/*

 * Copyright (c) 2013, 2016, 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;

import sun.jvmstat.monitor.MonitorException;

import sun.jvmstat.monitor.MonitoredHost;

import sun.jvmstat.monitor.MonitoredVm;

import sun.jvmstat.monitor.VmIdentifier;

import jdk.test.lib.process.ProcessTools;

/**

 * PerfCounters can be used to get a performance counter from the currently

 * executing VM.

 *

 * Throws a runtime exception if an error occurs while communicating with the

 * currently executing VM.

 */

public class PerfCounters {

    private final static MonitoredVm vm;

    static {

        try {

            String pid = Long.toString(ProcessTools.getProcessId());

            VmIdentifier vmId = new VmIdentifier(pid);

            MonitoredHost host = MonitoredHost.getMonitoredHost(vmId);

            vm = host.getMonitoredVm(vmId);

        } catch (Exception e) {

            throw new RuntimeException("Could not connect to the VM");

        }

    }

    /**

     * Returns the performance counter with the given name.

     *

     * @param name The name of the performance counter.

     * @throws IllegalArgumentException If no counter with the given name exists.

     * @throws MonitorException If an error occurs while communicating with the VM.

     * @return The performance counter with the given name.

     */

    public static PerfCounter findByName(String name)

        throws MonitorException, IllegalArgumentException {

        Monitor m = vm.findByName(name);

        if (m == null) {

            throw new IllegalArgumentException("Did not find a performance counter with name " + name);

        }

        return new PerfCounter(m, name);

    }

}