/*******************************************************************************
 * Copyright (c) 2000, 2005 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwt.internal.Lock;

import tango.core.Thread;
import tango.core.sync.Mutex;
import tango.core.sync.Condition;

/**
 * Instance of this represent a recursive monitor.
 */
public class Lock {
    int count, waitCount;
    Thread owner;
    Mutex mutex;
    Condition cond;

    public this() {
        mutex = new Mutex;
        cond = new Condition(mutex);
    }
/**
 * Locks the monitor and returns the lock count. If
 * the lock is owned by another thread, wait until
 * the lock is released.
 *
 * @return the lock count
 */
public int lock() {
    synchronized (mutex) {
        Thread current = Thread.getThis();
        if (owner !is current) {
            waitCount++;
            while (count > 0) {
                try {
                    cond.wait();
                } catch (SyncException e) {
                    /* Wait forever, just like synchronized blocks */
                }
            }
            --waitCount;
            owner = current;
        }
        return ++count;
    }
}

/**
 * Unlocks the monitor. If the current thread is not
 * the monitor owner, do nothing.
 */
public void unlock() {
    synchronized (mutex) {
        Thread current = Thread.getThis();
        if (owner is current) {
            if (--count is 0) {
                owner = null;
                if (waitCount > 0) cond.notifyAll();
            }
        }
    }
}
}