public abstract class BoundedOutOfOrdernessTimestampExtractor<T> extends Object implements AssignerWithPeriodicWatermarks<T>
AssignerWithPeriodicWatermarksused to emit Watermarks that lag behind the element with the maximum timestamp (in event time) seen so far by a fixed amount of time,
t_late. This can help reduce the number of elements that are ignored due to lateness when computing the final result for a given window, in the case where we know that elements arrive no later than
t_lateunits of time after the watermark that signals that the system event-time has advanced past their (event-time) timestamp.
|Constructor and Description|
|Modifier and Type||Method and Description|
Extracts the timestamp from the given element.
Assigns a timestamp to an element, in milliseconds since the Epoch.
Returns the current watermark.
public BoundedOutOfOrdernessTimestampExtractor(Time maxOutOfOrderness)
public long getMaxOutOfOrdernessInMillis()
public abstract long extractTimestamp(T element)
element- The element that the timestamp is extracted from.
public final Watermark getCurrentWatermark()
nullto indicate that no new Watermark is available.
The returned watermark will be emitted only if it is non-null and its timestamp is larger than that of the previously emitted watermark (to preserve the contract of ascending watermarks). If the current watermark is still identical to the previous one, no progress in event time has happened since the previous call to this method. If a null value is returned, or the timestamp of the returned watermark is smaller than that of the last emitted one, then no new watermark will be generated.
The interval in which this method is called and Watermarks are generated depends on
public final long extractTimestamp(T element, long previousElementTimestamp)
The method is passed the previously assigned timestamp of the element. That previous
timestamp may have been assigned from a previous assigner, by ingestion time. If the element
did not carry a timestamp before, this value is
element- The element that the timestamp will be assigned to.
previousElementTimestamp- The previous internal timestamp of the element, or a negative value, if no timestamp has been assigned yet.
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