2041154 - Prototype a fast path to inform APZ-aware registration to APZ

Status: RESOLVED FIXED

(Core :: Panning and Zooming, task, P2)

Description

[Hiroyuki Ikezoe (:hiro)]

It may have impacts on temu.com (bug 2031963).

Comment 1

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 2041154 - Fast-path notify APZ on non-passive APZ-aware listener registration. r?botond

When a touchstart JS handler dynamically registers a non-passive
touchmove (or similar APZ-aware) listener, APZ doesn't learn about
eApzAwareListeners until the next painted WebRender transaction has
been scene-swapped on the compositor -- ~70 ms after the listener
add on temu.com. The first touchmove arrives at APZ well before
that, the cached touchstart hit-test is reused, and the block stays
committed to async-scroll.

Add a direct content -> APZ IPC (NotifyApzAwareListenerAdded) carrying
the nearest scroll container's ViewID. APZCTreeManager records the
(LayersId, ScrollId) pair under mMapLock; WRHitTester ORs in
eApzAwareListeners when a hit-test result's target APZC equals that
pair or descends from it within the same layers id.

EventListenerManager::ProcessApzAwareEventListenerAdd resolves the
ScrollId via FindIDFor (not FindOrCreateIDFor): if no ViewID has
been assigned yet, or the element has no primary frame / scroll
container ancestor, fall back to the existing SchedulePaint path so
the regular display-list rebuild propagates the flag.

Fast-path entries are kept until the layer tree is removed
(NotifyLayerTreeRemoved). Clearing them in PrepareNodeForLayer would
race against a paint that was in flight when the listener was added.

Add MOZ_LOG=apz.fastpath logging on both sides to trace the flow.

Comment 2

[Hiroyuki Ikezoe (:hiro)]

here is a try run: https://treeherder.mozilla.org/jobs?repo=try&revision=a3decc355228aa5627dffc47ebe96aa664c10d38

Comment 3

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 2041154 - Add mFirstMoveSeen to TouchCounter. r?botond

Comment 4

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 2041154 - Propagate the initial touch move information to InputQueue from APZCTreeManager. r?botond

In a subsequent change the information will be used.

Comment 5

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 2041154 - Encapsulate the long-tap touchmove content-response condition in a TouchBlockState method. r?botond

Comment 6

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 2041154 - Wait for a content response on the first touch-move if needed. r?botond

Comment 7

[Hiroyuki Ikezoe (:hiro)]

With uploaded patches now the fast-path works independently from bug 1839095 (though some of patches have been migrated from bug 1839095, and the mochitest in D302255 is same as the one in bug 1839095).

Comment 8

[Hiroyuki Ikezoe (:hiro)]

Here is a try run: https://treeherder.mozilla.org/jobs?repo=try&revision=0137f84408b8604356e8cce54b1503fe6bfc3237

Botond, would you mind trying it to see whether the temu case is affected by these patches or not? Thanks!

(Note that the try run has just started, so building hasn't yet finished)

Comment 9

[Hiroyuki Ikezoe (:hiro)]

Today I opened the temu link in bug 2031963 on a local built with the patches here in this bug. I could see the dialog in question and dragging images doesn't cause any scrolling in RDM. So I think this fast-path route has impacts on the site.

Comment 10

[Botond Ballo [:botond]]

(In reply to Hiroyuki Ikezoe (:hiro) from comment #8)

Here is a try run: https://treeherder.mozilla.org/jobs?repo=try&revision=0137f84408b8604356e8cce54b1503fe6bfc3237

Botond, would you mind trying it to see whether the temu case is affected by these patches or not? Thanks!

I tested in GeckoView Example, and I can confirm that a 2026-05-24 nightly build is affected by bug 2031963 (scrolling of the page happens while trying to drag the images), but the build from the linked Try push is unaffected!

