640 lines
14 KiB
Go
640 lines
14 KiB
Go
// Copyright 2009 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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package net
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import (
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"io"
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"os"
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"sync"
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"syscall"
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"time"
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)
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// Network file descriptor.
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type netFD struct {
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// locking/lifetime of sysfd
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sysmu sync.Mutex
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sysref int
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closing bool
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// immutable until Close
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sysfd int
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family int
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proto int
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sysfile *os.File
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cr chan bool
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cw chan bool
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net string
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laddr Addr
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raddr Addr
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// owned by client
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rdeadline_delta int64
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rdeadline int64
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rio sync.Mutex
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wdeadline_delta int64
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wdeadline int64
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wio sync.Mutex
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// owned by fd wait server
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ncr, ncw int
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}
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type InvalidConnError struct{}
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func (e *InvalidConnError) String() string { return "invalid net.Conn" }
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func (e *InvalidConnError) Temporary() bool { return false }
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func (e *InvalidConnError) Timeout() bool { return false }
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// A pollServer helps FDs determine when to retry a non-blocking
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// read or write after they get EAGAIN. When an FD needs to wait,
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// send the fd on s.cr (for a read) or s.cw (for a write) to pass the
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// request to the poll server. Then receive on fd.cr/fd.cw.
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// When the pollServer finds that i/o on FD should be possible
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// again, it will send fd on fd.cr/fd.cw to wake any waiting processes.
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// This protocol is implemented as s.WaitRead() and s.WaitWrite().
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//
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// There is one subtlety: when sending on s.cr/s.cw, the
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// poll server is probably in a system call, waiting for an fd
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// to become ready. It's not looking at the request channels.
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// To resolve this, the poll server waits not just on the FDs it has
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// been given but also its own pipe. After sending on the
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// buffered channel s.cr/s.cw, WaitRead/WaitWrite writes a
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// byte to the pipe, causing the pollServer's poll system call to
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// return. In response to the pipe being readable, the pollServer
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// re-polls its request channels.
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//
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// Note that the ordering is "send request" and then "wake up server".
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// If the operations were reversed, there would be a race: the poll
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// server might wake up and look at the request channel, see that it
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// was empty, and go back to sleep, all before the requester managed
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// to send the request. Because the send must complete before the wakeup,
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// the request channel must be buffered. A buffer of size 1 is sufficient
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// for any request load. If many processes are trying to submit requests,
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// one will succeed, the pollServer will read the request, and then the
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// channel will be empty for the next process's request. A larger buffer
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// might help batch requests.
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//
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// To avoid races in closing, all fd operations are locked and
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// refcounted. when netFD.Close() is called, it calls syscall.Shutdown
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// and sets a closing flag. Only when the last reference is removed
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// will the fd be closed.
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type pollServer struct {
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cr, cw chan *netFD // buffered >= 1
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pr, pw *os.File
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poll *pollster // low-level OS hooks
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sync.Mutex // controls pending and deadline
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pending map[int]*netFD
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deadline int64 // next deadline (nsec since 1970)
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}
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func (s *pollServer) AddFD(fd *netFD, mode int) {
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intfd := fd.sysfd
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if intfd < 0 {
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// fd closed underfoot
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if mode == 'r' {
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fd.cr <- true
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} else {
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fd.cw <- true
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}
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return
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}
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s.Lock()
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var t int64
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key := intfd << 1
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if mode == 'r' {
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fd.ncr++
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t = fd.rdeadline
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} else {
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fd.ncw++
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key++
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t = fd.wdeadline
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}
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s.pending[key] = fd
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doWakeup := false
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if t > 0 && (s.deadline == 0 || t < s.deadline) {
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s.deadline = t
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doWakeup = true
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}
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wake, err := s.poll.AddFD(intfd, mode, false)
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if err != nil {
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panic("pollServer AddFD " + err.String())
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}
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if wake {
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doWakeup = true
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}
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s.Unlock()
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if doWakeup {
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s.Wakeup()
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}
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}
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var wakeupbuf [1]byte
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func (s *pollServer) Wakeup() { s.pw.Write(wakeupbuf[0:]) }
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func (s *pollServer) LookupFD(fd int, mode int) *netFD {
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key := fd << 1
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if mode == 'w' {
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key++
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}
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netfd, ok := s.pending[key]
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if !ok {
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return nil
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}
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s.pending[key] = nil, false
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return netfd
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}
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func (s *pollServer) WakeFD(fd *netFD, mode int) {
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if mode == 'r' {
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for fd.ncr > 0 {
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fd.ncr--
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fd.cr <- true
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}
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} else {
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for fd.ncw > 0 {
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fd.ncw--
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fd.cw <- true
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}
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}
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}
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func (s *pollServer) Now() int64 {
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return time.Nanoseconds()
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}
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func (s *pollServer) CheckDeadlines() {
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now := s.Now()
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// TODO(rsc): This will need to be handled more efficiently,
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// probably with a heap indexed by wakeup time.
