StateStoreCoordinatorRef — RPC Endpoint Reference to StateStoreCoordinator

StateStoreCoordinatorRef is used to (let the tasks on Spark executors to) send messages to the StateStoreCoordinator (that lives on the driver).

StateStoreCoordinatorRef is given the RpcEndpointRef to the StateStoreCoordinator RPC endpoint when created.

StateStoreCoordinatorRef is created through StateStoreCoordinatorRef helper object when requested to create one for the driver (when StreamingQueryManager is created) or an executor (when StateStore helper object is requested for the RPC endpoint reference to StateStoreCoordinator for Executors).

Table 1. StateStoreCoordinatorRef’s Methods and Underlying RPC Messages
Method	Description
`deactivateInstances`	`deactivateInstances(runId: UUID): Unit` Requests the RpcEndpointRef to send a DeactivateInstances synchronous message with the given `runId` and waits for a `true` / `false` response Used exclusively when `StreamingQueryManager` is requested to handle termination of a streaming query (when `StreamExecution` is requested to run a streaming query and the query has finished (running streaming batches)).
`getLocation`	`getLocation( stateStoreProviderId: StateStoreProviderId): Option[String]` Requests the RpcEndpointRef to send a GetLocation synchronous message with the given StateStoreProviderId and waits for the location Used when: `StateStoreAwareZipPartitionsRDD` is requested for the preferred locations of a partition (when `StreamingSymmetricHashJoinExec` physical operator is requested to execute and generate a recipe for a distributed computation (as an RDD[InternalRow])) `StateStoreRDD` is requested for preferred locations for a task for a partition
`reportActiveInstance`	`reportActiveInstance( stateStoreProviderId: StateStoreProviderId, host: String, executorId: String): Unit` Requests the RpcEndpointRef to send a ReportActiveInstance one-way asynchronous (fire-and-forget) message with the given StateStoreProviderId, `host` and `executorId` Used exclusively when `StateStore` utility is requested for reportActiveStoreInstance (when `StateStore` utility is requested to look up the StateStore by StateStoreProviderId)
`stop`	`stop(): Unit` Requests the RpcEndpointRef to send a StopCoordinator synchronous message Used exclusively for unit testing
`verifyIfInstanceActive`	`verifyIfInstanceActive( stateStoreProviderId: StateStoreProviderId, executorId: String): Boolean` Requests the RpcEndpointRef to send a VerifyIfInstanceActive synchronous message with the given StateStoreProviderId and `executorId`, and waits for a `true` / `false` response Used exclusively when `StateStore` helper object is requested for verifyIfStoreInstanceActive (when requested to doMaintenance from a running MaintenanceTask daemon thread)

Creating StateStoreCoordinatorRef to StateStoreCoordinator RPC Endpoint for Driver — `forDriver` Factory Method

forDriver(env: SparkEnv): StateStoreCoordinatorRef

forDriver…FIXME

Note	`forDriver` is used exclusively when `StreamingQueryManager` is created.

Creating StateStoreCoordinatorRef to StateStoreCoordinator RPC Endpoint for Executor — `forExecutor` Factory Method

forExecutor(env: SparkEnv): StateStoreCoordinatorRef

forExecutor…FIXME

Note	`forExecutor` is used exclusively when `StateStore` helper object is requested for the RPC endpoint reference to StateStoreCoordinator for Executors.

StateStoreCoordinatorRef