/*

  * 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.ooc.command;

 import com.google.common.base.Preconditions;

 import org.apache.giraph.bsp.BspService;

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

 import org.apache.giraph.ooc.OutOfCoreEngine;

 import org.apache.giraph.ooc.data.DiskBackedEdgeStore;

 import org.apache.giraph.ooc.data.DiskBackedMessageStore;

 import org.apache.giraph.ooc.data.DiskBackedPartitionStore;

 import java.io.IOException;

 /**

  * IOCommand to load partition data, edge data (if in INPUT_SUPERSTEP), and

  * message data (if in compute supersteps). Also, this command can be used to

  * prefetch a partition to be processed in the next superstep.

  */

 public class LoadPartitionIOCommand extends IOCommand {

   /**

    * Which superstep this partition should be loaded for? (can be current

    * superstep or next superstep -- in case of prefetching).

    */

   private final long superstep;

   /**

    * Constructor

    *

    * @param oocEngine out-of-core engine

    * @param partitionId id of the partition to be loaded

    * @param superstep superstep to load the partition for

    */

   public LoadPartitionIOCommand(OutOfCoreEngine oocEngine, int partitionId,

                                 long superstep) {

     super(oocEngine, partitionId);

     this.superstep = superstep;

   }

   @Override

   public boolean execute() throws IOException {

     boolean executed = false;

     if (oocEngine.getMetaPartitionManager()

         .startLoadingPartition(partitionId, superstep)) {

       long currentSuperstep = oocEngine.getSuperstep();

       DiskBackedPartitionStore partitionStore =

           (DiskBackedPartitionStore)

               oocEngine.getServerData().getPartitionStore();

       numBytesTransferred +=

           partitionStore.loadPartitionData(partitionId);

       if (currentSuperstep == BspService.INPUT_SUPERSTEP &&

           superstep == currentSuperstep) {

         DiskBackedEdgeStore edgeStore =

             (DiskBackedEdgeStore) oocEngine.getServerData().getEdgeStore();

         numBytesTransferred +=

             edgeStore.loadPartitionData(partitionId);

       }

       MessageStore messageStore;

       if (currentSuperstep == superstep) {

         messageStore = oocEngine.getServerData().getCurrentMessageStore();

       } else {

         Preconditions.checkState(superstep == currentSuperstep + 1);

         messageStore = oocEngine.getServerData().getIncomingMessageStore();

       }

       if (messageStore != null) {

         numBytesTransferred += ((DiskBackedMessageStore) messageStore)

             .loadPartitionData(partitionId);

       }

       oocEngine.getMetaPartitionManager()

           .doneLoadingPartition(partitionId, superstep);

       executed = true;

     }

     return executed;

   }

   @Override

   public IOCommandType getType() {

     return IOCommandType.LOAD_PARTITION;

   }

   @Override

   public String toString() {

     return "LoadPartitionIOCommand: (partitionId = " + partitionId + ", " +

         "superstep = " + superstep + ")";

   }

 }