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var next_deadline int64
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for key, fd := range s.pending {
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var t int64
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var mode int
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if key&1 == 0 {
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mode = 'r'
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} else {
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mode = 'w'
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}
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if mode == 'r' {
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t = fd.rdeadline
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} else {
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t = fd.wdeadline
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}
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if t > 0 {
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if t <= now {
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s.pending[key] = nil, false
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if mode == 'r' {
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s.poll.DelFD(fd.sysfd, mode)
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fd.rdeadline = -1
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} else {
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s.poll.DelFD(fd.sysfd, mode)
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fd.wdeadline = -1
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}
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s.WakeFD(fd, mode)
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} else if next_deadline == 0 || t < next_deadline {
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next_deadline = t
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}
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}
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}
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s.deadline = next_deadline
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}
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func (s *pollServer) Run() {
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var scratch [100]byte
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s.Lock()
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defer s.Unlock()
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for {
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var t = s.deadline
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if t > 0 {
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t = t - s.Now()
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if t <= 0 {
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s.CheckDeadlines()
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continue
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}
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}
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fd, mode, err := s.poll.WaitFD(s, t)
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if err != nil {
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print("pollServer WaitFD: ", err.String(), "\n")
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return
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}
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if fd < 0 {
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// Timeout happened.
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s.CheckDeadlines()
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continue
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}
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if fd == s.pr.Fd() {
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// Drain our wakeup pipe (we could loop here,
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// but it's unlikely that there are more than
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// len(scratch) wakeup calls).
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s.pr.Read(scratch[0:])
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s.CheckDeadlines()
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} else {
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netfd := s.LookupFD(fd, mode)
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if netfd == nil {
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print("pollServer: unexpected wakeup for fd=", fd, " mode=", string(mode), "\n")
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continue
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}
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s.WakeFD(netfd, mode)
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}
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}
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}
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func (s *pollServer) WaitRead(fd *netFD) {
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s.AddFD(fd, 'r')
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<-fd.cr
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}
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func (s *pollServer) WaitWrite(fd *netFD) {
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s.AddFD(fd, 'w')
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<-fd.cw
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}
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// Network FD methods.
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// All the network FDs use a single pollServer.
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var pollserver *pollServer
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var onceStartServer sync.Once
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func startServer() {
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p, err := newPollServer()
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if err != nil {
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print("Start pollServer: ", err.String(), "\n")
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}
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pollserver = p
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}
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func newFD(fd, family, proto int, net string) (f *netFD, err os.Error) {
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onceStartServer.Do(startServer)
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if e := syscall.SetNonblock(fd, true); e != 0 {
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return nil, os.Errno(e)
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}
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f = &netFD{
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sysfd: fd,
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family: family,
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proto: proto,
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net: net,
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}
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f.cr = make(chan bool, 1)
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f.cw = make(chan bool, 1)
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return f, nil
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}
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func (fd *netFD) setAddr(laddr, raddr Addr) {
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fd.laddr = laddr
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fd.raddr = raddr
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var ls, rs string
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if laddr != nil {
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ls = laddr.String()
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}
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if raddr != nil {
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rs = raddr.String()
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}
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fd.sysfile = os.NewFile(fd.sysfd, fd.net+":"+ls+"->"+rs)
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}
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func (fd *netFD) connect(ra syscall.Sockaddr) (err os.Error) {
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e := syscall.Connect(fd.sysfd, ra)
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if e == syscall.EINPROGRESS {
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var errno int
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pollserver.WaitWrite(fd)
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e, errno = syscall.GetsockoptInt(fd.sysfd, syscall.SOL_SOCKET, syscall.SO_ERROR)
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if errno != 0 {
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return os.NewSyscallError("getsockopt", errno)
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}
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}
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if e != 0 {
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return os.Errno(e)
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}
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return nil
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}
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// Add a reference to this fd.
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func (fd *netFD) incref() {
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fd.sysmu.Lock()
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fd.sysref++
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fd.sysmu.Unlock()
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}
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// Remove a reference to this FD and close if we've been asked to do so (and
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// there are no references left.
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func (fd *netFD) decref() {
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fd.sysmu.Lock()
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fd.sysref--
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if fd.closing && fd.sysref == 0 && fd.sysfd >= 0 {
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// In case the user has set linger, switch to blocking mode so
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// the close blocks. As long as this doesn't happen often, we
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// can handle the extra OS processes. Otherwise we'll need to
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// use the pollserver for Close too. Sigh.
