(PECL pecl_http >= 0.1.0)
http_cache_etag — Caching by ETag
$etag
] )Attempts to cache the sent entity by its ETag, either supplied or generated by the hash algorithm specified by the INI-опцию http.etag.mode.
If the clients If-None-Match header matches the supplied/calculated ETag, the body is considered cached on the clients side and a 304 Not Modified status code is issued.
A log entry is written to the cache log if the INI-опцию http.log.cache is set and the cache attempt was successful.
Замечание: Эта функция может быть использована совместно с http_send_data(), http_send_file() и http_send_stream().
If this function is used outside the http_send_*() API, it facilitates the ob_etaghandler().
etagcustom ETag
Возвращает FALSE или выходит при успешном завершении работы with 304 Not Modified if the entity is cached.
Смотрите INI-опцию
http.force_exit для пояснения термина "выходит".
Пример #1 A http_cache_etag() example
<?php
http_cache_etag();
http_send_data("data");
?>