# File lib/active_support/cache.rb, line 271
      def fetch(name, options = nil)
        if block_given?
          options = merged_options(options)
          key = namespaced_key(name, options)
          unless options[:force]
            entry = instrument(:read, name, options) do |payload|
              payload[:super_operation] = :fetch if payload
              read_entry(key, options)
            end
          end
          if entry && entry.expired?
            race_ttl = options[:race_condition_ttl].to_f
            if race_ttl and Time.now.to_f - entry.expires_at <= race_ttl
              entry.expires_at = Time.now + race_ttl
              write_entry(key, entry, :expires_in => race_ttl * 2)
            else
              delete_entry(key, options)
            end
            entry = nil
          end

          if entry
            instrument(:fetch_hit, name, options) { |payload| }
            entry.value
          else
            result = instrument(:generate, name, options) do |payload|
              yield
            end
            write(name, result, options)
            result
          end
        else
          read(name, options)
        end
      end