Contact emails

suzukike...@chromium.org, yyanagis...@chromium.org

Explainer

https://github.com/WICG/service-worker-static-routing-api/blob/main/resource-timing-api.md

Specification

None

Summary

Adds timing information for ServiceWorker Static Routing API, exposed in
navigation timing API and resource timing API for developer use.

Service Worker provides timing information to mark certain points in time.
We add two ServiceWorker Static Routing API-relevant timing information:
workerRouterEvaluationStart, time to start matching a request with
registered router rules, and workerCacheLookupStart, time to start looking
up the cache storage if the source is "cache". In addition, we also add two
router source information, the matched router source and the final router
source.


Blink component

Blink>ServiceWorker
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EServiceWorker>

Motivation

Service Worker provides timing information to mark certain points in time.
This is exposed and used by the navigation timing API as well as the
resource timing API. It currently records two times:

- Start time

- Fetch event dispatch time

However, it currently does not have any fields related to the ServiceWorker
Static Routing API. Developers would benefit from having fields that
provide information such as:

- the matched route (the route that the Static Routing API evaluated)

- the actual source from which the resource was retrieved

- the time it took to match the route

- the time to look up the cache for the cache source

This information will allow developers to measure the latency incurred by
the API such as router evaluation time or time required to conduct cache
lookup, or determine if the matched source is the final source used (can
find out if the matched source failed to get the resource or not, and which
source was used as the alternative).


Initial public proposal

https://github.com/w3c/resource-timing/issues/389

TAG review

None

TAG review status

Pending

Risks

Interoperability and Compatibility

The original ServiceWorker static routing API has received positive signals
from Firefox <https://github.com/mozilla/standards-positions/issues/828>,
WebKit <https://github.com/WebKit/standards-positions/issues/206> and Web
developers. We are planning to start requesting signals for the timing
information addition soon.

There are no compatibility risks, as this proposal only adds new fields to
the timing information and will not modify any of the existing fields.

Gecko: No signal

WebKit: No signal

Web developers: No signals

Other signals:

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that
it has potentially high risk for Android WebView-based applications?

None


Debuggability

None


Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>
?

We have an in-flight CL which adds wpt tests.(link
<https://chromium-review.googlesource.com/c/chromium/src/+/5521193>)

Flag name on chrome://flags

None

Finch feature name

ServiceWorkerStaticRouterTimingInfo

Non-finch justification

None

Requires code in //chrome?

False

Tracking bug

https://crbug.com/41496865

Estimated milestones

No milestones specified


Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/6309742380318720?gate=6008560617259008

This intent message was generated by Chrome Platform Status
<https://chromestatus.com/>.

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