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require 'rack/body_proxy'
module Flipper
module Middleware
class Memoizer
# Public: Initializes an instance of the Memoizer middleware. Flipper must
# be configured with a default instance or the flipper instance must be
# setup in the env of the request. You can do this by using the
# Flipper::Middleware::SetupEnv middleware.
#
# app - The app this middleware is included in.
# opts - The Hash of options.
# :preload_all - Boolean of whether or not to preload all features.
# :preload - Array of Symbol feature names to preload.
#
# Examples
#
# use Flipper::Middleware::Memoizer
#
# # using with preload_all features
# use Flipper::Middleware::Memoizer, preload_all: true
#
# # using with preload specific features
# use Flipper::Middleware::Memoizer, preload: [:stats, :search, :some_feature]
#
def initialize(app, opts = {})
if opts.is_a?(Flipper::DSL) || opts.is_a?(Proc)
raise 'Flipper::Middleware::Memoizer no longer initializes with a flipper instance or block. Read more at: https://git.io/vSo31.' # rubocop:disable LineLength
end
@app = app
@opts = opts
@env_key = opts.fetch(:env_key, 'flipper')
end
def call(env)
request = Rack::Request.new(env)
if skip_memoize?(request)
@app.call(env)
else
memoized_call(env)
end
end
private
def skip_memoize?(request)
@opts[:unless] && @opts[:unless].call(request)
end
def memoized_call(env)
reset_on_body_close = false
flipper = env.fetch(@env_key) { Flipper }
original = flipper.memoizing?
flipper.memoize = true
flipper.preload_all if @opts[:preload_all]
if (preload = @opts[:preload])
flipper.preload(preload)
end
response = @app.call(env)
response[2] = Rack::BodyProxy.new(response[2]) do
flipper.memoize = original
end
reset_on_body_close = true
response
ensure
flipper.memoize = original if flipper && !reset_on_body_close
end
end
end
end
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