FileCleaner.java
/*
* 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
*
* https://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.commons.io;
import java.io.File;
/**
* Keeps track of files awaiting deletion, and deletes them when an associated marker object is reclaimed by the garbage collector.
* <p>
* This utility creates a background thread to handle file deletion. Each file to be deleted is registered with a handler object. When the handler object is
* garbage collected, the file is deleted.
* </p>
* <p>
* In an environment with multiple class loaders (a servlet container, for example), you should consider stopping the background thread if it is no longer
* needed. This is done by invoking the method {@link #exitWhenFinished}, typically in
* {@code javax.servlet.ServletContextListener.contextDestroyed(javax.servlet.ServletContextEvent)} or similar.
* </p>
*
* @deprecated Use {@link FileCleaningTracker}.
*/
@Deprecated
public class FileCleaner {
/**
* The instance to use for the deprecated, static methods.
*/
private static final FileCleaningTracker INSTANCE = new FileCleaningTracker();
private static final Object LOCK = new Object();
/**
* Call this method to cause the file cleaner thread to terminate when there are no more objects being tracked for deletion.
* <p>
* In a simple environment, you don't need this method as the file cleaner thread will simply exit when the JVM exits. In a more complex environment, with
* multiple class loaders (such as an application server), you should be aware that the file cleaner thread will continue running even if the class loader
* it was started from terminates. This can constitute a memory leak.
* </p>
* <p>
* For example, suppose that you have developed a web application, which contains the Commons IO jar file in your WEB-INF/lib directory. In other words, the
* FileCleaner class is loaded through the class loader of your web application. If the web application is terminated, but the servlet container is still
* running, then the file cleaner thread will still exist, posing a memory leak.
* </p>
* <p>
* This method allows the thread to be terminated. Simply call this method in the resource cleanup code, such as
* {@code javax.servlet.ServletContextListener.contextDestroyed(javax.servlet.ServletContextEvent)}. One called, no new objects can be tracked by the file
* cleaner.
* </p>
*
* @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}.
*/
@Deprecated
public static void exitWhenFinished() {
synchronized (LOCK) {
INSTANCE.exitWhenFinished();
}
}
/**
* Gets the singleton instance, which is used by the deprecated, static methods. This is mainly useful for code, which wants to support the new
* {@link FileCleaningTracker} class while maintain compatibility with the deprecated {@link FileCleaner}.
*
* @return The singleton instance.
*/
public static FileCleaningTracker getInstance() {
return INSTANCE;
}
/**
* Gets the number of files currently being tracked, and therefore awaiting deletion.
*
* @return The number of files being tracked.
* @deprecated Use {@link FileCleaningTracker#getTrackCount()}.
*/
@Deprecated
public static int getTrackCount() {
return INSTANCE.getTrackCount();
}
/**
* Track the specified file, using the provided marker, deleting the file when the marker instance is garbage collected. The
* {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
*
* @param file The file to be tracked, not null.
* @param marker The marker object used to track the file, not null.
* @throws NullPointerException if the file is null.
* @deprecated Use {@link FileCleaningTracker#track(File, Object)}.
*/
@Deprecated
public static void track(final File file, final Object marker) {
INSTANCE.track(file, marker);
}
/**
* Track the specified file, using the provided marker, deleting the file when the marker instance is garbage collected. The specified deletion strategy is
* used.
*
* @param file The file to be tracked, not null.
* @param marker The marker object used to track the file, not null.
* @param deleteStrategy The strategy to delete the file, null means normal.
* @throws NullPointerException if the file is null.
* @deprecated Use {@link FileCleaningTracker#track(File, Object, FileDeleteStrategy)}.
*/
@Deprecated
public static void track(final File file, final Object marker, final FileDeleteStrategy deleteStrategy) {
INSTANCE.track(file, marker, deleteStrategy);
}
/**
* Track the specified file, using the provided marker, deleting the file when the marker instance is garbage collected. The
* {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used.
*
* @param path The full path to the file to be tracked, not null.
* @param marker The marker object used to track the file, not null.
* @throws NullPointerException if the path is null.
* @deprecated Use {@link FileCleaningTracker#track(String, Object)}.
*/
@Deprecated
public static void track(final String path, final Object marker) {
INSTANCE.track(path, marker);
}
/**
* Track the specified file, using the provided marker, deleting the file when the marker instance is garbage collected. The specified deletion strategy is
* used.
*
* @param path The full path to the file to be tracked, not null.
* @param marker The marker object used to track the file, not null.
* @param deleteStrategy The strategy to delete the file, null means normal.
* @throws NullPointerException if the path is null.
* @deprecated Use {@link FileCleaningTracker#track(String, Object, FileDeleteStrategy)}.
*/
@Deprecated
public static void track(final String path, final Object marker, final FileDeleteStrategy deleteStrategy) {
INSTANCE.track(path, marker, deleteStrategy);
}
/**
* Construct a new instance.
*/
public FileCleaner() {
// empty
}
}