fixed Delay filter

src/main/java/teetime/stage/basic/Delay.java

 package teetime.stage.basic;
 
+import java.util.LinkedList;
+import java.util.List;
+
 import teetime.framework.AbstractStage;
 import teetime.framework.InputPort;
 import teetime.framework.OutputPort;
@@ -10,18 +13,22 @@ public class Delay<T> extends AbstractStage {
 	private final InputPort<Long> timestampTriggerInputPort = this.createInputPort();
 	private final OutputPort<T> outputPort = this.createOutputPort();
 
+	private final List<T> bufferedElements = new LinkedList<T>();
+
 	@Override
 	public void executeWithPorts() {
+		T element = inputPort.receive();
+		if (null != element) {
+			bufferedElements.add(element);
+		}
+
 		Long timestampTrigger = this.timestampTriggerInputPort.receive();
 		if (null == timestampTrigger) {
 			return;
 		}
-		// System.out.println("got timestamp; #elements: " + this.getInputPort().pipe.size());
 
-		// System.out.println("#elements: " + this.getInputPort().pipe.size());
-		// TODO implement receiveAll() and sendMultiple()
-		while (!this.inputPort.getPipe().isEmpty()) {
-			T element = this.inputPort.receive();
+		while (!bufferedElements.isEmpty()) {
+			element = bufferedElements.remove(0);
 			this.send(this.outputPort, element);
 		}
 	}