org.apache.flink.runtime.state.memory

Class MemoryStateBackend

java.lang.Object

org.apache.flink.runtime.state.AbstractStateBackend

org.apache.flink.runtime.state.memory.MemoryStateBackend

All Implemented Interfaces:

Serializable

public class MemoryStateBackend
extends AbstractStateBackend

A AbstractStateBackend that stores all its data and checkpoints in memory and has no capabilities to spill to disk. Checkpoints are serialized and the serialized data is transferred

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MemoryStateBackend.MemoryCheckpointOutputStream A CheckpointStateOutputStream that writes into a byte array.

Nested classes/interfaces inherited from class org.apache.flink.runtime.state.AbstractStateBackend

AbstractStateBackend.CheckpointStateOutputStream, AbstractStateBackend.CheckpointStateOutputView

Field Summary

Fields inherited from class org.apache.flink.runtime.state.AbstractStateBackend

currentKey, keySerializer, keyValueStatesByName, userCodeClassLoader

Constructor Summary

Constructors

Constructor and Description
MemoryStateBackend() Creates a new memory state backend that accepts states whose serialized forms are up to the default state size (5 MB).
MemoryStateBackend(int maxStateSize) Creates a new memory state backend that accepts states whose serialized forms are up to the given number of bytes.

Method Summary

Modifier and Type	Method and Description
<S extends Serializable> StateHandle<S>	checkpointStateSerializable(S state, long checkpointID, long timestamp) Serialized the given state into bytes using Java serialization and creates a state handle that can re-create that state.
void	close() Closes the state backend, releasing all internal resources, but does not delete any persistent checkpoint data.
static MemoryStateBackend	create() Gets the default instance of this state backend, using the default maximal state size.
AbstractStateBackend.CheckpointStateOutputStream	createCheckpointStateOutputStream(long checkpointID, long timestamp) Creates an output stream that writes into the state of the given checkpoint.
<N,T,ACC> org.apache.flink.api.common.state.FoldingState<T,ACC>	createFoldingState(org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer, org.apache.flink.api.common.state.FoldingStateDescriptor<T,ACC> stateDesc) Creates and returns a new FoldingState.
<N,T> org.apache.flink.api.common.state.ListState<T>	createListState(org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer, org.apache.flink.api.common.state.ListStateDescriptor<T> stateDesc) Creates and returns a new ListState.
<N,T> org.apache.flink.api.common.state.ReducingState<T>	createReducingState(org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer, org.apache.flink.api.common.state.ReducingStateDescriptor<T> stateDesc) Creates and returns a new ReducingState.
<N,V> org.apache.flink.api.common.state.ValueState<V>	createValueState(org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer, org.apache.flink.api.common.state.ValueStateDescriptor<V> stateDesc) Creates and returns a new ValueState.
void	disposeAllStateForCurrentJob() Disposes all state associated with the current job.
String	toString()

Methods inherited from class org.apache.flink.runtime.state.AbstractStateBackend

createCheckpointStateOutputView, dispose, getCurrentKey, getPartitionedState, initializeForJob, injectKeyValueStateSnapshots, mergePartitionedStates, notifyOfCompletedCheckpoint, setCurrentKey, snapshotPartitionedState

Methods inherited from class java.lang.Object

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

Constructor Detail

MemoryStateBackend

public MemoryStateBackend()

Creates a new memory state backend that accepts states whose serialized forms are up to the default state size (5 MB).

MemoryStateBackend

public MemoryStateBackend(int maxStateSize)

Creates a new memory state backend that accepts states whose serialized forms are up to the given number of bytes.

Parameters:

maxStateSize - The maximal size of the serialized state

Method Detail

disposeAllStateForCurrentJob

public void disposeAllStateForCurrentJob()

Description copied from class: AbstractStateBackend

Disposes all state associated with the current job.

Specified by:

disposeAllStateForCurrentJob in class AbstractStateBackend

close

public void close()
           throws Exception

Description copied from class: AbstractStateBackend

Closes the state backend, releasing all internal resources, but does not delete any persistent checkpoint data.

