AIMLWatcher.java

/*
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 2 of the License, or (at your option) any later
 * version. You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

package org.aitools.programd.util;

import java.io.IOException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.Timer;
import java.util.TimerTask;

import org.aitools.programd.Core;
import org.aitools.util.resource.URLTools;
import org.apache.log4j.Logger;

/**
 * Watches a set of AIML files. Any file changes will be loaded automatically.
 * 
 * @author Jon Baer
 * @author <a href="mailto:noel@aitools.org">Noel Bush</a>
 */
public class AIMLWatcher {

  /**
   * A {@link java.util.TimerTask TimerTask} for checking changed AIML files.
   */
  private class CheckAIMLTask extends TimerTask {

    /**
     * Creates a new CheckAIMLTask.
     */
    public CheckAIMLTask() {
      super();
    }

    /**
     * @see java.util.TimerTask#run()
     */
    @SuppressWarnings("boxing")
    @Override
    public void run() {
      synchronized (AIMLWatcher.this) {
        for (URL path : AIMLWatcher.this.watchMap.keySet()) {
          long previousTime = AIMLWatcher.this.watchMap.get(path);
          if (previousTime != 0) {
            long lastModified = URLTools.getLastModified(path);
            if (lastModified > previousTime) {
              AIMLWatcher.this.watchMap.put(path, lastModified);
              AIMLWatcher.this.reload(path);
            }
          }
        }
      }
    }
  }

  /** The Timer that handles watching AIML files. */
  private Timer timer;

  private Core _core;

  /** Used for storing information about file changes. */
  protected Map<URL, Long> watchMap = new HashMap<URL, Long>();

  protected Logger logger = Logger.getLogger("programd");

  /**
   * Creates a new AIMLWatcher using the given Graphmaster
   * 
   * @param core the Core to use
   */
  public AIMLWatcher(Core core) {
    this._core = core;
    this.logger = this._core.getLogger();
  }

  /**
   * Adds a file to the watchlist.
   * 
   * @param path the path to the file
   */
  @SuppressWarnings("boxing")
  public void addWatchFile(URL path) {
    /*
     * if (this.logger.isDebugEnabled()) { this.logger.debug(String.format("Adding watch file \"%s\".", path)); }
     */
    synchronized (this) {
      if (URLTools.seemsToExist(path)) {
        if (this.watchMap.containsKey(path)) {
          this.watchMap.put(path, URLTools.getLastModified(path));
        }
      }
      else {
        this.logger.warn(String.format("AIMLWatcher cannot read path \"%s\"", URLTools.unescape(path)),
            new IOException());
      }
    }
  }

  /**
   * Reloads AIML from a given path.
   * 
   * @param path the path to reload
   */
  protected void reload(URL path) {
    this.logger.info(String.format("AIMLWatcher reloading \"%s\".", URLTools.unescape(path)));
    this._core.reload(path);
  }

  /**
   * Starts the AIMLWatcher.
   */
  public void start() {
    this.timer = new Timer(true);
    this.timer.schedule(new CheckAIMLTask(), 0, this._core.getSettings().getAIMLWatcherTimer());
  }

  /**
   * Stops the AIMLWatcher.
   */
  public void stop() {
    if (this.timer != null) {
      this.timer.cancel();
    }
  }
}