1751402 - Check if event timestamp is negative and record error instead of adding to payload

Status: RESOLVED FIXED

(Data Platform and Tools Graveyard :: Glean.js, defect, P1)

Description

[Beatriz Rizental [:brizental]]

I noticed we are getting a few schema rejection errors due to negative timestamps from QML. That is happening because QML does not provide the performance.now API which is a monotonically increasing timer, so we use Date.now() which is not necessarily monotically increasing.

Ideally we should record an error when this happens instead of uploading an invalid ping which will get rejected.

Comment 1

[Beatriz Rizental [:brizental]]

Reminder: this might be a bug in Glean.js, please check.

Comment 2

[Beatriz Rizental [:brizental]]

I investigated this a bit and I have hypothesis to what may be happening here.

1. The events database simply sorts the timestamps, but if we receive a negative timestamp it doesn't do anything about it. Say we get events with the following timestamps: -20, 10, 0. Those would get sorted like: -20, 0, 10. Without worries about the negative timestamp.
2. Can we get negative timestamps though? Turns out in QML we can: https://github.com/mozilla/glean.js/blob/a91dee541c8936eeab7f4118bf3cf3f8841c76eb/glean/src/core/utils.ts#L188. I remember doing that for some reason, but I can't remember why.

Comment 3

[GitHub Bugzilla PR Linker]

Attachment: Link to GitHub pull-request: https://github.com/mozilla/glean.js/pull/1130