/*

  * 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;

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

 import java.io.DataInput;

 import java.io.DataOutput;

 import java.io.IOException;

 import java.util.concurrent.ConcurrentMap;

 import org.apache.giraph.conf.ImmutableClassesGiraphConfiguration;

 import org.apache.giraph.factories.MessageValueFactory;

 import org.apache.giraph.utils.ExtendedByteArrayOutputBuffer;

 import org.apache.giraph.utils.ExtendedByteArrayOutputBuffer.IndexAndDataOut;

 import org.apache.giraph.utils.ExtendedDataOutput;

 import org.apache.giraph.utils.VertexIdMessageIterator;

 import org.apache.giraph.utils.VertexIdMessages;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 /**

  * Implementation of {@link SimpleMessageStore} where multiple messages are

  * stored as a list of long pointers to extended data output objects

  * Used when there is no combiner provided.

  *

  * @param <I> vertexId type

  * @param <M> message type

  */

 public class PointerListPerVertexStore<I extends WritableComparable,

   M extends Writable> extends AbstractListPerVertexStore<I, M, LongArrayList> {

   /** Buffers of byte array outputs used to store messages - thread safe */

   private final ExtendedByteArrayOutputBuffer bytesBuffer;

   /**

    * Constructor

    *

    * @param messageValueFactory Message class held in the store

    * @param partitionInfo Partition split info

    * @param config Hadoop configuration

    */

   public PointerListPerVertexStore(

     MessageValueFactory<M> messageValueFactory,

     PartitionSplitInfo<I> partitionInfo,

     ImmutableClassesGiraphConfiguration<I, ?, ?> config

   ) {

     super(messageValueFactory, partitionInfo, config);

     bytesBuffer = new ExtendedByteArrayOutputBuffer(config);

   }

   @Override

   public boolean isPointerListEncoding() {

     return true;

   }

   @Override

   protected LongArrayList createList() {

     return new LongArrayList();

   }

   @Override

   public void addPartitionMessages(

     int partitionId, VertexIdMessages<I, M> messages) {

     try {

       VertexIdMessageIterator<I, M> vertexIdMessageIterator =

           messages.getVertexIdMessageIterator();

       long pointer = 0;

       LongArrayList list;

       while (vertexIdMessageIterator.hasNext()) {

         vertexIdMessageIterator.next();

         M msg = vertexIdMessageIterator.getCurrentMessage();

         list = getOrCreateList(vertexIdMessageIterator);

         if (vertexIdMessageIterator.isNewMessage()) {

           IndexAndDataOut indexAndDataOut = bytesBuffer.getIndexAndDataOut();

           pointer = indexAndDataOut.getIndex();

           pointer <<= 32;

           ExtendedDataOutput dataOutput = indexAndDataOut.getDataOutput();

           pointer += dataOutput.getPos();

           msg.write(dataOutput);

         }

         synchronized (list) {

           list.add(pointer);

         }

       }

     } catch (IOException e) {

       throw new RuntimeException("addPartitionMessages: IOException while" +

           " adding messages for a partition: " + e);

     }

   }

   @Override

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

     LongArrayList list = getOrCreateList(vertexId);

     IndexAndDataOut indexAndDataOut = bytesBuffer.getIndexAndDataOut();

     long pointer = indexAndDataOut.getIndex();

     pointer <<= 32;

     ExtendedDataOutput dataOutput = indexAndDataOut.getDataOutput();

     pointer += dataOutput.getPos();

     message.write(dataOutput);

     synchronized (list) {

       list.add(pointer);

     }

   }

   /**

    * Get messages as an iterable from message storage

    *

    * @param pointers list of pointers to messages

    * @return Messages as an iterable

    */

   @Override

   public Iterable<M> getMessagesAsIterable(LongArrayList pointers) {

     return new PointerListMessagesIterable<>(messageValueFactory, pointers,

       bytesBuffer);

   }

   @Override

   protected int getNumberOfMessagesIn(ConcurrentMap<I,

     LongArrayList> partitionMap) {

     int numberOfMessages = 0;

     for (LongArrayList list : partitionMap.values()) {

       numberOfMessages += list.size();

     }

     return numberOfMessages;

   }

   // FIXME -- complete these for check-pointing

   @Override

   protected void writeMessages(LongArrayList messages, DataOutput out)

     throws IOException {

   }

   @Override

   protected LongArrayList readFieldsForMessages(DataInput in)

     throws IOException {

     return null;

   }

 }