clustering.services-implementation failed to register listner.

System tests for VTN frequently fails.

https://jenkins.opendaylight.org/integration/job/integration-master-csit-karaf-vtn-only/
https://jenkins.opendaylight.org/integration/job/integration-master-csit-karaf-vtn-all/

We've found out that the root cause of this failure is in clustering.

We sometimes observe that clustering.services-implementation fails to register listener.
Which listener the clustering.services-implementation fails to register changes each time.

We observed that when the clustering.services-implementation fails to register topologymanager.edgesDB, system tests for VTN failed.

2014-09-24 14:29:00,198 | TRACE | Local user karaf | \
ClusterGlobalManager | \
98 - org.opendaylight.controller.clustering.services-implementation - \
0.4.3.Helium | setCacheUpdateAware: \
org.opendaylight.controller.topologymanager.internal.\
TopologyManagerImpl@ceb60d

2014-09-24 14:29:00,199 | TRACE | Local user karaf | \
ClusterManagerCommon | \
98 - org.opendaylight.controller.clustering.services-implementation - \
0.4.3.Helium | CacheUpdateAware being set on container:default

2014-09-24 14:29:00,199 | TRACE | Local user karaf | \
ClusterManagerCommon | \
98 - org.opendaylight.controller.clustering.services-implementation - \
0.4.3.Helium | cachenames provided below:

2014-09-24 14:29:00,199 | DEBUG | Local user karaf | \
ClusterManagerCommon | \
98 - org.opendaylight.controller.clustering.services-implementation - \
0.4.3.Helium | Cache topologymanager.edgesDB didn't exist when \
org.opendaylight.controller.topologymanager.internal.\
TopologyManagerImpl@ceb60d tried to register to its updates

Because if the clustering.services-implementation fails to register topologymanager.edgesDB, dijkstra_impelmentation fails to create route information, and IRouting.getRoute(Node, Node) returns null, VTN Manager thinks there are no route between hosts, and eventually VTN Manager does not try to forward packets and install flow entries.

That is why System tests for VTN frequently fails.