question: private void signalControlOpEnd ( ) { controlOperationExecuting . set ( false ) ; LockSupport . unpark ( controlWaiters . peek ( ) ) ; if ( controlWaiters . size ( ) == 0 ) { Thread t = evalWaiters . poll ( ) ; while ( t != null ) { LockSupport . unpark ( t ) ; t = evalWaiters . poll ( ) ; } } }
target:  Called when a control operation is finished.  Releases the lock for the next thread trying to call a control operation.  If there are no additional threads trying to call control operations then unpark any evaluation threads that are waiting.