How to use a ReentrantLock for the instances of a message-driven bean?

[aqtwrdnr]

I have a message driven bean (of which multiple instances are spawned by JBoss), and one of the instances will eventually detect some special condition on which I want all message driven bean instances to skip any new messages they receive.

I was thinking about using a ReentrantLock when this special condition occurs and check it before processing messages. However, how do I distribute the same ReentrantLock between my MDB instances? I see different solutions, but I do not know which one is preferred:

1. use a private final static Lock = new ReentrantLock() : final because java ee does not allow non-final static variables.
2. use an env-entry to define the ReentrantLock and use it in all instances.
3. Create a SingletonBean which holds the ReentrantLock and retrieve the lock from it in the MDB instances.

What would be the preferred way?

Thanks in advance!

Barry NL

[rhanus]

I would prefer the third option definitely but different sync primitive

something like a startup's singleton ejb with read lock checking method and AtomicBoolean property as the message processing guard

very roughly:

@Startup

@Singleton

public class MessageGuardService {

private AtomicBoolean skipProcessing = new AtomicBoolean(false);

@Lock(LockType.READ)

  public boolean mayProcess(Message message) {

     if ( should_skip_processing(message) {

     skipProcessing.set(true);

     }

     return skipProcessing .get();

  }

}

[sfcoy]

Are you only running a single JBossAS/WildFly node, or is it a multi-node environment?

Java synchronization primitives will not be very useful if you have a fail-over.

[aqtwrdnr]

Currently I am using a final static ReentrantLock and this seems to work ok (as long as I'm running in a single JVM). But I prefer a MessageGuardService-like solution like rhanus proposed, so that will be the accepted answer.