1 files changed, 360 insertions, 0 deletions
diff --git a/libgo/go/net/fd_poll_unix.go b/libgo/go/net/fd_poll_unix.go
new file mode 100644
index 0000000..307e577
--- /dev/null
+++ b/libgo/go/net/fd_poll_unix.go
@@ -0,0 +1,360 @@
+// Copyright 2013 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.
+
+// +build freebsd netbsd openbsd
+
+package net
+
+import (
+	"os"
+	"runtime"
+	"sync"
+	"syscall"
+	"time"
+)
+
+// A pollServer helps FDs determine when to retry a non-blocking
+// read or write after they get EAGAIN.  When an FD needs to wait,
+// call s.WaitRead() or s.WaitWrite() to pass the request to the poll server.
+// When the pollServer finds that i/o on FD should be possible
+// again, it will send on fd.cr/fd.cw to wake any waiting goroutines.
+//
+// To avoid races in closing, all fd operations are locked and
+// refcounted. when netFD.Close() is called, it calls syscall.Shutdown
+// and sets a closing flag. Only when the last reference is removed
+// will the fd be closed.
+
+type pollServer struct {
+	pr, pw     *os.File
+	poll       *pollster // low-level OS hooks
+	sync.Mutex           // controls pending and deadline
+	pending    map[int]*pollDesc
+	deadline   int64 // next deadline (nsec since 1970)
+}
+
+// A pollDesc contains netFD state related to pollServer.
+type pollDesc struct {
+	// immutable after Init()
+	pollServer *pollServer
+	sysfd      int
+	cr, cw     chan error
+
+	// mutable, protected by pollServer mutex
+	closing  bool
+	ncr, ncw int
+
+	// mutable, safe for concurrent access
+	rdeadline, wdeadline deadline
+}
+
+func newPollServer() (s *pollServer, err error) {
+	s = new(pollServer)
+	if s.pr, s.pw, err = os.Pipe(); err != nil {
+		return nil, err
+	}
+	if err = syscall.SetNonblock(int(s.pr.Fd()), true); err != nil {
+		goto Errno
+	}
+	if err = syscall.SetNonblock(int(s.pw.Fd()), true); err != nil {
+		goto Errno
+	}
+	if s.poll, err = newpollster(); err != nil {
+		goto Error
+	}
+	if _, err = s.poll.AddFD(int(s.pr.Fd()), 'r', true); err != nil {
+		s.poll.Close()
+		goto Error
+	}
+	s.pending = make(map[int]*pollDesc)
+	go s.Run()
+	return s, nil
+
+Errno:
+	err = &os.PathError{
+		Op:   "setnonblock",
+		Path: s.pr.Name(),
+		Err:  err,
+	}
+Error:
+	s.pr.Close()
+	s.pw.Close()
+	return nil, err
+}
+
+func (s *pollServer) AddFD(pd *pollDesc, mode int) error {
+	s.Lock()
+	intfd := pd.sysfd
+	if intfd < 0 || pd.closing {
+		// fd closed underfoot
+		s.Unlock()
+		return errClosing
+	}
+
+	var t int64
+	key := intfd << 1
+	if mode == 'r' {
+		pd.ncr++
+		t = pd.rdeadline.value()
+	} else {
+		pd.ncw++
+		key++
+		t = pd.wdeadline.value()
+	}
+	s.pending[key] = pd
+	doWakeup := false
+	if t > 0 && (s.deadline == 0 || t < s.deadline) {
+		s.deadline = t
+		doWakeup = true
+	}
+
+	wake, err := s.poll.AddFD(intfd, mode, false)
+	s.Unlock()
+	if err != nil {
+		return err
+	}
+	if wake || doWakeup {
+		s.Wakeup()
+	}
+	return nil
+}
+
+// Evict evicts pd from the pending list, unblocking
+// any I/O running on pd.  The caller must have locked
+// pollserver.
+// Return value is whether the pollServer should be woken up.
+func (s *pollServer) Evict(pd *pollDesc) bool {
+	pd.closing = true
+	doWakeup := false
+	if s.pending[pd.sysfd<<1] == pd {
+		s.WakeFD(pd, 'r', errClosing)
+		if s.poll.DelFD(pd.sysfd, 'r') {
+			doWakeup = true
+		}
+		delete(s.pending, pd.sysfd<<1)
+	}
+	if s.pending[pd.sysfd<<1|1] == pd {
+		s.WakeFD(pd, 'w', errClosing)
+		if s.poll.DelFD(pd.sysfd, 'w') {
+			doWakeup = true
+		}
+		delete(s.pending, pd.sysfd<<1|1)
+	}
+	return doWakeup
+}
+
+var wakeupbuf [1]byte
+
+func (s *pollServer) Wakeup() { s.pw.Write(wakeupbuf[0:]) }
+
+func (s *pollServer) LookupFD(fd int, mode int) *pollDesc {
+	key := fd << 1
+	if mode == 'w' {
+		key++
+	}
+	netfd, ok := s.pending[key]
+	if !ok {
+		return nil
+	}
+	delete(s.pending, key)
+	return netfd
+}
+
+func (s *pollServer) WakeFD(pd *pollDesc, mode int, err error) {
+	if mode == 'r' {
+		for pd.ncr > 0 {
+			pd.ncr--
+			pd.cr <- err
+		}
+	} else {
+		for pd.ncw > 0 {
+			pd.ncw--
+			pd.cw <- err
+		}
+	}
+}
+
+func (s *pollServer) CheckDeadlines() {
+	now := time.Now().UnixNano()
+	// TODO(rsc): This will need to be handled more efficiently,
+	// probably with a heap indexed by wakeup time.