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/d2d42a16143a
https://hg.mozilla.org/integration/autoland/rev/808d0c89f3ea
Add mFirstMoveSeen to TouchCounter. r=botond
https://github.com/mozilla-firefox/firefox/commit/7dd47e25e2c1
https://hg.mozilla.org/integration/autoland/rev/676d3e2a40d6
Propagate the initial touch move information to InputQueue from APZCTreeManager. r=botond
https://github.com/mozilla-firefox/firefox/commit/6688fc7f91e4
https://hg.mozilla.org/integration/autoland/rev/82dfaeaf599e
Encapsulate the long-tap touchmove content-response condition in a TouchBlockState method. r=botond
https://github.com/mozilla-firefox/firefox/commit/2dc34faf3e61
https://hg.mozilla.org/integration/autoland/rev/becd0349cbe5
Fast-path notify APZ on non-passive APZ-aware listener registration. r=botond
https://github.com/mozilla-firefox/firefox/commit/a25969b6d2c9
https://hg.mozilla.org/integration/autoland/rev/909577e462d4
Wait for a content response on the first touch-move if needed. r=botond

Comment 12

[agoloman]

https://hg.mozilla.org/mozilla-central/rev/808d0c89f3ea
https://hg.mozilla.org/mozilla-central/rev/676d3e2a40d6
https://hg.mozilla.org/mozilla-central/rev/82dfaeaf599e
https://hg.mozilla.org/mozilla-central/rev/becd0349cbe5
https://hg.mozilla.org/mozilla-central/rev/909577e462d4

Comment 13

[amarc]

backed out for causing https://bugzilla.mozilla.org/show_bug.cgi?id=2043349

Comment 14

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/940d4836920e
https://hg.mozilla.org/integration/autoland/rev/f4f0298cb163
Revert "Bug 2041154 - Wait for a content response on the first touch-move if needed. r=botond" for causing bug 2043349

Comment 15

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 2041154 - Add mochitests for first touch-move content-response wait across the four eApzAwareListeners / eIrregularArea dispatch-to-content cases. r?botond

TargetConfirmationFlags.mDispatchToContent is not specific to
eApzAwareListeners, it can have other values. The four tests are to make
sure that the newly apprived eApzAwareListeners flag via the fast-path
doesn't prevent scrolling unexpectedly or does prevent scrolling
properly.

• helper_bug2043349-static.html: static non-passive touchmove with
  preventDefault. Initial hit-test has eApzAwareListeners only.
  preventDefault is honored, no scrolling.
• helper_bug2043349-irregular.html: clip-path:polygon irregular area
  with no APZ-aware listener. Initial hit-test has eIrregularArea
  only. scrolling proceeds.
• helper_bug2043349-irregular-dynamic.html: irregular area plus a
  non-passive touchmove with preventDefault added by the touchstart
  handler. Initial hit-test has eIrregularArea; eApzAwareListeners is
  added via the fast path. preventDefault is honored, no
  scrolling.
• helper_bug2043349-irregular-static.html: irregular area plus a
  static non-passive touchmove with preventDefault. Initial hit-test
  has both eApzAwareListeners and eIrregularArea.
  preventDefault is honored, no scrolling.

Comment 16

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 2041154 - Only wait for content response on first touch-move when the APZ-aware listener was just discovered via the fast path. r?botond

D302255 introduced a wait for a content response on the first
touch-move whenever the touch block dispatches to content, to give
a freshly-registered APZ-aware listener a chance to preventDefault().
That condition is too broad: it also fires on blocks whose
eApzAwareListeners flag came from the original hit-test, causing
scroll lag on Android.

Comment 17

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 2041154 - Narrow the APZ-aware listener fast-path IPC to non-passive touchmove listeners only. r?botond

Comment 18

[Cristian Tuns]

Backout merged to central: https://hg.mozilla.org/mozilla-central/rev/f4f0298cb163

Comment 19

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 2041154 - Do not wait the additional content response for touchmove during fast-fling. r?botond

Comment 20

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 2041154 - Factor out the utility function for fast fling. r?botond

Comment 21

[Phabricator Automation]

Comment on attachment 9591724 [details]
Bug 2041154 - Only wait for content response on first touch-move when the APZ-aware listener was just discovered via the fast path. r?botond

Revision D303520 was moved to bug 2044829. Setting attachment 9591724 [details] to obsolete.

Comment 22

[Phabricator Automation]

Comment on attachment 9591725 [details]
Bug 2041154 - Narrow the APZ-aware listener fast-path IPC to non-passive touchmove listeners only. r?botond

Revision D303521 was moved to bug 2044829. Setting attachment 9591725 [details] to obsolete.

