1187760 - [EME] Add telemetry to report requestMediaKeySystemAccess latency

Status: RESOLVED FIXED

(Core :: Audio/Video: Playback, defect, P1)

Description

[Chris Pearce [:cpearce (Not reading bugmail)]]

If we had telemetry to report how long navigator.requestMediaKeySystemAccess() takes, we'd know whether our Adobe CDM downloads are timing out or not.

Comment 1

[Chris Pearce [:cpearce (Not reading bugmail)]]

Netflix have started setting a timeout of about 2 seconds when they call navigator.requestMediaKeySystemAccess(), and if we don't resolve before the timeout expires, they navigate (which causes our navigator.requestMediaKeySystemAccess() promise to reject) and throw up a "Install SilverLight" page.

So it doesn't make sense to report telemetry for the elapsed time taken to fulfil the promise as a means to determine whether the CDM download is working, since Netflix is canceling our promise.

Comment 2

[Chris Pearce [:cpearce (Not reading bugmail)]]

Actually, this is useful, as if it takes us longer than one second to resolve the navigator.requestMediaKeySystemAccess() promise, Netflix will fallback to Silverlight, and we don't want that.

So this telemetry is a way to track our fallback-to-Silverlight rate.

Comment 3

[Chris Pearce [:cpearce (Not reading bugmail)]]

Attachment: Patch: Add telemetry to record navigator.requestMediaKeySystemAccess latency.

Add telemetry to report how long it takes us to resolve or reject the promise returned by navigator.requestMediaKeySystemAccess().

This enables us to track how often Netflix falls back to Silverlight, since they do so if either the navigator.requestMediaKeySystemAccess() rejects, or takes more than 1 second to resolve.

opt-out telemetry, so r? vladan.

Comment 4

[Vladan Djeric (:vladan)]

Comment on attachment 8664020 [details] [diff] [review]
Patch: Add telemetry to record navigator.requestMediaKeySystemAccess latency.

Review of attachment 8664020 [details] [diff] [review]:
-----------------------------------------------------------------

::: toolkit/components/telemetry/Histograms.json
@@ +9376,5 @@
> +    "kind": "exponential",
> +    "high": "60000",
> +    "n_buckets": 60,
> +    "releaseChannelCollection": "opt-out",
> +    "description": "Time spent waiting for a navigator.requestMediaKeySystemAccess call to succeed."

indicate time units in the description or the histogram name (e.g. .._LATENCY_MS)

Comment 5

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/71b0991c0f1d

Comment 6

[Chris Pearce [:cpearce (Not reading bugmail)]]

Uplift needed.

Comment 7

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/71b0991c0f1d

Comment 8

[Chris Pearce [:cpearce (Not reading bugmail)]]

We can get by without uplift I think.