pkuwm commented on a change in pull request #924: WIP: fix ZkHelixPropertyStore
loses Zookeeper notification issue
URL: https://github.com/apache/helix/pull/924#discussion_r401176227
##########
File path:
zookeeper-api/src/main/java/org/apache/helix/zookeeper/zkclient/ZkClient.java
##########
@@ -1073,10 +1073,24 @@ protected void processStateChanged(WatchedEvent event)
{
fireStateChangedEvent(event.getState());
+ // This following is the case for sharedZkClient
if (!isManagingZkConnection()) {
+ /*
+ For SharedZkClient, we will not invoke fireNewSessionEvents and we will
invoke fireAllEvents
+ This keeps the same behavior as original SharedZkClient.
+ Invoking fireAllEvents is important to make sure HelixPropertyStore
working correctly.
+ */
+ if ((event.getState() == KeeperState.SyncConnected) &&
(!_isNewSessionEventFired) && (!"0"
+ .equals(getHexSessionId()))) {
+ fireAllEvents();
+ _isNewSessionEventFired = true;
+ } else if (event.getState() == KeeperState.Expired) {
+ _isNewSessionEventFired = false;
+ }
Review comment:
If we remove ` _isNewSessionEventFired = false;` in `reconnect()` and do
below code, it seems more concise and easier to maintain.
`_isNewSessionEventFired` is only changed in this code block. What do you think?
```java
if (event.getState() == KeeperState.SyncConnected &&
!_isNewSessionEventFired && !"0".equals(getHexSessionId())) {
if (isManagingZkConnection()) {
/*
* Before the new zookeeper instance is connected to the zookeeper
service and its session
* is established, its session id is 0.
* New session event is not fired until the new zookeeper session
receives the first
* SyncConnected state(the zookeeper session is established).
* Now the session id is available and non-zero, and we can fire new
session events.
*/
fireNewSessionEvents();
}
/*
* Set it true to avoid firing events again for the same session next
time
* when SyncConnected events are received.
*/
_isNewSessionEventFired = true;
/*
* With this first SyncConnected state, we just get connected to
zookeeper service after
* reconnecting when the session expired. Because previous session
expired, we also have to
* notify all listeners that something might have changed.
*/
fireAllEvents();
} else if (event.getState() == KeeperState.Expired) {
if (isManagingZkConnection()) {
reconnectOnExpiring();
}
_isNewSessionEventFired = false;
}
```
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