[Nfd-dev] Review request for incoming data processing

[Alex Afanasyev]

> On Nov 17, 2020, at 2:26 PM, Davide Pesavento <davidepesa at gmail.com> wrote:
> 
> See https://redmine.named-data.net/issues/4290 for some background and
> discussion (the first ~20 comments or so).
> 
> If I remember correctly, strategies don't have "to be prepared to
> receive both" because the afterReceiveData trigger has a default
> implementation that invokes beforeSatisfyInterest + sends the Data to
> all valid downstreams.

Yeah, I forgot to delete this part.  Yet still, you cannot override just afterReceiveData, as it will not be always called.

My kind of meta question is why not just have one branch and only have beforeSatisfyInterest trigger? Why both?   But will check the referenced redmine comments in case it already has an answer.

-
Alex

> This was done for backward compatibility as
> well as simplicity, since most strategies don't need the additional
> control provided by afterReceiveData.
> 
> The current algorithm could be refined to check whether multiple
> different strategies have control over the satisfied PIT entries or
> it's the same strategy for all PIT entries. It's only the former case
> that is problematic. This logic would be more complex to implement
> though.
> 
> Davide
> 
> On Tue, Nov 17, 2020 at 1:57 PM Alex Afanasyev via Nfd-dev
> <nfd-dev at lists.cs.ucla.edu> wrote:
>> 
>> While reviewing our current implementation of the incoming data processing pipeline, I noticed a difference on how we deal with data matching a single PIT entry and multiple PIT entries.  Quite frankly, I have completely forgotten our previous discussions regarding this difference, but I'm not sure, at this time, can fully comprehend the reasoning for a difference.   The only difference, as far as I can see, is that strategy either going to receive "afterReceivedData" trigger or "beforeSatisfyInterest" trigger... yet it has to be prepare to receive both.
>> 
>> My quick glance in strategy implementation shows:
>> 
>> - access-strategy overrides only beforeSatisfyInterest; afterRecieveData is kept from the base class and will invoke beforeSatisfyInterest + sends data
>> 
>> - asf-strategy the same. only beforeSatisfyInterest is implemented, leaving base class afterRetreiveData to call beforeSatisfyInterest
>> 
>> - ncc-strategy the same
>> 
>> - self-learning strategy (the merged code) overrides ONLY afterReceiveData. Unless I'm missing it, it basically will be failing in the case multiple PIT entries will match (intentional or a bug?)
>> 
>> - other strategies in mainstrem NFD don't override either. Cannot say for experimental strategies in ndnSIM forks.
>> 
>> 
>> My objective for this email to remember the reason why we did this and maybe re-evaluate the decision, as it doesn't look too obvious to me and potentially error prone.
>> 
>> ______________
>> Alex Afanasyev
>> Assistant Professor, SCIS, Florida International University
>> 11200 SW 8th Street, PG6 Room 140D, Miami, FL 33199
>> phone: +1.305.348.4960 (office); email: aa at cs.fiu.edu
>> web: https://users.cs.fiu.edu/~afanasyev/
>> 
>> 
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>> Nfd-dev mailing list
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______________
Alex Afanasyev
Assistant Professor, SCIS, Florida International University
11200 SW 8th Street, PG6 Room 140D, Miami, FL 33199
phone: +1.305.348.4960 (office); email: aa at cs.fiu.edu
web: https://users.cs.fiu.edu/~afanasyev/


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