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:

IterableStateSnapshot<K,N,S>, 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	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

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Iterator<StateEntry<K,N,S>>`	`getIterator(int keyGroupId)`
`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)`	`CopyOnWriteStateTable` could naturally support a kind of prefix-compressed format (grouping by namespace, writing the namespace only once per group instead for each mapping).

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
  - getIterator
```
public Iterator<StateEntry<K,N,S>> getIterator(int keyGroupId)
```
    Specified by:
    
    getIterator in interface IterableStateSnapshot<K,N,S>
  - writeStateInKeyGroup
```
public void writeStateInKeyGroup(@Nonnull
                                 org.apache.flink.core.memory.DataOutputView dov,
                                 int keyGroupId)
                          throws IOException
```
    CopyOnWriteStateTable 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.

Class CopyOnWriteStateTableSnapshot<K,​N,​S>

Nested Class Summary

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

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

owningStateTable

localKeySerializer

localNamespaceSerializer

localStateSerializer

stateSnapshotTransformer

Method Detail

getStateMapSnapshotForKeyGroup

release

getMetaInfoSnapshot

getKeyGroupWriter

getIterator

writeStateInKeyGroup

Class CopyOnWriteStateTableSnapshot<K,N,S>