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syscall.SetNonblock(fd.sysfd, false)
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fd.sysfile.Close()
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fd.sysfile = nil
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fd.sysfd = -1
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}
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fd.sysmu.Unlock()
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}
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func (fd *netFD) Close() os.Error {
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if fd == nil || fd.sysfile == nil {
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return os.EINVAL
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}
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fd.incref()
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syscall.Shutdown(fd.sysfd, syscall.SHUT_RDWR)
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fd.closing = true
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fd.decref()
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return nil
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}
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func (fd *netFD) Read(p []byte) (n int, err os.Error) {
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if fd == nil {
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return 0, os.EINVAL
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}
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fd.rio.Lock()
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defer fd.rio.Unlock()
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fd.incref()
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defer fd.decref()
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if fd.sysfile == nil {
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return 0, os.EINVAL
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}
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if fd.rdeadline_delta > 0 {
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fd.rdeadline = pollserver.Now() + fd.rdeadline_delta
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} else {
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fd.rdeadline = 0
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}
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var oserr os.Error
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for {
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var errno int
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n, errno = syscall.Read(fd.sysfile.Fd(), p)
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if (errno == syscall.EAGAIN || errno == syscall.EINTR) && fd.rdeadline >= 0 {
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pollserver.WaitRead(fd)
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continue
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}
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if errno != 0 {
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n = 0
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oserr = os.Errno(errno)
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} else if n == 0 && errno == 0 && fd.proto != syscall.SOCK_DGRAM {
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err = os.EOF
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}
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break
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}
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if oserr != nil {
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err = &OpError{"read", fd.net, fd.raddr, oserr}
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}
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return
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}
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func (fd *netFD) ReadFrom(p []byte) (n int, sa syscall.Sockaddr, err os.Error) {
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if fd == nil || fd.sysfile == nil {
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return 0, nil, os.EINVAL
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}
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fd.rio.Lock()
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defer fd.rio.Unlock()
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fd.incref()
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defer fd.decref()
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if fd.rdeadline_delta > 0 {
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fd.rdeadline = pollserver.Now() + fd.rdeadline_delta
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} else {
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fd.rdeadline = 0
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}
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var oserr os.Error
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for {
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var errno int
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n, sa, errno = syscall.Recvfrom(fd.sysfd, p, 0)
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if (errno == syscall.EAGAIN || errno == syscall.EINTR) && fd.rdeadline >= 0 {
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pollserver.WaitRead(fd)
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continue
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}
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if errno != 0 {
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n = 0
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oserr = os.Errno(errno)
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}
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break
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}
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if oserr != nil {
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err = &OpError{"read", fd.net, fd.laddr, oserr}
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}
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return
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}
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func (fd *netFD) ReadMsg(p []byte, oob []byte) (n, oobn, flags int, sa syscall.Sockaddr, err os.Error) {
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if fd == nil || fd.sysfile == nil {
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return 0, 0, 0, nil, os.EINVAL
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}
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fd.rio.Lock()
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defer fd.rio.Unlock()
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fd.incref()
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defer fd.decref()
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if fd.rdeadline_delta > 0 {
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fd.rdeadline = pollserver.Now() + fd.rdeadline_delta
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} else {
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fd.rdeadline = 0
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}
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var oserr os.Error
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for {
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var errno int
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n, oobn, flags, sa, errno = syscall.Recvmsg(fd.sysfd, p, oob, 0)
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if (errno == syscall.EAGAIN || errno == syscall.EINTR) && fd.rdeadline >= 0 {
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pollserver.WaitRead(fd)
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continue
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}
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if errno != 0 {
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oserr = os.Errno(errno)
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}
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if n == 0 {
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oserr = os.EOF
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}
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break
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}
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if oserr != nil {
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err = &OpError{"read", fd.net, fd.laddr, oserr}
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return
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}
