WaterMarkEventGenerator (Storm 2.7.1 API)

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

All Methods Instance Methods Concrete Methods
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 Detail
  - 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 Detail
  - 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()
```