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134 lines
3.9 KiB
134 lines
3.9 KiB
// Protocol Buffers for Go with Gadgets
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//
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// Copyright (c) 2013, The GoGo Authors. All rights reserved.
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// http://github.com/gogo/protobuf
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// Modified from original GoGo Protobuf to return number of bytes written.
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package protoio
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import (
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"bytes"
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"encoding/binary"
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"io"
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"sync"
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"github.com/gogo/protobuf/proto"
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)
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// NewDelimitedWriter writes a varint-delimited Protobuf message to a writer. It is
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// equivalent to the gogoproto NewDelimitedWriter, except WriteMsg() also returns the
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// number of bytes written, which is necessary in the p2p package.
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func NewDelimitedWriter(w io.Writer) WriteCloser {
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return &varintWriter{w, make([]byte, binary.MaxVarintLen64), nil}
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}
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type varintWriter struct {
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w io.Writer
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lenBuf []byte
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buffer []byte
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}
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func (w *varintWriter) WriteMsg(msg proto.Message) (int, error) {
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if m, ok := msg.(marshaler); ok {
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n, ok := getSize(m)
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if ok {
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if n+binary.MaxVarintLen64 >= len(w.buffer) {
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w.buffer = make([]byte, n+binary.MaxVarintLen64)
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}
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lenOff := binary.PutUvarint(w.buffer, uint64(n))
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_, err := m.MarshalTo(w.buffer[lenOff:])
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if err != nil {
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return 0, err
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}
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_, err = w.w.Write(w.buffer[:lenOff+n])
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return lenOff + n, err
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}
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}
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// fallback
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data, err := proto.Marshal(msg)
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if err != nil {
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return 0, err
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}
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length := uint64(len(data))
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n := binary.PutUvarint(w.lenBuf, length)
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_, err = w.w.Write(w.lenBuf[:n])
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if err != nil {
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return 0, err
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}
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_, err = w.w.Write(data)
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return len(data) + n, err
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}
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func (w *varintWriter) Close() error {
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if closer, ok := w.w.(io.Closer); ok {
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return closer.Close()
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}
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return nil
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}
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func varintWrittenBytes(m marshaler, size int) ([]byte, error) {
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buf := make([]byte, size+binary.MaxVarintLen64)
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n := binary.PutUvarint(buf, uint64(size))
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nw, err := m.MarshalTo(buf[n:])
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if err != nil {
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return nil, err
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}
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return buf[:n+nw], nil
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}
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var bufPool = &sync.Pool{
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New: func() interface{} {
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return new(bytes.Buffer)
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},
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}
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func MarshalDelimited(msg proto.Message) ([]byte, error) {
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// The goal here is to write proto message as is knowning already if
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// the exact size can be retrieved and if so just use that.
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if m, ok := msg.(marshaler); ok {
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size, ok := getSize(msg)
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if ok {
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return varintWrittenBytes(m, size)
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}
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}
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// Otherwise, go down the route of using proto.Marshal,
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// and use the buffer pool to retrieve a writer.
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buf := bufPool.Get().(*bytes.Buffer)
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defer bufPool.Put(buf)
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buf.Reset()
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_, err := NewDelimitedWriter(buf).WriteMsg(msg)
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if err != nil {
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return nil, err
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}
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// Given that we are reusing buffers, we should
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// make a copy of the returned bytes.
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bytesCopy := make([]byte, buf.Len())
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copy(bytesCopy, buf.Bytes())
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return bytesCopy, nil
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}
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