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* 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
// Package encoding defines the interface for the compressor and the functions
// to register and get the compossor.
// This package is EXPERIMENTAL.
package encoding
import (
var registerCompressor = make(map[string]Compressor)
// Compressor is used for compressing and decompressing when sending or receiving messages.
type Compressor interface {
// Compress writes the data written to wc to w after compressing it. If an error
// occurs while initializing the compressor, that error is returned instead.
Compress(w io.Writer) (io.WriteCloser, error)
// Decompress reads data from r, decompresses it, and provides the uncompressed data
// via the returned io.Reader. If an error occurs while initializing the decompressor, that error
// is returned instead.
Decompress(r io.Reader) (io.Reader, error)
// Name is the name of the compression codec and is used to set the content coding header.
Name() string
// RegisterCompressor registers the compressor with gRPC by its name. It can be activated when
// sending an RPC via grpc.UseCompressor(). It will be automatically accessed when receiving a
// message based on the content coding header. Servers also use it to send a response with the
// same encoding as the request.
// NOTE: this function must only be called during initialization time (i.e. in an init() function). If
// multiple Compressors are registered with the same name, the one registered last will take effect.
func RegisterCompressor(c Compressor) {
registerCompressor[c.Name()] = c
// GetCompressor returns Compressor for the given compressor name.
func GetCompressor(name string) Compressor {
return registerCompressor[name]
// Identity specifies the optional encoding for uncompressed streams.
// It is intended for grpc internal use only.
const Identity = "identity"