Github user dragonsinth commented on a diff in the pull request:
https://github.com/apache/curator/pull/47#discussion_r18800916
--- Diff:
curator-recipes/src/main/java/org/apache/curator/framework/recipes/shared/SharedValue.java
---
@@ -129,29 +127,19 @@ public void setValue(byte[] newValue) throws Exception
* value is updated. i.e. if the value is not successful you can get
the updated value
* by calling {@link #getValue()}.
*
+ * @deprecated use {@link #trySetValue(VersionedValue, byte[])} for
stronger atomicity
+ * guarantees. Even if this object's internal state is up-to-date, the
caller has no way to
+ * ensure that they've read the most recently seen value.
+ *
* @param newValue the new value to attempt
* @return true if the change attempt was successful, false if not. If
the change
* was not successful, {@link #getValue()} will return the updated
value
* @throws Exception ZK errors, interruptions, etc.
*/
+ @Deprecated
public boolean trySetValue(byte[] newValue) throws Exception
{
- Preconditions.checkState(state.get() == State.STARTED, "not
started");
-
- try
- {
- VersionedValue<byte[]> localCopy = currentValue.get();
-
client.setData().withVersion(localCopy.getVersion()).forPath(path, newValue);
- currentValue.set(new
VersionedValue<byte[]>(localCopy.getVersion() + 1, Arrays.copyOf(newValue,
newValue.length)));
- return true;
- }
- catch ( KeeperException.BadVersionException ignore )
- {
- // ignore
- }
-
- readValue();
- return false;
+ return trySetValue(currentValue.get(), newValue);
}
--- End diff --
No, not really. The old version used a synchronized block. This version
uses a compare-and-set loop. It's only a difference in how concurrency is
handled, it's not an algorithm change. For all practical purposes, the CAS
loop almost never executes more than once.
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