code: /*
   * 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.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>
   * 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
   * {@link javax.servlet.ServletContextListener#contextDestroyed} or similar.
   *
   * @author Noel Bergman
   * @author Martin Cooper
   * @version $Id: FileCleaner.java 723969 2008-12-06 11:00:40Z sebb $
   * @deprecated Use {@link FileCleaningTracker}
   */
  @Deprecated
  public class FileCleaner {
      /**
       * The instance to use for the deprecated, static methods.
       */
      static final FileCleaningTracker theInstance = new FileCleaningTracker();
  
      //-----------------------------------------------------------------------
      /**
       * 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(File file, Object marker) {
          theInstance.track(file, marker);
      }
  
      /**
       * Track the specified file, using the provided marker, deleting the file
       * when the marker instance is garbage collected.
       * The speified 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(File file, Object marker, FileDeleteStrategy deleteStrategy) {
          theInstance.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(String path, Object marker) {
          theInstance.track(path, marker);
      }
  
      /**
       * Track the specified file, using the provided marker, deleting the file
       * when the marker instance is garbage collected.
       * The speified 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(String path, Object marker, FileDeleteStrategy deleteStrategy) {
          theInstance.track(path, marker, deleteStrategy);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Retrieve 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 theInstance.getTrackCount();
      }
  
      /**
       * 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 consitute a memory leak.
       * <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>
       * This method allows the thread to be terminated. Simply call this method
       * in the resource cleanup code, such as {@link javax.servlet.ServletContextListener#contextDestroyed}.
       * One called, no new objects can be tracked by the file cleaner.
       * @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}.
       */
      @Deprecated
      public static synchronized void exitWhenFinished() {
          theInstance.exitWhenFinished();
      }
  
      /**
       * Returns 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 theInstance;
      }
  }
  