(PECL pecl_http >= 0.10.0)
HttpResponse::setCache — Set cache
Whether it should be attempted to cache the entity.
This will result in necessary caching headers and checks of clients If-Modified-Since and If-None-Match headers. If one of those headers matches a 304 Not Modified status code will be issued.
Note:
If you're using sessions, be sure that you set session.cache_limiter to something more appropriate than "no-cache"!
whether caching should be attempted
成功时返回 TRUE， 或者在失败时返回 FALSE.