i3wangyi commented on a change in pull request #688: Fix the watcher leakage
issue
URL: https://github.com/apache/helix/pull/688#discussion_r373696834
##########
File path:
helix-core/src/main/java/org/apache/helix/manager/zk/zookeeper/ZkClient.java
##########
@@ -1309,22 +1306,24 @@ public void run() throws Exception {
}
}
- private void fireChildChangedEvents(final String path, Set<IZkChildListener>
childListeners) {
+ private void fireChildChangedEvents(final String path, Set<IZkChildListener>
childListeners, boolean pathExists) {
try {
- final ZkPathStatRecord pathStatRecord = new ZkPathStatRecord(path);
for (final IZkChildListener listener : childListeners) {
_eventThread.send(new ZkEvent("Children of " + path + " changed sent
to " + listener) {
@Override
public void run() throws Exception {
- // Reinstall watch before listener callbacks to check the znode
status
- if (!pathStatRecord.pathChecked()) {
- pathStatRecord.recordPathStat(getStat(path, hasListeners(path)),
- OptionalLong.empty());
- }
List<String> children = null;
- if (pathStatRecord.pathExists()) {
+ if (pathExists) {
try {
+ //TODO: duplicate reads when multiple child listener exists
children = getChildren(path);
+ if (children != null) {
+ for (String child : children) {
+ // add the exists watcher for all child path, it's to
prevent watcher missing
+ // in case of node recreation shortly after deletion
+ watchForData(path + "/" + child);
Review comment:
That's true... However, I do feel it's odd to connect the relationship
between two separate classes as it violates the separation of concern. I could
either delete the added part or just add the change but remove the code path in
CallbackListener. Which one do you prefer?
To make things easier, I will mark it as a TODO (IMO, Re-install watchers
should be the concern of ZkClient(Watcher) class, not CallbackHandler).
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