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writer.go
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writer.go
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/*
* Copyright 2022 CloudWeGo Authors
*
* 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.
*
* The MIT License (MIT)
*
* Copyright (c) 2015-present Aliaksandr Valialkin, VertaMedia, Kirill Danshin, Erik Dubbelboer, FastHTTP Authors
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* This file may have been modified by CloudWeGo authors. All CloudWeGo
* Modifications are Copyright 2022 CloudWeGo Authors.
*/
package stackless
import (
"fmt"
"io"
"github.com/cloudwego/hertz/pkg/common/bytebufferpool"
"github.com/cloudwego/hertz/pkg/common/errors"
)
// Writer is an interface stackless writer must conform to.
//
// The interface contains common subset for Writers from compress/* packages.
type Writer interface {
Write(p []byte) (int, error)
Flush() error
Close() error
Reset(w io.Writer)
}
// NewWriterFunc must return new writer that will be wrapped into
// stackless writer.
type NewWriterFunc func(w io.Writer) Writer
// NewWriter creates a stackless writer around a writer returned
// from newWriter.
//
// The returned writer writes data to dstW.
//
// Writers that use a lot of stack space may be wrapped into stackless writer,
// thus saving stack space for high number of concurrently running goroutines.
func NewWriter(dstW io.Writer, newWriter NewWriterFunc) Writer {
w := &writer{
dstW: dstW,
}
w.zw = newWriter(&w.xw)
return w
}
type writer struct {
dstW io.Writer
zw Writer
xw xWriter
err error
n int
p []byte
op op
}
type op int
const (
opWrite op = iota
opFlush
opClose
opReset
)
func (w *writer) Write(p []byte) (int, error) {
w.p = p
err := w.do(opWrite)
w.p = nil
return w.n, err
}
func (w *writer) Flush() error {
return w.do(opFlush)
}
func (w *writer) Close() error {
return w.do(opClose)
}
func (w *writer) Reset(dstW io.Writer) {
w.xw.Reset()
w.do(opReset) //nolint:errcheck
w.dstW = dstW
}
func (w *writer) do(op op) error {
w.op = op
if !stacklessWriterFunc(w) {
return errHighLoad
}
err := w.err
if err != nil {
return err
}
if w.xw.bb != nil && len(w.xw.bb.B) > 0 {
_, err = w.dstW.Write(w.xw.bb.B)
}
w.xw.Reset()
return err
}
var errHighLoad = errors.NewPublic("cannot compress data due to high load")
var stacklessWriterFunc = NewFunc(writerFunc)
func writerFunc(ctx interface{}) {
w := ctx.(*writer)
switch w.op {
case opWrite:
w.n, w.err = w.zw.Write(w.p)
case opFlush:
w.err = w.zw.Flush()
case opClose:
w.err = w.zw.Close()
case opReset:
w.zw.Reset(&w.xw)
w.err = nil
default:
panic(fmt.Sprintf("BUG: unexpected op: %d", w.op))
}
}
type xWriter struct {
bb *bytebufferpool.ByteBuffer
}
func (w *xWriter) Write(p []byte) (int, error) {
if w.bb == nil {
w.bb = bufferPool.Get()
}
return w.bb.Write(p)
}
func (w *xWriter) Reset() {
if w.bb != nil {
bufferPool.Put(w.bb)
w.bb = nil
}
}
var bufferPool bytebufferpool.Pool