/*

  * 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.master.input;

 import org.apache.giraph.worker.WorkerInfo;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Map;

 import java.util.concurrent.atomic.AtomicInteger;

 /**

  * Organizer for mapping splits on master. Mapping splits need all to be

  * given to all workers, unlike vertex and edge splits which are read by

  * exactly one worker each

  */

 public class MappingInputSplitsMasterOrganizer

     implements InputSplitsMasterOrganizer {

   /** List of splits */

   private final List<byte[]> splits;

   /** Map from worker task id to atomic pointer in splits list */

   private final Map<Integer, AtomicInteger>

       workerTaskIdToNextSplitIndexMap;

   /**

    * Constructor

    *

    * @param serializedSplits Splits

    * @param workers List of workers

    */

   public MappingInputSplitsMasterOrganizer(List<byte[]> serializedSplits,

       List<WorkerInfo> workers) {

     this.splits = serializedSplits;

     workerTaskIdToNextSplitIndexMap = new HashMap<>();

     for (WorkerInfo worker : workers) {

       workerTaskIdToNextSplitIndexMap.put(

           worker.getTaskId(), new AtomicInteger(0));

     }

   }

   @Override

   public byte[] getSerializedSplitFor(int workerTaskId) {

     AtomicInteger nextSplitIndex =

         workerTaskIdToNextSplitIndexMap.get(workerTaskId);

     int splitIndex = nextSplitIndex.getAndIncrement();

     return splitIndex < splits.size() ? splits.get(splitIndex) : null;

   }

 }