1 files changed, 238 insertions, 0 deletions
diff --git a/src/net/pipe.go b/src/net/pipe.go
new file mode 100644
index 0000000..f174193
--- /dev/null
+++ b/src/net/pipe.go
@@ -0,0 +1,238 @@
+// 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.
+
+package net
+
+import (
+	"io"
+	"os"
+	"sync"
+	"time"
+)
+
+// pipeDeadline is an abstraction for handling timeouts.
+type pipeDeadline struct {
+	mu     sync.Mutex // Guards timer and cancel
+	timer  *time.Timer
+	cancel chan struct{} // Must be non-nil
+}
+
+func makePipeDeadline() pipeDeadline {
+	return pipeDeadline{cancel: make(chan struct{})}
+}
+
+// set sets the point in time when the deadline will time out.
+// A timeout event is signaled by closing the channel returned by waiter.
+// Once a timeout has occurred, the deadline can be refreshed by specifying a
+// t value in the future.
+//
+// A zero value for t prevents timeout.
+func (d *pipeDeadline) set(t time.Time) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	if d.timer != nil && !d.timer.Stop() {
+		<-d.cancel // Wait for the timer callback to finish and close cancel
+	}
+	d.timer = nil
+
+	// Time is zero, then there is no deadline.
+	closed := isClosedChan(d.cancel)
+	if t.IsZero() {
+		if closed {
+			d.cancel = make(chan struct{})
+		}
+		return
+	}
+
+	// Time in the future, setup a timer to cancel in the future.
+	if dur := time.Until(t); dur > 0 {
+		if closed {
+			d.cancel = make(chan struct{})
+		}
+		d.timer = time.AfterFunc(dur, func() {
+			close(d.cancel)
+		})
+		return
+	}
+
+	// Time in the past, so close immediately.
+	if !closed {
+		close(d.cancel)
+	}
+}
+
+// wait returns a channel that is closed when the deadline is exceeded.
+func (d *pipeDeadline) wait() chan struct{} {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	return d.cancel
+}
+
+func isClosedChan(c <-chan struct{}) bool {
+	select {
+	case <-c:
+		return true
+	default:
+		return false
+	}
+}
+
+type pipeAddr struct{}
+
+func (pipeAddr) Network() string { return "pipe" }
+func (pipeAddr) String() string  { return "pipe" }
+
+type pipe struct {
+	wrMu sync.Mutex // Serialize Write operations
+
+	// Used by local Read to interact with remote Write.
+	// Successful receive on rdRx is always followed by send on rdTx.
+	rdRx <-chan []byte
+	rdTx chan<- int
+
+	// Used by local Write to interact with remote Read.
+	// Successful send on wrTx is always followed by receive on wrRx.
+	wrTx chan<- []byte
+	wrRx <-chan int
+
+	once       sync.Once // Protects closing localDone
+	localDone  chan struct{}
+	remoteDone <-chan struct{}
+
+	readDeadline  pipeDeadline
+	writeDeadline pipeDeadline
+}
+
+// Pipe creates a synchronous, in-memory, full duplex
+// network connection; both ends implement the Conn interface.
+// Reads on one end are matched with writes on the other,
+// copying data directly between the two; there is no internal
+// buffering.
+func Pipe() (Conn, Conn) {
+	cb1 := make(chan []byte)
+	cb2 := make(chan []byte)
+	cn1 := make(chan int)
+	cn2 := make(chan int)
+	done1 := make(chan struct{})
+	done2 := make(chan struct{})
+
+	p1 := &pipe{
+		rdRx: cb1, rdTx: cn1,
+		wrTx: cb2, wrRx: cn2,
+		localDone: done1, remoteDone: done2,
+		readDeadline:  makePipeDeadline(),
+		writeDeadline: makePipeDeadline(),
+	}
+	p2 := &pipe{
+		rdRx: cb2, rdTx: cn2,
+		wrTx: cb1, wrRx: cn1,
+		localDone: done2, remoteDone: done1,
+		readDeadline:  makePipeDeadline(),
+		writeDeadline: makePipeDeadline(),
+	}
+	return p1, p2
+}
+
+func (*pipe) LocalAddr() Addr  { return pipeAddr{} }
+func (*pipe) RemoteAddr() Addr { return pipeAddr{} }
+
+func (p *pipe) Read(b []byte) (int, error) {
+	n, err := p.read(b)
+	if err != nil && err != io.EOF && err != io.ErrClosedPipe {
+		err = &OpError{Op: "read", Net: "pipe", Err: err}
+	}
+	return n, err
+}
+
+func (p *pipe) read(b []byte) (n int, err error) {
+	switch {
+	case isClosedChan(p.localDone):
+		return 0, io.ErrClosedPipe
+	case isClosedChan(p.remoteDone):
+		return 0, io.EOF
+	case isClosedChan(p.readDeadline.wait()):
+		return 0, os.ErrDeadlineExceeded
+	}
+
+	select {
+	case bw := <-p.rdRx:
+		nr := copy(b, bw)
+		p.rdTx <- nr
+		return nr, nil
+	case <-p.localDone:
+		return 0, io.ErrClosedPipe
+	case <-p.remoteDone:
+		return 0, io.EOF
+	case <-p.readDeadline.wait():
+		return 0, os.ErrDeadlineExceeded
+	}
+}
+
+func (p *pipe) Write(b []byte) (int, error) {
+	n, err := p.write(b)
+	if err != nil && err != io.ErrClosedPipe {
+		err = &OpError{Op: "write", Net: "pipe", Err: err}
+	}
+	return n, err
+}
+
+func (p *pipe) write(b []byte) (n int, err error) {
+	switch {
+	case isClosedChan(p.localDone):
+		return 0, io.ErrClosedPipe
+	case isClosedChan(p.remoteDone):
+		return 0, io.ErrClosedPipe
+	case isClosedChan(p.writeDeadline.wait()):
+		return 0, os.ErrDeadlineExceeded
+	}
+
+	p.wrMu.Lock() // Ensure entirety of b is written together
+	defer p.wrMu.Unlock()
+	for once := true; once || len(b) > 0; once = false {
+		select {
+		case p.wrTx <- b:
+			nw := <-p.wrRx
+			b = b[nw:]
+			n += nw
+		case <-p.localDone:
+			return n, io.ErrClosedPipe
+		case <-p.remoteDone:
+			return n, io.ErrClosedPipe
+		case <-p.writeDeadline.wait():
+			return n, os.ErrDeadlineExceeded
+		}
+	}
+	return n, nil
+}
+
+func (p *pipe) SetDeadline(t time.Time) error {
+	if isClosedChan(p.localDone) || isClosedChan(p.remoteDone) {
+		return io.ErrClosedPipe
+	}
+	p.readDeadline.set(t)
+	p.writeDeadline.set(t)
+	return nil
+}
+
+func (p *pipe) SetReadDeadline(t time.Time) error {
+	if isClosedChan(p.localDone) || isClosedChan(p.remoteDone) {
+		return io.ErrClosedPipe
+	}
+	p.readDeadline.set(t)
+	return nil
+}
+
+func (p *pipe) SetWriteDeadline(t time.Time) error {
+	if isClosedChan(p.localDone) || isClosedChan(p.remoteDone) {
+		return io.ErrClosedPipe
+	}
+	p.writeDeadline.set(t)
+	return nil
+}
+
+func (p *pipe) Close() error {
+	p.once.Do(func() { close(p.localDone) })
+	return nil
+}