/*

 * Copyright (c) 2002, 2012, 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.  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

 * questions.

 */

package sun.nio.ch;

// Special-purpose data structure for sets of native threads

class NativeThreadSet {

    private long[] elts;

    private int used = 0;

    private boolean waitingToEmpty;

    NativeThreadSet(int n) {

        elts = new long[n];

    }

    // Adds the current native thread to this set, returning its index so that

    // it can efficiently be removed later.

    //

    int add() {

        long th = NativeThread.current();

        // 0 and -1 are treated as placeholders, not real thread handles

        if (th == 0)

            th = -1;

        synchronized (this) {

            int start = 0;

            if (used >= elts.length) {

                int on = elts.length;

                int nn = on * 2;

                long[] nelts = new long[nn];

                System.arraycopy(elts, 0, nelts, 0, on);

                elts = nelts;

                start = on;

            }

            for (int i = start; i < elts.length; i++) {

                if (elts[i] == 0) {

                    elts[i] = th;

                    used++;

                    return i;

                }

            }

            assert false;

            return -1;

        }

    }

    // Removes the thread at the given index.

    //

    void remove(int i) {

        synchronized (this) {

            elts[i] = 0;

            used--;

            if (used == 0 && waitingToEmpty)

                notifyAll();

        }

    }

    // Signals all threads in this set.

    //

    synchronized void signalAndWait() {

        boolean interrupted = false;

        while (used > 0) {

            int u = used;

            int n = elts.length;

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

                long th = elts[i];

                if (th == 0)

                    continue;

                if (th != -1)

                    NativeThread.signal(th);

                if (--u == 0)

                    break;

            }

            waitingToEmpty = true;

            try {

                wait(50);

            } catch (InterruptedException e) {

                interrupted = true;

            } finally {

                waitingToEmpty = false;

            }

        }

        if (interrupted)

            Thread.currentThread().interrupt();

    }

}