org.apache.flink.runtime.state.Snapshotable Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
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*/
package org.apache.flink.runtime.state;
import org.apache.flink.runtime.checkpoint.CheckpointOptions;
import java.util.concurrent.RunnableFuture;
/**
* Interface for operators that can perform snapshots of their state.
*
* @param Generic type of the state object that is created as handle to snapshots.
* @param Generic type of the state object that used in restore.
*/
public interface Snapshotable {
/**
* Operation that writes a snapshot into a stream that is provided by the given {@link CheckpointStreamFactory} and
* returns a @{@link 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.
*
* @param checkpointId The ID of the checkpoint.
* @param timestamp The timestamp of the checkpoint.
* @param streamFactory The factory that we can use for writing our state to streams.
* @param checkpointOptions Options for how to perform this checkpoint.
* @return A runnable future that will yield a {@link StateObject}.
*/
RunnableFuture snapshot(
long checkpointId,
long timestamp,
CheckpointStreamFactory streamFactory,
CheckpointOptions checkpointOptions) 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.
*
* @param state the old state to restore.
*/
void restore(R state) throws Exception;
}