Specify how `timeOrigin` is computed #7339

noamr · 2021-11-15T12:19:57Z

The time origin, which is the epoch for all performance timeline APIs,
was previously defined here.

This PR makes its computation explicity, without changing its current
definition and behavior.

time origin becomes an environment settings object algorithm,
computed differently for windows vs. worker scopes
The 4 places where this timestamp is set are creation of an
about:blank context, beginning of navigation, confirmation of an
unload prompt, and creating a worker.
The timestamp is a shared monotonic clock value, which is defined
in HR-TIME (and internally in ECMAScript).

As part of this PR, also refactored unload prompts to return a result
rather than rely on a somewhat hand-wavy "refused to allow" property.

See w3c/hr-time#131
and w3c/navigation-timing#166

At least two implementers are interested (and none opposed):
- This is already implemented.
Tests are written and can be reviewed and commented upon at:
- Existing tests: https://github.com/web-platform-tests/wpt/tree/master/hr-time
Implementation bugs are filed:
- N/A, no behavior change

(See WHATWG Working Mode: Changes for more details.)

/browsers.html ( diff )
/browsing-the-web.html ( diff )
/dom.html ( diff )
/history.html ( diff )
/infrastructure.html ( diff )
/webappapis.html ( diff )
/window-object.html ( diff )
/workers.html ( diff )
/worklets.html ( diff )

See whatwg/html#7339 `time origin` is now an `environment settings object` algorithm, so the reference here should forward there. Closes #131

noamr · 2021-11-15T12:38:53Z

source

@@ -87911,7 +87940,7 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
   data-x="concept-response-timing-info">timing info</span>,
   <span data-x="navigation-params-response">response</span>'s <span
   data-x="concept-response-service-worker-timing-info">service worker timing info</span>,
-   <var>redirectCount</var>, and <var>navigationType</var>.</p></li>
+   <var>redirectCount</var>, <var>navigationType</var>, and <var>previousTimeOrigin</var>.</p></li>


We need to pass the previous time origin because of w3c/navigation-timing#166

I was just about to ask the same... Worthwhile to add a note?

Also, can you clarify why this is correct? Are we replacing the value later?

We will need to adjust the values of the ResourceTiming attributes in navigation timing. I didn't get to that patch yet...

Added a note below

yoavweiss

If I'm trying to extract the high-level design here:

We're setting loadTimingInfo's startTime when a new browsing context is created
When navigating, we set the navigationParams startTime to the moment of the navigation, but then override it after the unload handlers ran.
When creating and initializing a Document, we keep the time origin of the previous document and use it for initialization.
At the same time, we use the navigationParams' startTime to initialize the Document's loadTimingInfo.

Is that about right? It might be useful to add a description outlining the role of the environment settings object's time origin, the navigationParams start time and the loadTimingInfo's startTime.

source

yoavweiss · 2021-11-15T14:32:52Z

source

@@ -87911,7 +87940,7 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
   data-x="concept-response-timing-info">timing info</span>,
   <span data-x="navigation-params-response">response</span>'s <span
   data-x="concept-response-service-worker-timing-info">service worker timing info</span>,
-   <var>redirectCount</var>, and <var>navigationType</var>.</p></li>
+   <var>redirectCount</var>, <var>navigationType</var>, and <var>previousTimeOrigin</var>.</p></li>


I was just about to ask the same... Worthwhile to add a note?

yoavweiss · 2021-11-15T14:48:41Z

source

@@ -87911,7 +87940,7 @@ interface <dfn interface>Location</dfn> { // but see also <a href="#the-location
   data-x="concept-response-timing-info">timing info</span>,
   <span data-x="navigation-params-response">response</span>'s <span
   data-x="concept-response-service-worker-timing-info">service worker timing info</span>,
-   <var>redirectCount</var>, and <var>navigationType</var>.</p></li>
+   <var>redirectCount</var>, <var>navigationType</var>, and <var>previousTimeOrigin</var>.</p></li>


Also, can you clarify why this is correct? Are we replacing the value later?

source

yoavweiss

Non-authoritative LGTM!!
Thanks for the latest revamp - the handling of unsafe timers is much clearer now

noamr · 2021-11-22T17:27:26Z

@domenic care to review?

