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

@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. Besides holding the CopyOnWriteStateTables internal entries at the time of the snapshot, this class is also responsible for preparing and writing the state in the process of checkpointing.

IMPORTANT: Please notice that snapshot integrity of entries in this class rely on proper copy-on-write semantics through the CopyOnWriteStateTable that created the snapshot object, but all objects in this snapshot must be considered as READ-ONLY!. The reason is that the objects held by this class may or may not be deep copies of original objects that may still used in the CopyOnWriteStateTable. This depends for each entry on whether or not it was subject to copy-on-write operations by the CopyOnWriteStateTable. Phrased differently: the CopyOnWriteStateTable provides copy-on-write isolation for this snapshot, but this snapshot does not isolate modifications from the CopyOnWriteStateTable!

Method Summary

Modifier and Type	Method and Description
void	release() Optional hook to release resources for this snapshot at the end of its lifecycle.
void	writeMappingsInKeyGroup(org.apache.flink.core.memory.DataOutputView dov, int keyGroupId)

Methods inherited from class java.lang.Object

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

Method Detail

release

public void release()

Optional hook to release resources for this snapshot at the end of its lifecycle.

writeMappingsInKeyGroup

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

Throws:

IOException