handle_expired_entry

# File activesupport/lib/active_support/cache.rb, line 564
        def handle_expired_entry(entry, key, options)
          if entry && entry.expired?
            race_ttl = options[:race_condition_ttl].to_i
            if race_ttl && (Time.now.to_f - entry.expires_at <= race_ttl)
              # When an entry has :race_condition_ttl defined, put the stale entry back into the cache
              # for a brief period while the entry is begin recalculated.
              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
          entry
        end