blob: 47da0f0bf71f0dbb36d90e7adc9249004ed199e4 (
plain)
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
|
// 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"
)
// fixedBuffer is an io.ReadWriter backed by a fixed size buffer.
// It never allocates, but moves old data as new data is written.
type fixedBuffer struct {
buf []byte
r, w int
}
var (
errReadEmpty = errors.New("read from empty fixedBuffer")
errWriteFull = errors.New("write on full fixedBuffer")
)
// Read copies bytes from the buffer into p.
// It is an error to read when no data is available.
func (b *fixedBuffer) Read(p []byte) (n int, err error) {
if b.r == b.w {
return 0, errReadEmpty
}
n = copy(p, b.buf[b.r:b.w])
b.r += n
if b.r == b.w {
b.r = 0
b.w = 0
}
return n, nil
}
// Len returns the number of bytes of the unread portion of the buffer.
func (b *fixedBuffer) Len() int {
return b.w - b.r
}
// Write copies bytes from p into the buffer.
// It is an error to write more data than the buffer can hold.
func (b *fixedBuffer) Write(p []byte) (n int, err error) {
// Slide existing data to beginning.
if b.r > 0 && len(p) > len(b.buf)-b.w {
copy(b.buf, b.buf[b.r:b.w])
b.w -= b.r
b.r = 0
}
// Write new data.
n = copy(b.buf[b.w:], p)
b.w += n
if n < len(p) {
err = errWriteFull
}
return n, err
}
|
