(PECL pecl_http:0.1.0-1.5.5)
http_cache_etag — Caching by ETag
Attempts to cache the sent entity by its ETag, either supplied or generated by the hash algorithm specified by the INI 设定 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 设定 http.log.cache is set and the cache attempt was successful.
Note: This function may be used in conjunction with http_send_data(), http_send_file() 和 http_send_stream().
If this function is used outside the http_send_*() API, it facilitates the ob_etaghandler().
custom ETag
Returns FALSE or exits on success with 304 Not Modified if the entity is cached. See the INI 设定 http.force_exit for what "exits" means.
Example#1 A http_cache_etag() example
<?php
http_cache_etag();
http_send_data("data");
?>