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// Copyright 2014 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 http2
import (
"errors"
"io"
"sync"
)
// pipe is a goroutine-safe io.Reader/io.Writer pair. It's like
// io.Pipe except there are no PipeReader/PipeWriter halves, and the
// underlying buffer is an interface. (io.Pipe is always unbuffered)
type pipe struct {
mu sync.Mutex
c sync.Cond // c.L must point to
b pipeBuffer
err error // read error once empty. non-nil means closed.
}
type pipeBuffer interface {
Len() int
io.Writer
io.Reader
}
// Read waits until data is available and copies bytes
// from the buffer into p.
func (p *pipe) Read(d []byte) (n int, err error) {
p.mu.Lock()
defer p.mu.Unlock()
if p.c.L == nil {
p.c.L = &p.mu
}
for {
if p.b.Len() > 0 {
return p.b.Read(d)
}
if p.err != nil {
return 0, p.err
}
p.c.Wait()
}
}
var errClosedPipeWrite = errors.New("write on closed buffer")
// Write copies bytes from p into the buffer and wakes a reader.
// It is an error to write more data than the buffer can hold.
func (p *pipe) Write(d []byte) (n int, err error) {
p.mu.Lock()
defer p.mu.Unlock()
if p.c.L == nil {
p.c.L = &p.mu
}
defer p.c.Signal()
if p.err != nil {
return 0, errClosedPipeWrite
}
return p.b.Write(d)
}
// CloseWithError causes Reads to wake up and return the
// provided err after all data has been read.
//
// The error must be non-nil.
func (p *pipe) CloseWithError(err error) {
if err == nil {
panic("CloseWithError must be non-nil")
}
p.mu.Lock()
defer p.mu.Unlock()
if p.c.L == nil {
p.c.L = &p.mu
}
defer p.c.Signal()
if p.err == nil {
p.err = err
}
}
// Err returns the error (if any) first set with CloseWithError.
// This is the error which will be returned after the reader is exhausted.
func (p *pipe) Err() error {
p.mu.Lock()
defer p.mu.Unlock()
return p.err
}
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