Github user dragonsinth commented on a diff in the pull request:
https://github.com/apache/curator/pull/47#discussion_r18633269
--- Diff:
curator-recipes/src/main/java/org/apache/curator/framework/recipes/shared/SharedValue.java
---
@@ -184,6 +178,25 @@ public boolean trySetValue(VersionedValue<byte[]>
newValue) throws Exception
return false;
}
+ private void updateValue(int version, byte[] bytes)
+ {
+ while (true)
+ {
+ VersionedValue<byte[]> current = currentValue.get();
+ if (current.getVersion() >= version)
+ {
+ // A newer version was concurrently set.
+ return;
+ }
+ if ( currentValue.compareAndSet(current, new
VersionedValue<byte[]>(version, bytes)) )
+ {
+ // Successfully set.
+ return;
+ }
+ // Lost a race, retry.
+ }
+ }
+
/**
--- End diff --
Ah, gotcha. So this isn't new behavior -- this is just a standard
compare-and-set loop that replaces the synchronized keyword. It's not round
tripping to the server multiple times. There's still only one attempt to set
the server value, and if it fails the calling methods return false. This is
just atomically setting currentValue. We could replace the loop with a
synchronized block, but performance would be worse.
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