Package org.apache.heron.api.windowing
Class WaterMarkEventGenerator<T extends Serializable>
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- org.apache.heron.api.windowing.WaterMarkEventGenerator<T>
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public class WaterMarkEventGenerator<T extends Serializable> extends Object
Tracks tuples across input streams and periodically emits watermark events. Watermark event timestamp is the minimum of the latest tuple timestamps across all the input streams (minus the lag). Once a watermark event is emitted any tuple coming with an earlier timestamp can be considered as late events.
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Constructor Summary
Constructors Constructor Description WaterMarkEventGenerator(WindowManager<T> windowManager, long watermarkIntervalMs, int eventTsLagMs, Set<org.apache.heron.api.generated.TopologyAPI.StreamId> inputStreams, Map<String,Object> topoConf)
Creates a new WatermarkEventGenerator.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
run()
void
start()
boolean
track(org.apache.heron.api.generated.TopologyAPI.StreamId stream, long ts)
Tracks the timestamp of the event in the stream, returns true if the event can be considered for processing or false if its a late event.
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Constructor Detail
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WaterMarkEventGenerator
public WaterMarkEventGenerator(WindowManager<T> windowManager, long watermarkIntervalMs, int eventTsLagMs, Set<org.apache.heron.api.generated.TopologyAPI.StreamId> inputStreams, Map<String,Object> topoConf)
Creates a new WatermarkEventGenerator.- Parameters:
windowManager
- The window manager this generator will submit watermark events to intervalwatermarkIntervalMs
- the interval at which watermarks should be emittedeventTsLagMs
- The max allowed lag behind the last watermark event before an event is considered lateinputStreams
- The input streams this generator is expected to handletopoConf
- topology configurations
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