network/protocol/Encodable.java

0001 /*
0002  * Licensed to the Apache Software Foundation (ASF) under one or more
0003  * contributor license agreements.  See the NOTICE file distributed with
0004  * this work for additional information regarding copyright ownership.
0005  * The ASF licenses this file to You under the Apache License, Version 2.0
0006  * (the "License"); you may not use this file except in compliance with
0007  * the License.  You may obtain a copy of the License at
0008  *
0009  *    http://www.apache.org/licenses/LICENSE-2.0
0010  *
0011  * Unless required by applicable law or agreed to in writing, software
0012  * distributed under the License is distributed on an "AS IS" BASIS,
0013  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0014  * See the License for the specific language governing permissions and
0015  * limitations under the License.
0016  */
0017
0018 package org.apache.spark.network.protocol;
0019
0020 import io.netty.buffer.ByteBuf;
0021
0022 /**
0023  * Interface for an object which can be encoded into a ByteBuf. Multiple Encodable objects are
0024  * stored in a single, pre-allocated ByteBuf, so Encodables must also provide their length.
0025  *
0026  * Encodable objects should provide a static "decode(ByteBuf)" method which is invoked by
0027  * {@link MessageDecoder}. During decoding, if the object uses the ByteBuf as its data (rather than
0028  * just copying data from it), then you must retain() the ByteBuf.
0029  *
0030  * Additionally, when adding a new Encodable Message, add it to {@link Message.Type}.
0031  */
0032 public interface Encodable {
0033   /** Number of bytes of the encoded form of this object. */
0034   int encodedLength();
0035
0036   /**
0037    * Serializes this object by writing into the given ByteBuf.
0038    * This method must write exactly encodedLength() bytes.
0039    */
0040   void encode(ByteBuf buf);
0041 }