1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache license, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the license for the specific language governing permissions and 15 * limitations under the license. 16 */ 17 package org.apache.logging.log4j.core.util; 18 19 import java.util.List; 20 21 import org.apache.logging.log4j.core.config.Configuration; 22 import org.apache.logging.log4j.core.config.ConfigurationListener; 23 import org.apache.logging.log4j.core.config.Reconfigurable; 24 25 /** 26 * Watches for changes in a Source and performs an action when it is modified. 27 * 28 * @see WatchManager 29 */ 30 public interface Watcher { 31 32 String CATEGORY = "Watcher"; 33 String ELEMENT_TYPE = "watcher"; 34 35 /** 36 * Returns the list of listeners for this configuration. 37 * @return The list of listeners. 38 */ 39 List<ConfigurationListener> getListeners(); 40 41 /** 42 * Called when the configuration has been modified. 43 * @param source The location of the configuration that was modified. 44 */ 45 void modified(); 46 47 /** 48 * Periodically called to determine if the configuration has been modified. 49 * @return true if the configuration was modified, false otherwise. 50 */ 51 boolean isModified(); 52 53 /** 54 * Returns the time the source was last modified or 0 if it is not available. 55 * @return the time the soruce was last modified. 56 */ 57 long getLastModified(); 58 59 /** 60 * Called when the Watcher is registered. 61 * @param source the Source that is being watched. 62 */ 63 void watching(Source source); 64 65 /** 66 * Returns the Source being monitored. 67 * @return the Source. 68 */ 69 Source getSource(); 70 71 /** 72 * Creates a new Watcher by copying the original and using the new Reconfigurable and listeners. 73 * @param reconfigurable The Reconfigurable. 74 * @param listeners the listeners. 75 * @param lastModifiedMillis The time the resource was last modified in milliseconds. 76 * @return A new Watcher. 77 */ 78 Watcher newWatcher(Reconfigurable reconfigurable, List<ConfigurationListener> listeners, long lastModifiedMillis); 79 }