/*

 * Copyright (c) 1994, 2005, 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

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 * questions.

 */

package sun.misc;

/**

 * ConditionLock is a Lock with a built in state variable.  This class

 * provides the ability to wait for the state variable to be set to a

 * desired value and then acquire the lock.<p>

 *

 * The lockWhen() and unlockWith() methods can be safely intermixed

 * with the lock() and unlock() methods. However if there is a thread

 * waiting for the state variable to become a particular value and you

 * simply call Unlock(), that thread will not be able to acquire the

 * lock until the state variable equals its desired value.

 *

 * @author      Peter King

 */

public final

class ConditionLock extends Lock {

    private int state = 0;

    /**

     * Creates a ConditionLock.

     */

    public ConditionLock () {

    }

    /**

     * Creates a ConditionLock in an initialState.

     */

    public ConditionLock (int initialState) {

        state = initialState;

    }

    /**

     * Acquires the lock when the state variable equals the desired state.

     *

     * @param desiredState the desired state

     * @exception  java.lang.InterruptedException if any thread has

     *               interrupted this thread.

     */

    public synchronized void lockWhen(int desiredState)

        throws InterruptedException

    {

        while (state != desiredState) {

            wait();

        }

        lock();

    }

    /**

     * Releases the lock, and sets the state to a new value.

     * @param newState the new state

     */

    public synchronized void unlockWith(int newState) {

        state = newState;

        unlock();

    }

}