001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.configuration2.reloading; 018 019/** 020 * <p> 021 * An interface to be implemented by objects which can detect whether a reload 022 * operation is required. 023 * </p> 024 * <p> 025 * This interface is used by a {@link ReloadingController} object. When a 026 * reloading check is to be performed, it is delegated to a concrete 027 * implementation. The implementation decides whether (specific) criteria for a 028 * reload are fulfilled, so that the controller can react accordingly. 029 * </p> 030 * <p> 031 * This interface does not define how a check for a reload is performed. This is 032 * completely up to a concrete implementation. There is just one method for 033 * executing the check and one method to notify the {@code ReloadingDetector} 034 * that the reload actually happened; this method can be used to reset the 035 * internal state so that the conditions for the next reload can be detected. 036 * </p> 037 * <p> 038 * When used together with {@code ReloadingController} an implementation does 039 * not have to be thread-safe. The controller takes care for synchronization so 040 * that an instance is accessed by a single thread only. 041 * </p> 042 * 043 * @since 2.0 044 */ 045public interface ReloadingDetector 046{ 047 /** 048 * Checks whether all criteria for a reload operation are fulfilled. This 049 * method is called by external components to find out when reloading should 050 * take place. 051 * 052 * @return <b>true</b> if a reload operation should be performed, 053 * <b>false</b> otherwise 054 */ 055 boolean isReloadingRequired(); 056 057 /** 058 * Notifies this object that a reload operation has been performed. This 059 * method is called after {@code reloadingRequired()} has returned 060 * <b>true</b>. It can be used to reset internal state in order to detect 061 * the next reload operation. 062 */ 063 void reloadingPerformed(); 064}