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AspectJ tools most notably contains the AspectJ compiler (AJC). AJC applies aspects to Java classes during compilation, fully replacing Javac for plain Java classes and also compiling native AspectJ or annotation-based @AspectJ syntax. Furthermore, AJC can weave aspects into existing class files in a post-compile binary weaving step. This library is a superset of AspectJ weaver and hence also of AspectJ runtime.

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/*******************************************************************************
 * Copyright (c) 2009, 2010 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.equinox.events;

/**
 * Defines constants for memory event handlers.  A memory event handler implements
 * the org.osgi.service.event.EventHandler interface as specified by the OSGi 
 * Event Admin Service Specification.
 * 
 * For example, the following handler is registered to handle critical memory
 * events:
 * 
 * BundleContext context = getContext();
 * EventHandler handler = getHandler();
 * Hashtable ht = new Hashtable();
 * ht.put(EventConstants.EVENT_TOPIC, MemoryEventConstants.TOPIC_CRITICAL);
 * context.registerService(EventHandler.class.getName(), handler, ht);
 * 
 * There is no policy implemented for sending memory events in Equinox or
 * Eclipse by default.  Another bundle must implement the policy that determines
 * when to send memory events.  This policy must use the Event Admin Service
 * to fire memory events to the registered handlers.
 * 
 * @since 3.6
 */
public final class MemoryEventConstants {
	private MemoryEventConstants() {
		// prevent construction.
	}

	/**
	 * The base topic that all memory events use.
	 */
	public static final String TOPIC_BASE = "org/eclipse/equinox/events/MemoryEvent/"; //$NON-NLS-1$

	/**
	 * A memory event topic for normal memory events.
	 * Indicates memory is running low at the lowest severity.
	 * Listeners are requested to release caches that can easily be recomputed.
	 * The Java VM is not seriously in trouble, but process size is getting higher than 
	 * is deemed acceptable.
	 */
	public static final String TOPIC_NORMAL = TOPIC_BASE + "NORMAL"; //$NON-NLS-1$

	/**
	 * A memory event topic for serious memory events.
	 * Indicates memory is running low at medium severity. 
	 * Listeners are requested to release complex intermediate models
	 * (.e.g. intermediate build results).
	 * Memory is getting low and may cause operating system level stress, such as swapping.
	 */
	public static final String TOPIC_SERIOUS = TOPIC_BASE + "SERIOUS"; //$NON-NLS-1$

	/**
	 * A memory event topic for critical memory events.
	 * Indicates memory is running low at highest severity.
	 * Listeners are requested to do what ever is possible to free memory.
	 * Things like free in memory caches, close editors and perspectives, 
	 * close database connections, etc.
	 * Restoring these resources and caches constitutes lots of work, but
	 * memory is so low that drastic measures are required.
	 */

	public static final String TOPIC_CRITICAL = TOPIC_BASE + "CRITICAL"; //$NON-NLS-1$

	/**
	 * A memory event topic for all memory events.
	 */
	public static final String TOPIC_ALL = TOPIC_BASE + "*"; //$NON-NLS-1$
}