pkuwm commented on a change in pull request #1066:
URL: https://github.com/apache/helix/pull/1066#discussion_r469416237
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File path: helix-core/src/main/java/org/apache/helix/HelixManager.java
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@@ -419,6 +420,17 @@ void
addExternalViewChangeListener(org.apache.helix.ExternalViewChangeListener l
*/
Long getSessionStartTime();
+ /**
+ * Checks whether the cluster manager is leader and returns the session ID
associated to the
+ * connection of cluster data store, if and only if it is leader.
+ *
+ * @return {@code Optional<String>} session ID is present inside the {@code
Optional} object
+ * if the cluster manager is leader. Otherwise, returns an empty {@code
Optional} object.
+ */
+ default Optional<String> getSessionIdIfLead() {
Review comment:
@jiajunwang Thanks for sharing your thought. I think the concept "fake
constant session" is like an empty `Optional` object? With `Optional`, it looks
more straightforward and clear than a fake constant session.
With a fake constant, we still need an `if` to check leadership for those
storage systems that have leadership. I would say `null` is kind of this fake
constant: if no session concept, then return null. And I think `Optional` is
better than `null` here.
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