Locking implementation

ExclusiveRunnerMutex.java

import java.util.Objects;

/** Executes a runnable as a critical section but without any blocking. 
 *  Number of executions is not guaranteed to match a number of invocations.
 *  Last invocation happens-before last execution.
 * 
 * **/
public final class ExclusiveRunner implements Runnable {
    private final Runnable delegate;
    private final Object lock = new Object();
    private boolean requested = false;
    private boolean busy = false;
    
    public ExclusiveRunner(Runnable delegate) {
        super();
        this.delegate = Objects.requireNonNull(delegate);
    }

    @Override
    public void run() {
        synchronized (lock) {
            requested = true;
            if (busy) {
                return;
            }
            busy = true;
        }
        for (;;) {
            synchronized (lock) {
                if (!requested) {
                    busy = false; 
                    return;
                }
                requested = false;
            }
            delegate.run();
        }
    }

}