/*

  * 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.block_app.migration;

 import java.util.Iterator;

 import org.apache.giraph.block_app.framework.AbstractBlockFactory;

 import org.apache.giraph.block_app.framework.block.Block;

 import org.apache.giraph.block_app.framework.block.PieceCount;

 import org.apache.giraph.block_app.framework.block.SequenceBlock;

 import org.apache.giraph.block_app.framework.piece.AbstractPiece;

 import org.apache.giraph.block_app.framework.piece.Piece;

 import org.apache.giraph.block_app.migration.MigrationAbstractComputation.MigrationFullAbstractComputation;

 import org.apache.giraph.block_app.migration.MigrationMasterCompute.MigrationFullMasterCompute;

 import org.apache.giraph.combiner.MessageCombiner;

 import org.apache.giraph.conf.GiraphConfiguration;

 import org.apache.giraph.function.Consumer;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import com.google.common.collect.AbstractIterator;

 import com.google.common.collect.Iterators;

 /**

  * BlockFactory to extend when using drop-in migration

  */

 public abstract class MigrationFullBlockFactory

     extends AbstractBlockFactory<MigrationSuperstepStage> {

   @Override

   public MigrationSuperstepStage createExecutionStage(

       GiraphConfiguration conf) {

     return new MigrationSuperstepStageImpl();

   }

   @Override

   protected Class<? extends MigrationWorkerContext> getWorkerContextValueClass(

       GiraphConfiguration conf) {

     return MigrationWorkerContext.class;

   }

   @SuppressWarnings("rawtypes")

   public <I extends WritableComparable, V extends Writable, E extends Writable,

   MR extends Writable, MS extends Writable>

   Block createMigrationAppBlock(

       Class<? extends MigrationFullAbstractComputation<I, V, E, MR, MS>>

         computationClass,

       MigrationFullMasterCompute masterCompute,

       Class<MS> messageClass,

       Class<? extends MessageCombiner<? super I, MS>> messageCombinerClass,

       GiraphConfiguration conf) {

     final MigrationPiece<I, V, E, MR, MS> piece =

         MigrationPiece.createFirstFullMigrationPiece(

             computationClass, masterCompute, messageClass,

             messageCombinerClass);

     piece.sanityTypeChecks(conf, null);

     return new SequenceBlock(

         new Piece<WritableComparable, Writable, Writable,

             Writable, MigrationSuperstepStage>() {

           @Override

           public MigrationSuperstepStage nextExecutionStage(

               MigrationSuperstepStage executionStage) {

             return executionStage.changedMigrationSuperstep(0);

           }

         },

         new Block() {

           private MigrationPiece curPiece = piece;

           @Override

           public Iterator<AbstractPiece> iterator() {

             return Iterators.concat(

                 Iterators.singletonIterator(curPiece),

                 new AbstractIterator<AbstractPiece>() {

                   @Override

                   protected AbstractPiece computeNext() {

                     curPiece = curPiece.getNextPiece();

                     if (curPiece == null) {

                       endOfData();

                     }

                     return curPiece;

                   }

                 });

           }

           @Override

           public void forAllPossiblePieces(Consumer<AbstractPiece> consumer) {

             consumer.apply(curPiece);

           }

           @Override

           public PieceCount getPieceCount() {

             return curPiece.getPieceCount();

           }

         }

     );

   }

 }