org.apache.flink.runtime.query

Class QueryableStateClient

java.lang.Object

org.apache.flink.runtime.query.QueryableStateClient

public class QueryableStateClient
extends Object

Client for queryable state.

You can mark state as queryable via StateDescriptor.setQueryable(String). The state instance created from this descriptor will be published for queries when it's created on the TaskManagers and the location will be reported to the JobManager.

The client resolves the location of the requested KvState via the JobManager. Resolved locations are cached. When the server address of the requested KvState instance is determined, the client sends out a request to the server.

Constructor Summary

Constructors

Constructor and Description
QueryableStateClient(Configuration config, HighAvailabilityServices highAvailabilityServices) Creates a client from the given configuration.
QueryableStateClient(KvStateLocationLookupService lookupService, KvStateClient kvStateClient, scala.concurrent.ExecutionContext executionContext) Creates a client.

Method Summary

Methods

Modifier and Type	Method and Description
scala.concurrent.ExecutionContext	getExecutionContext() Returns the execution context of this client.
scala.concurrent.Future<byte[]>	getKvState(JobID jobId, String queryableStateName, int keyHashCode, byte[] serializedKeyAndNamespace) Returns a future holding the serialized request result.
void	shutDown() Shuts down the client and all components.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

QueryableStateClient

public QueryableStateClient(Configuration config,
                    HighAvailabilityServices highAvailabilityServices)
                     throws Exception

Creates a client from the given configuration.

This will create multiple Thread pools: one for the started actor system and another for the network client.

Parameters:

config - Configuration to use.

highAvailabilityServices - Service factory for high availability services

Throws:

Exception - Failures are forwarded

QueryableStateClient

public QueryableStateClient(KvStateLocationLookupService lookupService,
                    KvStateClient kvStateClient,
                    scala.concurrent.ExecutionContext executionContext)

Creates a client.

Parameters:

lookupService - Location lookup service

kvStateClient - Network client for queries

executionContext - Execution context for futures

Method Detail

getExecutionContext

public scala.concurrent.ExecutionContext getExecutionContext()

Returns the execution context of this client.

Returns:

The execution context used by the client.

shutDown

public void shutDown()

Shuts down the client and all components.

getKvState

public scala.concurrent.Future<byte[]> getKvState(JobID jobId,
                                         String queryableStateName,
                                         int keyHashCode,
                                         byte[] serializedKeyAndNamespace)

Returns a future holding the serialized request result.

If the server does not serve a KvState instance with the given ID, the Future will be failed with a UnknownKvStateID.

If the KvState instance does not hold any data for the given key and namespace, the Future will be failed with a UnknownKeyOrNamespace.

All other failures are forwarded to the Future.

Parameters:

jobId - JobID of the job the queryable state belongs to

queryableStateName - Name under which the state is queryable

keyHashCode - Integer hash code of the key (result of a call to Object.hashCode()

serializedKeyAndNamespace - Serialized key and namespace to query KvState instance with

Returns:

Future holding the serialized result