/*

 * Copyright (c) 2005, 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.

 */

/*

 * @test

 * @bug 6303187

 * @summary Test that no locks are held when a monitor attribute is sampled

 * or notif delivered.

 * @author Eamonn McManus

 * @run clean StringMonitorDeadlockTest

 * @run build StringMonitorDeadlockTest

 * @run main StringMonitorDeadlockTest 1

 * @run main StringMonitorDeadlockTest 2

 * @run main StringMonitorDeadlockTest 3

 * @run main StringMonitorDeadlockTest 4

 */

import java.lang.management.ManagementFactory;

import java.util.concurrent.atomic.AtomicInteger;

import javax.management.Attribute;

import javax.management.JMX;

import javax.management.MBeanServer;

import javax.management.Notification;

import javax.management.NotificationListener;

import javax.management.ObjectName;

import javax.management.monitor.StringMonitor;

import javax.management.monitor.StringMonitorMBean;

public class StringMonitorDeadlockTest {

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

        if (args.length != 1)

            throw new Exception("Arg should be test number");

        int testNo = Integer.parseInt(args[0]) - 1;

        TestCase test = testCases[testNo];

        System.out.println("Test: " + test.getDescription());

        test.run();

        System.out.println("Test passed");

    }

    private static enum When {IN_GET_ATTRIBUTE, IN_NOTIFY};

    private static abstract class TestCase {

        TestCase(String description, When when) {

            this.description = description;

            this.when = when;

        }

        void run() throws Exception {

            final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();

            final ObjectName observedName = new ObjectName("a:b=c");

            final ObjectName monitorName = new ObjectName("a:type=Monitor");

            mbs.registerMBean(new StringMonitor(), monitorName);

            final StringMonitorMBean monitorProxy =

                JMX.newMBeanProxy(mbs, monitorName, StringMonitorMBean.class);

            final TestMBean observedProxy =

                JMX.newMBeanProxy(mbs, observedName, TestMBean.class);

            final Runnable sensitiveThing = new Runnable() {

                public void run() {

                    doSensitiveThing(monitorProxy, observedName);

                }

            };

            final Runnable nothing = new Runnable() {

                public void run() {}

            };

            final Runnable withinGetAttribute =

                (when == When.IN_GET_ATTRIBUTE) ? sensitiveThing : nothing;

            mbs.registerMBean(new Test(withinGetAttribute), observedName);

            monitorProxy.addObservedObject(observedName);

            monitorProxy.setObservedAttribute("Thing");

            monitorProxy.setStringToCompare("old");

            monitorProxy.setGranularityPeriod(10L); // 10 ms

            monitorProxy.setNotifyDiffer(true);

            monitorProxy.start();

            final int initGetCount = observedProxy.getGetCount();

            int getCount = initGetCount;

            for (int i = 0; i < 500; i++) { // 500 * 10 = 5 seconds

                getCount = observedProxy.getGetCount();

                if (getCount != initGetCount)

                    break;

                Thread.sleep(10);

            }

            if (getCount <= initGetCount)

                throw new Exception("Test failed: presumable deadlock");

            // This won't show up as a deadlock in CTRL-\ or in

            // ThreadMXBean.findDeadlockedThreads(), because they don't

            // see that thread A is waiting for thread B (B.join()), and

            // thread B is waiting for a lock held by thread A

            // Now we know the monitor has observed the initial value,

            // so if we want to test notify behaviour we can trigger by

            // exceeding the threshold.

            if (when == When.IN_NOTIFY) {

                final AtomicInteger notifCount = new AtomicInteger();

                final NotificationListener listener = new NotificationListener() {

                    public void handleNotification(Notification n, Object h) {

                        Thread t = new Thread(sensitiveThing);

                        t.start();

                        try {

                            t.join();

                        } catch (InterruptedException e) {

                            throw new RuntimeException(e);

                        }

                        notifCount.incrementAndGet();

                    }

                };

                mbs.addNotificationListener(monitorName, listener, null, null);

                observedProxy.setThing("new");

                for (int i = 0; i < 500 && notifCount.get() == 0; i++)

                    Thread.sleep(10);

                if (notifCount.get() == 0)

                    throw new Exception("Test failed: presumable deadlock");

            }

        }

        abstract void doSensitiveThing(StringMonitorMBean monitorProxy,

                                       ObjectName observedName);

        String getDescription() {

            return description;

        }

        private final String description;

        private final When when;

    }

    private static final TestCase[] testCases = {

        new TestCase("Remove monitored MBean within monitored getAttribute",

                     When.IN_GET_ATTRIBUTE) {

            @Override

            void doSensitiveThing(StringMonitorMBean monitorProxy,

                                  ObjectName observedName) {

                monitorProxy.removeObservedObject(observedName);

            }

        },

        new TestCase("Stop monitor within monitored getAttribute",

                     When.IN_GET_ATTRIBUTE) {

            @Override

            void doSensitiveThing(StringMonitorMBean monitorProxy,

                                  ObjectName observedName) {

                monitorProxy.stop();

            }

        },

        new TestCase("Remove monitored MBean within threshold listener",

                     When.IN_NOTIFY) {

            @Override

            void doSensitiveThing(StringMonitorMBean monitorProxy,

                                  ObjectName observedName) {

                monitorProxy.removeObservedObject(observedName);

            }

        },

        new TestCase("Stop monitor within threshold listener",

                     When.IN_NOTIFY) {

            @Override

            void doSensitiveThing(StringMonitorMBean monitorProxy,

                                  ObjectName observedName) {

                monitorProxy.stop();

            }

        },

    };

    public static interface TestMBean {

        public String getThing();

        public void setThing(String thing);

        public int getGetCount();

    }

    public static class Test implements TestMBean {

        public Test(Runnable runWithinGetAttribute) {

            this.runWithinGetAttribute = runWithinGetAttribute;

        }

        public String getThing() {

            Thread t = new Thread(runWithinGetAttribute);

            t.start();

            try {

                t.join();

            } catch (InterruptedException e) {

                throw new RuntimeException(e);

            }

            getCount++;

            return thing;

        }

        public void setThing(String thing) {

            this.thing = thing;

        }

        public int getGetCount() {

            return getCount;

        }

        private final Runnable runWithinGetAttribute;

        private volatile int getCount;

        private volatile String thing;

    }

}