Contents

require 'infopark_component_cache/cache_storage'

module InfoparkComponentCache
  # @author Tomasz Przedmojski <[e-mail]>
  #
  # @abstract
  # This is abstract base class for any Cache Guards.
  # Any class inheriting ConsistencyGuard should implement #consistent?
  # and #guard!
  #
  # Cache Guard is a class that promises some consistency, for example
  # that no changes to the database accured between calls to #guard!
  # and #consistent?
  #
  # This consistency is crucial for the function of cache, because
  # inconsistent cache is (automatically) invalidated.
  class ConsistencyGuard
    attr_reader :component

    def initialize(component)
      @component = component
    end

    # @return [CacheStorage] instance of CacheStorage
    def cache
      CacheStorage.instance
    end

    # @abstract
    # This method returns true if the consistenty guarded by this class
    # is fulfilled and false otherwise.
    def consistent?
      raise TypeError, "Abstract method consistent? called"
    end

    # @abstract
    # This method is called whenever cache is updated for the component.
    # Any values checked by #consistent? can be persisted here. Use #{cache}
    # for persistence but mind the possible inconsistencies.
    def guard!
      raise TypeError, "Abstract method guard! called"
    end
  end
end

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
infopark_component_cache-1.1.0	lib/infopark_component_cache/consistency_guard.rb
infopark_component_cache-1.0.0	lib/infopark_component_cache/consistency_guard.rb