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# i use this method instead of "render"
render_from_cache_or_render(:cache_key =>”cache key”, :cache_expire_after => ConstantHelper::TAG_CLOUD_EXPIRED_IN, # minute

# implementation
def render_from_cache_or_render(p_args)

    return render(p_args) if true == p_args[:cache_off]

    # check from cache
    cache_key = p_args[:cache_key]
    cached_content = CacheService.get_cache(cache_key)

    if not cached_content.nil? and not cached_content.empty?
      return cached_content
    else
    content = render(p_args)
    
    # cache expire time if defined
    cache_expire_time_in_minutes = p_args[:cache_expire_after] || 60
      CacheService.add_cache(cache_key, cache_expire_time_in_minutes, content)
      return content
    end
end


# complete source code of cache service
module Cache
    class Item
      attr_accessor :key, :expire_time, :content, :created_on

      def initialize(p_key, p_expire_time, p_content)
        @key = p_key
        @expire_time = p_expire_time * 60 # in minutes
        @content = p_content
        @created_on = Time.now
      end
    end
end

class CacheService
    @@CACHES = {}
    @@CACHE_EXPIRE_TIMES = {}

    def self.add_cache(p_key, p_expire_time, p_content)
      cache_item = Cache::Item.new(p_key, p_expire_time, p_content)
      @@CACHES[p_key.to_sym] = cache_item
    end

    def self.get_cache(p_key)
      # load content from cache
      cached_content = @@CACHES[p_key.to_sym]
      return nil if cached_content.nil?

      # verify cache validity
      return cached_content.content if not expired?(cached_content)
      return nil
    end

    private
    def self.expired?(p_cache)
      # find time difference
      time_difference = Time.now - p_cache.created_on
      return true if time_difference > p_cache.expire_time
    end
 end