StreamingTemplateRenderer fails to forward I18n.locale in layouts

[mfo]

Hello,

I recently used the option render stream: true to render some actions ( Ruby 2.4.1p111 / Rails 5.1.3 )

We noticed that our layout failed to keep the current locale [I18n.locale]. After some explorations, here is what happens :

• the I18n gems stores the current config in a Thread.current[:local]
• the StreamingTemplateRenderer streams the response via a Fiber.resume pattern
• unfortunatelly the Fiber does not keeps the Thread.current[:i18n_config]

This commit includes a simple fix: keeping a reference of the I18n.config above the Fiber scope and re-applying this reference to I18n.config.

Here is a link to a gist (https://gist.github.com/mfo/e8e5d51fe52f6cacd33ea778b1ef6c6d) with other options :

• FiberWithI18n -> copy the I18n.config from caller
• FiberWithLocalsFromCallerThread -> copy all caller's threads local vars within the Fiber locals hash [it's a bit overkill but it may be useful for other gems/parts of rails]
• you can switch implementations from the gist (and fails the test using normal Fiber class)

[rails-bot]

Thanks for the pull request, and welcome! The Rails team is excited to review your changes, and you should hear from @eileencodes (or someone else) soon.

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[mfo]

Maybe you are in holiday and in this case I wish you the best :-)

In case I missed something and it's a pain to deal with this issue, here is a simple rails app which reproduces this bug with a dedicated test : https://github.com/mfo/rails_30361
involved files :

• the test: https://github.com/mfo/rails_30361/blob/master/test/controllers/page_controller_test.rb
• the tested controller using a render stream: true with a set_locale : https://github.com/mfo/rails_30361/blob/master/app/controllers/page_controller.rb
• the layout rendering the wrong locale (default) https://github.com/mfo/rails_30361/blob/master/app/views/layouts/application.html.erb
• the view rendering the expected locale : https://github.com/mfo/rails_30361/blob/master/app/views/page/index.html.erb

[eileencodes]

Hey @mfo sorry for the delay on merging this. I think this looks good. Can you squash your commits into 1 single commit? Thanks!

[mfo]

I assumed you ran out of coffee : no worries for the delay ;-) It's squashed & up to date with rails/master. Thanks for your work. 👍

[mfo]

Sorry I'm closing/reopening this PR to relaunch the CI which failed on some apt-get :

apt-get install failed
The command "sudo -E apt-get -yq --no-install-suggests --no-install-recommends --force-yes install ffmpeg mupdf mupdf-tools" failed and exited with 100 during .

[mfo]

again I'm trying to pass the tests which sometimes fails and sometimes succeed ; let me know if I can help :-)

[eileencodes]

The failures aren't related to your branch so I merged. Sorry for the delay with this. Appreciate your time and patience! 😄

[mfo]

Thanks for your work Eileen and no worry for the delay.