Bug 301257 - MemoryEventConstants is misspelledv20100208

1 files changed, 78 insertions, 0 deletions

diff --git a/bundles/org.eclipse.equinox.common/src/org/eclipse/equinox/events/MemoryEventConstants.java b/bundles/org.eclipse.equinox.common/src/org/eclipse/equinox/events/MemoryEventConstants.java
new file mode 100644
index 000000000..864982f5b
--- /dev/null
+++ b/bundles/org.eclipse.equinox.common/src/org/eclipse/equinox/events/MemoryEventConstants.java
@@ -0,0 +1,78 @@
+/*******************************************************************************
+ * Copyright (c) 2009, 2010 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ * 
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.equinox.events;
+
+/**
+ * Defines constants for memory event handlers.  A memory event handler implements
+ * the <code>org.osgi.service.event.EventHandler</code> interface as specified by the OSGi 
+ * Event Admin Service Specification.
+ * <p>
+ * For example, the following handler is registered to handle critical memory
+ * events:
+ * <pre>
+ * 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);
+ * </pre>
+ * 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.
+ * </p>
+ * @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 + "*"; //$NON-NLS-1$
+}