instance method truncate_key

# File activesupport/lib/active_support/cache.rb, line 991
        def truncate_key(key)
          if key && @max_key_size && key.bytesize > @max_key_size
            suffix = ":hash:#{ActiveSupport::Digest.hexdigest(key)}"
            truncate_at = @max_key_size - suffix.bytesize
            key = key.byteslice(0, truncate_at)
            key.scrub!("")
            "#{key}#{suffix}"
          else
            key
          end
        end