1846389 - [wpt-sync] Sync PR 41265 - Add append_to argument to Clone() to avoid extra InsertedInto calls

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, task, P4)

Description

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Sync web-platform-tests PR 41265 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/41265
Details from upstream follow.

Mason Freed <[e-mail]> wrote:

Add append_to argument to Clone() to avoid extra InsertedInto calls

Because of the order of operations for Clone(), previous to this CL,
the typical sequence would be:

1. Clone the element
2. Clone the children of the element (recursing to step #1).
3. AppendChild() each cloned child to its parent cloned element.
4. (in the caller of Clone) AppendChild the cloned element to its
   eventual parent.

Because each AppendChild triggers a call to Node::InsertedInto() for
all descendants of the appended element [1], the fact that the tree
is constructed bottom-up (leaf nodes first) means that InsertedInto()
is called N^2 times, where N is the depth of the cloned tree.

Because clone-and-append is a very common pattern, this CL adds an
append_to argument to Clone(), which appends to the parent before
appending the children.

This CL also adds a perf test for this scenario (cloning a deep tree).
Locally, on a debug build, this test gives 0.13 runs/s before this CL,
and 0.40 runs/s after, for a 3.1X speedup.

[1] https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/dom/container_node.cc;l=1006;drc=5d60017dba57e86d477634812e1340127734f8a7

Bug: 1453291
Change-Id: Icdd75c45aa5ecc4fe8bb5d1ff0b7a2b27bec2171
Cq-Do-Not-Cancel-Tryjobs: true
Reviewed-on: https://chromium-review.googlesource.com/4728983
WPT-Export-Revision: f09d0b0e757070fa10e9789d2d6438ba6c4c7d2e

Comment 1

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Pushed to try (stability) https://treeherder.mozilla.org/#/jobs?repo=try&revision=489ae36d5910fc839018a5cc9696a2b9dbde4750

Comment 2

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Test result changes from PR not available.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/mozilla-central/rev/1294fa7756a0
[wpt PR 41265] - Add append_to argument to Clone() to avoid extra InsertedInto calls, a=testonly

Comment 4

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/1294fa7756a0