/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 1997-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * Oracle and Java are registered trademarks of Oracle and/or its affiliates.
 * Other names may be trademarks of their respective owners.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common
 * Development and Distribution License("CDDL") (collectively, the
 * "License"). You may not use this file except in compliance with the
 * License. You can obtain a copy of the License at
 * http://www.netbeans.org/cddl-gplv2.html
 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
 * specific language governing permissions and limitations under the
 * License.  When distributing the software, include this License Header
 * Notice in each file and include the License file at
 * nbbuild/licenses/CDDL-GPL-2-CP.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the GPL Version 2 section of the License file that
 * accompanied this code. If applicable, add the following below the
 * License Header, with the fields enclosed by brackets [] replaced by
 * your own identifying information:
 * "Portions Copyrighted [year] [name of copyright owner]"
 *
 * Contributor(s):
 * The Original Software is NetBeans. The Initial Developer of the Original
 * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
 * Microsystems, Inc. All Rights Reserved.
 *
 * If you wish your version of this file to be governed by only the CDDL
 * or only the GPL Version 2, indicate your decision by adding
 * "[Contributor] elects to include this software in this distribution
 * under the [CDDL or GPL Version 2] license." If you do not indicate a
 * single choice of license, a recipient has the option to distribute
 * your version of this file under either the CDDL, the GPL Version 2 or
 * to extend the choice of license to its licensees as provided above.
 * However, if you add GPL Version 2 code and therefore, elected the GPL
 * Version 2 license, then the option applies only if the new code is
 * made subject to such option by the copyright holder.
 */

package org.graalvm.visualvm.lib.jfluid.server.system;


/**
 * Provides methods for monitoring GC activities.
 *
 * @author  Misha Dmitriev
 */
public class GC {
    //~ Static fields/initializers -----------------------------------------------------------------------------------------------

    public static final int OBSERVED_PERIODS = 10; // must match OBSERVED_PERIODS in GC.c

    //~ Methods ------------------------------------------------------------------------------------------------------------------

    public static native int getCurrentGCEpoch();

    /**
     * Returns the following two numbers:
     * metrics[0] - (Sum GC pause time for the last 10 periods) / (Total execution time for the last 10 periods) * 1000
     * metrics[1] - last GC pause in microseconds
     */
    public static native void getGCRelativeTimeMetrics(long[] metrics);

    public static native void getGCStartFinishTimes(long[] start, long[] finish);

    public static native void activateGCEpochCounter(boolean activate);

    /** Should be called at earliest possible time */
    public static void initialize() {
        // Doesn't do anything in this version
    }

    /**
     * Returns true if two instances of class Object are adjacent in memory.
     * Used by our memory leak monitoring mechanism.
     * Doesn't work (always returns true) in vanilla JDK 1.5
     */
    public static native boolean objectsAdjacent(Object o1, Object o2);

    public static native void resetGCEpochCounter();

    public static native void runGC();
}
