Imported Upstream version 60upstream/60

1 files changed, 182 insertions, 0 deletions

diff --git a/src/pkg/net/fd_linux.go b/src/pkg/net/fd_linux.go
new file mode 100644
index 000000000..70fc344b2
--- /dev/null
+++ b/src/pkg/net/fd_linux.go
@@ -0,0 +1,182 @@
+// 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
+	// Must hold pollServer lock
+	events map[int]uint32
+
+	// An event buffer for EpollWait.
+	// Used without a lock, may only be used by WaitFD.
+	waitEventBuf [10]syscall.EpollEvent
+	waitEvents   []syscall.EpollEvent
+
+	// An event buffer for EpollCtl, to avoid a malloc.
+	// Must hold pollServer lock.
+	ctlEvent syscall.EpollEvent
+}
+
+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, and since 2.6.8 the kernel ignores it anyhow.
+	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) (bool, os.Error) {
+	// pollServer is locked.
+
+	var already bool
+	p.ctlEvent.Fd = int32(fd)
+	p.ctlEvent.Events, already = p.events[fd]
+	if !repeat {
+		p.ctlEvent.Events |= syscall.EPOLLONESHOT
+	}
+	if mode == 'r' {
+		p.ctlEvent.Events |= readFlags
+	} else {
+		p.ctlEvent.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, &p.ctlEvent); e != 0 {
+		return false, os.NewSyscallError("epoll_ctl", e)
+	}
+	p.events[fd] = p.ctlEvent.Events
+	return false, nil
+}
+
+func (p *pollster) StopWaiting(fd int, bits uint) {
+	// pollServer is locked.
+
+	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 {
+		p.ctlEvent.Fd = int32(fd)
+		p.ctlEvent.Events = events
+		if e := syscall.EpollCtl(p.epfd, syscall.EPOLL_CTL_MOD, fd, &p.ctlEvent); 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) {
+	// pollServer is locked.
+
+	if mode == 'r' {
+		p.StopWaiting(fd, readFlags)
+	} else {
+		p.StopWaiting(fd, writeFlags)
+	}
+
+	// Discard any queued up events.
+	i := 0
+	for i < len(p.waitEvents) {
+		if fd == int(p.waitEvents[i].Fd) {
+			copy(p.waitEvents[i:], p.waitEvents[i+1:])
+			p.waitEvents = p.waitEvents[:len(p.waitEvents)-1]
+		} else {
+			i++
+		}
+	}
+}
+
+func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err os.Error) {
+	for len(p.waitEvents) == 0 {
+		var msec int = -1
+		if nsec > 0 {
+			msec = int((nsec + 1e6 - 1) / 1e6)
+		}
+
+		s.Unlock()
+		n, e := syscall.EpollWait(p.epfd, p.waitEventBuf[0:], msec)
+		s.Lock()
+
+		if e != 0 {
+			if e == syscall.EAGAIN || e == syscall.EINTR {
+				continue
+			}
+			return -1, 0, os.NewSyscallError("epoll_wait", e)
+		}
+		if n == 0 {
+			return -1, 0, nil
+		}
+		p.waitEvents = p.waitEventBuf[0:n]
+	}
+
+	ev := &p.waitEvents[0]
+	p.waitEvents = p.waitEvents[1:]
+
+	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))
+}