org.apache.flink.runtime.state.CompositeStateHandle Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* 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;
/**
* Base of all snapshots that are taken by {@link StateBackend}s and some other
* components in tasks.
*
* Each snapshot is composed of a collection of {@link StateObject}s some of
* which may be referenced by other checkpoints. The shared states will be
* registered at the given {@link SharedStateRegistry} when the handle is
* received by the {@link org.apache.flink.runtime.checkpoint.CheckpointCoordinator}
* and will be discarded when the checkpoint is discarded.
*
*
The {@link SharedStateRegistry} is responsible for the discarding of registered
* shared states. Before their first registration through
* {@link #registerSharedStates(SharedStateRegistry)}, newly created shared state is still owned by
* this handle and considered as private state until it is registered for the first time. Registration
* transfers ownership to the {@link SharedStateRegistry}.
* The composite state handle should only delete all private states in the
* {@link StateObject#discardState()} method, the {@link SharedStateRegistry} is responsible for
* deleting shared states after they were registered.
*/
public interface CompositeStateHandle extends StateObject {
/**
* Register both newly created and already referenced shared states in the given
* {@link SharedStateRegistry}. This method is called when the checkpoint
* successfully completes or is recovered from failures.
*
* After this is completed, newly created shared state is considered as published is no longer
* owned by this handle. This means that it should no longer be deleted as part of calls to
* {@link #discardState()}. Instead, {@link #discardState()} will trigger an unregistration
* from the registry.
*
* @param stateRegistry The registry where shared states are registered.
*/
void registerSharedStates(SharedStateRegistry stateRegistry);
}