/*

 * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

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

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

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

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

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

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import sun.jvmstat.monitor.Monitor;

/**

 * Represents a performance counter in the JVM.

 *

 * See http://openjdk.java.net/groups/hotspot/docs/Serviceability.html#bjvmstat

 * for more details about performance counters.

 */

public class PerfCounter {

    private final Monitor monitor;

    private final String name;

    PerfCounter(Monitor monitor, String name) {

        this.monitor = monitor;

        this.name = name;

    }

    /**

     * Returns the value of this performance counter as a long.

     *

     * @return The long value of this performance counter

     * @throws RuntimeException If the value of the performance counter isn't a long

     */

    public long longValue() {

        Object value = monitor.getValue();

        if (value instanceof Long) {

            return ((Long) value).longValue();

        }

        throw new RuntimeException("Expected " + monitor.getName() + " to have a long value");

    }

    /**

     * Returns the name of the performance counter.

     *

     * @return The name of the performance counter.

     */

    public String getName() {

        return name;

    }

    @Override

    public String toString() {

        return name;

    }

}