/*

 * Copyright (C) 2015 - EfficiOS Inc., Alexandre Montplaisir <alexmonthy@efficios.com>

 *

 * This library is free software; you can redistribute it and/or modify it

 * under the terms of the GNU Lesser General Public License, version 2.1 only,

 * as published by the Free Software Foundation.

 *

 * This library 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 Lesser General Public License

 * for more details.

 *

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

 * along with this library; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

package org.lttng.ust.agent.filter;

import org.lttng.ust.agent.session.EventRule;

/**

 * Filter notification listener interface.

 * 

 * Applications wanting to be notified of event filtering rule changes should

 * implement this interface, then register their listener using

 * {@link FilterChangeNotifier#registerListener}.

 * 

 * 

 * The callbacks defined in this interface will be called whenever an event rule

 * is added or removed. The manager will take care of the reference-counting in

 * case multiple tracing sessions enable the exact same rules. For example, the

 * {@link #eventRuleRemoved} callback is only called when there are no more

 * session interested into it.

 * 

 * 

 * Do not forget to unregister the listener after use, using

 * {@link FilterChangeNotifier#unregisterListener}. If you do not, or if

 * you use an anonymous listener for example, these will remain attached until

 * the complete shutdown of the application.

 * 

 * 

 * Only one thread is used to dispatch notifications, sequentially. This means

 * that if a callback hangs it will prevent other listeners from receiving

 * notifications. Please take care of not blocking inside the listener

 * callbacks, and use separate threads for potentially long or blocking

 * operations.

 * 

 *

 * @author Alexandre Montplaisir

 */

public interface IFilterChangeListener {

	/**

	 * Notification that a new event rule is now enabled in the tracing

	 * sessions.

	 *

	 * @param rule

	 *            The event rule that was enabled

	 */

	void eventRuleAdded(EventRule rule);

	/**

	 * Notification that an existing event rule is now disabled in the tracing

	 * sessions.

	 *

	 * @param rule

	 *            The event rule that was disabled

	 */

	void eventRuleRemoved(EventRule rule);

}