org.apache.flink.runtime.state

Class GenericReducingState<K,N,T,Backend extends AbstractStateBackend,W extends ValueState<T> & KvState<K,N,ValueState<T>,ValueStateDescriptor<T>,Backend>>

java.lang.Object

org.apache.flink.runtime.state.GenericReducingState<K,N,T,Backend,W>

Type Parameters:

K - The type of the key.

N - The type of the namespace.

T - The type of the values stored in this ReducingState.

Backend - The type of AbstractStateBackend that manages this KvState.

W - Generic type that extends both the underlying ValueState and KvState.

All Implemented Interfaces:

MergingState<T,T>, ReducingState<T>, State, KvState<K,N,ReducingState<T>,ReducingStateDescriptor<T>,Backend>

public class GenericReducingState<K,N,T,Backend extends AbstractStateBackend,W extends ValueState<T> & KvState<K,N,ValueState<T>,ValueStateDescriptor<T>,Backend>>
extends Object
implements ReducingState<T>, KvState<K,N,ReducingState<T>,ReducingStateDescriptor<T>,Backend>

Generic implementation of ReducingState based on a wrapped ValueState.

Constructor Summary

Constructors

Constructor and Description
GenericReducingState(ValueState<T> wrappedState, ReduceFunction<T> reduceFunction) Creates a new ReducingState that wraps the given ValueState.

Method Summary

Modifier and Type	Method and Description
void	add(T value) Updates the operator state accessible by MergingState.get() by adding the given value to the list of values.
void	clear() Removes the value mapped under the current key.
void	dispose() Disposes the key/value state, releasing all occupied resources.
T	get() Returns the current value for the state.
void	setCurrentKey(K key) Sets the current key, which will be used when using the state access methods.
void	setCurrentNamespace(N namespace) Sets the current namespace, which will be used when using the state access methods.
KvStateSnapshot<K,N,ReducingState<T>,ReducingStateDescriptor<T>,Backend>	snapshot(long checkpointId, long timestamp) Creates a snapshot of this state.

Methods inherited from class java.lang.Object

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

Constructor Detail

GenericReducingState

public GenericReducingState(ValueState<T> wrappedState,
                            ReduceFunction<T> reduceFunction)

Creates a new ReducingState that wraps the given ValueState. The ValueState must have a default value of null.

Parameters:

wrappedState - The wrapped ValueState

reduceFunction - The ReduceFunction to use for combining values.

Method Detail

setCurrentKey

public void setCurrentKey(K key)

Description copied from interface: KvState

Sets the current key, which will be used when using the state access methods.

Specified by:

setCurrentKey in interface KvState<K,N,ReducingState<T>,ReducingStateDescriptor<T>,Backend extends AbstractStateBackend>

Parameters:

key - The key.

setCurrentNamespace

public void setCurrentNamespace(N namespace)

Description copied from interface: KvState

Sets the current namespace, which will be used when using the state access methods.

Specified by:

setCurrentNamespace in interface KvState<K,N,ReducingState<T>,ReducingStateDescriptor<T>,Backend extends AbstractStateBackend>

Parameters:

namespace - The namespace.

snapshot

public KvStateSnapshot<K,N,ReducingState<T>,ReducingStateDescriptor<T>,Backend> snapshot(long checkpointId,
                                                                                         long timestamp)
                                                                                  throws Exception

Description copied from interface: KvState

Creates a snapshot of this state.

Specified by:

snapshot in interface KvState<K,N,ReducingState<T>,ReducingStateDescriptor<T>,Backend extends AbstractStateBackend>

Parameters:

checkpointId - The ID of the checkpoint for which the snapshot should be created.

timestamp - The timestamp of the checkpoint.

Returns:

A snapshot handle for this key/value state.

Throws:

Exception - Exceptions during snapshotting the state should be forwarded, so the system can react to failed snapshots.

dispose

public void dispose()

Description copied from interface: KvState

Disposes the key/value state, releasing all occupied resources.

Specified by:

dispose in interface KvState<K,N,ReducingState<T>,ReducingStateDescriptor<T>,Backend extends AbstractStateBackend>

get

public T get()
      throws Exception

Description copied from interface: MergingState

Returns the current value for the state. When the state is not partitioned the returned value is the same for all inputs in a given operator instance. If state partitioning is applied, the value returned depends on the current operator input, as the operator maintains an independent state for each partition.

Specified by:

get in interface MergingState<T,T>

Returns:

The operator state value corresponding to the current input.

Throws:

Exception - Thrown if the system cannot access the state.

add

public void add(T value)
         throws Exception

Description copied from interface: MergingState

Updates the operator state accessible by MergingState.get() by adding the given value to the list of values. The next time MergingState.get() is called (for the same state partition) the returned state will represent the updated list.

Specified by:

add in interface MergingState<T,T>

Parameters:

value - The new value for the state.

Throws:

IOException - Thrown if the system cannot access the state.

Exception

clear

public void clear()

Description copied from interface: State

Removes the value mapped under the current key.

Specified by:

clear in interface State