Comment 23

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/e9ef82decbb3
https://hg.mozilla.org/integration/autoland/rev/f952dfe00ca6
Add mFirstMoveSeen to TouchCounter. r=botond
https://github.com/mozilla-firefox/firefox/commit/4fadd6573742
https://hg.mozilla.org/integration/autoland/rev/23ca22e2ea76
Propagate the initial touch move information to InputQueue from APZCTreeManager. r=botond
https://github.com/mozilla-firefox/firefox/commit/f1ed0b7d9aa1
https://hg.mozilla.org/integration/autoland/rev/404f97262394
Encapsulate the long-tap touchmove content-response condition in a TouchBlockState method. r=botond
https://github.com/mozilla-firefox/firefox/commit/f7b7a2394baa
https://hg.mozilla.org/integration/autoland/rev/dc308925a994
Fast-path notify APZ on non-passive APZ-aware listener registration. r=botond
https://github.com/mozilla-firefox/firefox/commit/10072211789a
https://hg.mozilla.org/integration/autoland/rev/0c2e63fb7cdd
Wait for a content response on the first touch-move if needed. r=botond
https://github.com/mozilla-firefox/firefox/commit/b99ea692a938
https://hg.mozilla.org/integration/autoland/rev/9d076f1c3d5a
Add mochitests for first touch-move content-response wait across the four eApzAwareListeners / eIrregularArea dispatch-to-content cases. r=botond
https://github.com/mozilla-firefox/firefox/commit/5aa21e186af9
https://hg.mozilla.org/integration/autoland/rev/f28fdce40ca2
Factor out the utility function for fast fling. r=botond
https://github.com/mozilla-firefox/firefox/commit/0e8e1f40989c
https://hg.mozilla.org/integration/autoland/rev/4adabd48fd0a
Do not wait the additional content response for touchmove during fast-fling. r=botond

Comment 24

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/aedfae2a7a54
https://hg.mozilla.org/integration/autoland/rev/7184efcc320a
Add mFirstMoveSeen to TouchCounter. r=botond
https://github.com/mozilla-firefox/firefox/commit/8008521c09ec
https://hg.mozilla.org/integration/autoland/rev/8e5e3b355053
Propagate the initial touch move information to InputQueue from APZCTreeManager. r=botond
https://github.com/mozilla-firefox/firefox/commit/b038350254bd
https://hg.mozilla.org/integration/autoland/rev/9f61d8a7373e
Encapsulate the long-tap touchmove content-response condition in a TouchBlockState method. r=botond
https://github.com/mozilla-firefox/firefox/commit/a7cf5ef9044c
https://hg.mozilla.org/integration/autoland/rev/147e8a2919a0
Fast-path notify APZ on non-passive APZ-aware listener registration. r=botond
https://github.com/mozilla-firefox/firefox/commit/656c61951aae
https://hg.mozilla.org/integration/autoland/rev/4bd9b34883f1
Wait for a content response on the first touch-move if needed. r=botond
https://github.com/mozilla-firefox/firefox/commit/5e16117b69bf
https://hg.mozilla.org/integration/autoland/rev/81168254915c
Add mochitests for first touch-move content-response wait across the four eApzAwareListeners / eIrregularArea dispatch-to-content cases. r=botond
https://github.com/mozilla-firefox/firefox/commit/4e66d86bb046
https://hg.mozilla.org/integration/autoland/rev/e70158e76862
Factor out the utility function for fast fling. r=botond
https://github.com/mozilla-firefox/firefox/commit/da66f8e44a54
https://hg.mozilla.org/integration/autoland/rev/22ef2c2275f5
Do not wait the additional content response for touchmove during fast-fling. r=botond

Comment 25

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/f952dfe00ca6
https://hg.mozilla.org/mozilla-central/rev/23ca22e2ea76
https://hg.mozilla.org/mozilla-central/rev/404f97262394
https://hg.mozilla.org/mozilla-central/rev/dc308925a994
https://hg.mozilla.org/mozilla-central/rev/0c2e63fb7cdd
https://hg.mozilla.org/mozilla-central/rev/9d076f1c3d5a
https://hg.mozilla.org/mozilla-central/rev/f28fdce40ca2
https://hg.mozilla.org/mozilla-central/rev/4adabd48fd0a
https://hg.mozilla.org/mozilla-central/rev/7184efcc320a
https://hg.mozilla.org/mozilla-central/rev/8e5e3b355053
https://hg.mozilla.org/mozilla-central/rev/9f61d8a7373e
https://hg.mozilla.org/mozilla-central/rev/147e8a2919a0
https://hg.mozilla.org/mozilla-central/rev/4bd9b34883f1
https://hg.mozilla.org/mozilla-central/rev/81168254915c
https://hg.mozilla.org/mozilla-central/rev/e70158e76862
https://hg.mozilla.org/mozilla-central/rev/22ef2c2275f5