lei-xia commented on a change in pull request #644: Customize IZkStateListener
to add handleNewSession(sessionId)
URL: https://github.com/apache/helix/pull/644#discussion_r354954437
##########
File path:
helix-core/src/main/java/org/apache/helix/manager/zk/ZKHelixManager.java
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@@ -1099,8 +1099,28 @@ public void handleStateChanged(KeeperState state) {
@Override
public void handleNewSession() throws Exception {
- LOG.info(
- "Handle new session, instance: " + _instanceName + ", type: " +
_instanceType);
+ handleNewSession(null);
+ }
+
+ @Override
+ public void handleNewSession(final String sessionId) throws Exception {
+ /*
+ * When Zk session is re-established, some old events from the previous
session might still be
+ * left in in the event queue. This may cause some issues related to
session expiration.
+ * Theoretically, an old event coming from an old session will be
re-triggered or reset in the
+ * new event, so we don't have to process the old event.
+ * Thus, if the session is expired, we will discard this session and will
NOT run following
+ * tasks for this session. If session id is null, it means this operation
is not session aware
+ * and so we don't have to check session expiration.
+ */
+ if (sessionId != null && !getSessionId().equals(sessionId)) {
+ LOG.info("Session: {} is not handled because it is expired.", sessionId);
Review comment:
Minor: also print out the current SessionId for debug purpose.
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