This project has retired. For details please refer to its Attic page.
ObjectHolder xref
View Javadoc

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.function;
19  
20  /**
21   * Default object holder, intermediary between producers and consumers.
22   *
23   * Holds value in memory, so can be used only when producer and consumer
24   * are in the same context.
25   *
26   * Useful when value is set on the master, and later read in block logic
27   * (RepeatUntilBlock), or in a different Piece, either on worker or master.
28   * If it is read within the same piece - just use local field.
29   *
30   * @param <T> Type of object to hold.
31   */
32  public class ObjectHolder<T> implements Supplier<T>, Consumer<T> {
33    /** value */
34    private T value;
35  
36    /**
37     * Constructor
38     * @param value initial value
39     */
40    public ObjectHolder(T value) {
41      this.value = value;
42    }
43  
44    /** Constructor */
45    public ObjectHolder() {
46    }
47  
48    @Override
49    public T get() {
50      return value;
51    }
52  
53    @Override
54    public void apply(T value) {
55      this.value = value;
56    }
57  
58    @Override
59    public String toString() {
60      return getClass() + " [value=" + value + "]";
61    }
62  }