(PECL pecl_http >= 0.1.0)
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 设置 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 设置 http.log.cache is set and the cache attempt was successful.
Note: 此函数可与 http_send_data(), http_send_file() 和 http_send_stream() 一同使用。
If this function is used outside the http_send_*() API, it facilitates the ob_etaghandler().
custom ETag
返回 FALSE 或在成功时返回出口信息 with 304 Not Modified if the entity is cached. 要知道“出口”的含义请查阅 INI 设置 http.force_exit。
Example #1 A http_cache_etag() example
<?php
http_cache_etag();
http_send_data("data");
?>