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 }