(PECL pecl_http >= 0.1.0)
http_cache_last_modified — Caching by last modification
$timestamp_or_expires
] )Attempts to cache the sent entity by its last modification date.
If the supplied argument is greater than 0, it is handled as timestamp and will be sent as date of last modification. If it is 0 or omitted, the current time will be sent as Last-Modified date. If it's negative, it is handled as expiration time in seconds, which means that if the requested last modification date is not between the calculated timespan, the Last-Modified header is updated and the actual body will be sent.
A log entry will be 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().
timestamp_or_expiresUnix timestamp
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_last_modified() example
Caching for 5 seconds.
<?php
http_cache_last_modified(-5);
printf("%s\n", http_date());
?>