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/*
*
* Copyright 2014 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 grpc
import (
"math"
"sync"
"github.com/golang/protobuf/proto"
)
// Codec defines the interface gRPC uses to encode and decode messages.
// Note that implementations of this interface must be thread safe;
// a Codec's methods can be called from concurrent goroutines.
type Codec interface {
// Marshal returns the wire format of v.
Marshal(v interface{}) ([]byte, error)
// Unmarshal parses the wire format into v.
Unmarshal(data []byte, v interface{}) error
// String returns the name of the Codec implementation. The returned
// string will be used as part of content type in transmission.
String() string
}
// protoCodec is a Codec implementation with protobuf. It is the default codec for gRPC.
type protoCodec struct {
}
type cachedProtoBuffer struct {
lastMarshaledSize uint32
proto.Buffer
}
func capToMaxInt32(val int) uint32 {
if val > math.MaxInt32 {
return uint32(math.MaxInt32)
}
return uint32(val)
}
func (p protoCodec) marshal(v interface{}, cb *cachedProtoBuffer) ([]byte, error) {
protoMsg := v.(proto.Message)
newSlice := make([]byte, 0, cb.lastMarshaledSize)
cb.SetBuf(newSlice)
cb.Reset()
if err := cb.Marshal(protoMsg); err != nil {
return nil, err
}
out := cb.Bytes()
cb.lastMarshaledSize = capToMaxInt32(len(out))
return out, nil
}
func (p protoCodec) Marshal(v interface{}) ([]byte, error) {
cb := protoBufferPool.Get().(*cachedProtoBuffer)
out, err := p.marshal(v, cb)
// put back buffer and lose the ref to the slice
cb.SetBuf(nil)
protoBufferPool.Put(cb)
return out, err
}
func (p protoCodec) Unmarshal(data []byte, v interface{}) error {
cb := protoBufferPool.Get().(*cachedProtoBuffer)
cb.SetBuf(data)
v.(proto.Message).Reset()
err := cb.Unmarshal(v.(proto.Message))
cb.SetBuf(nil)
protoBufferPool.Put(cb)
return err
}
func (protoCodec) String() string {
return "proto"
}
var (
protoBufferPool = &sync.Pool{
New: func() interface{} {
return &cachedProtoBuffer{
Buffer: proto.Buffer{},
lastMarshaledSize: 16,
}
},
}
)
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