org.apache.flink.runtime.state.SnapshotStrategy Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* 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
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.state;
import org.apache.flink.annotation.Internal;
import org.apache.flink.core.fs.CloseableRegistry;
import org.apache.flink.runtime.checkpoint.CheckpointOptions;
import org.apache.flink.util.function.SupplierWithException;
import javax.annotation.Nonnull;
/**
* 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 {@link
* SnapshotStrategyRunner}.
*
* @param type of the returned state object that represents the result of the snapshot
* operation.
* @param type of produced resources in the synchronous part.
*/
@Internal
public interface SnapshotStrategy {
/**
* Performs the synchronous part of the snapshot. It returns resources which can be later on
* used in the asynchronous part.
*
* @param checkpointId The ID of the checkpoint.
* @return Resources needed to finish the snapshot.
*/
SR syncPrepareResources(long checkpointId) throws Exception;
/**
* Operation that writes a snapshot into a stream that is provided by the given {@link
* CheckpointStreamFactory} and returns a @{@link SupplierWithException} that gives a state
* handle to the snapshot.
*
* @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 supplier that will yield a {@link StateObject}.
*/
SnapshotResultSupplier asyncSnapshot(
SR syncPartResource,
long checkpointId,
long timestamp,
@Nonnull CheckpointStreamFactory streamFactory,
@Nonnull CheckpointOptions checkpointOptions);
/**
* A supplier for a {@link SnapshotResult} with an access to a {@link CloseableRegistry} for io
* tasks that need to be closed when cancelling the async part of the checkpoint.
*
* @param type of the returned state object that represents the result of the snapshot *
* operation.
*/
@FunctionalInterface
interface SnapshotResultSupplier {
/**
* Performs the asynchronous part of a checkpoint and returns the snapshot result.
*
* @param snapshotCloseableRegistry A registry for io tasks to close on cancel.
* @return A snapshot result
*/
SnapshotResult get(CloseableRegistry snapshotCloseableRegistry) throws Exception;
}
}