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The Apache Log4j Implementation
/*
* 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.util;
import java.io.File;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.AbstractLifeCycle;
import org.apache.logging.log4j.core.config.ConfigurationScheduler;
import org.apache.logging.log4j.status.StatusLogger;
/**
* Manages {@link FileWatcher}s.
*
* @see FileWatcher
* @see ConfigurationScheduler
*/
public class WatchManager extends AbstractLifeCycle {
private static Logger logger = StatusLogger.getLogger();
private final ConcurrentMap watchers = new ConcurrentHashMap<>();
private int intervalSeconds = 0;
private ScheduledFuture future;
private final ConfigurationScheduler scheduler;
public WatchManager(final ConfigurationScheduler scheduler) {
this.scheduler = scheduler;
}
/**
* Resets all file monitors to their current last modified time. If this manager does not watch any file, nothing
* happens.
*
* This allows you to start, stop, reset and start again a manager, without triggering file modified events if the a
* watched file has changed during the period of time when the manager was stopped.
*
*
* @since 2.11.0
*/
public void reset() {
logger.debug("Resetting {}", this);
for (final File file : watchers.keySet()) {
reset(file);
}
}
/**
* Resets the file monitor for the given file being watched to its current last modified time. If this manager does
* not watch the given file, nothing happens.
*
* This allows you to start, stop, reset and start again a manager, without triggering file modified events if the
* given watched file has changed during the period of time when the manager was stopped.
*
*
* @param file
* the file for the monitor to reset.
* @since 2.11.0
*/
public void reset(final File file) {
if (file == null) {
return;
}
final FileMonitor fileMonitor = watchers.get(file);
if (fileMonitor != null) {
final long lastModifiedMillis = file.lastModified();
if (lastModifiedMillis != fileMonitor.lastModifiedMillis) {
if (logger.isDebugEnabled()) {
logger.debug("Resetting file monitor for '{}' from {} ({}) to {} ({})", file,
millisToString(fileMonitor.lastModifiedMillis), fileMonitor.lastModifiedMillis,
millisToString(lastModifiedMillis), lastModifiedMillis);
}
fileMonitor.setLastModifiedMillis(lastModifiedMillis);
}
}
}
public void setIntervalSeconds(final int intervalSeconds) {
if (!isStarted()) {
if (this.intervalSeconds > 0 && intervalSeconds == 0) {
scheduler.decrementScheduledItems();
} else if (this.intervalSeconds == 0 && intervalSeconds > 0) {
scheduler.incrementScheduledItems();
}
this.intervalSeconds = intervalSeconds;
}
}
/**
* Gets how often this manager checks for file modifications.
*
* @return how often, in seconds, this manager checks for file modifications.
*/
public int getIntervalSeconds() {
return this.intervalSeconds;
}
@Override
public void start() {
super.start();
if (intervalSeconds > 0) {
future = scheduler.scheduleWithFixedDelay(new WatchRunnable(), intervalSeconds, intervalSeconds,
TimeUnit.SECONDS);
}
}
@Override
public boolean stop(final long timeout, final TimeUnit timeUnit) {
setStopping();
final boolean stopped = stop(future);
setStopped();
return stopped;
}
/**
* Unwatches the given file.
*
* @param file
* the file to stop watching.
* @since 2.11.0
*/
public void unwatchFile(final File file) {
logger.debug("Unwatching file '{}'", file);
watchers.remove(file);
}
/**
* Watches the given file.
*
* @param file
* the file to watch.
* @param watcher
* the watcher to notify of file changes.
*/
public void watchFile(final File file, final FileWatcher watcher) {
final long lastModified = file.lastModified();
if (logger.isDebugEnabled()) {
logger.debug("Watching file '{}' for lastModified {} ({})", file, millisToString(lastModified), lastModified);
}
watchers.put(file, new FileMonitor(lastModified, watcher));
}
public Map getWatchers() {
final Map map = new HashMap<>(watchers.size());
for (final Map.Entry entry : watchers.entrySet()) {
map.put(entry.getKey(), entry.getValue().fileWatcher);
}
return map;
}
private String millisToString(final long millis) {
return new Date(millis).toString();
}
private final class WatchRunnable implements Runnable {
// Use a hard class reference here in case a refactoring changes the class name.
private final String SIMPLE_NAME = WatchRunnable.class.getSimpleName();
@Override
public void run() {
logger.trace("{} run triggered.", SIMPLE_NAME);
for (final Map.Entry entry : watchers.entrySet()) {
final File file = entry.getKey();
final FileMonitor fileMonitor = entry.getValue();
final long lastModfied = file.lastModified();
if (fileModified(fileMonitor, lastModfied)) {
if (logger.isInfoEnabled()) {
logger.info("File '{}' was modified on {} ({}), previous modification was on {} ({})", file,
millisToString(lastModfied), lastModfied, millisToString(fileMonitor.lastModifiedMillis),
fileMonitor.lastModifiedMillis);
}
fileMonitor.lastModifiedMillis = lastModfied;
fileMonitor.fileWatcher.fileModified(file);
}
}
logger.trace("{} run ended.", SIMPLE_NAME);
}
private boolean fileModified(final FileMonitor fileMonitor, final long lastModifiedMillis) {
return lastModifiedMillis != fileMonitor.lastModifiedMillis;
}
}
private final class FileMonitor {
private final FileWatcher fileWatcher;
private volatile long lastModifiedMillis;
public FileMonitor(final long lastModifiedMillis, final FileWatcher fileWatcher) {
this.fileWatcher = fileWatcher;
this.lastModifiedMillis = lastModifiedMillis;
}
private void setLastModifiedMillis(final long lastModifiedMillis) {
this.lastModifiedMillis = lastModifiedMillis;
}
@Override
public String toString() {
return "FileMonitor [fileWatcher=" + fileWatcher + ", lastModifiedMillis=" + lastModifiedMillis + "]";
}
}
@Override
public String toString() {
return "WatchManager [intervalSeconds=" + intervalSeconds + ", watchers=" + watchers + ", scheduler="
+ scheduler + ", future=" + future + "]";
}
}