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.config; 018 019import java.io.File; 020import java.util.List; 021import java.util.concurrent.atomic.AtomicInteger; 022import java.util.concurrent.locks.Lock; 023import java.util.concurrent.locks.ReentrantLock; 024 025/** 026 * Configuration monitor that periodically checks the timestamp of the configuration file and calls the 027 * ConfigurationListeners when an update occurs. 028 */ 029public class FileConfigurationMonitor implements ConfigurationMonitor { 030 031 private static final int MASK = 0x0f; 032 033 private static final int MIN_INTERVAL = 5; 034 035 private static final int MILLIS_PER_SECOND = 1000; 036 037 private final File file; 038 039 private long lastModified; 040 041 private final List<ConfigurationListener> listeners; 042 043 private final int intervalSeconds; 044 045 private long nextCheck; 046 047 private final AtomicInteger counter = new AtomicInteger(0); 048 049 private static final Lock LOCK = new ReentrantLock(); 050 051 private final Reconfigurable reconfigurable; 052 053 /** 054 * Constructor. 055 * @param reconfigurable The Configuration that can be reconfigured. 056 * @param file The File to monitor. 057 * @param listeners The List of ConfigurationListeners to notify upon a change. 058 * @param intervalSeconds The monitor interval in seconds. The minimum interval is 5 seconds. 059 */ 060 public FileConfigurationMonitor(final Reconfigurable reconfigurable, final File file, 061 final List<ConfigurationListener> listeners, 062 final int intervalSeconds) { 063 this.reconfigurable = reconfigurable; 064 this.file = file; 065 this.lastModified = file.lastModified(); 066 this.listeners = listeners; 067 this.intervalSeconds = (intervalSeconds < MIN_INTERVAL ? MIN_INTERVAL : intervalSeconds) * MILLIS_PER_SECOND; 068 this.nextCheck = System.currentTimeMillis() + intervalSeconds; 069 } 070 071 /** 072 * Called to determine if the configuration has changed. 073 */ 074 @Override 075 public void checkConfiguration() { 076 final long current = System.currentTimeMillis(); 077 if (((counter.incrementAndGet() & MASK) == 0) && (current >= nextCheck)) { 078 LOCK.lock(); 079 try { 080 nextCheck = current + intervalSeconds; 081 if (file.lastModified() > lastModified) { 082 lastModified = file.lastModified(); 083 for (final ConfigurationListener listener : listeners) { 084 final Thread thread = new Thread(new ReconfigurationWorker(listener, reconfigurable)); 085 thread.setDaemon(true); 086 thread.start(); 087 } 088 } 089 } finally { 090 LOCK.unlock(); 091 } 092 } 093 } 094 095 private class ReconfigurationWorker implements Runnable { 096 097 private final ConfigurationListener listener; 098 private final Reconfigurable reconfigurable; 099 100 public ReconfigurationWorker(final ConfigurationListener listener, final Reconfigurable reconfigurable) { 101 this.listener = listener; 102 this.reconfigurable = reconfigurable; 103 } 104 105 @Override 106 public void run() { 107 listener.onChange(reconfigurable); 108 } 109 } 110}