org.apache.flink.runtime.state.heap.AbstractHeapMergingState 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
* 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.heap;
import org.apache.flink.api.common.state.MergingState;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.runtime.state.StateTransformationFunction;
import org.apache.flink.runtime.state.internal.InternalMergingState;
import java.util.Collection;
/**
* Base class for {@link MergingState} ({@link InternalMergingState}) that is stored on the heap.
*
* @param The type of the key.
* @param The type of the namespace.
* @param The type of the input elements.
* @param The type of the values in the state.
* @param The type of the output elements.
*/
abstract class AbstractHeapMergingState
extends AbstractHeapAppendingState
implements InternalMergingState {
/**
* The merge transformation function that implements the merge logic.
*/
private final MergeTransformation mergeTransformation;
/**
* Creates a new key/value state for the given hash map of key/value pairs.
*
* @param stateTable The state table for which this state is associated to.
* @param keySerializer The serializer for the keys.
* @param valueSerializer The serializer for the state.
* @param namespaceSerializer The serializer for the namespace.
* @param defaultValue The default value for the state.
*/
protected AbstractHeapMergingState(
StateTable stateTable,
TypeSerializer keySerializer,
TypeSerializer valueSerializer,
TypeSerializer namespaceSerializer,
SV defaultValue) {
super(stateTable, keySerializer, valueSerializer, namespaceSerializer, defaultValue);
this.mergeTransformation = new MergeTransformation();
}
@Override
public void mergeNamespaces(N target, Collection sources) throws Exception {
if (sources == null || sources.isEmpty()) {
return; // nothing to do
}
final StateTable map = stateTable;
SV merged = null;
// merge the sources
for (N source : sources) {
// get and remove the next source per namespace/key
SV sourceState = map.removeAndGetOld(source);
if (merged != null && sourceState != null) {
merged = mergeState(merged, sourceState);
} else if (merged == null) {
merged = sourceState;
}
}
// merge into the target, if needed
if (merged != null) {
map.transform(target, merged, mergeTransformation);
}
}
protected abstract SV mergeState(SV a, SV b) throws Exception;
final class MergeTransformation implements StateTransformationFunction {
@Override
public SV apply(SV targetState, SV merged) throws Exception {
if (targetState != null) {
return mergeState(targetState, merged);
} else {
return merged;
}
}
}
}