/*
    * 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.messages;
  
  import org.apache.giraph.factories.MessageValueFactory;
  import org.apache.giraph.utils.ExtendedDataInput;
  import org.apache.giraph.utils.Factory;
  import org.apache.giraph.utils.RepresentativeByteStructIterable;
  import org.apache.hadoop.io.Writable;
  
  /**
   * Special iterable that recycles the message
   *
   * @param <M> Message data
   */
  public class MessagesIterable<M extends Writable>
      extends RepresentativeByteStructIterable<M> {
    /** Message class */
    private final MessageValueFactory<M> messageValueFactory;
  
    /**
     * Constructor
     *
     * @param dataInputFactory Factory for data inputs
     * @param messageValueFactory factory for creating message values
     */
    public MessagesIterable(
        Factory<? extends ExtendedDataInput> dataInputFactory,
        MessageValueFactory<M> messageValueFactory) {
      super(dataInputFactory);
      this.messageValueFactory = messageValueFactory;
    }
  
    @Override
    protected M createWritable() {
      return messageValueFactory.newInstance();
    }
  }