org.apache.flink.streaming.api.functions.windowing.delta.ExtractionAwareDeltaFunction Maven / Gradle / Ivy
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* 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
* limitations under the License.
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package org.apache.flink.streaming.api.functions.windowing.delta;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.streaming.api.functions.windowing.delta.extractor.Extractor;
/**
* Extend this abstract class to implement a delta function which is aware of
* extracting the data on which the delta is calculated from a more complex data
* structure. For example in case you want to be able to run a delta only on one
* field of a Tuple type or only on some fields from an array.
*
* @param
* The input data type. The input of this type will be passed to the
* extractor which will transform into a TO-object. The delta
* function then runs on this TO-object.
* @param
* The type on which the delta function runs. (The type of the delta
* function)
*/
@PublicEvolving
public abstract class ExtractionAwareDeltaFunction implements DeltaFunction {
private static final long serialVersionUID = 6927486219702689554L;
private Extractor converter;
public ExtractionAwareDeltaFunction(Extractor converter) {
this.converter = converter;
}
/**
* This method takes the two data point and runs the set extractor on it.
* The delta function implemented at {@link #getNestedDelta} is then called
* with the extracted data. In case no extractor is set the input data gets
* passes to {@link #getNestedDelta} as-is. The return value is just
* forwarded from {@link #getNestedDelta}.
*
* @param oldDataPoint
* the older data point as raw data (before extraction).
* @param newDataPoint
* the new data point as raw data (before extraction).
* @return the delta between the two points.
*/
@SuppressWarnings("unchecked")
@Override
public double getDelta(DATA oldDataPoint, DATA newDataPoint) {
if (converter == null) {
// In case no conversion/extraction is required, we can cast DATA to
// TO
// => Therefore, "unchecked" warning is suppressed for this method.
return getNestedDelta((TO) oldDataPoint, (TO) newDataPoint);
} else {
return getNestedDelta(converter.extract(oldDataPoint), converter.extract(newDataPoint));
}
}
/**
* This method is exactly the same as
* {@link DeltaFunction#getDelta(Object, Object)} except that it gets the
* result of the previously done extractions as input. Therefore, this
* method only does the actual calculation of the delta but no data
* extraction or conversion.
*
* @param oldDataPoint
* the older data point.
* @param newDataPoint
* the new data point.
* @return the delta between the two points.
*/
public abstract double getNestedDelta(TO oldDataPoint, TO newDataPoint);
}