mirror of
https://github.com/prometheus/prometheus.git
synced 2024-12-28 23:19:41 -08:00
50 lines
1.3 KiB
Go
50 lines
1.3 KiB
Go
|
// Copyright 2016 The CMux Authors. All rights reserved.
|
||
|
|
//
|
||
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
// you may not use this file except in compliance with the License.
|
||
|
|
// You may obtain a copy of the License at
|
||
|
|
//
|
||
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
//
|
||
|
|
// Unless required by applicable law or agreed to in writing, software
|
||
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
|
||
|
|
// implied. See the License for the specific language governing
|
||
|
|
// permissions and limitations under the License.
|
||
|
|
|
||
|
|
package cmux
|
||
|
|
|
||
|
|
import (
|
||
|
|
"bytes"
|
||
|
|
"io"
|
||
|
|
)
|
||
|
|
|
||
|
|
// bufferedReader is an optimized implementation of io.Reader that behaves like
|
||
|
|
// ```
|
||
|
|
// io.MultiReader(bytes.NewReader(buffer.Bytes()), io.TeeReader(source, buffer))
|
||
|
|
// ```
|
||
|
|
// without allocating.
|
||
|
|
type bufferedReader struct {
|
||
|
|
source io.Reader
|
||
|
|
buffer *bytes.Buffer
|
||
|
|
bufferRead int
|
||
|
|
bufferSize int
|
||
|
|
}
|
||
|
|
|
||
|
|
func (s *bufferedReader) Read(p []byte) (int, error) {
|
||
|
|
// Functionality of bytes.Reader.
|
||
|
|
bn := copy(p, s.buffer.Bytes()[s.bufferRead:s.bufferSize])
|
||
|
|
s.bufferRead += bn
|
||
|
|
|
||
|
|
p = p[bn:]
|
||
|
|
|
||
|
|
// Funtionality of io.TeeReader.
|
||
|
|
sn, sErr := s.source.Read(p)
|
||
|
|
if sn > 0 {
|
||
|
|
if wn, wErr := s.buffer.Write(p[:sn]); wErr != nil {
|
||
|
|
return bn + wn, wErr
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return bn + sn, sErr
|
||
|
|
}
|