/*

 * Copyright (c) 2014, 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.

 */

/**

 * This test is useful for finding out whether a Thread can have a

 * private variable indicate whether or not it is finished, and to illustrate

 * the ease with which Threads terminate each other.

 *

 * @test

 */

public class CancellableThreadTest {

    public static final int THREADPAIRS = Integer.parseInt(System.getProperty("test.threadpairs", "128"));

    public static void main(String args[]) {

        Thread[] threads = new Thread[THREADPAIRS];

        Canceller[] cancellers = new Canceller[THREADPAIRS];

        System.out.println("Running with " + THREADPAIRS + " thread pairs");

        for (int i = 0; i < THREADPAIRS; i++) {

            cancellers[i] = new Canceller(i);

            threads[i] = new Thread(cancellers[i]);

            threads[i].start();

        }

        for (int i = 0; i < THREADPAIRS; i++) {

            try {

                threads[i].join();

            } catch (InterruptedException e) {

            }

            if (cancellers[i].failed) {

                throw new RuntimeException(" Test failed in " + i + " th pair. See error messages above.");

            }

        }

    }

}

class Canceller implements Runnable {

    private final CancellableTimer timer;

    public final String name;

    public volatile boolean failed = false;

    private volatile boolean hasBeenNotified = false;

    public Canceller(int index) {

        this.name = "Canceller #" + index;

        timer = new CancellableTimer(index, this);

    }

    public void setHasBeenNotified() {

        hasBeenNotified = true;

    }

    /**

     * This method contains the "action" of this Canceller Thread.

     * It starts a CancellableTimer, waits, and then interrupts the

     * CancellableTimer after the CancellableTimer notifies it.  It then

     * tries to join the CancellableTimer to itself and reports on whether

     * it was successful in doing so.

     */

    public void run() {

        Thread timerThread = new Thread(timer);

        try {

            synchronized(this) {

                timerThread.start();

                wait();

            }

        } catch (InterruptedException e) {

            System.err.println(name + " was interrupted during wait()");

            failed = true;

        }

        if (!hasBeenNotified) {

            System.err.println(name + ".hasBeenNotified is not true as expected");

            failed = true;

        }

        synchronized (timer) {

            timerThread.interrupt();

        }

        try {

            timerThread.join();

        } catch (InterruptedException ie) {

            System.err.println(name + " was interrupted while joining " +

                    timer.name);

            failed = true;

        }

        if (timerThread.isAlive()) {

            System.err.println(timer.name + " is still alive after " + name +

                    " attempted to join it.");

            failed = true;

        }

    }

}

/**

 * This non-public class is the Thread which the Canceller Thread deliberately

 * interrupts and then joins to itself after this Thread has slept for a few milliseconds.

 */

class CancellableTimer implements Runnable {

    public final String name;

    private final Canceller myCanceller;

    public CancellableTimer(int index, Canceller aCanceller) {

        this.name = "CancellableTimer #" + index;

        this.myCanceller = aCanceller;

    }

    /**

     * This is where this CancellableTimer does its work. It notifies its

     * Canceller, waits for the Canceller to interrupt it, then catches the

     * InterruptedException, and sleeps for a few milliseconds before exiting.

     */

    public void run() {

        try {

            synchronized (this) {

                synchronized (myCanceller) {

                    myCanceller.setHasBeenNotified();

                    myCanceller.notify();

                }

                wait();

            }

        } catch (InterruptedException first) {

            // isInterrupted should've been cleared here and we should not register a

            // second interrupt

            if (Thread.currentThread().isInterrupted()) {

                System.err.println(name + " should not register an interrupt here");

                myCanceller.failed = true;

            }

            try {

                Thread.sleep(1);

            } catch (InterruptedException e) {

                System.err.println(name + " was interrupted when sleeping");

                myCanceller.failed = true;

            }

        }

    }

}