/*

 * Copyright (c) 2018, 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 8201315

 * @summary Test that channels can be registered, interest ops can changed,

 *          and keys cancelled while a selection operation is in progress.

 */

import java.io.IOException;

import java.nio.channels.Pipe;

import java.nio.channels.SelectionKey;

import java.nio.channels.Selector;

import java.util.concurrent.Callable;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.Future;

import java.util.concurrent.Phaser;

public class RegisterDuringSelect {

    static Callable<Void> selectLoop(Selector sel, Phaser barrier) {

        return new Callable<Void>() {

            @Override

            public Void call() throws IOException {

                for (;;) {

                    sel.select();

                    if (sel.isOpen()) {

                        barrier.arriveAndAwaitAdvance();

                    } else {

                        // closed

                        return null;

                    }

                }

            }

        };

    }

    /**

     * Invoke register, interestOps, and cancel concurrently with a thread

     * doing a selection operation

     */

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

        Future<Void> result;

        ExecutorService pool = Executors.newFixedThreadPool(1);

        try (Selector sel = Selector.open()) {

            Phaser barrier = new Phaser(2);

            // submit task to do the select loop

            result = pool.submit(selectLoop(sel, barrier));

            Pipe p = Pipe.open();

            try {

                Pipe.SourceChannel sc = p.source();

                sc.configureBlocking(false);

                System.out.println("register ...");

                SelectionKey key = sc.register(sel, SelectionKey.OP_READ);

                if (!sel.keys().contains(key))

                    throw new RuntimeException("key not in key set");

                sel.wakeup();

                barrier.arriveAndAwaitAdvance();

                System.out.println("interestOps ...");

                key.interestOps(0);

                sel.wakeup();

                barrier.arriveAndAwaitAdvance();

                System.out.println("cancel ...");

                key.cancel();

                sel.wakeup();

                barrier.arriveAndAwaitAdvance();

                if (sel.keys().contains(key))

                    throw new RuntimeException("key not removed from key set");

            } finally {

                p.source().close();

                p.sink().close();

            }

        } finally {

            pool.shutdown();

        }

        // ensure selectLoop completes without exception

        result.get();

    }

}