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// Copyright 2010 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 select(2).
package net
import (
"errors"
"os"
"syscall"
)
type pollster struct {
readFds, writeFds, repeatFds *syscall.FdSet
maxFd int
readyReadFds, readyWriteFds *syscall.FdSet
nReady int
lastFd int
closed bool
}
func newpollster() (p *pollster, err error) {
p = new(pollster)
p.readFds = new(syscall.FdSet)
p.writeFds = new(syscall.FdSet)
p.repeatFds = new(syscall.FdSet)
p.readyReadFds = new(syscall.FdSet)
p.readyWriteFds = new(syscall.FdSet)
p.maxFd = -1
p.nReady = 0
p.lastFd = 0
return p, nil
}
func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, error) {
// pollServer is locked.
if p.closed {
return false, errors.New("pollster closed")
}
if mode == 'r' {
syscall.FDSet(fd, p.readFds)
} else {
syscall.FDSet(fd, p.writeFds)
}
if repeat {
syscall.FDSet(fd, p.repeatFds)
}
if fd > p.maxFd {
p.maxFd = fd
}
return true, nil
}
func (p *pollster) DelFD(fd int, mode int) bool {
// pollServer is locked.
if p.closed {
return false
}
if mode == 'r' {
if !syscall.FDIsSet(fd, p.readFds) {
print("Select unexpected fd=", fd, " for read\n")
return false
}
syscall.FDClr(fd, p.readFds)
} else {
if !syscall.FDIsSet(fd, p.writeFds) {
print("Select unexpected fd=", fd, " for write\n")
return false
}
syscall.FDClr(fd, p.writeFds)
}
// Doesn't matter if not already present.
syscall.FDClr(fd, p.repeatFds)
// We don't worry about maxFd here.
return true
}
func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err error) {
if p.nReady == 0 {
var timeout *syscall.Timeval
var tv syscall.Timeval
timeout = nil
if nsec > 0 {
tv = syscall.NsecToTimeval(nsec)
timeout = &tv
}
var n int
var e error
var tmpReadFds, tmpWriteFds syscall.FdSet
for {
if p.closed {
return -1, 0, errors.New("pollster closed")
}
// Temporary syscall.FdSet's into which the values are copied
// because select mutates the values.
tmpReadFds = *p.readFds
tmpWriteFds = *p.writeFds
s.Unlock()
n, e = syscall.Select(p.maxFd+1, &tmpReadFds, &tmpWriteFds, nil, timeout)
s.Lock()
if e != syscall.EINTR {
break
}
}
if e == syscall.EBADF {
// Some file descriptor has been closed.
tmpReadFds = syscall.FdSet{}
tmpWriteFds = syscall.FdSet{}
n = 0
for i := 0; i < p.maxFd+1; i++ {
if syscall.FDIsSet(i, p.readFds) {
var s syscall.Stat_t
if syscall.Fstat(i, &s) == syscall.EBADF {
syscall.FDSet(i, &tmpReadFds)
n++
}
} else if syscall.FDIsSet(i, p.writeFds) {
var s syscall.Stat_t
if syscall.Fstat(i, &s) == syscall.EBADF {
syscall.FDSet(i, &tmpWriteFds)
n++
}
}
}
} else if e != nil {
return -1, 0, os.NewSyscallError("select", e)
}
if n == 0 {
return -1, 0, nil
}
p.nReady = n
*p.readyReadFds = tmpReadFds
*p.readyWriteFds = tmpWriteFds
p.lastFd = 0
}
flag := false
for i := p.lastFd; i < p.maxFd+1; i++ {
if syscall.FDIsSet(i, p.readyReadFds) {
flag = true
mode = 'r'
syscall.FDClr(i, p.readyReadFds)
} else if syscall.FDIsSet(i, p.readyWriteFds) {
flag = true
mode = 'w'
syscall.FDClr(i, p.readyWriteFds)
}
if flag {
if !syscall.FDIsSet(i, p.repeatFds) {
p.DelFD(i, mode)
}
p.nReady--
p.lastFd = i
return i, mode, nil
}
}
// Will not reach here. Just to shut up the compiler.
return -1, 0, nil
}
func (p *pollster) Close() error {
p.closed = true
return nil
}
|
