github.com/zuoyebang/bitalostable@v1.0.1-0.20240229032404-e3b99a834294/sstable/compression_cgo.go (about)

     1  // Copyright 2021 The LevelDB-Go and Pebble Authors. All rights reserved. Use
     2  // of this source code is governed by a BSD-style license that can be found in
     3  // the LICENSE file.
     4  
     5  //go:build cgo
     6  // +build cgo
     7  
     8  package sstable
     9  
    10  import (
    11  	"bytes"
    12  
    13  	"github.com/DataDog/zstd"
    14  )
    15  
    16  // decodeZstd decompresses b with the Zstandard algorithm.
    17  // It reuses the preallocated capacity of decodedBuf if it is sufficient.
    18  // On success, it returns the decoded byte slice.
    19  func decodeZstd(decodedBuf, b []byte) ([]byte, error) {
    20  	return zstd.Decompress(decodedBuf, b)
    21  }
    22  
    23  // encodeZstd compresses b with the Zstandard algorithm at default compression
    24  // level (level 3). It reuses the preallocated capacity of compressedBuf if it
    25  // is sufficient. The subslice `compressedBuf[:varIntLen]` should already encode
    26  // the length of `b` before calling encodeZstd. It returns the encoded byte
    27  // slice, including the `compressedBuf[:varIntLen]` prefix.
    28  func encodeZstd(compressedBuf []byte, varIntLen int, b []byte) []byte {
    29  	buf := bytes.NewBuffer(compressedBuf[:varIntLen])
    30  	writer := zstd.NewWriterLevel(buf, 3)
    31  	writer.Write(b)
    32  	writer.Close()
    33  	return buf.Bytes()
    34  }