class Rack::Cache::CacheControl

private cache.
the origin server. The s-maxage directive is always ignored by a
to respond to a subsequent request without first revalidating it with
that the shared cache must not use the entry after it becomes stale
also implies the semantics of the proxy-revalidate directive. i.e.,
max-age directive or the expires header. The s-maxage directive
this directive overrides the maximum age specified by either the
cache (but not for a private cache), the maximum age specified by
If a response includes an s-maxage directive, then for a shared

def shared_max_age
  self['s-maxage'].to_i  if key?('s-maxage')
end