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package com.lti.utils.synchronization;

/**
 * Useful class for setting a flag between threads. For simple uses, this class
 * is not that useful, since boolean access is guaranteed to be atomic.
 *
 * @author Ken Larson
 */
public class SynchronizedBoolean
{
    private boolean b = false;

    public SynchronizedBoolean()
    {
        super();
    }

    public SynchronizedBoolean(boolean initValue)
    {
        this.b = initValue;
    }

    /**
     *
     * If the value is oldValue, set to newValue and return true, otherwise
     * return false.
     */
    public synchronized boolean getAndSet(boolean oldValue, boolean newValue)
    {
        if (b != oldValue)
            return false;
        setValue(newValue);
        return true;
    }

    public synchronized boolean getValue()
    {
        return b;
    }

    public synchronized void setValue(boolean newValue)
    {
        if (b != newValue)
        {
            b = newValue;
            notifyAll();
        }

    }

    public synchronized void waitUntil(boolean value)
            throws InterruptedException
    {
        while (b != value)
        {
            wait();
        }

    }

    /**
     * @return true if value matches value, false if timeout occurred
     */
    public synchronized boolean waitUntil(boolean value, int timeout)
            throws InterruptedException
    {
        long start = System.currentTimeMillis();
        while (b != value)
        {
            long now = System.currentTimeMillis();
            long diff = now - start;
            long wait = timeout - diff;
            if (wait <= 0)
                return false;
            wait(wait);
        }
        return true;

    }

}