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return
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}
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func (fd *netFD) Write(p []byte) (n int, err os.Error) {
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if fd == nil {
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return 0, os.EINVAL
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}
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fd.wio.Lock()
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defer fd.wio.Unlock()
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fd.incref()
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defer fd.decref()
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if fd.sysfile == nil {
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return 0, os.EINVAL
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}
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if fd.wdeadline_delta > 0 {
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fd.wdeadline = pollserver.Now() + fd.wdeadline_delta
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} else {
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fd.wdeadline = 0
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}
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nn := 0
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var oserr os.Error
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for {
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n, errno := syscall.Write(fd.sysfile.Fd(), p[nn:])
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if n > 0 {
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nn += n
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}
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if nn == len(p) {
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break
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}
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if (errno == syscall.EAGAIN || errno == syscall.EINTR) && fd.wdeadline >= 0 {
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pollserver.WaitWrite(fd)
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continue
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}
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if errno != 0 {
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n = 0
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oserr = os.Errno(errno)
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break
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}
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if n == 0 {
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oserr = io.ErrUnexpectedEOF
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break
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}
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}
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if oserr != nil {
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err = &OpError{"write", fd.net, fd.raddr, oserr}
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}
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return nn, err
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}
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func (fd *netFD) WriteTo(p []byte, sa syscall.Sockaddr) (n int, err os.Error) {
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if fd == nil || fd.sysfile == nil {
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return 0, os.EINVAL
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}
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fd.wio.Lock()
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defer fd.wio.Unlock()
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fd.incref()
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defer fd.decref()
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if fd.wdeadline_delta > 0 {
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fd.wdeadline = pollserver.Now() + fd.wdeadline_delta
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} else {
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fd.wdeadline = 0
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}
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var oserr os.Error
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for {
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errno := syscall.Sendto(fd.sysfd, p, 0, sa)
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if (errno == syscall.EAGAIN || errno == syscall.EINTR) && fd.wdeadline >= 0 {
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pollserver.WaitWrite(fd)
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continue
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}
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if errno != 0 {
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oserr = os.Errno(errno)
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}
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break
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}
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if oserr == nil {
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n = len(p)
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} else {
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err = &OpError{"write", fd.net, fd.raddr, oserr}
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}
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return
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}
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func (fd *netFD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oobn int, err os.Error) {
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if fd == nil || fd.sysfile == nil {
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return 0, 0, os.EINVAL
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}
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fd.wio.Lock()
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defer fd.wio.Unlock()
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fd.incref()
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defer fd.decref()
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if fd.wdeadline_delta > 0 {
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fd.wdeadline = pollserver.Now() + fd.wdeadline_delta
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} else {
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fd.wdeadline = 0
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}
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|
var oserr os.Error
|
|
for {
|
|
var errno int
|
|
errno = syscall.Sendmsg(fd.sysfd, p, oob, sa, 0)
|
|
if (errno == syscall.EAGAIN || errno == syscall.EINTR) && fd.wdeadline >= 0 {
|
|
pollserver.WaitWrite(fd)
|
|
continue
|
|
}
|
|
if errno != 0 {
|
|
oserr = os.Errno(errno)
|
|
}
|
|
break
|
|
}
|
|
if oserr == nil {
|
|
n = len(p)
|
|
oobn = len(oob)
|
|
} else {
|
|
err = &OpError{"write", fd.net, fd.raddr, oserr}
|
|
}
|
|
return
|
|
}
|
|
|
|
func (fd *netFD) accept(toAddr func(syscall.Sockaddr) Addr) (nfd *netFD, err os.Error) {
|
|
if fd == nil || fd.sysfile == nil {
|
|
return nil, os.EINVAL
|
|
}
|
|
|
|
fd.incref()
|
|
defer fd.decref()
|
|
|
|
// See ../syscall/exec.go for description of ForkLock.
|
|
// It is okay to hold the lock across syscall.Accept
|
|
// because we have put fd.sysfd into non-blocking mode.
|
|
syscall.ForkLock.RLock()
|
|
var s, e int
|
|
var sa syscall.Sockaddr
|
|
for {
|
|
if fd.closing {
|
|
syscall.ForkLock.RUnlock()
|
|
return nil, os.EINVAL
|
|
}
|
|
s, sa, e = syscall.Accept(fd.sysfd)
|
|
if e != syscall.EAGAIN && e != syscall.EINTR {
|
|
break
|
|
}
|
|
syscall.ForkLock.RUnlock()
|
|
pollserver.WaitRead(fd)
|
|
syscall.ForkLock.RLock()
|
|
}
|
|
if e != 0 {
|
|
syscall.ForkLock.RUnlock()
|
|
return nil, &OpError{"accept", fd.net, fd.laddr, os.Errno(e)}
|
|
}
|
|
syscall.CloseOnExec(s)
|
|
syscall.ForkLock.RUnlock()
|
|
|
|
if nfd, err = newFD(s, fd.family, fd.proto, fd.net); err != nil {
|
|
syscall.Close(s)
|
|
return nil, err
|
|
}
|
|
nfd.setAddr(fd.laddr, toAddr(sa))
|
|
return nfd, nil
|
|
}
|
|
|
|
func (fd *netFD) dup() (f *os.File, err os.Error) {
|
|
ns, e := syscall.Dup(fd.sysfd)
|
|
if e != 0 {
|
|
return nil, &OpError{"dup", fd.net, fd.laddr, os.Errno(e)}
|
|
}
|
|
|
|
// We want blocking mode for the new fd, hence the double negative.
|
|
if e = syscall.SetNonblock(ns, false); e != 0 {
|
|
return nil, &OpError{"setnonblock", fd.net, fd.laddr, os.Errno(e)}
|
|
}
|
|
|
|
return os.NewFile(ns, fd.sysfile.Name()), nil
|
|
}
|
|
|
|
func closesocket(s int) (errno int) {
|
|
return syscall.Close(s)
|
|
}
|