org.apache.flink.runtime.state

Interface KvState<K,N,S extends org.apache.flink.api.common.state.State,SD extends org.apache.flink.api.common.state.StateDescriptor<S,?>,Backend extends AbstractStateBackend>

Type Parameters:

K - The type of the key.

N - The type of the namespace.

S - The type of State this KvState holds.

SD - The type of the StateDescriptor for state S.

Backend - The type of AbstractStateBackend that manages this KvState.

All Known Implementing Classes:

AbstractFsState, AbstractHeapState, AbstractMemState, FsFoldingState, FsListState, FsReducingState, FsValueState, GenericFoldingState, GenericListState, GenericReducingState, MemFoldingState, MemListState, MemReducingState, MemValueState

public interface KvState<K,N,S extends org.apache.flink.api.common.state.State,SD extends org.apache.flink.api.common.state.StateDescriptor<S,?>,Backend extends AbstractStateBackend>

Key/Value state implementation for user-defined state. The state is backed by a state backend, which typically follows one of the following patterns: Either the state is stored in the key/value state object directly (meaning in the executing JVM) and snapshotted by the state backend into some store (during checkpoints), or the key/value state is in fact backed by an external key/value store as the state backend, and checkpoints merely record the metadata of what is considered part of the checkpoint.

Method Summary

Modifier and Type	Method and Description
void	dispose() Disposes the key/value state, releasing all occupied resources.
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,S,SD,Backend>	snapshot(long checkpointId, long timestamp) Creates a snapshot of this state.

Method Detail

setCurrentKey

void setCurrentKey(K key)

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

Parameters:

key - The key.

setCurrentNamespace

void setCurrentNamespace(N namespace)

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

Parameters:

namespace - The namespace.

snapshot

KvStateSnapshot<K,N,S,SD,Backend> snapshot(long checkpointId,
                                           long timestamp)
                                    throws Exception

Creates a snapshot of this state.

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

void dispose()

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