org.apache.logging.log4j.core.config.FileConfigurationMonitor Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache license, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the license for the specific language governing permissions and
* limitations under the license.
*/
package org.apache.logging.log4j.core.config;
import java.io.File;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* Configuration monitor that periodically checks the timestamp of the configuration file and calls the
* ConfigurationListeners when an update occurs.
*/
public class FileConfigurationMonitor implements ConfigurationMonitor {
private static final int MASK = 0x0f;
private static final int MIN_INTERVAL = 5;
private static final int MILLIS_PER_SECOND = 1000;
private final File file;
private long lastModified;
private final List listeners;
private final int intervalSeconds;
private long nextCheck;
private final AtomicInteger counter = new AtomicInteger(0);
private static final Lock LOCK = new ReentrantLock();
private final Reconfigurable reconfigurable;
/**
* Constructor.
* @param reconfigurable The Configuration that can be reconfigured.
* @param file The File to monitor.
* @param listeners The List of ConfigurationListeners to notify upon a change.
* @param intervalSeconds The monitor interval in seconds. The minimum interval is 5 seconds.
*/
public FileConfigurationMonitor(final Reconfigurable reconfigurable, final File file,
final List listeners,
final int intervalSeconds) {
this.reconfigurable = reconfigurable;
this.file = file;
this.lastModified = file.lastModified();
this.listeners = listeners;
this.intervalSeconds = (intervalSeconds < MIN_INTERVAL ? MIN_INTERVAL : intervalSeconds) * MILLIS_PER_SECOND;
this.nextCheck = System.currentTimeMillis() + intervalSeconds;
}
/**
* Called to determine if the configuration has changed.
*/
@Override
public void checkConfiguration() {
final long current = System.currentTimeMillis();
if (((counter.incrementAndGet() & MASK) == 0) && (current >= nextCheck)) {
LOCK.lock();
try {
nextCheck = current + intervalSeconds;
if (file.lastModified() > lastModified) {
lastModified = file.lastModified();
for (final ConfigurationListener listener : listeners) {
final Thread thread = new Thread(new ReconfigurationWorker(listener, reconfigurable));
thread.setDaemon(true);
thread.start();
}
}
} finally {
LOCK.unlock();
}
}
}
private class ReconfigurationWorker implements Runnable {
private final ConfigurationListener listener;
private final Reconfigurable reconfigurable;
public ReconfigurationWorker(final ConfigurationListener listener, final Reconfigurable reconfigurable) {
this.listener = listener;
this.reconfigurable = reconfigurable;
}
@Override
public void run() {
listener.onChange(reconfigurable);
}
}
}