bug 3829: adding a null check against rare race condition of mark passing between leg finish checks

Change-Id: Ifb2a76c0bd2bcedcdddf6a4667f53ecf80095f60

java/com.sap.sailing.domain/src/com/sap/sailing/domain/leaderboard/impl/AbstractSimpleLeaderboardImpl.java

@@ -1745,8 +1745,12 @@ public abstract class AbstractSimpleLeaderboardImpl implements Leaderboard, Race
             result.timeInMilliseconds = time.asMillis();
             result.finished = trackedLeg.hasFinishedLeg(timePoint);
             final TimePoint legFinishTime = trackedLeg.getFinishTime();
+            // See bug 3829: there is an unlikely possibility that legFinishTime is null and the call to hasFinishedLeg below
+            // says that the leg has already finished. This can happen if the corresponding mark passing arrives between the two
+            // calls. To avoid having to use expensive locking, we'll just double-check here if legFinishTime is null and
+            // treat this as if trackedLeg.hasFinishedLeg(timePoint) had returned false.
             result.correctedTotalTime = trackedLeg.hasStartedLeg(timePoint) ? trackedLeg.getTrackedLeg().getTrackedRace().getRankingMetric().getCorrectedTime(trackedLeg.getCompetitor(),
-                    trackedLeg.hasFinishedLeg(timePoint) ? legFinishTime : timePoint, cache) : null;
+                    trackedLeg.hasFinishedLeg(timePoint) && legFinishTime != null ? legFinishTime : timePoint, cache) : null;
             // fetch the leg gap in own corrected time from the ranking metric
             final Duration gapToLeaderInOwnTime = trackedLeg.getTrackedLeg().getTrackedRace().getRankingMetric().
                     getLegGapToLegLeaderInOwnTime(trackedLeg, timePoint, rankingInfo, cache);

java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/TrackedLegOfCompetitor.java

@@ -195,6 +195,10 @@ public interface TrackedLegOfCompetitor extends Serializable {
      */
     TimePoint getStartTime();
     
+    /**
+     * @return <code>null</code> if the competitor hasn't finished this leg yet; the time point when the competitor passed
+     * the end waypoint of this leg otherwise
+     */
     TimePoint getFinishTime();
 
     /**