org.apache.flink.streaming.api.transformations.SelectTransformation Maven / Gradle / Ivy
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* 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
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*/
package org.apache.flink.streaming.api.transformations;
import org.apache.flink.annotation.Internal;
import org.apache.flink.streaming.api.operators.ChainingStrategy;
import org.apache.flink.shaded.guava18.com.google.common.collect.Lists;
import java.util.Collection;
import java.util.List;
/**
* This transformation represents a selection of only certain upstream elements. This must
* follow a {@link org.apache.flink.streaming.api.transformations.SplitTransformation} that
* splits elements into several logical streams with assigned names.
*
* This does not create a physical operation, it only affects how upstream operations are
* connected to downstream operations.
*
* @param The type of the elements that result from this {@code SelectTransformation}
*/
@Internal
public class SelectTransformation extends StreamTransformation {
private final StreamTransformation input;
private final List selectedNames;
/**
* Creates a new {@code SelectionTransformation} from the given input that only selects
* the streams with the selected names.
*
* @param input The input {@code StreamTransformation}
* @param selectedNames The names from the upstream {@code SplitTransformation} that this
* {@code SelectTransformation} selects.
*/
public SelectTransformation(StreamTransformation input,
List selectedNames) {
super("Select", input.getOutputType(), input.getParallelism());
this.input = input;
this.selectedNames = selectedNames;
}
/**
* Returns the input {@code StreamTransformation}.
*/
public StreamTransformation getInput() {
return input;
}
/**
* Returns the names of the split streams that this {@code SelectTransformation} selects.
*/
public List getSelectedNames() {
return selectedNames;
}
@Override
public Collection> getTransitivePredecessors() {
List> result = Lists.newArrayList();
result.add(this);
result.addAll(input.getTransitivePredecessors());
return result;
}
@Override
public final void setChainingStrategy(ChainingStrategy strategy) {
throw new UnsupportedOperationException("Cannot set chaining strategy on Select Transformation.");
}
}