Package org.apache.flink.runtime.state

Interface SnapshotStrategy<S extends StateObject,SR extends SnapshotResources>

Type Parameters:

S - type of the returned state object that represents the result of the snapshot operation.

SR - type of produced resources in the synchronous part.

All Known Implementing Classes:

ForStIncrementalSnapshotStrategy, ForStSnapshotStrategyBase, RocksDBSnapshotStrategyBase, RocksIncrementalSnapshotStrategy, RocksNativeFullSnapshotStrategy, SavepointSnapshotStrategy

@Internal
public interface SnapshotStrategy<S extends StateObject,SR extends SnapshotResources>

Interface for different snapshot approaches in state backends. Implementing classes should ideally be stateless or at least threadsafe, it can be called in parallel by multiple checkpoints.

The interface can be later on executed in a synchronous or asynchronous manner. See SnapshotStrategyRunner.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	SnapshotStrategy.SnapshotResultSupplier<S extends StateObject>	A supplier for a SnapshotResult with an access to a CloseableRegistry for io tasks that need to be closed when cancelling the async part of the checkpoint.

Method Summary

Modifier and Type	Method	Description
SnapshotStrategy.SnapshotResultSupplier<S>	asyncSnapshot(SR syncPartResource, long checkpointId, long timestamp, CheckpointStreamFactory streamFactory, CheckpointOptions checkpointOptions)	Operation that writes a snapshot into a stream that is provided by the given CheckpointStreamFactory and returns a @SupplierWithException that gives a state handle to the snapshot.
SR	syncPrepareResources(long checkpointId)	Performs the synchronous part of the snapshot.

Method Detail

syncPrepareResources

SR syncPrepareResources(long checkpointId)
                 throws Exception

Performs the synchronous part of the snapshot. It returns resources which can be later on used in the asynchronous part.

Parameters:

checkpointId - The ID of the checkpoint.

Returns:

Resources needed to finish the snapshot.

Throws:

Exception

asyncSnapshot

SnapshotStrategy.SnapshotResultSupplier<S> asyncSnapshot(SR syncPartResource,
                                                         long checkpointId,
                                                         long timestamp,
                                                         @Nonnull
                                                         CheckpointStreamFactory streamFactory,
                                                         @Nonnull
                                                         CheckpointOptions checkpointOptions)

Operation that writes a snapshot into a stream that is provided by the given CheckpointStreamFactory and returns a @SupplierWithException that gives a state handle to the snapshot.

Parameters:

checkpointId - The ID of the checkpoint.

timestamp - The timestamp of the checkpoint.

streamFactory - The factory that we can use for writing our state to streams.

checkpointOptions - Options for how to perform this checkpoint.

Returns:

A supplier that will yield a StateObject.