/*

  * 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.comm.messages.primitives;

 import com.google.common.collect.Lists;

 import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;

 import java.io.DataInput;

 import java.io.DataOutput;

 import java.io.IOException;

 import java.util.Collections;

 import java.util.Iterator;

 import java.util.List;

 import org.apache.giraph.combiner.MessageCombiner;

 import org.apache.giraph.comm.messages.MessageStore;

 import org.apache.giraph.comm.messages.PartitionSplitInfo;

 import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;

 import org.apache.giraph.factories.MessageValueFactory;

 import org.apache.giraph.types.ops.PrimitiveIdTypeOps;

 import org.apache.giraph.types.ops.TypeOpsUtils;

 import org.apache.giraph.types.ops.collections.Basic2ObjectMap;

 import org.apache.giraph.types.ops.collections.WritableWriter;

 import org.apache.giraph.utils.EmptyIterable;

 import org.apache.giraph.utils.VertexIdMessageIterator;

 import org.apache.giraph.utils.VertexIdMessages;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 /**

  * Special message store to be used when IDs are primitive and message doesn't

  * need to be, and message combiner is used.

  * Data is backed by primitive keyed maps in order to decrease number of

  * objects and get better performance.

  * (keys are using primitives, values are using objects, even if they

  * are primitive)

  *

  * @param <I> Vertex id type

  * @param <M> Message type

  */

 public class IdOneMessagePerVertexStore<I extends WritableComparable,

     M extends Writable> implements MessageStore<I, M> {

   /** Map from partition id to map from vertex id to message */

   private final Int2ObjectOpenHashMap<Basic2ObjectMap<I, M>> map;

   /** Message value factory */

   private final MessageValueFactory<M> messageValueFactory;

   /** Message messageCombiner */

   private final MessageCombiner<? super I, M> messageCombiner;

   /** Partition split info */

   private final PartitionSplitInfo<I> partitionInfo;

   /** Giraph configuration */

   private final ImmutableClassesGiraphConfiguration<I, ?, ?> config;

   /** Vertex id TypeOps */

   private final PrimitiveIdTypeOps<I> idTypeOps;

   /** WritableWriter for values in this message store */

   private final WritableWriter<M> messageWriter = new WritableWriter<M>() {

     @Override

     public M readFields(DataInput in) throws IOException {

       M message = messageValueFactory.newInstance();

       message.readFields(in);

       return message;

     }

     @Override

     public void write(DataOutput out, M value) throws IOException {

       value.write(out);

     }

   };

   /**

    * Constructor

    *

    * @param messageValueFactory Message value factory

    * @param partitionInfo Partition split info

    * @param messageCombiner Message messageCombiner

    * @param config Config

    */

   public IdOneMessagePerVertexStore(

       MessageValueFactory<M> messageValueFactory,

       PartitionSplitInfo<I> partitionInfo,

       MessageCombiner<? super I, M> messageCombiner,

       ImmutableClassesGiraphConfiguration<I, ?, ?> config) {

     this.partitionInfo = partitionInfo;

     this.config = config;

     this.messageValueFactory = messageValueFactory;

     this.messageCombiner = messageCombiner;

     idTypeOps = TypeOpsUtils.getPrimitiveIdTypeOps(config.getVertexIdClass());

     map = new Int2ObjectOpenHashMap<>();

     for (int partitionId : partitionInfo.getPartitionIds()) {

       Basic2ObjectMap<I, M> partitionMap = idTypeOps.create2ObjectOpenHashMap(

         Math.max(10, (int) partitionInfo.getPartitionVertexCount(partitionId)),

         messageWriter

       );

       map.put(partitionId, partitionMap);

     }

   }

   /**

    * Get map which holds messages for partition which vertex belongs to.

    *

    * @param vertexId Id of the vertex

    * @return Map which holds messages for partition which vertex belongs to.

