Clustering: Update Cluster datastore to provide notification/API to check its availability for clients

When attempting to install via karaf odl-mdsal-all, one gets the following errors.

Steps to reproduce:

• Download latest integration branch
• maven clean install
• karaf + install:feature odl-mdsal-all

opendaylight-user@root>Exception in thread "config-pusher" java.lang.IllegalStateException: Failed to send commit for configuration 04-xsql.xml(odl-mdsal-all,odl-mdsal-xsql)
at org.opendaylight.controller.netconf.persist.impl.ConfigPusherImpl.sendRequestGetResponseCheckIsOK(ConfigPusherImpl.java:292)
at org.opendaylight.controller.netconf.persist.impl.ConfigPusherImpl.pushConfig(ConfigPusherImpl.java:246)
at org.opendaylight.controller.netconf.persist.impl.ConfigPusherImpl.pushConfigWithConflictingVersionRetries(ConfigPusherImpl.java:135)
at org.opendaylight.controller.netconf.persist.impl.ConfigPusherImpl.internalPushConfigs(ConfigPusherImpl.java:111)
at org.opendaylight.controller.netconf.persist.impl.ConfigPusherImpl.process(ConfigPusherImpl.java:78)
at org.opendaylight.controller.netconf.persist.impl.osgi.ConfigPersisterActivator$InnerCustomizer$1.run(ConfigPersisterActivator.java:178)
at java.lang.Thread.run(Thread.java:744)
Caused by: java.lang.IllegalStateException: Error - getInstance() failed for ModuleIdentifier

{factoryName='XSQL', instanceName='XSQL'}

in transaction TransactionIdentifier

{name='ConfigTransaction-50-52'}

at org.opendaylight.controller.config.manager.impl.ConfigTransactionControllerImpl.secondPhaseCommit(ConfigTransactionControllerImpl.java:402)
at org.opendaylight.controller.config.manager.impl.ConfigRegistryImpl.secondPhaseCommit(ConfigRegistryImpl.java:282)
at org.opendaylight.controller.config.manager.impl.ConfigRegistryImpl.commitConfig(ConfigRegistryImpl.java:229)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:75)
at sun.reflect.GeneratedMethodAccessor28.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:279)
at com.sun.jmx.mbeanserver.ConvertingMethod.invokeWithOpenReturn(ConvertingMethod.java:193)
at com.sun.jmx.mbeanserver.ConvertingMethod.invokeWithOpenReturn(ConvertingMethod.java:175)
at com.sun.jmx.mbeanserver.MXBeanIntrospector.invokeM2(MXBeanIntrospector.java:117)
at com.sun.jmx.mbeanserver.MXBeanIntrospector.invokeM2(MXBeanIntrospector.java:54)
at com.sun.jmx.mbeanserver.MBeanIntrospector.invokeM(MBeanIntrospector.java:237)
at com.sun.jmx.mbeanserver.PerInterface.invoke(PerInterface.java:138)
at com.sun.jmx.mbeanserver.MBeanSupport.invoke(MBeanSupport.java:252)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at com.sun.jmx.mbeanserver.MXBeanProxy$InvokeHandler.invoke(MXBeanProxy.java:150)
at com.sun.jmx.mbeanserver.MXBeanProxy.invoke(MXBeanProxy.java:167)
at javax.management.MBeanServerInvocationHandler.invoke(MBeanServerInvocationHandler.java:252)
at com.sun.proxy.$Proxy31.commitConfig(Unknown Source)
at org.opendaylight.controller.config.util.ConfigRegistryJMXClient.commitConfig(ConfigRegistryJMXClient.java:102)
at org.opendaylight.controller.netconf.confignetconfconnector.transactions.TransactionProvider.commitTransaction(TransactionProvider.java:110)
at org.opendaylight.controller.netconf.confignetconfconnector.operations.Commit.handleWithNoSubsequentOperations(Commit.java:55)
at org.opendaylight.controller.netconf.util.mapping.AbstractLastNetconfOperation.handle(AbstractLastNetconfOperation.java:33)
at org.opendaylight.controller.netconf.util.mapping.AbstractNetconfOperation.handle(AbstractNetconfOperation.java:105)
at org.opendaylight.controller.netconf.persist.impl.ConfigPusherImpl.sendRequestGetResponseCheckIsOK(ConfigPusherImpl.java:287)
... 6 more
Caused by: java.lang.IllegalStateException: Failed to read pre-existing data
at org.opendaylight.controller.md.sal.binding.impl.AbstractReadWriteTransaction.ensureParentsByMerge(AbstractReadWriteTransaction.java:55)
at org.opendaylight.controller.md.sal.binding.impl.AbstractWriteTransaction.put(AbstractWriteTransaction.java:44)
at org.opendaylight.controller.md.sal.binding.impl.ForwardedBackwardsCompatibleDataBroker$ForwardedBackwardsCompatibleTransacion.putOperationalData(ForwardedBackwardsCompatibleDataBroker.java:218)
at org.opendaylight.controller.md.sal.binding.impl.ForwardedBackwardsCompatibleDataBroker$ForwardedBackwardsCompatibleTransacion.putOperationalData(ForwardedBackwardsCompatibleDataBroker.java:186)
at org.opendaylight.xsql.XSQLProvider.buildXSQL(XSQLProvider.java:31)
at org.opendaylight.yang.gen.v1.http.netconfcentral.org.ns.xsql.rev140626.XSQLModule.createInstance(XSQLModule.java:26)
at org.opendaylight.yang.gen.v1.http.netconfcentral.org.ns.xsql.rev140626.AbstractXSQLModule.getInstance(AbstractXSQLModule.java:95)
at sun.reflect.GeneratedMethodAccessor31.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.opendaylight.controller.config.manager.impl.dependencyresolver.DependencyResolverManager$1.handleInvocation(DependencyResolverManager.java:152)
at com.google.common.reflect.AbstractInvocationHandler.invoke(AbstractInvocationHandler.java:70)
at com.sun.proxy.$Proxy70.getInstance(Unknown Source)
at org.opendaylight.controller.config.manager.impl.ConfigTransactionControllerImpl.secondPhaseCommit(ConfigTransactionControllerImpl.java:396)
... 36 more
Caused by: ReadFailedException

