/*

  * 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.primitives;

 import org.apache.giraph.bsp.CentralizedServiceWorker;

 import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;

 import org.apache.giraph.edge.AbstractEdgeStore;

 import org.apache.giraph.edge.OutEdges;

 import org.apache.giraph.utils.VertexIdEdgeIterator;

 import org.apache.hadoop.io.LongWritable;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.util.Progressable;

 import it.unimi.dsi.fastutil.longs.Long2ObjectMap;

 import it.unimi.dsi.fastutil.longs.Long2ObjectMaps;

 import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;

 import java.io.DataInput;

 import java.io.DataOutput;

 import java.io.IOException;

 import java.util.Iterator;

 import java.util.Map;

 /**

  * Special edge store to be used when ids are LongWritable.

  * Uses fastutil primitive maps in order to decrease number of objects and

  * get better performance.

  *

  * @param <V> Vertex value

  * @param <E> Edge value

  */

 public class LongEdgeStore<V extends Writable, E extends Writable>

   extends AbstractEdgeStore<LongWritable, V, E, Long,

   Long2ObjectMap.Entry<OutEdges<LongWritable, E>>> {

   /**

    * Constructor.

    *

    * @param service Service worker

    * @param configuration Configuration

    * @param progressable Progressable

    */

   public LongEdgeStore(

     CentralizedServiceWorker<LongWritable, V, E> service,

     ImmutableClassesGiraphConfiguration<LongWritable, V, E> configuration,

     Progressable progressable) {

     super(service, configuration, progressable);

   }

   @Override

   protected LongWritable getVertexId(

     Long2ObjectMap.Entry<OutEdges<LongWritable, E>> entry,

     LongWritable representativeVertexId) {

     representativeVertexId.set(entry.getLongKey());

     return representativeVertexId;

   }

   @Override

   protected LongWritable createVertexId(

     Long2ObjectMap.Entry<OutEdges<LongWritable, E>> entry) {

     return new LongWritable(entry.getLongKey());

   }

   @Override

   protected OutEdges<LongWritable, E> getPartitionEdges(

     Long2ObjectMap.Entry<OutEdges<LongWritable, E>> entry) {

     return entry.getValue();

   }

   @Override

   protected void writeVertexKey(Long key, DataOutput output)

       throws IOException {

     output.writeLong(key);

   }

   @Override

   protected Long readVertexKey(DataInput input) throws IOException {

     return input.readLong();

   }

   @Override

   protected Iterator<Long2ObjectMap.Entry<OutEdges<LongWritable, E>>>

   getPartitionEdgesIterator(

       Map<Long, OutEdges<LongWritable, E>> partitionEdges) {

     return ((Long2ObjectMap<OutEdges<LongWritable, E>>) partitionEdges)

         .long2ObjectEntrySet()

         .iterator();

   }

   @Override

   protected Long2ObjectMap<OutEdges<LongWritable, E>> getPartitionEdges(

     int partitionId) {

     Long2ObjectMap<OutEdges<LongWritable, E>> partitionEdges =

       (Long2ObjectMap<OutEdges<LongWritable, E>>)

         transientEdges.get(partitionId);

     if (partitionEdges == null) {

       Long2ObjectMap<OutEdges<LongWritable, E>> newPartitionEdges =

           Long2ObjectMaps.synchronize(

               new Long2ObjectOpenHashMap<OutEdges<LongWritable, E>>());

       partitionEdges = (Long2ObjectMap<OutEdges<LongWritable, E>>)

           transientEdges.putIfAbsent(partitionId,

           newPartitionEdges);

       if (partitionEdges == null) {

         partitionEdges = newPartitionEdges;

       }

     }

     return partitionEdges;

   }

   @Override

   protected OutEdges<LongWritable, E> getVertexOutEdges(

     VertexIdEdgeIterator<LongWritable, E> vertexIdEdgeIterator,

     Map<Long, OutEdges<LongWritable, E>> partitionEdgesIn) {

     Long2ObjectMap<OutEdges<LongWritable, E>> partitionEdges =

         (Long2ObjectMap<OutEdges<LongWritable, E>>) partitionEdgesIn;

     LongWritable vertexId = vertexIdEdgeIterator.getCurrentVertexId();

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

     if (outEdges == null) {

       synchronized (partitionEdges) {

         outEdges = partitionEdges.get(vertexId.get());

         if (outEdges == null) {

           outEdges = configuration.createAndInitializeInputOutEdges();

           partitionEdges.put(vertexId.get(), outEdges);

         }

       }

     }

     return outEdges;

   }

 }