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1/*
2 *
3 * Copyright 2018 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19// Package proto defines the protobuf codec. Importing this package will
20// register the codec.
21package proto
22
23import (
24	"math"
25	"sync"
26
27	"github.com/golang/protobuf/proto"
28	"google.golang.org/grpc/encoding"
29)
30
31// Name is the name registered for the proto compressor.
32const Name = "proto"
33
34func init() {
35	encoding.RegisterCodec(codec{})
36}
37
38// codec is a Codec implementation with protobuf. It is the default codec for gRPC.
39type codec struct{}
40
41type cachedProtoBuffer struct {
42	lastMarshaledSize uint32
43	proto.Buffer
44}
45
46func capToMaxInt32(val int) uint32 {
47	if val > math.MaxInt32 {
48		return uint32(math.MaxInt32)
49	}
50	return uint32(val)
51}
52
53func marshal(v interface{}, cb *cachedProtoBuffer) ([]byte, error) {
54	protoMsg := v.(proto.Message)
55	newSlice := make([]byte, 0, cb.lastMarshaledSize)
56
57	cb.SetBuf(newSlice)
58	cb.Reset()
59	if err := cb.Marshal(protoMsg); err != nil {
60		return nil, err
61	}
62	out := cb.Bytes()
63	cb.lastMarshaledSize = capToMaxInt32(len(out))
64	return out, nil
65}
66
67func (codec) Marshal(v interface{}) ([]byte, error) {
68	if pm, ok := v.(proto.Marshaler); ok {
69		// object can marshal itself, no need for buffer
70		return pm.Marshal()
71	}
72
73	cb := protoBufferPool.Get().(*cachedProtoBuffer)
74	out, err := marshal(v, cb)
75
76	// put back buffer and lose the ref to the slice
77	cb.SetBuf(nil)
78	protoBufferPool.Put(cb)
79	return out, err
80}
81
82func (codec) Unmarshal(data []byte, v interface{}) error {
83	protoMsg := v.(proto.Message)
84	protoMsg.Reset()
85
86	if pu, ok := protoMsg.(proto.Unmarshaler); ok {
87		// object can unmarshal itself, no need for buffer
88		return pu.Unmarshal(data)
89	}
90
91	cb := protoBufferPool.Get().(*cachedProtoBuffer)
92	cb.SetBuf(data)
93	err := cb.Unmarshal(protoMsg)
94	cb.SetBuf(nil)
95	protoBufferPool.Put(cb)
96	return err
97}
98
99func (codec) Name() string {
100	return Name
101}
102
103var protoBufferPool = &sync.Pool{
104	New: func() interface{} {
105		return &cachedProtoBuffer{
106			Buffer:            proto.Buffer{},
107			lastMarshaledSize: 16,
108		}
109	},
110}
111