Optimize hash alloc

[ericproulx]

This PR is all about hash allocation.

Double splat operator

Many functions had a **options or **_options where a simple options or options = {} can do the work.

Double splat is useful when keywords are passed explicitly or when you have keyword arguments. Something like

def my_function(**options)
  puts options
end

my_function(first_param: 'a', second_param: 'b')
# options = { first_param: 'a', second_param: 'b' }

def my_function(first_param:, **options)
  puts options
end

my_function(first_param: 'a', second_param: 'b')
# options = { second_param: 'b' }

Most of our internal functions are just passing a plain Hash that had to be ** because of the declared **options. The validator factory is a great example

module Grape
  module Validations
    class ValidatorFactory
      def self.create_validator(**options)
        options[:validator_class].new(options[:attributes],
                                      options[:options],
                                      options[:required],
                                      options[:params_scope],
                                      **options[:opts])
      end
    end
  end
end

the create_validator function is called like this

 yield Grape::Validations::ValidatorFactory.create_validator(**saved_validation)

and saved_validation is a plain Hash

Namespace

I found a @namespace_description in lib/grape/dsl/routing.rb#namespace that wasn't use at all so I removed it. It was creating some hashes.

Exceptions

• Grape::Exceptions::Base had a **_options. I had to update Grape::Exceptions::Validation declaration and super usage to fit the expected parameters.

Validators

Grape:: Validations::Validators::Base had a *opts. It's been replaced by opts since its a static hash

Routing HEAD

I've optimized the mount_in function and add_head_not_allowed_methods_and_options_methods.

HEAD and GET are identical except that HEAD does not return content. Instead of creating a new Route for the HEAD, I've just dup the GET and replace the @request_method to HEAD

Benchmark

Before

Total allocated: 51146165 bytes (221499 objects)
Total retained:  5971658 bytes (15564 objects)

allocated memory by class
-----------------------------------
  27633240  Hash  <=====
   9604928  String
   6485704  Array
   4663405  Regexp
   2274584  ActiveSupport::OrderedOptions
    178224  Grape::Router::Route
    166896  Grape::Router::Pattern
     72720  Grape::Path
     30432  MatchData
     29400  Grape::Router::GreedyRoute
      1704  Class
      1224  Enumerator
       560  Proc
       488  Module
       448  Rack::Utils::HeaderHash


retained memory by class
-----------------------------------
   2274584  ActiveSupport::OrderedOptions
   1811845  Regexp
    933629  String
    305928  Array
    267800  Hash  <=====
    178224  Grape::Router::Route
    166896  Grape::Router::Pattern
     29400  Grape::Router::GreedyRoute
      1240  Class
       488  Module

Total allocated: 29384381 bytes (176924 objects)
Total retained:  5177218 bytes (12359 objects)

allocated memory by class
-----------------------------------
   9604928  String
   6699632  Hash  <=====
   6157528  Array
   4663405  Regexp
   1810584  ActiveSupport::OrderedOptions
    178224  Grape::Router::Route
    130896  Grape::Router::Pattern
     72720  Grape::Path
     30432  MatchData
     29400  Grape::Router::GreedyRoute


retained memory by class
-----------------------------------
   1811845  Regexp
   1810584  ActiveSupport::OrderedOptions
    933629  String
    178224  Grape::Router::Route
    144320  Hash  <=====
    134968  Array
    130896  Grape::Router::Pattern
     29400  Grape::Router::GreedyRoute
      1240  Class
       488  Module
       400  Proc
       280  Grape::Middleware::Stack::Middleware
       256  <<Unknown>>
       224  Rack::Utils::HeaderHash
       168  ActiveSupport::HashWithIndifferentAccess

[dblock]

👏