org.apache.flink.runtime.state.internal.InternalMergingState Maven / Gradle / Ivy
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* 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,
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* See the License for the specific language governing permissions and
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*/
package org.apache.flink.runtime.state.internal;
import org.apache.flink.api.common.state.MergingState;
import java.util.Collection;
/**
* The peer to the {@link MergingState} in the internal state type hierarchy.
*
* See {@link InternalKvState} for a description of the internal state hierarchy.
*
* @param The type of key the state is associated to
* @param The type of the namespace
* @param The type of elements added to the state
* @param The type of elements in the state
* @param The type of elements
*/
public interface InternalMergingState extends InternalAppendingState, MergingState {
/**
* Merges the state of the current key for the given source namespaces into the state of
* the target namespace.
*
* @param target The target namespace where the merged state should be stored.
* @param sources The source namespaces whose state should be merged.
*
* @throws Exception The method may forward exception thrown internally (by I/O or functions).
*/
void mergeNamespaces(N target, Collection sources) throws Exception;
}