org.apache.flink.runtime.state.heap

Class CopyOnWriteStateTableSnapshot<K,N,S>

java.lang.Object

org.apache.flink.runtime.state.heap.CopyOnWriteStateTableSnapshot<K,N,S>

Type Parameters:

K - type of key

N - type of namespace

S - type of state

All Implemented Interfaces:

StateSnapshot, StateSnapshot.StateKeyGroupWriter

@Internal
public class CopyOnWriteStateTableSnapshot<K,N,S>
extends Object

This class represents the snapshot of a CopyOnWriteStateTable and has a role in operator state checkpointing. This class is also responsible for writing the state in the process of checkpointing.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.runtime.state.StateSnapshot

StateSnapshot.StateKeyGroupWriter

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.flink.api.common.typeutils.TypeSerializer<K>	localKeySerializer A local duplicate of the table's key serializer.
protected org.apache.flink.api.common.typeutils.TypeSerializer<N>	localNamespaceSerializer A local duplicate of the table's namespace serializer.
protected org.apache.flink.api.common.typeutils.TypeSerializer<S>	localStateSerializer A local duplicate of the table's state serializer.
protected StateTable<K,N,S>	owningStateTable The StateTable from which this snapshot was created.
protected StateSnapshotTransformer<S>	stateSnapshotTransformer

Method Summary

Modifier and Type	Method and Description
StateSnapshot.StateKeyGroupWriter	getKeyGroupWriter() This method returns StateSnapshot.StateKeyGroupWriter and should be called in the asynchronous part of the snapshot.
StateMetaInfoSnapshot	getMetaInfoSnapshot() Returns a snapshot of the state's meta data.
protected StateMapSnapshot<K,N,S,? extends StateMap<K,N,S>>	getStateMapSnapshotForKeyGroup(int keyGroup) Return the state map snapshot for the key group.
void	release() Release the snapshot.
void	writeStateInKeyGroup(org.apache.flink.core.memory.DataOutputView dov, int keyGroupId) Implementation note: we currently chose the same format between NestedMapsStateTable and CopyOnWriteStateTable.

Methods inherited from class java.lang.Object

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

Field Detail

owningStateTable

protected final StateTable<K,N,S> owningStateTable

The StateTable from which this snapshot was created.

localKeySerializer

@Nonnull
protected final org.apache.flink.api.common.typeutils.TypeSerializer<K> localKeySerializer

A local duplicate of the table's key serializer.

localNamespaceSerializer

@Nonnull
protected final org.apache.flink.api.common.typeutils.TypeSerializer<N> localNamespaceSerializer

A local duplicate of the table's namespace serializer.

localStateSerializer

@Nonnull
protected final org.apache.flink.api.common.typeutils.TypeSerializer<S> localStateSerializer

A local duplicate of the table's state serializer.

stateSnapshotTransformer

@Nullable
protected final StateSnapshotTransformer<S> stateSnapshotTransformer

Method Detail

getStateMapSnapshotForKeyGroup

protected StateMapSnapshot<K,N,S,? extends StateMap<K,N,S>> getStateMapSnapshotForKeyGroup(int keyGroup)

Return the state map snapshot for the key group. If the snapshot does not exist, return null.

release

public void release()

Description copied from interface: StateSnapshot

Release the snapshot. All snapshots should be released when they are no longer used because some implementation can only release resources after a release. Produced StateSnapshot.StateKeyGroupWriter should no longer be used after calling this method.

getMetaInfoSnapshot

@Nonnull
public StateMetaInfoSnapshot getMetaInfoSnapshot()

Description copied from interface: StateSnapshot

Returns a snapshot of the state's meta data.

Specified by:

getMetaInfoSnapshot in interface StateSnapshot

getKeyGroupWriter

public StateSnapshot.StateKeyGroupWriter getKeyGroupWriter()

Description copied from interface: StateSnapshot

This method returns StateSnapshot.StateKeyGroupWriter and should be called in the asynchronous part of the snapshot.

Specified by:

getKeyGroupWriter in interface StateSnapshot

writeStateInKeyGroup

public void writeStateInKeyGroup(@Nonnull
                                 org.apache.flink.core.memory.DataOutputView dov,
                                 int keyGroupId)
                          throws IOException

Implementation note: we currently chose the same format between NestedMapsStateTable and CopyOnWriteStateTable.

NestedMapsStateTable could naturally support a kind of prefix-compressed format (grouping by namespace, writing the namespace only once per group instead for each mapping). We might implement support for different formats later (tailored towards different state table implementations).

Specified by:

writeStateInKeyGroup in interface StateSnapshot.StateKeyGroupWriter

Parameters:

dov - the output.

keyGroupId - the key-group to write.

Throws:

IOException - on write-related problems.