespec)
}
*t = syscall.NsecToTimespec(nsec)
}
s.Unlock()
nn, e := syscall.Kevent(p.kq, nil, p.eventbuf[:], t)
s.Lock()
if e != nil {
if e == syscall.EINTR {
continue
}
return -1, 0, os.NewSyscallError("kevent", e)
}
if nn == 0 {
return -1, 0, nil
}
p.events = p.eventbuf[0:nn]
}
ev := &p.events[0]
p.events = p.events[1:]
fd = int(ev.Ident)
if ev.Filter == syscall.EVFILT_READ {
mode = 'r'
} else {
mode = 'w'
}
return fd, mode, nil
}
func (p *pollster) Close() error { return os.NewSyscallError("close", syscall.Close(p.kq)) }
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