1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
|
// 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 lazily initialized to &p.mu
b pipeBuffer
err error // read error once empty. non-nil means closed.
breakErr error // immediate read error (caller doesn't see rest of b)
donec chan struct{} // closed on error
readFn func() // optional code to run in Read before error
}
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.breakErr != nil {
return 0, p.breakErr
}
if p.b.Len() > 0 {
return p.b.Read(d)
}
if p.err != nil {
if p.readFn != nil {
p.readFn() // e.g. copy trailers
p.readFn = nil // not sticky like p.err
}
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 the next Read (waking up a current blocked
// Read if needed) to return the provided err after all data has been
// read.
//
// The error must be non-nil.
func (p *pipe) CloseWithError(err error) { p.closeWithError(&p.err, err, nil) }
// BreakWithError causes the next Read (waking up a current blocked
// Read if needed) to return the provided err immediately, without
// waiting for unread data.
func (p *pipe) BreakWithError(err error) { p.closeWithError(&p.breakErr, err, nil) }
// closeWithErrorAndCode is like CloseWithError but also sets some code to run
// in the caller's goroutine before returning the error.
func (p *pipe) closeWithErrorAndCode(err error, fn func()) { p.closeWithError(&p.err, err, fn) }
func (p *pipe) closeWithError(dst *error, err error, fn func()) {
if err == nil {
panic("err 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 *dst != nil {
// Already been done.
return
}
p.readFn = fn
*dst = err
p.closeDoneLocked()
}
// requires p.mu be held.
func (p *pipe) closeDoneLocked() {
if p.donec == nil {
return
}
// Close if unclosed. This isn't racy since we always
// hold p.mu while closing.
select {
case <-p.donec:
default:
close(p.donec)
}
}
// Err returns the error (if any) first set by BreakWithError or CloseWithError.
func (p *pipe) Err() error {
p.mu.Lock()
defer p.mu.Unlock()
if p.breakErr != nil {
return p.breakErr
}
return p.err
}
// Done returns a channel which is closed if and when this pipe is closed
// with CloseWithError.
func (p *pipe) Done() <-chan struct{} {
p.mu.Lock()
defer p.mu.Unlock()
if p.donec == nil {
p.donec = make(chan struct{})
if p.err != nil || p.breakErr != nil {
// Already hit an error.
p.closeDoneLocked()
}
}
return p.donec
}
|
