org.apache.flink.streaming.api.transformations.CoFeedbackTransformation Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* 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.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.dag.Transformation;
import org.apache.flink.shaded.guava30.com.google.common.collect.Lists;
import java.util.Collections;
import java.util.List;
/**
* This represents a feedback point in a topology. The type of the feedback elements need not match
* the type of the upstream {@code Transformation} because the only allowed operations after a
* {@code CoFeedbackTransformation} are {@link
* org.apache.flink.streaming.api.transformations.TwoInputTransformation TwoInputTransformations}.
* The upstream {@code Transformation} will be connected to the first input of the Co-Transform
* while the feedback edges will be connected to the second input.
*
* Both the partitioning of the input and the feedback edges is preserved. They can also have
* differing partitioning strategies. This requires, however, that the parallelism of the feedback
* {@code Transformations} must match the parallelism of the input {@code Transformation}.
*
*
The upstream {@code Transformation} is not wired to this {@code CoFeedbackTransformation}. It
* is instead directly wired to the {@code TwoInputTransformation} after this {@code
* CoFeedbackTransformation}.
*
*
This is different from Iterations in batch processing.
*
* @see org.apache.flink.streaming.api.transformations.FeedbackTransformation
* @param The type of the feedback elements.
*/
@Internal
public class CoFeedbackTransformation extends Transformation {
private final List> feedbackEdges;
private final Long waitTime;
/**
* Creates a new {@code CoFeedbackTransformation} from the given input.
*
* @param parallelism The parallelism of the upstream {@code Transformation} and the feedback
* edges.
* @param feedbackType The type of the feedback edges
* @param waitTime The wait time of the feedback operator. After the time expires the operation
* will close and not receive any more feedback elements.
*/
public CoFeedbackTransformation(
int parallelism, TypeInformation feedbackType, Long waitTime) {
super("CoFeedback", feedbackType, parallelism);
this.waitTime = waitTime;
this.feedbackEdges = Lists.newArrayList();
}
/**
* Adds a feedback edge. The parallelism of the {@code Transformation} must match the
* parallelism of the input {@code Transformation} of the upstream {@code Transformation}.
*
* @param transform The new feedback {@code Transformation}.
*/
public void addFeedbackEdge(Transformation transform) {
if (transform.getParallelism() != this.getParallelism()) {
throw new UnsupportedOperationException(
"Parallelism of the feedback stream must match the parallelism of the original"
+ " stream. Parallelism of original stream: "
+ this.getParallelism()
+ "; parallelism of feedback stream: "
+ transform.getParallelism());
}
feedbackEdges.add(transform);
}
/** Returns the list of feedback {@code Transformations}. */
public List> getFeedbackEdges() {
return feedbackEdges;
}
/**
* Returns the wait time. This is the amount of time that the feedback operator keeps listening
* for feedback elements. Once the time expires the operation will close and will not receive
* further elements.
*/
public Long getWaitTime() {
return waitTime;
}
@Override
public List> getTransitivePredecessors() {
return Collections.singletonList(this);
}
@Override
public List> getInputs() {
return Collections.emptyList();
}
}