ReentrantLock: How to know which code succesfully locked something?

[luxspes]

Hi!

The @Synchronized annotation makes really easy to serialize access to a particular component, and if the timeout configured for @Synchronized component ends, then it throws an exception like this one:

could not acquire lock on @Synchronized component SomeComponent

The stacktrace that comes with that exception makes it easy to know which code was trying to get a lock on the component SomeComponent and failed, but what I would like to know is the the caller (and all the stacktrace) that was the last one to succesfully lock the component SomeComponent.

Any one knows how to do that?

[luxspes]

Solved it like this:

@Interceptor(type=InterceptorType.CLIENT)
public class ConfigurableSynchronizationInterceptor extends AbstractInterceptor
{   
        
     org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(ConfigurableSynchronizationInterceptor.class);
     
     public ConfigurableSynchronizationInterceptor() {
          log.debug("Constructor");
          
     }
     
     
     private String getStackTrace(Throwable t)
    {
        StringWriter sw = new StringWriter();
        PrintWriter pw = new PrintWriter(sw, true);
        t.printStackTrace(pw);
        pw.flush();
        sw.flush();
        return sw.toString();
    }

     
   /**
      * 
      */
     private static final long serialVersionUID = 6644552930765616337L;
     private ReentrantLock lock = new ReentrantLock(true);
     private String lockedStacktrace;
   
   @AroundInvoke
   public Object aroundInvoke(InvocationContext invocation) throws Exception
   {      
        log.debug("Will try to get lock for: "+getComponent().getName());
        SynchronizationConfiguration cfg=(SynchronizationConfiguration) Component.getInstance("synchronizationConfiguration");
        if ( lock.tryLock( cfg.getSynchronizationTimeOut()/*getComponent().getTimeout()*/, TimeUnit.MILLISECONDS ) )
      {
         try
         {
              lockedStacktrace = this.getStackTrace(new RuntimeException("Succesfully locked stacktrace"));
              return invocation.proceed();
         }
         finally
         {
              lockedStacktrace = null;
              lock.unlock();
         }
      }
      else
      {           
           throw new LockTimeoutException("could not acquire lock on @Synchronized component: " + 
               getComponent().getName()+" because someone else got it at: "+lockedStacktrace);
      }
   }
   
   public boolean isInterceptorEnabled()
   {
      return getComponent().isSynchronize();
   }

}

Basically when I succesfully get the lock I store a string representation of the stacktrace, and, if a component fails to get the lock, I take that stored stacktrace representation and append it to the message of the LockTimeoutException.

IMO (unless it is wrong), this should be part for Seam core behavior...

[luxspes]

And so I create JBSEAM-4472