zstd.go raw

   1  /*
   2   * SPDX-FileCopyrightText: © Hypermode Inc. <hello@hypermode.com>
   3   * SPDX-License-Identifier: Apache-2.0
   4   */
   5  
   6  package y
   7  
   8  import (
   9  	"sync"
  10  
  11  	"github.com/klauspost/compress/zstd"
  12  )
  13  
  14  var (
  15  	decoder *zstd.Decoder
  16  	encoder *zstd.Encoder
  17  
  18  	encOnce, decOnce sync.Once
  19  )
  20  
  21  // ZSTDDecompress decompresses a block using ZSTD algorithm.
  22  func ZSTDDecompress(dst, src []byte) ([]byte, error) {
  23  	decOnce.Do(func() {
  24  		var err error
  25  		decoder, err = zstd.NewReader(nil)
  26  		Check(err)
  27  	})
  28  	return decoder.DecodeAll(src, dst[:0])
  29  }
  30  
  31  // ZSTDCompress compresses a block using ZSTD algorithm.
  32  func ZSTDCompress(dst, src []byte, compressionLevel int) ([]byte, error) {
  33  	encOnce.Do(func() {
  34  		var err error
  35  		level := zstd.EncoderLevelFromZstd(compressionLevel)
  36  		encoder, err = zstd.NewWriter(nil, zstd.WithEncoderLevel(level))
  37  		Check(err)
  38  	})
  39  	return encoder.EncodeAll(src, dst[:0]), nil
  40  }
  41  
  42  // ZSTDCompressBound returns the worst case size needed for a destination buffer.
  43  // Klauspost ZSTD library does not provide any API for Compression Bound. This
  44  // calculation is based on the DataDog ZSTD library.
  45  // See https://pkg.go.dev/github.com/DataDog/zstd#CompressBound
  46  func ZSTDCompressBound(srcSize int) int {
  47  	lowLimit := 128 << 10 // 128 kB
  48  	var margin int
  49  	if srcSize < lowLimit {
  50  		margin = (lowLimit - srcSize) >> 11
  51  	}
  52  	return srcSize + (srcSize >> 8) + margin
  53  }
  54