| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you 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 compression |
| |
| import ( |
| "github.com/klauspost/compress/zstd" |
| ) |
| |
| type zstdProvider struct { |
| compressionLevel Level |
| encoder *zstd.Encoder |
| decoder *zstd.Decoder |
| } |
| |
| func newPureGoZStdProvider(level Level) Provider { |
| var zstdLevel zstd.EncoderLevel |
| p := &zstdProvider{} |
| switch level { |
| case Default: |
| zstdLevel = zstd.SpeedDefault |
| case Faster: |
| zstdLevel = zstd.SpeedFastest |
| case Better: |
| zstdLevel = zstd.SpeedBetterCompression |
| } |
| p.encoder, _ = zstd.NewWriter(nil, zstd.WithEncoderLevel(zstdLevel)) |
| p.decoder, _ = zstd.NewReader(nil) |
| return p |
| } |
| |
| func (p *zstdProvider) CompressMaxSize(srcSize int) int { |
| // from zstd.h |
| // this formula ensures that bound(A) + bound(B) <= bound(A+B) as long as A and B >= 128 KB |
| lowLimit := 128 << 10 // 128 kB |
| var margin int |
| if srcSize < lowLimit { |
| margin = (lowLimit - srcSize) >> 11 |
| } |
| return srcSize + (srcSize >> 8) + margin |
| } |
| |
| func (p *zstdProvider) Compress(dst, src []byte) []byte { |
| return p.encoder.EncodeAll(src, dst) |
| } |
| |
| func (p *zstdProvider) Decompress(dst, src []byte, originalSize int) ([]byte, error) { |
| return p.decoder.DecodeAll(src, dst) |
| } |
| |
| func (p *zstdProvider) Close() error { |
| p.decoder.Close() |
| return p.encoder.Close() |
| } |
| |
| func (p *zstdProvider) Clone() Provider { |
| return newPureGoZStdProvider(p.compressionLevel) |
| } |