Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/1153#discussion_r41150514
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/leaderelection/LeaderElectionService.java
---
@@ -67,4 +67,20 @@
* @return true if the associated {@link LeaderContender} is the
leader, otherwise false
*/
boolean hasLeadership();
+
+ /**
+ * [EXPERIMENTAL] Returns <code>true</code> if the {@link
LeaderContender} is leader. A call
+ * to this method might block.
+ *
+ * <p>This forces a synchronous check at the respective state backend.
It is possible
+ * that is does not reflect the current state at the {@link
LeaderContender}, which is notified
+ * asynchronously. Therefore it is possible that {@link
#hasLeadership()} and {@link
+ * #syncHasLeadership()} have different return values.
+ *
+ * @TODO @tillrohrmann Is it OK to collapse this with {@link
#hasLeadership()}?
+ *
+ * @return true if the associated {@link LeaderContender} is the
leader, otherwise false
+ */
+ boolean syncHasLeadership();
--- End diff --
Hmm, but the Javadoc suggests a wrong guarantee which does not always hold
true. The thing is that we don't really know what are the chances to observe a
wrong leadership and to what extent this method decreases them.
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