/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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 org.apache.giraph.comm.aggregators;

 import java.io.IOException;

 import org.apache.giraph.comm.GlobalCommType;

 import org.apache.giraph.utils.WritableUtils;

 import org.apache.hadoop.io.Writable;

 /**

  * Implementation of {@link CountingOutputStream} which allows writing of

  * reduced values in the form of pair (name, type, value)

  *

  * There are two modes:

  * - when class of the value is written into the stream.

  * - when it isn't, and reader needs to know Class of the value in order

  *   to read it.

  */

 public class GlobalCommValueOutputStream extends CountingOutputStream {

   /** whether to write Class object for values into the stream */

   private final boolean writeClass;

   /**

    * Constructor

    *

    * @param writeClass boolean whether to write Class object for values

    */

   public GlobalCommValueOutputStream(boolean writeClass) {

     this.writeClass = writeClass;

   }

   /**

    * Write global communication object to the stream

    * and increment internal counter

    *

    * @param name Name

    * @param type Global communication type

    * @param value Object value

    * @return Number of bytes occupied by the stream

    * @throws IOException

    */

   public int addValue(String name, GlobalCommType type,

       Writable value) throws IOException {

     incrementCounter();

     dataOutput.writeUTF(name);

     dataOutput.writeByte(type.ordinal());

     if (writeClass) {

       WritableUtils.writeWritableObject(value, dataOutput);

     } else {

       value.write(dataOutput);

     }

     return getSize();

   }

 }