CoreShutdownHook.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;

/**
 * Runs the shutdown method of a Core when it is started. This is intended to be attached via
 * {@link java.lang.Runtime#addShutdownHook Runtime.addShutdownHook()} for any configuration where it is possible that
 * the entire system may exit. Of course this doesn't apply to many cases (such as if the Core is a component in an
 * application server), so this may not always be used. When this class's {@link #run} method is called, it first checks
 * that the {@link Core} has not been shut down already.
 * 
 * @author <a href="mailto:noel@aitools.org">Noel Bush</a>
 */
public class CoreShutdownHook extends Thread {

  private Core _core;

  /**
   * Creates a new <code>CoreShutdownHook</code> to manage the shutdown of the given Core
   * 
   * @param core the Core whose shutdown method should be run when this thread is run
   */
  public CoreShutdownHook(Core core) {
    super("Core Shutdown Thread");
    this._core = core;
  }

  /**
   * Shuts down the Core assigned to this thread.
   * 
   * @see Thread#run
   */
  @Override
  public void run() {
    // The Core may already have been shut down -- don't do it again.
    if (this._core.getStatus() != Core.Status.SHUT_DOWN) {
      this._core.shutdown();
    }
  }
}