/*

  * 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.partition;

 import java.util.List;

 import java.util.Map;

 import java.util.Set;

 import org.apache.giraph.worker.WorkerInfo;

 /**

  * Describes what is required to send and wait for in a potential partition

  * exchange between workers.

  */

 public class PartitionExchange {

   /** Workers that I am dependent on before I can continue */

   private final Set<WorkerInfo> myDependencyWorkerSet;

   /** Workers that I need to sent partitions to */

   private final Map<WorkerInfo, List<Integer>> sendWorkerPartitionMap;

   /**

    * Only constructor.

    *

    * @param myDependencyWorkerSet All the workers I must wait for

    * @param sendWorkerPartitionMap Partitions I need to send to other workers

    */

   public PartitionExchange(

       Set<WorkerInfo> myDependencyWorkerSet,

       Map<WorkerInfo, List<Integer>> sendWorkerPartitionMap) {

     this.myDependencyWorkerSet = myDependencyWorkerSet;

     this.sendWorkerPartitionMap = sendWorkerPartitionMap;

   }

   /**

    * Get the workers that I must wait for

    *

    * @return Set of workers I must wait for

    */

   public Set<WorkerInfo> getMyDependencyWorkerSet() {

     return myDependencyWorkerSet;

   }

   /**

    * Get a mapping of worker to list of partition ids I need to send to.

    *

    * @return Mapping of worker to partition id list I will send to.

    */

   public Map<WorkerInfo, List<Integer>> getSendWorkerPartitionMap() {

     return sendWorkerPartitionMap;

   }

   /**

    * Is this worker involved in a partition exchange?  Receiving or sending?

    *

    * @return True if needs to be involved in the exchange, false otherwise.

    */

   public boolean doExchange() {

     return !myDependencyWorkerSet.isEmpty() ||

         !sendWorkerPartitionMap.isEmpty();

   }

 }