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WorkerObserver 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  
19  package org.apache.giraph.worker;
20  
21  import org.apache.giraph.conf.ImmutableClassesGiraphConfigurable;
22  
23  /**
24   * Observer for worker. The user can subclass and register an observer with the
25   * Giraph framework. The framework will execute methods of the observer at
26   * designated moments of computation on each worker.
27   * It can implement ContextSettable if it needs to access job counters.
28   */
29  public interface WorkerObserver extends ImmutableClassesGiraphConfigurable {
30    /**
31     * Initialize the observer. This method is executed once on each worker before
32     * loading.
33     */
34    void preLoad();
35  
36    /**
37     * Initialize the observer. This method is executed once on each worker after
38     * loading before the first superstep starts.
39     */
40    void preApplication();
41  
42    /**
43     * Execute the observer. This method is executed once on each worker before
44     * each superstep starts.
45     *
46     * @param superstep number of superstep
47     */
48    void preSuperstep(long superstep);
49  
50    /**
51     * Execute the observer. This method is executed once on each worker after
52     * each superstep ends.
53     *
54     * @param superstep number of superstep
55     */
56    void postSuperstep(long superstep);
57  
58    /**
59     * Finalize the observer. This method is executed once on each worker after
60     * the last superstep ends before saving.
61     */
62    void postApplication();
63  
64    /**
65     * Finalize the observer. This method is executed once on each worker after
66     * saving.
67     */
68    void postSave();
69  }