org.apache.flink.runtime.state.CheckpointStreamFactory Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.state;
import java.io.IOException;
import java.util.List;
/**
* A factory for checkpoint output streams, which are used to persist data for checkpoints.
*
* Stream factories can be created from the {@link CheckpointStorageAccess} through {@link
* CheckpointStorageAccess#resolveCheckpointStorageLocation(long,
* CheckpointStorageLocationReference)}.
*/
public interface CheckpointStreamFactory {
/**
* Creates an new {@link CheckpointStateOutputStream}. When the stream is closed, it returns a
* state handle that can retrieve the state back.
*
* @param scope The state's scope, whether it is exclusive or shared.
* @return An output stream that writes state for the given checkpoint.
* @throws IOException Exceptions may occur while creating the stream and should be forwarded.
*/
CheckpointStateOutputStream createCheckpointStateOutputStream(CheckpointedStateScope scope)
throws IOException;
/**
* Tells if we can duplicate the given {@link StreamStateHandle} into the path corresponding to
* the given {@link CheckpointedStateScope}.
*
*
This should be a rather cheap operation, preferably not involving any remote accesses.
*
* @param stateHandle The handle to duplicate
* @param scope Scope determining the location to duplicate into
* @return true, if we can perform the duplication
*/
boolean canFastDuplicate(StreamStateHandle stateHandle, CheckpointedStateScope scope)
throws IOException;
/**
* Duplicates {@link StreamStateHandle} into the path corresponding to * the given {@link
* CheckpointedStateScope}.
*
*
You should first check if you can duplicate with {@link
* #canFastDuplicate(StreamStateHandle, CheckpointedStateScope)}.
*
* @param stateHandles The handles to duplicate
* @param scope Scope determining the location to duplicate into
* @return The duplicated handle
*/
List duplicate(
List stateHandles, CheckpointedStateScope scope) throws IOException;
}