Package org.apache.storm.windowing

Class WaterMarkEventGenerator<T>

java.lang.Object

org.apache.storm.windowing.WaterMarkEventGenerator<T>

All Implemented Interfaces:

Runnable

public class WaterMarkEventGenerator<T>
extends Object
implements Runnable

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.

Constructor Summary

Constructors

Constructor	Description
WaterMarkEventGenerator(WindowManager<T> windowManager, int intervalMs, int eventTsLagMs, Set<GlobalStreamId> inputStreams)	Creates a new WatermarkEventGenerator.

Method Summary

Modifier and Type	Method	Description
void	run()
void	shutdown()
void	start()
boolean	track(GlobalStreamId 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.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

WaterMarkEventGenerator

public WaterMarkEventGenerator(WindowManager<T> windowManager,
 int intervalMs,
 int eventTsLagMs,
 Set<GlobalStreamId> inputStreams)

Creates a new WatermarkEventGenerator.

Parameters:

windowManager - The window manager this generator will submit watermark events to

intervalMs - The generator will check if it should generate a watermark event with this interval

eventTsLagMs - The max allowed lag behind the last watermark event before an event is considered late

inputStreams - The input streams this generator is expected to handle

Method Details

track

public boolean track(GlobalStreamId 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.

run

public void run()

Specified by:

run in interface Runnable

start

public void start()

shutdown

public void shutdown()