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register.go
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register.go
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/*
* zipindex, (C)2021 MinIO, Inc.
*
* 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.
*/
// Contains code that is
//
// Copyright 2010 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 zipindex
import (
"errors"
"io"
"sync"
"github.com/klauspost/compress/flate"
"github.com/klauspost/compress/zstd"
)
// A Decompressor returns a new decompressing reader, reading from r.
// The ReadCloser's Close method must be used to release associated resources.
// The Decompressor itself must be safe to invoke from multiple goroutines
// simultaneously, but each returned reader will be used only by
// one goroutine at a time.
type Decompressor func(r io.Reader) io.ReadCloser
var flateReaderPool sync.Pool
func newFlateReader(r io.Reader) io.ReadCloser {
fr, ok := flateReaderPool.Get().(io.ReadCloser)
if ok {
fr.(flate.Resetter).Reset(r, nil)
} else {
fr = flate.NewReader(r)
}
return &pooledFlateReader{fr: fr}
}
type pooledFlateReader struct {
mu sync.Mutex // guards Close and Read
fr io.ReadCloser
}
func (r *pooledFlateReader) Read(p []byte) (n int, err error) {
r.mu.Lock()
defer r.mu.Unlock()
if r.fr == nil {
return 0, errors.New("Read after Close")
}
return r.fr.Read(p)
}
func (r *pooledFlateReader) Close() error {
r.mu.Lock()
defer r.mu.Unlock()
var err error
if r.fr != nil {
err = r.fr.Close()
flateReaderPool.Put(r.fr)
r.fr = nil
}
return err
}
var (
decompressors sync.Map // map[uint16]Decompressor
)
func init() {
RegisterDecompressor(Store, io.NopCloser)
RegisterDecompressor(Deflate, newFlateReader)
RegisterDecompressor(Zstd, zstd.ZipDecompressor(zstd.WithDecoderLowmem(true)))
}
// RegisterDecompressor allows custom decompressors for a specified method ID.
// The common methods Store (0) and Deflate (8) and Zstandard (93) are built in.
func RegisterDecompressor(method uint16, dcomp Decompressor) {
decompressors.Store(method, dcomp)
}
func decompressor(method uint16) Decompressor {
di, ok := decompressors.Load(method)
if !ok {
return nil
}
return di.(Decompressor)
}