public synchronized void listenOn ( Cache < CounterKey , CounterValue > cache ) throws InterruptedException { if ( ! topologyListener . registered ) { this . cache = cache ; topologyListener . register ( cache ) ; } if ( ! listenersRegistered ) { this . cache . addListener ( valueListener , CounterKeyFilter . getInstance ( ) ) ; listenersRegistered = true ; } }
It registers the cache listeners if they aren t already registered .