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.logging.log4j.core.util; 018 019import java.util.List; 020 021import org.apache.logging.log4j.core.config.Configuration; 022import org.apache.logging.log4j.core.config.ConfigurationListener; 023import org.apache.logging.log4j.core.config.Reconfigurable; 024 025/** 026 * Watches for changes in a Source and performs an action when it is modified. 027 * 028 * @see WatchManager 029 */ 030public interface Watcher { 031 032 String CATEGORY = "Watcher"; 033 String ELEMENT_TYPE = "watcher"; 034 035 /** 036 * Returns the list of listeners for this configuration. 037 * @return The list of listeners. 038 */ 039 List<ConfigurationListener> getListeners(); 040 041 /** 042 * Called when the configuration has been modified. 043 * @param source The location of the configuration that was modified. 044 */ 045 void modified(); 046 047 /** 048 * Periodically called to determine if the configuration has been modified. 049 * @return true if the configuration was modified, false otherwise. 050 */ 051 boolean isModified(); 052 053 /** 054 * Returns the time the source was last modified or 0 if it is not available. 055 * @return the time the soruce was last modified. 056 */ 057 long getLastModified(); 058 059 /** 060 * Called when the Watcher is registered. 061 * @param source the Source that is being watched. 062 */ 063 void watching(Source source); 064 065 /** 066 * Returns the Source being monitored. 067 * @return the Source. 068 */ 069 Source getSource(); 070 071 /** 072 * Creates a new Watcher by copying the original and using the new Reconfigurable and listeners. 073 * @param reconfigurable The Reconfigurable. 074 * @param listeners the listeners. 075 * @param lastModifiedMillis The time the resource was last modified in milliseconds. 076 * @return A new Watcher. 077 */ 078 Watcher newWatcher(Reconfigurable reconfigurable, List<ConfigurationListener> listeners, long lastModifiedMillis); 079}