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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 epoll(7).
package net
import (
"os"
"syscall"
)
const (
readFlags = syscall.EPOLLIN | syscall.EPOLLRDHUP
writeFlags = syscall.EPOLLOUT
)
type pollster struct {
epfd int
// Events we're already waiting for
events map[int]uint32
}
func newpollster() (p *pollster, err os.Error) {
p = new(pollster)
var e int
// The arg to epoll_create is a hint to the kernel
// about the number of FDs we will care about.
// We don't know.
if p.epfd, e = syscall.EpollCreate(16); e != 0 {
return nil, os.NewSyscallError("epoll_create", e)
}
p.events = make(map[int]uint32)
return p, nil
}
func (p *pollster) AddFD(fd int, mode int, repeat bool) os.Error {
var ev syscall.EpollEvent
var already bool
ev.Fd = int32(fd)
ev.Events, already = p.events[fd]
if !repeat {
ev.Events |= syscall.EPOLLONESHOT
}
if mode == 'r' {
ev.Events |= readFlags
} else {
ev.Events |= writeFlags
}
var op int
if already {
op = syscall.EPOLL_CTL_MOD
} else {
op = syscall.EPOLL_CTL_ADD
}
if e := syscall.EpollCtl(p.epfd, op, fd, &ev); e != 0 {
return os.NewSyscallError("epoll_ctl", e)
}
p.events[fd] = ev.Events
return nil
}
func (p *pollster) StopWaiting(fd int, bits uint) {
events, already := p.events[fd]
if !already {
print("Epoll unexpected fd=", fd, "\n")
return
}
// If syscall.EPOLLONESHOT is not set, the wait
// is a repeating wait, so don't change it.
if events&syscall.EPOLLONESHOT == 0 {
return
}
// Disable the given bits.
// If we're still waiting for other events, modify the fd
// event in the kernel. Otherwise, delete it.
events &= ^uint32(bits)
if int32(events)&^syscall.EPOLLONESHOT != 0 {
var ev syscall.EpollEvent
ev.Fd = int32(fd)
ev.Events = events
if e := syscall.EpollCtl(p.epfd, syscall.EPOLL_CTL_MOD, fd, &ev); e != 0 {
print("Epoll modify fd=", fd, ": ", os.Errno(e).String(), "\n")
}
p.events[fd] = events
} else {
if e := syscall.EpollCtl(p.epfd, syscall.EPOLL_CTL_DEL, fd, nil); e != 0 {
print("Epoll delete fd=", fd, ": ", os.Errno(e).String(), "\n")
}
p.events[fd] = 0, false
}
}
func (p *pollster) DelFD(fd int, mode int) {
if mode == 'r' {
p.StopWaiting(fd, readFlags)
} else {
p.StopWaiting(fd, writeFlags)
}
}
func (p *pollster) WaitFD(nsec int64) (fd int, mode int, err os.Error) {
// Get an event.
var evarray [1]syscall.EpollEvent
ev := &evarray[0]
var msec int = -1
if nsec > 0 {
msec = int((nsec + 1e6 - 1) / 1e6)
}
n, e := syscall.EpollWait(p.epfd, evarray[0:], msec)
for e == syscall.EAGAIN || e == syscall.EINTR {
n, e = syscall.EpollWait(p.epfd, evarray[0:], msec)
}
if e != 0 {
return -1, 0, os.NewSyscallError("epoll_wait", e)
}
if n == 0 {
return -1, 0, nil
}
fd = int(ev.Fd)
if ev.Events&writeFlags != 0 {
p.StopWaiting(fd, writeFlags)
return fd, 'w', nil
}
if ev.Events&readFlags != 0 {
p.StopWaiting(fd, readFlags)
return fd, 'r', nil
}
// Other events are error conditions - wake whoever is waiting.
events, _ := p.events[fd]
if events&writeFlags != 0 {
p.StopWaiting(fd, writeFlags)
return fd, 'w', nil
}
p.StopWaiting(fd, readFlags)
return fd, 'r', nil
}
func (p *pollster) Close() os.Error {
return os.NewSyscallError("close", syscall.Close(p.epfd))
}
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