class Flipper::Middleware::Memoizer

Public Class Methods

new(app, opts = {}) click to toggle source

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 - Boolean to preload all features or Array of Symbol feature names to preload.

Examples

use Flipper::Middleware::Memoizer

# using with preload_all features
use Flipper::Middleware::Memoizer, preload: true

# using with preload specific features
use Flipper::Middleware::Memoizer, preload: [:stats, :search, :some_feature]
# File lib/flipper/middleware/memoizer.rb, line 23
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.'
  end

  if opts[:preload_all]
    warn "Flipper::Middleware::Memoizer: `preload_all` is deprecated, use `preload: true`"
    opts[:preload] = true
  end

  @app = app
  @opts = opts
  @env_key = opts.fetch(:env_key, 'flipper')
end

Public Instance Methods

call(env) click to toggle source
# File lib/flipper/middleware/memoizer.rb, line 38
def call(env)
  request = Rack::Request.new(env)

  if memoize?(request)
    memoized_call(env)
  else
    @app.call(env)
  end
end

Private Instance Methods

memoize?(request) click to toggle source
# File lib/flipper/middleware/memoizer.rb, line 50
def memoize?(request)
  if @opts[:if]
    @opts[:if].call(request)
  elsif @opts[:unless]
    !@opts[:unless].call(request)
  else
    true
  end
end
memoized_call(env) click to toggle source
# File lib/flipper/middleware/memoizer.rb, line 60
def memoized_call(env)
  reset_on_body_close = false
  flipper = env.fetch(@env_key) { Flipper }

  # Already memoizing. This instance does not need to do anything.
  if flipper.memoizing?
    warn "Flipper::Middleware::Memoizer appears to be running twice. Read how to resolve this at https://github.com/jnunemaker/flipper/pull/523"
    return @app.call(env)
  end

  flipper.memoize = true

  case @opts[:preload]
  when true then flipper.preload_all
  when Array then flipper.preload(@opts[:preload])
  end

  response = @app.call(env)
  response[2] = Rack::BodyProxy.new(response[2]) do
    flipper.memoize = false
  end
  reset_on_body_close = true
  response
ensure
  flipper.memoize = false if flipper && !reset_on_body_close
end