i3wangyi commented on a change in pull request #363: Fix the race condition
while Helix refresh cluster status cache.
URL: https://github.com/apache/helix/pull/363#discussion_r308446844
##########
File path:
helix-core/src/main/java/org/apache/helix/controller/dataproviders/BaseControllerDataProvider.java
##########
@@ -290,12 +296,20 @@ private void updateIdealRuleMap() {
}
public synchronized void refresh(HelixDataAccessor accessor) {
+ refresh(accessor, new HashSet<>());
+ }
+
+ /**
+ * @param accessor
+ * @param refreshedType Record the types that has been updated during the
refresh.
+ */
+ protected synchronized void refresh(HelixDataAccessor accessor,
Set<HelixConstants.ChangeType> refreshedType) {
// Refresh raw data
_clusterConfig =
accessor.getProperty(accessor.keyBuilder().clusterConfig());
- refreshIdealState(accessor);
- refreshLiveInstances(accessor);
- refreshInstanceConfigs(accessor);
- refreshResourceConfig(accessor);
+ refreshIdealState(accessor, refreshedType);
Review comment:
I have some concerns about using an extra Set object to remember what has
been refreshed. It's not about correctness or performance, but just feel it's
redundant or unnecessary. I noticed the `refreshXXX` method is 99% same only
differs in the type, so I guess we can avoid the extra set if we could do the
refactor in the second phase with something like this :
```
Set<HelixConstants.ChangeType>
refreshProperties(List<HelixConstants.ChangeType> properties) {
Set<HelixConstants.ChangeType> refreshed = new HashSet<>();
for (HelixConstants.ChangeType property : properties) {
if (_propertyDataChangedMap.get(property).getAndSet(false)) {
_proepertyCacheMap.get(property).refresh(accessor);
LogUtil.logInfo(logger, getClusterEventId(), String
.format("Reloaded %s for cluster %s, %s pipeline. Cnt: %s",
property, _clusterName,
getPipelineName(),
_resourceConfigCache.getPropertyMap().keySet().size()));
refreshed.add(property);
}
}
return refreshed;
}
```
And the client who uses it like
```
Set<HelixConstants.ChangeType> refreshed =
refreshProperties(ImmutableList.of(xxxxx));
```
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