org.apache.flink.streaming.api.operators.StreamGroupedReduce 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,
* 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.streaming.api.operators;
import org.apache.flink.annotation.Internal;
import org.apache.flink.api.common.functions.ReduceFunction;
import org.apache.flink.api.common.state.ValueState;
import org.apache.flink.api.common.state.ValueStateDescriptor;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;
/**
* A {@link StreamOperator} for executing a {@link ReduceFunction} on a
* {@link org.apache.flink.streaming.api.datastream.KeyedStream}.
*/
@Internal
public class StreamGroupedReduce extends AbstractUdfStreamOperator>
implements OneInputStreamOperator {
private static final long serialVersionUID = 1L;
private static final String STATE_NAME = "_op_state";
private transient ValueState values;
private TypeSerializer serializer;
public StreamGroupedReduce(ReduceFunction reducer, TypeSerializer serializer) {
super(reducer);
this.serializer = serializer;
}
@Override
public void open() throws Exception {
super.open();
ValueStateDescriptor stateId = new ValueStateDescriptor<>(STATE_NAME, serializer);
values = getPartitionedState(stateId);
}
@Override
public void processElement(StreamRecord element) throws Exception {
IN value = element.getValue();
IN currentValue = values.value();
if (currentValue != null) {
IN reduced = userFunction.reduce(currentValue, value);
values.update(reduced);
output.collect(element.replace(reduced));
} else {
values.update(value);
output.collect(element.replace(value));
}
}
}