/*

  * 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.framework.piece;

 import org.apache.giraph.block_app.framework.api.BlockWorkerApi;

 import org.apache.giraph.block_app.framework.api.BlockWorkerValueAccessor;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 /**

  * Piece that should be extended when WorkerContext is used.

  *

  * @param <I> Vertex id type

  * @param <V> Vertex value type

  * @param <E> Edge value type

  * @param <M> Message type

  * @param <WV> Worker value type

  * @param <WM> Worker message type

  * @param <S> Execution stage type

  */

 @SuppressWarnings("rawtypes")

 public class PieceWithWorkerContext<I extends WritableComparable,

     V extends Writable, E extends Writable, M extends Writable, WV,

     WM extends Writable, S>

     extends DefaultParentPiece<I, V, E, M, WV, WM, S> {

   /**

    * Get global worker value.

    * Value returned can be accessed from may threads, and so all

    * accesses to it should be done in a thread-safe manner!

    *

    * This is the only place in Blocks Framework where you need

    * to take care of concurrency.

    */

   @SuppressWarnings("unchecked")

   public WV getWorkerValue(BlockWorkerApi<I> workerApi) {

     return (WV) ((BlockWorkerValueAccessor) workerApi).getWorkerValue();

   }

 }