source: trunk/src/org/expeditee/core/BlockingRunnable.java@ 1097

package org.expeditee.core;

/**
 * A Runnable which can be asked to block the calling thread until
 * execution of the given code has completed. Runnable's run() method
 * is used as part of the implementation so user code should be specified
 * by overriding the execute() method instead.
 * 
 * @author cts16
 */
public abstract class BlockingRunnable implements Runnable {

        /** Whether the code has finished executing or not. */
        private boolean _done;
        /** Synchronisation object to prevent race conditions. */
        private Object _lock;
        
        public BlockingRunnable()
        {
                _done = false;
                _lock = new Object();
        }
        
        /** Should be overridden to specify user behaviour. */
        public abstract void execute();
        
        @Override
        public final void run()
        {
                execute();
                
                // Mark as finished and wake any blocked threads
                synchronized (_lock) {
                        _done = true;
                        _lock.notifyAll();
                }
        }
        
        /** Can be called to block the calling thread until the execute() method returns. */
        public final void blockUntilDone()
        {
                synchronized (_lock) {
                        while (!_done) {
                                try {
                                        _lock.wait();
                                } catch (InterruptedException e) {
                                        // Do nothing, just try waiting again
                                }
                        }
                }
        }
}