Specified by:

close in class AbstractStateBackend

Throws:

Exception - Exceptions can be forwarded and will be logged by the system

createValueState

public <N,V> org.apache.flink.api.common.state.ValueState<V> createValueState(org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer,
                                                                              org.apache.flink.api.common.state.ValueStateDescriptor<V> stateDesc)
                                                                       throws Exception

Description copied from class: AbstractStateBackend

Creates and returns a new ValueState.

Specified by:

createValueState in class AbstractStateBackend

Type Parameters:

N - The type of the namespace.

V - The type of the value that the ValueState can store.

Parameters:

namespaceSerializer - TypeSerializer for the state namespace.

stateDesc - The StateDescriptor that contains the name of the state.

Throws:

Exception

createListState

public <N,T> org.apache.flink.api.common.state.ListState<T> createListState(org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer,
                                                                            org.apache.flink.api.common.state.ListStateDescriptor<T> stateDesc)
                                                                     throws Exception

Description copied from class: AbstractStateBackend

Creates and returns a new ListState.

Specified by:

createListState in class AbstractStateBackend

Type Parameters:

N - The type of the namespace.

T - The type of the values that the ListState can store.

Parameters:

namespaceSerializer - TypeSerializer for the state namespace.

stateDesc - The StateDescriptor that contains the name of the state.

Throws:

Exception

createReducingState

public <N,T> org.apache.flink.api.common.state.ReducingState<T> createReducingState(org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer,
                                                                                    org.apache.flink.api.common.state.ReducingStateDescriptor<T> stateDesc)
                                                                             throws Exception

Description copied from class: AbstractStateBackend

Creates and returns a new ReducingState.

Specified by:

createReducingState in class AbstractStateBackend

Type Parameters:

N - The type of the namespace.

T - The type of the values that the ListState can store.

Parameters:

namespaceSerializer - TypeSerializer for the state namespace.

stateDesc - The StateDescriptor that contains the name of the state.

Throws:

Exception

createFoldingState

public <N,T,ACC> org.apache.flink.api.common.state.FoldingState<T,ACC> createFoldingState(org.apache.flink.api.common.typeutils.TypeSerializer<N> namespaceSerializer,
                                                                                          org.apache.flink.api.common.state.FoldingStateDescriptor<T,ACC> stateDesc)
                                                                                   throws Exception

Description copied from class: AbstractStateBackend

Creates and returns a new FoldingState.

Specified by:

createFoldingState in class AbstractStateBackend

Type Parameters:

N - The type of the namespace.

T - Type of the values folded into the state

ACC - Type of the value in the state *

Parameters:

namespaceSerializer - TypeSerializer for the state namespace.

stateDesc - The StateDescriptor that contains the name of the state.

Throws:

Exception

checkpointStateSerializable

public <S extends Serializable> StateHandle<S> checkpointStateSerializable(S state,
                                                                           long checkpointID,
                                                                           long timestamp)
                                                                    throws Exception

Serialized the given state into bytes using Java serialization and creates a state handle that can re-create that state.

Specified by:

checkpointStateSerializable in class AbstractStateBackend

Type Parameters:

S - The type of the state.

Parameters:

state - The state to checkpoint.

checkpointID - The ID of the checkpoint.

timestamp - The timestamp of the checkpoint.

Returns:

A state handle that contains the given state serialized as bytes.

Throws:

Exception - Thrown, if the serialization fails.

createCheckpointStateOutputStream

public AbstractStateBackend.CheckpointStateOutputStream createCheckpointStateOutputStream(long checkpointID,
                                                                                          long timestamp)
                                                                                   throws Exception

Description copied from class: AbstractStateBackend

Creates an output stream that writes into the state of the given checkpoint. When the stream is closes, it returns a state handle that can retrieve the state back.

Specified by:

createCheckpointStateOutputStream in class AbstractStateBackend

Parameters:

checkpointID - The ID of the checkpoint.

timestamp - The timestamp of the checkpoint.

Returns:

An output stream that writes state for the given checkpoint.

Throws:

Exception - Exceptions may occur while creating the stream and should be forwarded.

toString

public String toString()

Overrides:

toString in class Object

create

public static MemoryStateBackend create()

Gets the default instance of this state backend, using the default maximal state size.

Returns:

The default instance of this state backend.