fixed error where application would hang for n seconds after pc was in standby. callbacks do not pause while in standby mode

Author: Death111

src/main/java/de/doubleslash/keeptime/common/DateFormatter.java

@@ -21,7 +21,7 @@ public static String secondsToHHMMSS(final long currentWorkSeconds) {
    }
 
    public static long getSecondsBewtween(final LocalDateTime startDate, final LocalDateTime endDate) {
-      return Duration.between(startDate, endDate).getSeconds();
+      return Math.abs(Duration.between(startDate, endDate).getSeconds());
    }
 
    public static String toDayDateString(final LocalDate newvalue) {

src/main/java/de/doubleslash/keeptime/view/time/Interval.java

@@ -1,47 +1,70 @@
 package de.doubleslash.keeptime.view.time;
 
+import java.time.LocalDateTime;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import de.doubleslash.keeptime.common.DateFormatter;
 import javafx.animation.Animation;
 import javafx.animation.KeyFrame;
 import javafx.animation.Timeline;
 import javafx.util.Duration;
 
 public class Interval {
 
-	public static List<CallBackListener> callBackListeners = new CopyOnWriteArrayList<>();
+   private final static Logger Log = LoggerFactory.getLogger(Interval.class);
+
+   public static List<CallBackListener> callBackListeners = new CopyOnWriteArrayList<>();
+
+   private static Timeline timelineSession;
+   private static LocalDateTime last = LocalDateTime.now();
+
+   public static void registerCallBack(final CallBackListener cbl) {
+      if (timelineSession == null) {
+         createTimeLine();
+      }
+      callBackListeners.add(cbl);
+   }
 
-	private static Timeline timelineSession;
+   /**
+    * only create timeLine if needed
+    */
+   private static void createTimeLine() {
+      timelineSession = new Timeline(new KeyFrame(Duration.seconds(1), (ae) -> {
+         debounceAndExecuteCallbacks();
+      }));
+      timelineSession.setCycleCount(Animation.INDEFINITE);
+      timelineSession.play();
 
-	public static void registerCallBack(CallBackListener cbl) {
-		if (timelineSession == null)
-			createTimeLine();
-		callBackListeners.add(cbl);
-	}
+   }
 
-	/**
-	 * only create timeLine if needed
-	 */
-	private static void createTimeLine() {
-		timelineSession = new Timeline(new KeyFrame(Duration.seconds(1), (ae) -> {
-			callBackListeners.forEach(CallBackListener::call);
-		}));
-		timelineSession.setCycleCount(Animation.INDEFINITE);
-		timelineSession.play();
+   private static void debounceAndExecuteCallbacks() {
+      final LocalDateTime now = LocalDateTime.now();
+      final long secondsBewtween = DateFormatter.getSecondsBewtween(last, now);
+      final int nanoBetween = java.time.Duration.between(last, now).abs().getNano();
 
-	}
+      // ignore callbacks faster than ~1 second (can happen if we were in standby)
+      // Log.debug("{} - {} = {}.{}", now, last, secondsBewtween, nanoBetween);
+      if (secondsBewtween >= 1 || nanoBetween > 900000000) {
+         callBackListeners.forEach(CallBackListener::call);
+         last = now;
+      }
+   }
 
-	public static void removeCallBack(CallBackListener cbl) {
-		if (timelineSession == null)
-			return;
+   public static void removeCallBack(final CallBackListener cbl) {
+      if (timelineSession == null) {
+         return;
+      }
 
-		callBackListeners.remove(cbl);
+      callBackListeners.remove(cbl);
 
-		if (callBackListeners.isEmpty()) {
-			timelineSession.stop();
-			timelineSession = null;
-		}
-	}
+      if (callBackListeners.isEmpty()) {
+         timelineSession.stop();
+         timelineSession = null;
+      }
+   }
 
 }