Processes header tags in a request and writes responses given on requested cache status.
|the client request used to determine cache control flow.
|the response to write cache headers to.
|if set to anything except .init, adds a Etag header to the response and enables handling of If-Match and If-None-Match cache control request headers.
|if set to anything except .init, adds a Last-Modified header to the response and enables handling of If-Modified-Since and If-Unmodified-Since cache control request headers.
|if set, adds or modifies the Cache-Control header in the response to this string. Might get an additional max-age value appended if max_age is set.
| optional duration to set the Expires header and Cache-Control max-age part to. (if no existing
max-age= part is given in the cache_control parameter)
true if the cache was already handled and no further response must be sent or
false if a response must be sent.