    */

   private Basic2ObjectMap<I, M> getPartitionMap(I vertexId) {

     return map.get(partitionInfo.getPartitionId(vertexId));

   }

   @Override

   public void addPartitionMessages(

       int partitionId,

       VertexIdMessages<I, M> messages) {

     Basic2ObjectMap<I, M> partitionMap = map.get(partitionId);

     synchronized (partitionMap) {

       VertexIdMessageIterator<I, M>

           iterator = messages.getVertexIdMessageIterator();

       // This loop is a little complicated as it is optimized to only create

       // the minimal amount of vertex id and message objects as possible.

       while (iterator.hasNext()) {

         iterator.next();

         I vertexId = iterator.getCurrentVertexId();

         M currentMessage =

             partitionMap.get(iterator.getCurrentVertexId());

         if (currentMessage == null) {

           M newMessage = messageCombiner.createInitialMessage();

           currentMessage = partitionMap.put(

               iterator.getCurrentVertexId(), newMessage);

           if (currentMessage == null) {

             currentMessage = newMessage;

           }

         }

         messageCombiner.combine(vertexId, currentMessage,

           iterator.getCurrentMessage());

       }

     }

   }

   /**

    * Adds a message for a particular vertex

    *

    * @param vertexId Id of target vertex

    * @param message  A message to send

    * @throws IOException

    */

   @Override

   public void addMessage(I vertexId, M message) throws IOException {

     Basic2ObjectMap<I, M> partitionMap = getPartitionMap(vertexId);

     synchronized (partitionMap) {

       M currentMessage = partitionMap.get(vertexId);

       if (currentMessage == null) {

         M newMessage = messageCombiner.createInitialMessage();

         currentMessage = partitionMap.put(vertexId, newMessage);

         if (currentMessage == null) {

           currentMessage = newMessage;

         }

       }

       messageCombiner.combine(vertexId, currentMessage, message);

     }

   }

   @Override

   public void clearPartition(int partitionId) {

     map.get(partitionId).clear();

   }

   @Override

   public boolean hasMessagesForVertex(I vertexId) {

     return getPartitionMap(vertexId).containsKey(vertexId);

   }

   @Override

   public boolean hasMessagesForPartition(int partitionId) {

     Basic2ObjectMap<I, M> partitionMessages = map.get(partitionId);

     return partitionMessages != null && partitionMessages.size() != 0;

   }

   @Override

   public Iterable<M> getVertexMessages(I vertexId) {

     Basic2ObjectMap<I, M> partitionMap = getPartitionMap(vertexId);

     if (!partitionMap.containsKey(vertexId)) {

       return EmptyIterable.get();

     } else {

       return Collections.singleton(partitionMap.get(vertexId));

     }

   }

   @Override

   public void clearVertexMessages(I vertexId) {

     getPartitionMap(vertexId).remove(vertexId);

   }

   @Override

   public void clearAll() {

     map.clear();

   }

   @Override

   public Iterable<I> getPartitionDestinationVertices(

       int partitionId) {

     Basic2ObjectMap<I, M> partitionMap = map.get(partitionId);

     List<I> vertices =

         Lists.newArrayListWithCapacity(partitionMap.size());

     Iterator<I> iterator = partitionMap.fastKeyIterator();

     while (iterator.hasNext()) {

       vertices.add(idTypeOps.createCopy(iterator.next()));

     }

     return vertices;

   }

   @Override

   public void writePartition(DataOutput out,

       int partitionId) throws IOException {

     Basic2ObjectMap<I, M> partitionMap = map.get(partitionId);

     partitionMap.write(out);

   }

   @Override

   public void readFieldsForPartition(DataInput in,

       int partitionId) throws IOException {

     Basic2ObjectMap<I, M> partitionMap = idTypeOps.create2ObjectOpenHashMap(

         messageWriter);

     partitionMap.readFields(in);

     synchronized (map) {

       map.put(partitionId, partitionMap);

     }

   }

   @Override

   public void finalizeStore() {

   }

   @Override

   public boolean isPointerListEncoding() {

     return false;

   }

 }