prometheus/vendor/google.golang.org/grpc/codec.go

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/*
*
* Copyright 2014, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
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,
}
},
}
)