org.apache.flink.runtime.state

Interface Snapshotable<S extends StateObject>

Type Parameters:

S - Generic type of the state object that is created as handle to snapshots.

All Known Subinterfaces:

OperatorStateBackend

All Known Implementing Classes:

AbstractKeyedStateBackend, DefaultOperatorStateBackend, HeapKeyedStateBackend

public interface Snapshotable<S extends StateObject>

Interface for operators that can perform snapshots of their state.

Method Summary

Methods

Modifier and Type	Method and Description
void	restore(Collection<S> state) Restores state that was previously snapshotted from the provided parameters.
RunnableFuture<S>	snapshot(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 @RunnableFuture that gives a state handle to the snapshot.

Method Detail

snapshot

RunnableFuture<S> snapshot(long checkpointId,
                         long timestamp,
                         CheckpointStreamFactory streamFactory,
                         CheckpointOptions checkpointOptions)
                                               throws Exception

Operation that writes a snapshot into a stream that is provided by the given CheckpointStreamFactory and returns a @RunnableFuture that gives a state handle to the snapshot. It is up to the implementation if the operation is performed synchronous or asynchronous. In the later case, the returned Runnable must be executed first before obtaining the handle.

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 runnable future that will yield a StateObject.

Throws:

Exception

restore

void restore(Collection<S> state)
             throws Exception

Restores state that was previously snapshotted from the provided parameters. Typically the parameters are state handles from which the old state is read.

Parameters:

state - the old state to restore.

Throws:

Exception