org.apache.flink.streaming.api.transformations

Class FeedbackTransformation<T>

java.lang.Object

org.apache.flink.streaming.api.transformations.StreamTransformation<T>

org.apache.flink.streaming.api.transformations.FeedbackTransformation<T>

Type Parameters:

T - The type of the input elements and the feedback elements.

@Internal
public class FeedbackTransformation<T>
extends StreamTransformation<T>

This represents a feedback point in a topology.

This is different from how iterations work in batch processing. Once a feedback point is defined you can connect one or several StreamTransformations as a feedback edges. Operations downstream from the feedback point will receive elements from the input of this feedback point and from the feedback edges.

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 StreamTransformations must match the parallelism of the input StreamTransformation.

The type of the input StreamTransformation and the feedback StreamTransformation must match.

Field Summary

Fields inherited from class org.apache.flink.streaming.api.transformations.StreamTransformation

bufferTimeout, id, idCounter, name, outputType, typeUsed

Constructor Summary

Constructors

Constructor and Description
FeedbackTransformation(StreamTransformation<T> input, Long waitTime) Creates a new FeedbackTransformation from the given input.

Method Summary

Modifier and Type	Method and Description
void	addFeedbackEdge(StreamTransformation<T> transform) Adds a feedback edge.
List<StreamTransformation<T>>	getFeedbackEdges() Returns the list of feedback StreamTransformations.
StreamTransformation<T>	getInput() Returns the input StreamTransformation of this FeedbackTransformation.
Collection<StreamTransformation<?>>	getTransitivePredecessors() Returns all transitive predecessor StreamTransformations of this StreamTransformation.
Long	getWaitTime() Returns the wait time.
void	setChainingStrategy(ChainingStrategy strategy) Sets the chaining strategy of this StreamTransformation.

Methods inherited from class org.apache.flink.streaming.api.transformations.StreamTransformation

equals, getBufferTimeout, getId, getName, getNewNodeId, getOutputType, getParallelism, getSlotSharingGroup, getUid, hashCode, setBufferTimeout, setName, setOutputType, setParallelism, setSlotSharingGroup, setUid, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

FeedbackTransformation

public FeedbackTransformation(StreamTransformation<T> input,
                              Long waitTime)

Creates a new FeedbackTransformation from the given input.

Parameters:

input - The input StreamTransformation

waitTime - The wait time of the feedback operator. After the time expires the operation will close and not receive any more feedback elements.

Method Detail

getInput

public StreamTransformation<T> getInput()

Returns the input StreamTransformation of this FeedbackTransformation.

addFeedbackEdge

public void addFeedbackEdge(StreamTransformation<T> transform)

Adds a feedback edge. The parallelism of the StreamTransformation must match the parallelism of the input StreamTransformation of this FeedbackTransformation

Parameters:

transform - The new feedback StreamTransformation.

getFeedbackEdges

public List<StreamTransformation<T>> getFeedbackEdges()

Returns the list of feedback StreamTransformations.

getWaitTime

public Long getWaitTime()

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.

setChainingStrategy

public final void setChainingStrategy(ChainingStrategy strategy)

Description copied from class: StreamTransformation

Sets the chaining strategy of this StreamTransformation.

Specified by:

setChainingStrategy in class StreamTransformation<T>

getTransitivePredecessors

public Collection<StreamTransformation<?>> getTransitivePredecessors()

Description copied from class: StreamTransformation

Returns all transitive predecessor StreamTransformations of this StreamTransformation. This is, for example, used when determining whether a feedback edge of an iteration actually has the iteration head as a predecessor.

Specified by:

getTransitivePredecessors in class StreamTransformation<T>

Returns:

The list of transitive predecessors.