[jboss-jira] [JBoss JIRA] Commented: (JBCACHE-629) SELECT FOR UPDATE semantics

SELECT FOR UPDATE semantics --------------------------- Key: JBCACHE-629 URL: http://jira.jboss.com/jira/browse/JBCACHE-629 Project: JBoss Cache Issue Type: Feature Request Security Level: Public(Everyone can see) Reporter: Brian Stansberry Assigned To: Manik Surtani Fix For: 2.0.0.GA, 2.0.0.BETA1 An API with semantics similar to a database SELECT FOR UPDATE would be useful -- e.g. getForUpdate(...) which acts like a get, but acquires a WL instead of a RL. Example situation: IsolationLevel is READ_COMMITTED - Two threads A and B. 1. Thread A starts a new Transaction. 2. Thread A calls get(Fqn for x, key for x) 3. Thread A modifies Object x (e.g x.setFoo("bar")). 4. Thread B calls get(Fqn for x, key for Object x) 5. Thread B calls x.getFoo() 6. Thread A calls put(Fqn for x, key for x, x); 7. Thread A rolls back the Transaction. Problem is in Step 5 Thread B sees uncommitted data, because the WL on the cache node is not acquired until Step 6. Only way to control this is for Thread A to synchronize on x and write x in such a way that access to all properties like Foo are synchronized. With getForUpdate, A would acquire the WL in step 1, thus blocking B from reading until the A's TX commits.