| // 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 ( |
| "bytes" |
| "compress/zlib" |
| "io" |
| ) |
| |
| type zlibProvider struct{} |
| |
| // NewZLibProvider returns a Provider interface |
| func NewZLibProvider() Provider { |
| return &zlibProvider{} |
| } |
| |
| func (zlibProvider) CompressMaxSize(originalSize int) int { |
| // Use formula from ZLib: https://github.com/madler/zlib/blob/cacf7f1d4e3d44d871b605da3b647f07d718623f/deflate.c#L659 |
| return originalSize + |
| ((originalSize + 7) >> 3) + ((originalSize + 63) >> 6) + 11 |
| } |
| |
| func (zlibProvider) Compress(dst, src []byte) []byte { |
| var b = bytes.NewBuffer(dst[:0]) |
| w := zlib.NewWriter(b) |
| |
| if _, err := w.Write(src); err != nil { |
| return nil |
| } |
| if err := w.Close(); err != nil { |
| return nil |
| } |
| |
| return b.Bytes() |
| } |
| |
| func (zlibProvider) Decompress(dst, src []byte, originalSize int) ([]byte, error) { |
| r, err := zlib.NewReader(bytes.NewReader(src)) |
| if err != nil { |
| return nil, err |
| } |
| |
| if cap(dst) >= originalSize { |
| dst = dst[0:originalSize] // Reuse dst buffer |
| } else { |
| dst = make([]byte, originalSize) |
| } |
| if _, err = io.ReadFull(r, dst); err != nil { |
| return nil, err |
| } |
| |
| if err = r.Close(); err != nil { |
| return nil, err |
| } |
| |
| return dst, nil |
| } |
| |
| func (zlibProvider) Clone() Provider { |
| return NewZLibProvider() |
| } |
| |
| func (zlibProvider) Close() error { |
| return nil |
| } |