This repository was archived by the owner on Feb 25, 2025. It is now read-only.
Switched Locale deprecation maps to jumptables and fixed minor bug with deprecated countries
#33123
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
with deprecated countries.
dnfield
reviewed
May 5, 2022
|
|
||
| // This map is generated by //flutter/tools/gen_locale.dart | ||
| // Mappings generated for language subtag registry as of 2019-02-27. | ||
| // static const Map<String, String> _deprecatedLanguageSubtagMap = <String, String>{ |
There was a problem hiding this comment.
nit: add something about this map being a more readable version of the jump table below.
| return x; | ||
| } | ||
|
|
||
| // This map is generated by //flutter/tools/gen_locale.dart |
There was a problem hiding this comment.
We should probably replace that file with your gist, no?
|
@dnfield, slava pointed out that we don't actually compile to jump tables with Dart, so the performance isn't always going to be faster than a map. I can switch it to a proper jump table like |
|
Abandoned for the alternative: #33140 |
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Localewhere deprecated countries would return all the same data, but the would not be considered==const Mapdata representing the deprecated languages and countries to jump tables. In microbenchmarks it behaves 2x faster in jit x64.==operator to prefer less lookup calls to deprecated tables.I made this change because
Localeis sometimes used as a key into a map, as it is in Flutter gallery. When it is used in a Map it'shashCodeis calculated, which is based on the country code and the language code, which requires lookups into these maps. I tried to memoize the values and the hashCode, but because of the limitations of Dart I couldn't do that (dart-lang/sdk#48948).The reason I identified this as a potential performance fix is that I setup Flutter to continuously build frames and navigated through the Material section of Flutter gallery and noticed that
Locale.hashCodeshows up pretty high. I also saw other Flutter users in Google using Locale as a key.Note:
customer: money.Pre-launch Checklist
writing and running engine tests.
///).If you need help, consider asking for advice on the #hackers-new channel on Discord.