forked from mystiq/dex
61 lines
1.3 KiB
Go
61 lines
1.3 KiB
Go
|
// 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
|
||
|
|
}
|