Closed Bug 1619349 Opened 5 months ago Closed 4 months ago

Add telemetry to determine potential impact of anti-font-fingerprinting measures

Categories

(Core :: Layout: Text and Fonts, enhancement, P3)

enhancement

Tracking

()

RESOLVED FIXED
mozilla76
Tracking Status
firefox76 --- fixed

People

(Reporter: jfkthame, Assigned: jfkthame)

References

Details

(Whiteboard: [layout:backlog:76])

Attachments

(3 files)

We are considering measures to limit font-based fingerprinting by restricting the set of fonts that are exposed via CSS font-family etc.

To better understand the potential impact of such changes, we should add telemetry to find out how frequently users may see rendering differences or breakage.

I propose that as an initial step, we should report:

  • How often does a page fail to find any font, and resort to hexbox rendering?
    • If the frequency of this rises noticeably when we make changes, that would suggest users are getting a bad experience
  • How often does a page use a locally-installed font that was not part of the default (OS-provided) font collection?
    • These are fonts that we are considering blocking, which means the rendering of the page would change
  • How often does font fallback end up using a non-OS-provided font?

We already have some webfont telemetry in place; this is probably a reasonable place to add installed-font telemetry as well.

Depends on: 1619350
Whiteboard: [layout:backlog:2020]
Attached file data-review request
Attachment #9133672 - Flags: data-review?(chutten)
Attachment #9133672 - Attachment filename: anti-font-fingerprinting-data-review.md → anti-font-fingerprinting-data-review.txt
Assignee: nobody → jfkthame
Status: NEW → ASSIGNED
Comment on attachment 9133672 [details]
data-review request

DATA COLLECTION REVIEW RESPONSE:

    Is there or will there be documentation that describes the schema for the ultimate data set available publicly, complete and accurate?

Yes. This collection is Telemetry so is documented in its definitions file [Histograms.json](https://hg.mozilla.org/mozilla-central/file/tip/toolkit/components/telemetry/Histograms.json) and the [Probe Dictionary](https://telemetry.mozilla.org/probe-dictionary/).

    Is there a control mechanism that allows the user to turn the data collection on and off?

Yes. This collection is Telemetry so can be controlled through Firefox's Preferences.

    If the request is for permanent data collection, is there someone who will monitor the data over time?

No. This collection will expire in Firefox 82.

    Using the category system of data types on the Mozilla wiki, what collection type of data do the requested measurements fall under?

Category 1, Technical.

    Is the data collection request for default-on or default-off?

Default on for all channels.

    Does the instrumentation include the addition of any new identifiers?

No.

    Is the data collection covered by the existing Firefox privacy notice?

Yes.

    Does there need to be a check-in in the future to determine whether to renew the data?

Yes. :jfkthame is responsible for renewing or removing the collection before it expires in Firefox 82.

---
Result: datareview+
Attachment #9133672 - Flags: data-review?(chutten) → data-review+
Attachment #9134986 - Attachment description: Bug 1619349 - patch 2 - Report font-matching statistics via telemetry ping. r=jwatt → Bug 1619349 - patch 2 - Report font-matching statistics via telemetry ping. r=chutten
Pushed by jkew@mozilla.com:
https://hg.mozilla.org/integration/autoland/rev/f8ca02252dfc
patch 1 - Record statistics about font-matching behavior in the presContext. r=jwatt
https://hg.mozilla.org/integration/autoland/rev/ba16b09b5da0
patch 2 - Report font-matching statistics via telemetry ping. r=chutten
Pushed by jkew@mozilla.com:
https://hg.mozilla.org/integration/autoland/rev/62f8ce89dce8
patch 1 - Record statistics about font-matching behavior in the presContext. r=jwatt
https://hg.mozilla.org/integration/autoland/rev/1a8269aa3f6e
patch 2 - Report font-matching statistics via telemetry ping. r=chutten
Status: ASSIGNED → RESOLVED
Closed: 4 months ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla76
Flags: needinfo?(jfkthame)
Regressions: 1627397
Regressions: 1627605
Whiteboard: [layout:backlog:2020] → [layout:backlog:76]
Depends on: 1633354
Duplicate of this bug: 1388743
See Also: → 1656133
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