/*

 * 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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

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 */

package com.apple.concurrent;

import java.util.List;

import java.util.concurrent.*;

class LibDispatchSerialQueue extends AbstractExecutorService {

        static final int RUNNING    = 0;

    static final int SHUTDOWN   = 1;

//  static final int STOP       = 2; // not supported by GCD

    static final int TERMINATED = 3;

    final Object lock = new Object();

        LibDispatchQueue nativeQueueWrapper;

    volatile int runState;

        LibDispatchSerialQueue(final long queuePtr) {

                nativeQueueWrapper = new LibDispatchQueue(queuePtr);

        }

        @Override

        public void execute(final Runnable task) {

                if (nativeQueueWrapper == null) return;

                LibDispatchNative.nativeExecuteAsync(nativeQueueWrapper.ptr, task);

        }

        @Override

        public boolean isShutdown() {

                return runState != RUNNING;

        }

        @Override

        public boolean isTerminated() {

                return runState == TERMINATED;

        }

        @Override

        public void shutdown() {

                synchronized (lock) {

                        if (runState != RUNNING) return;

                        runState = SHUTDOWN;

                        execute(new Runnable() {

                                public void run() {

                                        synchronized (lock) {

                                                runState = TERMINATED;

                                                lock.notifyAll(); // for the benefit of awaitTermination()

                                        }

                                }

                        });

                        nativeQueueWrapper = null;

                }

        }

        @Override

        public List<Runnable> shutdownNow() {

                shutdown();

                return null;

        }

        @Override

        public boolean awaitTermination(final long timeout, final TimeUnit unit) throws InterruptedException {

                if (runState == TERMINATED) return true;

                final long millis = unit.toMillis(timeout);

                if (millis <= 0) return false;

                synchronized (lock) {

                        if (runState == TERMINATED) return true;

                        lock.wait(timeout);

                        if (runState == TERMINATED) return true;

                }

                return false;

        }

}