Append middlewares to service only once even when config is included multiple times

[marian13]

• When the already added config is included multiple times, it appends middlewares again and again.

• Check the following example:

  task playground

  class TestMiddleware < ConvenientService::Core::MethodChainMiddleware
    def next(...)
      chain.next(...)
    end
  end

  module FirstConfig
    def self.included(service_class)
      service_class.include ConvenientService::Standard::Config
  
      service_class.middlewares :result do
        use TestMiddleware
      end
    end
  end

  module SecondConfig
    def self.included(service_class)
      service_class.include ConvenientService::Standard::Config
  
      service_class.middlewares :result do
        use TestMiddleware
      end
    end
  end

  class Service
    include FirstConfig
    include SecondConfig
  end

  Service.middlewares(:result).to_a
  # => [ConvenientService::Common::Plugins::NormalizesEnv::Middleware, ConvenientService::Service::Plugins::HasResult::Middleware, ConvenientService::Service::Plugins::HasResultSteps::Middleware, ConvenientService::Common::Plugins::HasCallbacks::Middleware, ConvenientService::Common::Plugins::HasAroundCallbacks::Middleware, ConvenientService::Service::Plugins::RaisesOnDoubleResult::Middleware, ConvenientService::Common::Plugins::CachesReturnValue::Middleware, TestMiddleware, TestMiddleware]

  Service.middlewares(:result).to_a.size
  # => 9

  class Service
    include FirstConfig
    include SecondConfig
  end

  Service.middlewares(:result).to_a.size
  # => 11

  class Service
    include FirstConfig
    include SecondConfig
  end

  Service.middlewares(:result).to_a.size
  # => 13

• In the future, a lot of the new predefined configs will be created, and some of them may have dependencies on each other.

• As a result, some middleware may be added multiple times unintentionally.

Complexity: Medium

Hard Requirements:

• Provide a simple way for the end user to avoid such behavior.
• include Config signature in class Service must be kept as it is, but module Config can be modified.
• Corresponding examples and docs should be updated.

[Olha-30]

According to my research, it also appends concerns again and again 🤔

Check this out here:

module TestConcern
  include ConvenientService::Support::Concern
end

module FirstConfig
  def self.included(service_class)
    service_class.include ConvenientService::Standard::Config

    service_class.concerns do
      use TestConcern
    end
  end
end

module SecondConfig
  def self.included(service_class)
    service_class.include ConvenientService::Standard::Config

    service_class.concerns do
      use TestConcern
    end
  end
end

class Service
  include FirstConfig
  include SecondConfig
end

Service.concerns.to_a.count
# => 16

class Service
  include FirstConfig
  include SecondConfig
end

Service.concerns.to_a.count
# => 18

class Service
  include FirstConfig
  include SecondConfig
end

Service.concerns.to_a.count
# => 20

[marian13]

According to my research, it also appends concerns again and again 🤔

Check this out here:

module TestConcern
  include ConvenientService::Support::Concern
end

module FirstConfig
  def self.included(service_class)
    service_class.include ConvenientService::Standard::Config

    service_class.concerns do
      use TestConcern
    end
  end
end

module SecondConfig
  def self.included(service_class)
    service_class.include ConvenientService::Standard::Config

    service_class.concerns do
      use TestConcern
    end
  end
end

class Service
  include FirstConfig
  include SecondConfig
end

Service.concerns.to_a.count
# => 16

class Service
  include FirstConfig
  include SecondConfig
end

Service.concerns.to_a.count
# => 18

class Service
  include FirstConfig
  include SecondConfig
end

Service.concerns.to_a.count
# => 20

Thanks, @Olha-30.

Appreciate your help a lot.

Could you also check a case when the config is defined as a concern, please?

For example:

module FirstConfig
  include ConvenientService::Support::Concern
  
  included do
    include ConvenientService::Standard::Config

    concerns do
      use TestConcern
    end
  end
end

[Olha-30]

@marian13, I have checked the case.
Here is the result:

module TestConcern
  include ConvenientService::Support::Concern
end

module FirstConfig
  include ConvenientService::Support::Concern
  
  included do
    include ConvenientService::Standard::Config

    concerns do
      use TestConcern
    end
  end
end

module SecondConfig
  include ConvenientService::Support::Concern
  
  included do
    include ConvenientService::Standard::Config

    concerns do
      use TestConcern
    end
  end
end

class Service
  include FirstConfig
  include SecondConfig
end

Service.concerns.to_a.count
# => 16

class Service
  include FirstConfig
  include SecondConfig
end

Service.concerns.to_a.count
# => 16

As you can see, the amount of concerns does NOT change, no matter how many times I include already-included modules.
So in conclusion, I guess that included in concerns already works like included_once. And the behavior of the regular included hook in simple modules differs from the concerns included, as it does NOT check if the same code was already triggered, and it triggers middlewares and concerns methods, in our case, again and again. Maybe it was one of the reasons for creating concerns in Rails? To improve performance? 🤔 (just assuming 😄)

[Olha-30]

Here is the mix example, using middlewares and concerns together:

class TestMiddleware < ConvenientService::Core::MethodChainMiddleware
  def next(...)
    chain.next(...)
  end
end

module TestConcern
  include ConvenientService::Support::Concern
end

module FirstConfig
  include ConvenientService::Support::Concern

  included do
    include ConvenientService::Standard::Config
  
    concerns do
      use TestConcern
    end
 
    middlewares :result do
      use TestMiddleware
    end
  end
end

module SecondConfig
  include ConvenientService::Support::Concern

  included do
    include ConvenientService::Standard::Config
  
    concerns do
      use TestConcern
    end
 
    middlewares :result do
      use TestMiddleware
    end
  end
end

class Service
  include FirstConfig
  include SecondConfig
end

Service.concerns.to_a.count
# => 16

Service.middlewares(:result).to_a.size
# => 9

class Service
  include FirstConfig
  include SecondConfig
end

Service.concerns.to_a.count
# => 16

Service.middlewares(:result).to_a.size
# => 9

The amount of concerns and middlewares does NOT change 😄

[marian13]

Thanks, @Olha-30.

Your improvements are merged as a part of #46.