Design Review #642

#642: User Timing

Opened Jun 2, 2021

Ya ya yawm TAG!

I'm requesting a TAG review of User Timing.

This is actually a request to confirm or amend previous review, as requested in the CR transition https://github.com/w3c/transitions/issues/338#issuecomment-850636248

This specification was originally developed in levels, Level 2 is a W3C Recommendation. Level 3 as WD introduced Ability to execute marks and measures across arbitrary timestamps and Support for reporting arbitrary metadata along with marks and measures. The WG wishes to drop levels, merge with the existing recommendation and use the process2020 living standard model.

Explainer¹ (minimally containing user needs and example code): giving the history of this spec, its scope is hopefully well-understood at this point. From the Director's comment in the CR transition request, it seems that only recent additions would eventually need a review.
Specification URL: https://w3c.github.io/user-timing/
Tests: [wpt folder(s), if available] https://wpt.fyi/results/user-timing
Security and Privacy self-review²: https://w3c.github.io/perf-security-privacy/#privacy-and-security-considerations
GitHub repo (if you prefer feedback filed there): https://github.com/w3c/user-timing/issues
Primary contacts (and their relationship to the specification): @yoavweiss, @caribouW3
Organization(s)/project(s) driving the specification: WebPerf WG

We'd prefer the TAG provide feedback as (please delete all but the desired option):

🐛 open issues in our GitHub repo for each point of feedback

💬 leave review feedback as a comment in this issue and @-notify [github usernames]

Thank you!

Discussions

Comment by @torgo Jun 29, 2021 (See Github)

Hi @caribouW3 can you please give us a bit more context on this review - specifically you mention that there have been "recent additions" that would require a re-review but can you please be specific about what those additions are and what kind of feedback you're seeking from the TAG on these?

Comment by @caribouW3 Jun 29, 2021 (See Github)

Hi! The additions were brought with level 3 in comparison to the level 2 REC (support for Web Workers and some processing clarifications) and they were reviewed in FPWD (https://lists.w3.org/Archives/Public/public-review-announce/2019Mar/0000.html)

Since then, there's not been significant changes: diff between FPWD and latest published draft: https://services.w3.org/htmldiff?doc1=https%3A%2F%2Fwww.w3.org%2FTR%2F2019%2FWD-user-timing-3-20190305%2F&doc2=https%3A%2F%2Fwww.w3.org%2FTR%2F2021%2FWD-user-timing-3-20210308%2F

This new wide review has been requested as part of CR transition w3c/transitions#338

Discussed Aug 30, 2021 (See Github)

Sangwhan: they are minor deltas. Not much change in terms of normative text. Changes to steps in the algorithm. New notion of a structured deserialise algorithm.. I don't know enough to say if this is significant, I don't think it is

Ken: I guess Tess would be more versed in this? It's very complicated

Sangwhan: [leaves comment]

Comment by @cynthia Aug 31, 2021 (See Github)

In 3.2.1.8, something that was previously assigned null is changed to something else - is this intentional? It seems like the structured deserialize procedure described here doesn't seem to set anything to null. (unless I'm missing something)

https://html.spec.whatwg.org/multipage/structured-data.html#structureddeserialize

Discussed Sep 1, 2021 (See Github)

closed

Comment by @yoavweiss Sep 1, 2021 (See Github)

You're talking about detail which is potentially set to null (in 3.1.3.9.2)? If so, my read is that serialize returns a { [[Type]]: "primitive", [[Value]]: null } and then deserialize sets the value to null in step 5.

At the same time, we could add a null check here if it makes things more readable.

Comment by @cynthia Sep 1, 2021 (See Github)

Ah, I see. Makes sense now - think adding a null check would make it readable. (and better conveys expectations) Thanks for the quick response!

Comment by @cynthia Sep 14, 2021 (See Github)

Based on @yoavweiss's update, we are happy with the change and think this is safe to close. Thanks for bringing this to our attention.