Contents

require 'infopark_component_cache/consistency_guard'

module InfoparkComponentCache
  module Guards
    # @author Tomasz Przedmojski <[e-mail]>
    #
    # This guard ensures that any object that becomes valid (through valid_from)
    # will cause inconsistency
    class ValidFrom < ConsistencyGuard
      def consistent?
        if min_valid_from_known?
          return no_changes_since?
        else
          return current_min_valid_from.nil?
        end
      end

      def guard!
        cache.write(cache_key, current_min_valid_from)
      end

      # @return true if a timestamp can be read from cache with {#cache_key}
      def min_valid_from_known?
        cache.exist?(cache_key) && cache.read(cache_key).kind_of?(Time)
      end

      # @return true if no obj has been changed since last {#guard!}
      def no_changes_since?
        current_min_valid_from == cache.read(cache_key) && current_min_valid_from > Time.now
      end

      # @return [String] the cache key for storing {#current_min_valid_from}
      def cache_key
        component.cache_key('min_valid_from')
      end

      # @return [Time] the timestamp of the most recent valid_from, or nil if none found
      def current_min_valid_from
        str_value = RailsConnector::Obj.where('valid_from > ?', Time.now.to_iso).minimum(:valid_from)
        if str_value.present?
          RailsConnector::DateAttribute.parse(str_value)
        else
          nil
        end
      end
    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/guards/valid_from.rb
infopark_component_cache-1.0.0	lib/infopark_component_cache/guards/valid_from.rb