/*

 * Copyright (c) 2011, 2017, 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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 * questions.

 */

/* @test

 * @bug 4268317 8132306 8175797

 * @summary Test if Reference.enqueue() works properly with GC

 * @run main ReferenceEnqueue

 */

import java.lang.ref.*;

import java.util.ArrayList;

import java.util.List;

public class ReferenceEnqueue {

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

        for (int i=0; i < 5; i++) {

            new WeakRef().run();

            new ExplicitEnqueue().run();

        }

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

    }

    static class WeakRef {

        final ReferenceQueue<Object> queue = new ReferenceQueue<Object>();

        final Reference<Object> ref;

        final int iterations = 1000;

        WeakRef() {

            this.ref = new WeakReference<Object>(new Object(), queue);

        }

        void run() throws InterruptedException {

            System.gc();

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

                System.gc();

                if (ref.isEnqueued()) {

                    break;

                }

                Thread.sleep(100);

            }

            if (ref.isEnqueued() == false) {

                // GC have not enqueued refWeak for the timeout period

                System.out.println("Reference not enqueued yet");

                return;

            }

            if (ref.enqueue() == true) {

                // enqueue() should return false since

                // ref is already enqueued by the GC

                throw new RuntimeException("Error: enqueue() returned true;"

                        + " expected false");

            }

            if (queue.poll() == null) {

                // poll() should return ref enqueued by the GC

                throw new RuntimeException("Error: poll() returned null;"

                        + " expected ref object");

            }

        }

    }

    static class ExplicitEnqueue {

        final ReferenceQueue<Object> queue = new ReferenceQueue<>();

        final List<Reference<Object>> refs = new ArrayList<>();

        final int iterations = 1000;

        ExplicitEnqueue() {

            this.refs.add(new SoftReference<>(new Object(), queue));

            this.refs.add(new WeakReference<>(new Object(), queue));

            // Can't test PhantomReference because get() always returns null.

        }

        void run() throws InterruptedException {

            for (Reference<Object> ref : refs) {

                if (ref.enqueue() == false) {

                    throw new RuntimeException("Error: enqueue failed");

                }

                    throw new RuntimeException("Error: referent must be cleared");

                }

            }

            System.gc();

            for (int i = 0; refs.size() > 0 && i < iterations; i++) {

                Reference<Object> ref = (Reference<Object>)queue.poll();

                if (ref == null) {

                    System.gc();

                    Thread.sleep(100);

                    continue;

                }

                if (refs.remove(ref) == false) {

                    throw new RuntimeException("Error: unknown reference " + ref);

                }

            }

            if (!refs.isEmpty()) {

                throw new RuntimeException("Error: not all references are removed");

            }

        }

    }

}