1318432 - Make it possible to switch on rust-url at runtime

Status: RESOLVED FIXED

(Core :: Networking, defect)

Description

[Manish Goregaokar [:manishearth]]

Currently, if MOZ_RUST_URLPARSE is set, each nsStandardURL will contain a mirror RustURL. When parsing/setting, the method is run on both. If there are mismatches when getting, the mismatch is reported via MOZ_LOG.

The inline MOZ_RUST_URLPARSE_FALLBACK define controls whether or not to fall back to the nsStandardURL value when there is a mismatch. It is enabled by default, but can be disabled to get an idea of what tests will fail with RustURL.

We should have a runtime pref that controls the fallback.

Comment 1

[Valentin Gosu [:valentin] (he/him)]

Attachment: Make it possible to switch on rust-url at runtime

MozReview-Commit-ID: 3BfqFWIpS7F

Comment 2

[Valentin Gosu [:valentin] (he/him)]

Comment on attachment 8812762 [details] [diff] [review]
Make it possible to switch on rust-url at runtime

Review of attachment 8812762 [details] [diff] [review]:
-----------------------------------------------------------------

This patch adds a runtime pref to enable the rust parser. It defaults to false as we have discovered several regressions (both crashes and performance) caused by bug 1151899.

Comment 3

[Valentin Gosu [:valentin] (he/him)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=0b9b15761f64

Comment 4

[Valentin Gosu [:valentin] (he/him)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/688a4bbf801804c595cd47f316501f437390c9cd
Bug 1318432 - Make it possible to switch on rust-url at runtime r=bagder

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/688a4bbf8018

Comment 6

[Joel Maher ( :jmaher ) (UTC -8)]

it appears that this change caused many performance improvements:
https://treeherder.mozilla.org/perf.html#/alerts?id=4261

Comment 7

[Manish Goregaokar [:manishearth]]

More accurately, it fixed a perf regression caused by https://bugzilla.mozilla.org/show_bug.cgi?id=1151899 :)