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b7f5d985f9
Make the pipe code take an interface as the backing store. Now a pipe is something that's goroutine-safe and does the Cond waits but its underlying data is now an interface: anything that's a ReaderWriter with a Len method (such as a *bytes.Buffer), or a fixedBuffer (renamed in this CL from 'buffer'). This opens the ground to having a non-fixed buffer used with pipe. This also moves the CloseWithError code up into the pipe code, out of fixedBuffer. Change-Id: Ia3b853e8aa8920807b705ff4e41bed934a8c67b7 Reviewed-on: https://go-review.googlesource.com/16312 Reviewed-by: Blake Mizerany <blake.mizerany@gmail.com>
83 lines
1.7 KiB
Go
83 lines
1.7 KiB
Go
// Copyright 2014 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 http2
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import (
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"errors"
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"io"
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"sync"
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)
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// pipe is a goroutine-safe io.Reader/io.Writer pair. It's like
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// io.Pipe except there are no PipeReader/PipeWriter halves, and the
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// underlying buffer is an interface. (io.Pipe is always unbuffered)
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type pipe struct {
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mu sync.Mutex
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c sync.Cond // c.L must point to
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b pipeBuffer
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err error // read error once empty. non-nil means closed.
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}
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type pipeBuffer interface {
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Len() int
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io.Writer
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io.Reader
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}
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// Read waits until data is available and copies bytes
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// from the buffer into p.
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func (p *pipe) Read(d []byte) (n int, err error) {
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p.mu.Lock()
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defer p.mu.Unlock()
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if p.c.L == nil {
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p.c.L = &p.mu
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}
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for {
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if p.b.Len() > 0 {
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return p.b.Read(d)
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}
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if p.err != nil {
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return 0, p.err
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}
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p.c.Wait()
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}
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}
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var errClosedPipeWrite = errors.New("write on closed buffer")
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// Write copies bytes from p into the buffer and wakes a reader.
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// It is an error to write more data than the buffer can hold.
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func (p *pipe) Write(d []byte) (n int, err error) {
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p.mu.Lock()
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defer p.mu.Unlock()
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if p.c.L == nil {
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p.c.L = &p.mu
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}
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defer p.c.Signal()
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if p.err != nil {
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return 0, errClosedPipeWrite
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}
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return p.b.Write(d)
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}
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// CloseWithError causes Reads to wake up and return the
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// provided err after all data has been read.
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//
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// The error must be non-nil.
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func (p *pipe) CloseWithError(err error) {
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if err == nil {
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panic("CloseWithError must be non-nil")
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}
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p.mu.Lock()
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defer p.mu.Unlock()
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if p.c.L == nil {
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p.c.L = &p.mu
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}
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defer p.c.Signal()
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if p.err == nil {
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p.err = err
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}
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}
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