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PieceWithWorkerContext xref
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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.giraph.block_app.framework.piece;
19  
20  import org.apache.giraph.block_app.framework.api.BlockWorkerApi;
21  import org.apache.giraph.block_app.framework.api.BlockWorkerValueAccessor;
22  import org.apache.hadoop.io.Writable;
23  import org.apache.hadoop.io.WritableComparable;
24  
25  /**
26   * Piece that should be extended when WorkerContext is used.
27   *
28   * @param <I> Vertex id type
29   * @param <V> Vertex value type
30   * @param <E> Edge value type
31   * @param <M> Message type
32   * @param <WV> Worker value type
33   * @param <WM> Worker message type
34   * @param <S> Execution stage type
35   */
36  @SuppressWarnings("rawtypes")
37  public class PieceWithWorkerContext<I extends WritableComparable,
38      V extends Writable, E extends Writable, M extends Writable, WV,
39      WM extends Writable, S>
40      extends DefaultParentPiece<I, V, E, M, WV, WM, S> {
41  
42    /**
43     * Get global worker value.
44     * Value returned can be accessed from may threads, and so all
45     * accesses to it should be done in a thread-safe manner!
46     *
47     * This is the only place in Blocks Framework where you need
48     * to take care of concurrency.
49     */
50    @SuppressWarnings("unchecked")
51    public WV getWorkerValue(BlockWorkerApi<I> workerApi) {
52      return (WV) ((BlockWorkerValueAccessor) workerApi).getWorkerValue();
53    }
54  }