/*

 * Copyright (c) 2003, 2013, 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

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 */

/*

 * @test

 * @bug     4530538

 * @summary Basic Test for HotspotThreadMBean.getInternalThreadCount()

 *          and getInternalThreadCpuTime()

 * @author  Mandy Chung

 */

import sun.management.*;

import java.util.*;

import java.lang.management.ThreadMXBean;

import java.lang.management.ManagementFactory;

public class GetInternalThreads {

    private final static HotspotThreadMBean mbean =

        ManagementFactoryHelper.getHotspotThreadMBean();

    // Minimum number of VM internal threads

    //   VM thread, watcher thread, Low memory detector, compiler thread

    private static final long MIN_VALUE_FOR_PASS = 4;

    private static final long MAX_VALUE_FOR_PASS = Long.MAX_VALUE;

    public static void main(String[] args) throws Exception {

        long value = mbean.getInternalThreadCount();

        if (value < MIN_VALUE_FOR_PASS || value > MAX_VALUE_FOR_PASS) {

            throw new RuntimeException("Internal thread count " +

                                       "illegal value: " + value + " " +

                                       "(MIN = " + MIN_VALUE_FOR_PASS + "; " +

                                       "MAX = " + MAX_VALUE_FOR_PASS + ")");

        }

        System.out.println("Internal Thread Count = " + value);

        ThreadMXBean thread =

            ManagementFactory.getThreadMXBean();

        if (!thread.isThreadCpuTimeSupported()) {

            System.out.println("Thread Cpu Time is not supported.");

            return;

        }

        while(!testCPUTime()) {

            Thread.sleep(100);

        }

    }

    private static boolean testCPUTime() {

        Map<String, Long> times = mbean.getInternalThreadCpuTimes();

        for(Map.Entry<String, Long> entry : times.entrySet())  {

            String threadName = entry.getKey();

            long cpuTime = entry.getValue();

            System.out.println("CPU time = " + cpuTime + " for " + threadName);

            if (cpuTime == -1) {

                // Can happen when there is a race between a thread being created

                // and the request to get its CPU time. The "/proc/..." structure might

                // not be ready at that time and the routine will return -1.

                System.out.println("Retry, proc structure might not be ready (-1)");

                return false;

            }

            if (cpuTime < 0) {

                throw new RuntimeException("Illegal CPU time: " + cpuTime);

            }

        }

        return true;

    }

}