source

domenic · 2021-11-22T20:41:21Z

source

-       unloaded</span>, then return.</p></li>
+       <li><p>If the result of calling <span>prompt to unload</span> with the
+       <span>active document</span> of the <var>specified browsing context</var> is
+       "<code data-x="">refuse</code>", then return.</p></li>


Preexisting problem, but if you could fix while you're here it'd be nice: since we're in a queued task, we use "abort these steps" instead of "return"

I think I commented on the wrong line. "close a browsing context" should be "return"; "traverse the history by a delta" should be "abort these steps".

source

The time origin, which is the epoch for all performance timeline APIs, was previously defined [here](https://w3c.github.io/hr-time/#dfn-time-origin). This PR makes its computation explicity, without changing its current definition and behavior. - `time origin` becomes an `environment settings object` algorithm, computed differently for windows vs. worker scopes - The 4 places where this timestamp is set are creation of an `about:blank` context, beginning of navigation, confirmation of an unload prompt, and creating a worker. - The timestamp is a `shared monotonic clock` value, which is defined in HR-TIME (and internally in ECMAScript). As part of this PR, also refactored unload prompts to return a result rather than rely on a somewhat hand-wavy "refused to allow" property. See w3c/hr-time#131 and w3c/navigation-timing#166

In [this HTML PR](whatwg/html#7339) we add a `time origin` getter to the `environment settings object`. We need to account for that value in service workers, which would be the time the worker environment is created.

source

noamr

Refactored worker creation time initialization to use closure variables instead of new associated things
Threaded through unsafeNavigationStartTime
Refactored prompt-result switch

source

domenic

Hooray!

* Remove own version of `timeOrigin` definition See whatwg/html#7339 `time origin` is now an `environment settings object` algorithm, so the reference here should forward there. Closes #131 * Refactor and add note

In [this HTML PR](whatwg/html#7339) we add a `time origin` getter to the `environment settings object`. We need to account for that value in service workers, which would be the time the worker environment is created.

noamr added a commit to w3c/hr-time that referenced this pull request Nov 15, 2021

Remove own version of timeOrigin definition

6103713

See whatwg/html#7339 `time origin` is now an `environment settings object` algorithm, so the reference here should forward there. Closes #131

noamr mentioned this pull request Nov 15, 2021

Remove own version of timeOrigin definition w3c/hr-time#132

Merged

4 tasks

noamr commented Nov 15, 2021

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noamr mentioned this pull request Nov 15, 2021

Using navigationStart as a baseline may expose cross-origin timing information w3c/navigation-timing#160

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yoavweiss reviewed Nov 15, 2021

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noamr mentioned this pull request Nov 15, 2021

Define timeOrigin in the HTML spec w3c/hr-time#131

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yoavweiss reviewed Nov 16, 2021

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noamr mentioned this pull request Nov 21, 2021

Time origin adjustment for navigation whatwg/fetch#1359

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noamr force-pushed the timeOrigin branch from 1884f4e to b25a0c7 Compare November 22, 2021 08:27

yoavweiss reviewed Nov 22, 2021

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yoavweiss approved these changes Nov 22, 2021

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domenic reviewed Nov 22, 2021

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noamr added 8 commits November 23, 2021 20:31

Add missing env settings override for window

c0810d1

Reword note a bit

432f343

No need to do weird adjustments

335f93e

Remove unnecessary offseting

75e959c

Refactor coarsening to happen earlier

0ce09e5

Clarify about:blank time origin

f5d2227

nits

28636f1

noamr mentioned this pull request Nov 24, 2021

Define the time origin for service workers w3c/ServiceWorker#1621

Merged

Fix nits and extra navigation-params creation sites

1a18641

noamr force-pushed the timeOrigin branch from 926b0eb to 1a18641 Compare November 24, 2021 16:02

domenic reviewed Nov 24, 2021

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Clarify prompts, lambdafy worker creation

940dfd2

noamr commented Nov 25, 2021

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Editorial nits, mostly wrapping

955d13f

domenic approved these changes Nov 29, 2021

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domenic merged commit 60c8bf6 into whatwg:main Nov 29, 2021

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Specify how `timeOrigin` is computed #7339

Specify how `timeOrigin` is computed #7339

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Specify how timeOrigin is computed #7339

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Specify how `timeOrigin` is computed #7339

Specify how `timeOrigin` is computed #7339

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