org.apache.flink.runtime.state

Class StateBackendLoader

java.lang.Object

org.apache.flink.runtime.state.StateBackendLoader

public class StateBackendLoader
extends Object

This class contains utility methods to load state backends from configurations.

Field Summary

Fields

Modifier and Type	Field and Description
static String	FS_STATE_BACKEND_NAME The shortcut configuration name for the FileSystem State backend
static String	MEMORY_STATE_BACKEND_NAME The shortcut configuration name for the MemoryState backend that checkpoints to the JobManager
static String	ROCKSDB_STATE_BACKEND_NAME The shortcut configuration name for the RocksDB State Backend

Method Summary

Modifier and Type	Method and Description
static StateBackend	fromApplicationOrConfigOrDefault(StateBackend fromApplication, Configuration config, ClassLoader classLoader, org.slf4j.Logger logger) Checks if an application-defined state backend is given, and if not, loads the state backend from the configuration, from the parameter 'state.backend', as defined in CheckpointingOptions.STATE_BACKEND.
static StateBackend	loadStateBackendFromConfig(ReadableConfig config, ClassLoader classLoader, org.slf4j.Logger logger) Loads the state backend from the configuration, from the parameter 'state.backend', as defined in CheckpointingOptions.STATE_BACKEND.
static boolean	stateBackendFromApplicationOrConfigOrDefaultUseManagedMemory(Configuration config, Optional<Boolean> stateBackendFromApplicationUsesManagedMemory, ClassLoader classLoader) Checks whether state backend uses managed memory, without having to deserialize or load the state backend.

Methods inherited from class java.lang.Object

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

Field Detail

MEMORY_STATE_BACKEND_NAME

public static final String MEMORY_STATE_BACKEND_NAME

The shortcut configuration name for the MemoryState backend that checkpoints to the JobManager

See Also:

Constant Field Values

FS_STATE_BACKEND_NAME

public static final String FS_STATE_BACKEND_NAME

The shortcut configuration name for the FileSystem State backend

See Also:

Constant Field Values

ROCKSDB_STATE_BACKEND_NAME

public static final String ROCKSDB_STATE_BACKEND_NAME

The shortcut configuration name for the RocksDB State Backend

See Also:

Constant Field Values

Method Detail

loadStateBackendFromConfig

public static StateBackend loadStateBackendFromConfig(ReadableConfig config,
                                                      ClassLoader classLoader,
                                                      @Nullable
                                                      org.slf4j.Logger logger)
                                               throws IllegalConfigurationException,
                                                      DynamicCodeLoadingException,
                                                      IOException

Loads the state backend from the configuration, from the parameter 'state.backend', as defined in CheckpointingOptions.STATE_BACKEND.

The state backends can be specified either via their shortcut name, or via the class name of a StateBackendFactory. If a StateBackendFactory class name is specified, the factory is instantiated (via its zero-argument constructor) and its StateBackendFactory.createFromConfig(ReadableConfig, ClassLoader) method is called.

Recognized shortcut names are '', '', and ''.

Parameters:

config - The configuration to load the state backend from

classLoader - The class loader that should be used to load the state backend

logger - Optionally, a logger to log actions to (may be null)

Returns:

The instantiated state backend.

Throws:

DynamicCodeLoadingException - Thrown if a state backend factory is configured and the factory class was not found or the factory could not be instantiated

IllegalConfigurationException - May be thrown by the StateBackendFactory when creating / configuring the state backend in the factory

IOException - May be thrown by the StateBackendFactory when instantiating the state backend

fromApplicationOrConfigOrDefault

public static StateBackend fromApplicationOrConfigOrDefault(@Nullable
                                                            StateBackend fromApplication,
                                                            Configuration config,
                                                            ClassLoader classLoader,
                                                            @Nullable
                                                            org.slf4j.Logger logger)
                                                     throws IllegalConfigurationException,
                                                            DynamicCodeLoadingException,
                                                            IOException

Checks if an application-defined state backend is given, and if not, loads the state backend from the configuration, from the parameter 'state.backend', as defined in CheckpointingOptions.STATE_BACKEND. If no state backend is configured, this instantiates the default state backend (the MemoryStateBackend).

If an application-defined state backend is found, and the state backend is a ConfigurableStateBackend, this methods calls ConfigurableStateBackend.configure(ReadableConfig, ClassLoader) on the state backend.

Refer to loadStateBackendFromConfig(ReadableConfig, ClassLoader, Logger) for details on how the state backend is loaded from the configuration.

Parameters:

config - The configuration to load the state backend from

classLoader - The class loader that should be used to load the state backend

logger - Optionally, a logger to log actions to (may be null)

Returns:

The instantiated state backend.

Throws:

DynamicCodeLoadingException - Thrown if a state backend factory is configured and the factory class was not found or the factory could not be instantiated

IllegalConfigurationException - May be thrown by the StateBackendFactory when creating / configuring the state backend in the factory

IOException - May be thrown by the StateBackendFactory when instantiating the state backend

stateBackendFromApplicationOrConfigOrDefaultUseManagedMemory

public static boolean stateBackendFromApplicationOrConfigOrDefaultUseManagedMemory(Configuration config,
                                                                                   Optional<Boolean> stateBackendFromApplicationUsesManagedMemory,
                                                                                   ClassLoader classLoader)

Checks whether state backend uses managed memory, without having to deserialize or load the state backend.

Parameters:

config - Cluster configuration.

stateBackendFromApplicationUsesManagedMemory - Whether the application-defined backend uses Flink's managed memory. Empty if application has not defined a backend.

classLoader - User code classloader.

Returns:

Whether the state backend uses managed memory.