| /* |
| * |
| * Copyright 2017 gRPC authors. |
| * |
| * 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. |
| * |
| */ |
| |
| // Package gzip implements and registers the gzip compressor |
| // during the initialization. |
| // This package is EXPERIMENTAL. |
| package gzip |
| |
| import ( |
| "compress/gzip" |
| "encoding/binary" |
| "fmt" |
| "io" |
| "io/ioutil" |
| "sync" |
| |
| "google.golang.org/grpc/encoding" |
| ) |
| |
| // Name is the name registered for the gzip compressor. |
| const Name = "gzip" |
| |
| func init() { |
| c := &compressor{} |
| c.poolCompressor.New = func() interface{} { |
| return &writer{Writer: gzip.NewWriter(ioutil.Discard), pool: &c.poolCompressor} |
| } |
| encoding.RegisterCompressor(c) |
| } |
| |
| type writer struct { |
| *gzip.Writer |
| pool *sync.Pool |
| } |
| |
| // SetLevel updates the registered gzip compressor to use the compression level specified (gzip.HuffmanOnly is not supported). |
| // NOTE: this function must only be called during initialization time (i.e. in an init() function), |
| // and is not thread-safe. |
| // |
| // The error returned will be nil if the specified level is valid. |
| func SetLevel(level int) error { |
| if level < gzip.DefaultCompression || level > gzip.BestCompression { |
| return fmt.Errorf("grpc: invalid gzip compression level: %d", level) |
| } |
| c := encoding.GetCompressor(Name).(*compressor) |
| c.poolCompressor.New = func() interface{} { |
| w, err := gzip.NewWriterLevel(ioutil.Discard, level) |
| if err != nil { |
| panic(err) |
| } |
| return &writer{Writer: w, pool: &c.poolCompressor} |
| } |
| return nil |
| } |
| |
| func (c *compressor) Compress(w io.Writer) (io.WriteCloser, error) { |
| z := c.poolCompressor.Get().(*writer) |
| z.Writer.Reset(w) |
| return z, nil |
| } |
| |
| func (z *writer) Close() error { |
| defer z.pool.Put(z) |
| return z.Writer.Close() |
| } |
| |
| type reader struct { |
| *gzip.Reader |
| pool *sync.Pool |
| } |
| |
| func (c *compressor) Decompress(r io.Reader) (io.Reader, error) { |
| z, inPool := c.poolDecompressor.Get().(*reader) |
| if !inPool { |
| newZ, err := gzip.NewReader(r) |
| if err != nil { |
| return nil, err |
| } |
| return &reader{Reader: newZ, pool: &c.poolDecompressor}, nil |
| } |
| if err := z.Reset(r); err != nil { |
| c.poolDecompressor.Put(z) |
| return nil, err |
| } |
| return z, nil |
| } |
| |
| func (z *reader) Read(p []byte) (n int, err error) { |
| n, err = z.Reader.Read(p) |
| if err == io.EOF { |
| z.pool.Put(z) |
| } |
| return n, err |
| } |
| |
| // RFC1952 specifies that the last four bytes "contains the size of |
| // the original (uncompressed) input data modulo 2^32." |
| // gRPC has a max message size of 2GB so we don't need to worry about wraparound. |
| func (c *compressor) DecompressedSize(buf []byte) int { |
| last := len(buf) |
| if last < 4 { |
| return -1 |
| } |
| return int(binary.LittleEndian.Uint32(buf[last-4 : last])) |
| } |
| |
| func (c *compressor) Name() string { |
| return Name |
| } |
| |
| type compressor struct { |
| poolCompressor sync.Pool |
| poolDecompressor sync.Pool |
| } |