/*

  * 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.graph.partition;

 import org.apache.giraph.graph.WorkerInfo;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import java.util.Collection;

 /**

  * Stores the {@link PartitionOwner} objects from the master and provides the

  * mapping of vertex to {@link PartitionOwner}. Also generates the partition

  * owner implementation.

  *

  * @param <I> Vertex id

  * @param <V> Vertex value

  * @param <E> Edge value

  * @param <M> Message data

  */

 @SuppressWarnings("rawtypes")

 public interface WorkerGraphPartitioner<I extends WritableComparable,

     V extends Writable, E extends Writable, M extends Writable> {

   /**

    * Instantiate the {@link PartitionOwner} implementation used to read the

    * master assignments.

    *

    * @return Instantiated {@link PartitionOwner} object

    */

   PartitionOwner createPartitionOwner();

   /**

    * Figure out the owner of a vertex

    *

    * @param vertexId Vertex id to get the partition for

    * @return Correct partition owner

    */

   PartitionOwner getPartitionOwner(I vertexId);

   /**

    * At the end of a superstep, workers have {@link PartitionStats} generated

    * for each of their partitions.  This method will allow the user to

    * modify or create their own {@link PartitionStats} interfaces to send to

    * the master.

    *

    * @param workerPartitionStats Stats generated by the infrastructure during

    *        the superstep

    * @param partitionStore Partition store for this worker

    *        (could be used to provide more useful stat information)

    * @return Final partition stats

    */

   Collection<PartitionStats> finalizePartitionStats(

       Collection<PartitionStats> workerPartitionStats,

       PartitionStore<I, V, E, M> partitionStore);

   /**

    * Get the partitions owners and update locally.  Returns the partitions

    * to send to other workers and other dependencies.

    *

    * @param myWorkerInfo Worker info.

    * @param masterSetPartitionOwners Master set partition owners, received

    *        prior to beginning the superstep

    * @param partitionStore Partition store for this worker

    *        (can be used to fill the return map of partitions to send)

    * @return Information for the partition exchange.

    */

   PartitionExchange updatePartitionOwners(

       WorkerInfo myWorkerInfo,

       Collection<? extends PartitionOwner> masterSetPartitionOwners,

       PartitionStore<I, V, E, M> partitionStore);

   /**

    * Get a collection of the {@link PartitionOwner} objects.

    *

    * @return Collection of owners for every partition.

    */

   Collection<? extends PartitionOwner> getPartitionOwners();

 }