/*

  * 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.edge;

 import org.apache.giraph.bsp.CentralizedServiceWorker;

 import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;

 import org.apache.giraph.utils.VertexIdEdgeIterator;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import org.apache.hadoop.util.Progressable;

 import com.google.common.collect.MapMaker;

 import java.io.DataInput;

 import java.io.DataOutput;

 import java.io.IOException;

 import java.util.Iterator;

 import java.util.Map;

 import java.util.concurrent.ConcurrentMap;

 /**

  * Simple in memory edge store which supports any type of ids.

  *

  * @param <I> Vertex id

  * @param <V> Vertex value

  * @param <E> Edge value

  */

 public class SimpleEdgeStore<I extends WritableComparable,

   V extends Writable, E extends Writable>

   extends AbstractEdgeStore<I, V, E, I,

   Map.Entry<I, OutEdges<I, E>>> {

   /**

    * Constructor.

    *

    * @param service Service worker

    * @param configuration Configuration

    * @param progressable Progressable

    */

   public SimpleEdgeStore(

     CentralizedServiceWorker<I, V, E> service,

     ImmutableClassesGiraphConfiguration<I, V, E> configuration,

     Progressable progressable) {

     super(service, configuration, progressable);

   }

   @Override

   protected I getVertexId(Map.Entry<I, OutEdges<I, E>> entry,

     I representativeVertexId) {

     return entry.getKey();

   }

   @Override

   protected I createVertexId(Map.Entry<I, OutEdges<I, E>> entry) {

     return entry.getKey();

   }

   @Override

   protected ConcurrentMap<I, OutEdges<I, E>> getPartitionEdges(

     int partitionId) {

     ConcurrentMap<I, OutEdges<I, E>> partitionEdges =

         (ConcurrentMap<I, OutEdges<I, E>>) transientEdges.get(partitionId);

     if (partitionEdges == null) {

       ConcurrentMap<I, OutEdges<I, E>> newPartitionEdges =

           new MapMaker().concurrencyLevel(

               configuration.getNettyServerExecutionConcurrency()).makeMap();

       partitionEdges = (ConcurrentMap<I, OutEdges<I, E>>)

           transientEdges.putIfAbsent(partitionId, newPartitionEdges);

       if (partitionEdges == null) {

         partitionEdges = newPartitionEdges;

       }

     }

     return partitionEdges;

   }

   @Override

   protected OutEdges<I, E> getPartitionEdges(

     Map.Entry<I, OutEdges<I, E>> entry) {

     return entry.getValue();

   }

   @Override

   protected void writeVertexKey(I key, DataOutput output) throws IOException {

     key.write(output);

   }

   @Override

   protected I readVertexKey(DataInput input) throws IOException {

     I id = configuration.createVertexId();

     id.readFields(input);

     return id;

   }

   @Override

   protected Iterator<Map.Entry<I, OutEdges<I, E>>>

   getPartitionEdgesIterator(Map<I, OutEdges<I, E>> partitionEdges) {

     return partitionEdges.entrySet().iterator();

   }

   @Override

   protected OutEdges<I, E> getVertexOutEdges(

       VertexIdEdgeIterator<I, E> vertexIdEdgeIterator,

       Map<I, OutEdges<I, E>> partitionEdgesIn) {

     ConcurrentMap<I, OutEdges<I, E>> partitionEdges =

         (ConcurrentMap<I, OutEdges<I, E>>) partitionEdgesIn;

     I vertexId = vertexIdEdgeIterator.getCurrentVertexId();

     OutEdges<I, E> outEdges = partitionEdges.get(vertexId);

     if (outEdges == null) {

       OutEdges<I, E> newOutEdges =

           configuration.createAndInitializeInputOutEdges();

       outEdges = partitionEdges.putIfAbsent(vertexId, newOutEdges);

       if (outEdges == null) {

         outEdges = newOutEdges;

         // Since we had to use the vertex id as a new key in the map,

         // we need to release the object.

         vertexIdEdgeIterator.releaseCurrentVertexId();

       }

     }

     return outEdges;

   }

 }