Hi Vishal,
the Trigger is not designed to augment records but just to control when a
window is evaluated.
I would recommend to use a ProcessFunction to enrich records with the
current watermark before passing them into the window operator.
The context object of the processElement() method gives access to the
current watermark and timestamp of a record.
Please note that watermarks are not deterministic but may depend on the
order in which parallel inputs are consumed by an operator.
Best, Fabian
2017-12-17 16:59 GMT+01:00 Vishal Santoshi <vishal.santo...@gmail.com>:
> An addendum
>
> Is the element reference IN in onElement(IN element.. ) in
> Trigger<IN,..>, the same as IN the one provided to add(IN value) in
> Accumulator<IN,..>. It seems that any mutations to IN in the onElement() is
> not visible to the Accumulator that is carrying it as a previous element
> reference albeit in the next invocation of add(). This seems to be only in
> distributed mode, which makes sense only if theses reference point to
> different objects.
>
> The pipeline
>
> .keyBy(keySelector)
> .window(EventTimeSessionWindows.<IN>withGap(gap))
> .trigger(new CountBasedWMAugmentationTrigger<IN,TimeWindow>(triggerCount))
> .aggregate(
> new AggregateFunction<IN, ACC, OUT>() {
>
> @Override
> public ACC createAccumulator() {
> ACC newInstance = (ACC) accumulator.clone();
> newInstance.resetLocal();
> return newInstance;
> }
>
> @Override
> public void add(IN value, ACC accumulator) {
>
> /** This method is called before onElement of the Trigger and
> keeps the reference to the last IN **/
>
>
> accumulator.add(value);
>
> }
> .....
>
> The Trigger
>
>
> public class CountBasedWMAugmentationTrigger<T extends
> Serializable & CountBasedWMAugmentationTrigger.HasWaterMark, W
> extends Window> extends Trigger<T, W> {
>
>
> @Override
>
> public TriggerResult onElement(T element, long timestamp, W window,
> TriggerContext ctx) throws Exception {
>
> /** The element T is mutated to carry the watermark **/
> *element.setWaterMark(ctx.getCurrentWatermark());*
>
> .
>
>
>
>
>
> On Sun, Dec 17, 2017 at 1:52 AM, Vishal Santoshi <
> vishal.santo...@gmail.com> wrote:
>
>> I want to augment a POJO in Trigger's onElement method, specifically
>> supply the POJO with the watermark from the TriggerContext. The sequence of
>> execution is this sequence
>>
>> 1. call to add() in the accumulator for the window and save the POJO
>> reference in the Accumulator.
>> 2. call to onElement on Tigger
>> 3. set watermark to the POJO
>>
>> The next add() method should have the last reference and any mutation
>> done in step 3.
>>
>> That works in a local test case, using LocalFlinkMiniCluster, as in I
>> have access to the mutation by the onElement() in the POJO in the
>> subsequent add(), but not on a distributed cluster. The specific question
>> I had is whether add() on a supplied accumulator on a window and
>> onElement() method of the trigger on that window are inline executions, on
>> the same thread or is there any serialization/deserialization IPC that
>> causes these divergence ( local versus distributed )
>>
>> Regards.
>>
>
>
