cubefs

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// Copyright 2013 Matt T. Proud
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//     http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package pbutil
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import (
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	"encoding/binary"
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	"io"
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	"github.com/golang/protobuf/proto"
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)
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// WriteDelimited encodes and dumps a message to the provided writer prefixed
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// with a 32-bit varint indicating the length of the encoded message, producing
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// a length-delimited record stream, which can be used to chain together
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// encoded messages of the same type together in a file.  It returns the total
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// number of bytes written and any applicable error.  This is roughly
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// equivalent to the companion Java API's MessageLite#writeDelimitedTo.
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func WriteDelimited(w io.Writer, m proto.Message) (n int, err error) {
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	buffer, err := proto.Marshal(m)
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	if err != nil {
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		return 0, err
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	}
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	var buf [binary.MaxVarintLen32]byte
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	encodedLength := binary.PutUvarint(buf[:], uint64(len(buffer)))
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	sync, err := w.Write(buf[:encodedLength])
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	if err != nil {
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		return sync, err
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	}
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	n, err = w.Write(buffer)
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	return n + sync, err
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}
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