{message=Error checking exists for path /(http://netconfcentral.org/ns/XSQL?revision=2014-06-26)XSQL, errorList=[RpcError [message=Error checking exists for path /(http://netconfcentral.org/ns/XSQL?revision=2014-06-26)XSQL, severity=ERROR, errorType=APPLICATION, tag=operation-failed, applicationTag=null, info=null, cause=org.opendaylight.controller.cluster.datastore.exceptions.TimeoutException: Sending message class org.opendaylight.controller.protobuff.messages.transaction.ShardTransactionMessages$CreateTransaction to actor ActorSelection[Anchor(akka://opendaylight-cluster-data/), Path(/user/shardmanager-operational/member-1-shard-default-operational)] failed]]}

at org.opendaylight.controller.cluster.datastore.TransactionProxy$NoOpTransactionContext.dataExists(TransactionProxy.java:846)
at org.opendaylight.controller.cluster.datastore.TransactionProxy.exists(TransactionProxy.java:258)
at org.opendaylight.controller.md.sal.dom.broker.impl.DOMForwardedReadWriteTransaction.exists(DOMForwardedReadWriteTransaction.java:54)
at org.opendaylight.controller.md.sal.binding.impl.AbstractReadWriteTransaction.ensureParentsByMerge(AbstractReadWriteTransaction.java:52)
... 49 more
Caused by: org.opendaylight.controller.cluster.datastore.exceptions.TimeoutException: Sending message class org.opendaylight.controller.protobuff.messages.transaction.ShardTransactionMessages$CreateTransaction to actor ActorSelection[Anchor(akka://opendaylight-cluster-data/), Path(/user/shardmanager-operational/member-1-shard-default-operational)] failed
at org.opendaylight.controller.cluster.datastore.utils.ActorContext.executeRemoteOperation(ActorContext.java:189)
at org.opendaylight.controller.cluster.datastore.utils.ActorContext.executeShardOperation(ActorContext.java:243)
at org.opendaylight.controller.cluster.datastore.TransactionProxy.createTransactionIfMissing(TransactionProxy.java:382)
at org.opendaylight.controller.cluster.datastore.TransactionProxy.exists(TransactionProxy.java:256)
... 51 more
Caused by: java.lang.IllegalStateException: Could not find leader so transaction cannot be created
at org.opendaylight.controller.cluster.datastore.Shard.onReceiveCommand(Shard.java:221)
at akka.persistence.UntypedPersistentActor.onReceive(Eventsourced.scala:430)
at org.opendaylight.controller.cluster.common.actor.MeteringBehavior.apply(MeteringBehavior.java:80)
at akka.actor.ActorCell$$anonfun$become$1.applyOrElse(ActorCell.scala:534)
at akka.persistence.Recovery$State$class.process(Recovery.scala:30)
at akka.persistence.ProcessorImpl$$anon$2.process(Processor.scala:103)
at akka.persistence.ProcessorImpl$$anon$2.aroundReceive(Processor.scala:114)
at akka.persistence.Recovery$class.aroundReceive(Recovery.scala:256)
at akka.persistence.UntypedPersistentActor.akka$persistence$Eventsourced$$super$aroundReceive(Eventsourced.scala:428)
at akka.persistence.Eventsourced$$anon$2.doAroundReceive(Eventsourced.scala:82)
at akka.persistence.Eventsourced$$anon$2.aroundReceive(Eventsourced.scala:78)
at akka.persistence.Eventsourced$class.aroundReceive(Eventsourced.scala:369)
at akka.persistence.UntypedPersistentActor.aroundReceive(Eventsourced.scala:428)
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:516)
at akka.actor.ActorCell.invoke(ActorCell.scala:487)
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:238)
at akka.dispatch.Mailbox.run(Mailbox.scala:220)
at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:393)
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)