/*

 *   SONEWS News Server

 *   see AUTHORS for the list of contributors

 *

 *   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 3 of the License, or

 *   (at your option) any later version.

 *

 *   This program is distributed in the hope that it will be useful,

 *   but WITHOUT ANY WARRANTY; without even the implied warranty of

 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *   GNU General Public License for more details.

 *

 *   You should have received a copy of the GNU General Public License

 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

package org.sonews.daemon;

import java.sql.SQLException;

import org.sonews.daemon.storage.Database;

import org.sonews.util.Log;

/**

 * Base class of all sonews threads.

 * Instances of this class will be automatically registered at the ShutdownHook

 * to be cleanly exited when the server is forced to exit.

 * @author Christian Lins

 * @since sonews/0.5.0

 */

public abstract class AbstractDaemon extends Thread

{

  /** This variable is write synchronized through setRunning */

  private boolean isRunning = false;

  /**

   * Protected constructor. Will be called by derived classes.

   */

  protected AbstractDaemon()

  {

    setDaemon(true); // VM will exit when all threads are daemons

    setName(getClass().getSimpleName());

  }

  /**

   * @return true if shutdown() was not yet called.

   */

  public boolean isRunning()

  {

    synchronized(this)

    {

      return this.isRunning;

    }

  }

  /**

   * Marks this thread to exit soon. Closes the associated Database connection

   * if available.

   * @throws java.sql.SQLException

   */

  void shutdownNow()

    throws SQLException

  {

    synchronized(this)

    {

      this.isRunning = false;

      Database db = Database.getInstance(false);

      if(db != null)

      {

        db.shutdown();

      }

    }

  }

  /**

   * Calls shutdownNow() but catches SQLExceptions if occurring.

   */

  public void shutdown()

  {

    try

    {

      shutdownNow();

    }

    catch(SQLException ex)

    {

      Log.msg(ex, true);

    }

  }

  /**

   * Starts this daemon.

   */

  @Override

  public void start()

  {

    synchronized(this)

    {

      this.isRunning = true;

    }

    super.start();

  }

}