discourse/lib/middleware/turbo_dev.rb

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module Middleware
# Cheat and bypass Rails in development mode if the client attempts to download a static asset
# that's already been downloaded.
#
# Also ensures that assets are not cached in development mode. Around Chrome 29, the behavior
# of `must-revalidate` changed and would often not request assets that had changed.
#
# To use, include in your project and add the following to development.rb:
#
# require 'middleware/turbo_dev'
# config.middleware.insert 0, Middleware::TurboDev
#
class TurboDev
def initialize(app, settings={})
@app = app
end
def call(env)
is_asset = (env['REQUEST_PATH'] =~ /^\/assets\//)
# hack to bypass all middleware if serving assets, a lot faster 4.5 seconds -> 1.5 seconds
if (etag = env['HTTP_IF_NONE_MATCH']) && is_asset
name = $'
etag = etag.gsub "\"", ""
asset = Rails.application.assets.find_asset(name)
if asset && asset.digest == etag
return [304,{},[]]
end
end
status, headers, response = @app.call(env)
headers['Cache-Control'] = 'no-cache' if is_asset
[status, headers, response]
end
end
end