caching_optional.rb

class Cache
  def self.fetch(table_name, fields, &block)
    result = redis.get(table_name + ':' + fields.values.join('|'))

    unless result
      # block allows us to try to look for the value elsewhere, if requested
      # NOTE: we are not currently passing a block, so this syntax is sufficiently fast
      # However, when a block is present it is faster to use block_given? and yield
      if block
        result = block.call
      end

      unless result.nil?
        redis.set(table_name + ':' + fields.values.join('|'), result)
      end
    end

    !result || result.empty? ? nil : result
  end
end