+
+	var nextDeadline int64
+	for key, pd := range s.pending {
+		var t int64
+		var mode int
+		if key&1 == 0 {
+			mode = 'r'
+		} else {
+			mode = 'w'
+		}
+		if mode == 'r' {
+			t = pd.rdeadline.value()
+		} else {
+			t = pd.wdeadline.value()
+		}
+		if t > 0 {
+			if t <= now {
+				delete(s.pending, key)
+				s.poll.DelFD(pd.sysfd, mode)
+				s.WakeFD(pd, mode, errTimeout)
+			} else if nextDeadline == 0 || t < nextDeadline {
+				nextDeadline = t
+			}
+		}
+	}
+	s.deadline = nextDeadline
+}
+
+func (s *pollServer) Run() {
+	var scratch [100]byte
+	s.Lock()
+	defer s.Unlock()
+	for {
+		var timeout int64 // nsec to wait for or 0 for none
+		if s.deadline > 0 {
+			timeout = s.deadline - time.Now().UnixNano()
+			if timeout <= 0 {
+				s.CheckDeadlines()
+				continue
+			}
+		}
+		fd, mode, err := s.poll.WaitFD(s, timeout)
+		if err != nil {
+			print("pollServer WaitFD: ", err.Error(), "\n")
+			return
+		}
+		if fd < 0 {
+			// Timeout happened.
+			s.CheckDeadlines()
+			continue
+		}
+		if fd == int(s.pr.Fd()) {
+			// Drain our wakeup pipe (we could loop here,
+			// but it's unlikely that there are more than
+			// len(scratch) wakeup calls).
+			s.pr.Read(scratch[0:])
+			s.CheckDeadlines()
+		} else {
+			pd := s.LookupFD(fd, mode)
+			if pd == nil {
+				// This can happen because the WaitFD runs without
+				// holding s's lock, so there might be a pending wakeup
+				// for an fd that has been evicted.  No harm done.
+				continue
+			}
+			s.WakeFD(pd, mode, nil)
+		}
+	}
+}
+
+func (pd *pollDesc) Close() {
+}
+
+func (pd *pollDesc) Lock() {
+	pd.pollServer.Lock()
+}
+
+func (pd *pollDesc) Unlock() {
+	pd.pollServer.Unlock()
+}
+
+func (pd *pollDesc) Wakeup() {
+	pd.pollServer.Wakeup()
+}
+
+func (pd *pollDesc) PrepareRead() error {
+	if pd.rdeadline.expired() {
+		return errTimeout
+	}
+	return nil
+}
+
+func (pd *pollDesc) PrepareWrite() error {
+	if pd.wdeadline.expired() {
+		return errTimeout
+	}
+	return nil
+}
+
+func (pd *pollDesc) WaitRead() error {
+	err := pd.pollServer.AddFD(pd, 'r')
+	if err == nil {
+		err = <-pd.cr
+	}
+	return err
+}
+
+func (pd *pollDesc) WaitWrite() error {
+	err := pd.pollServer.AddFD(pd, 'w')
+	if err == nil {
+		err = <-pd.cw
+	}
+	return err
+}
+
+func (pd *pollDesc) Evict() bool {
+	return pd.pollServer.Evict(pd)
+}
+
+// Spread network FDs over several pollServers.
+
+var pollMaxN int
+var pollservers []*pollServer
+var startServersOnce []func()
+
+var canCancelIO = true // used for testing current package
+
+func sysInit() {
+	pollMaxN = runtime.NumCPU()
+	if pollMaxN > 8 {
+		pollMaxN = 8 // No improvement then.
+	}
+	pollservers = make([]*pollServer, pollMaxN)
+	startServersOnce = make([]func(), pollMaxN)
+	for i := 0; i < pollMaxN; i++ {
+		k := i
+		once := new(sync.Once)
+		startServersOnce[i] = func() { once.Do(func() { startServer(k) }) }
+	}
+}
+
+func startServer(k int) {
+	p, err := newPollServer()
+	if err != nil {
+		panic(err)
+	}
+	pollservers[k] = p
+}
+
+func (pd *pollDesc) Init(fd *netFD) error {
+	pollN := runtime.GOMAXPROCS(0)
+	if pollN > pollMaxN {
+		pollN = pollMaxN
+	}
+	k := fd.sysfd % pollN
+	startServersOnce[k]()
+	pd.sysfd = fd.sysfd
+	pd.pollServer = pollservers[k]
+	pd.cr = make(chan error, 1)
+	pd.cw = make(chan error, 1)
+	return nil
+}
+
+// TODO(dfc) these unused error returns could be removed
+
+func setReadDeadline(fd *netFD, t time.Time) error {
+	fd.pd.rdeadline.setTime(t)
+	return nil
+}
+
+func setWriteDeadline(fd *netFD, t time.Time) error {
+	fd.pd.wdeadline.setTime(t)
+	return nil
+}
+
+func setDeadline(fd *netFD, t time.Time) error {
+	setReadDeadline(fd, t)
+	setWriteDeadline(fd, t)
+	return nil
+}