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<?php /* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
/** * HTTP::Header::Cache * * PHP versions 4 and 5 * * @category HTTP * @package HTTP_Header * @author Wolfram Kriesing <wk@visionp.de> * @author Michael Wallner <mike@php.net> * @copyright 2003-2005 The Authors * @license BSD, revised * @version CVS: $Id: Cache.php 304418 2010-10-15 13:18:02Z clockwerx $ * @link http://pear.php.net/package/HTTP_Header */
/** * Requires HTTP_Header */ require_once 'HTTP/Header.php';
/** * HTTP_Header_Cache * * This package provides methods to easier handle caching of HTTP pages. That * means that the pages can be cached at the client (user agent or browser) and * your application only needs to send "hey client you already have the pages". * * Which is done by sending the HTTP-Status "304 Not Modified", so that your * application load and the network traffic can be reduced, since you only need * to send the complete page once. This is really an advantage e.g. for * generated style sheets, or simply pages that do only change rarely. * * Usage: * <code> * require_once 'HTTP/Header/Cache.php'; * $httpCache = new HTTP_Header_Cache(4, 'weeks'); * $httpCache->sendHeaders(); * // your code goes here * </code> * * @package HTTP_Header * @category HTTP * @access public * @version $Revision: 304418 $ */ class HTTP_Header_Cache extends HTTP_Header { /** * Constructor * * Set the amount of time to cache. * * @access public * @return object HTTP_Header_Cache * @param int $expires * @param string $unit */ function HTTP_Header_Cache($expires = 0, $unit = 'seconds') { parent::HTTP_Header(); $this->setHeader('Pragma', 'cache'); $this->setHeader('Last-Modified', $this->getCacheStart()); $this->setHeader('Cache-Control', 'private, must-revalidate, max-age=0'); if ($expires) { if (!$this->isOlderThan($expires, $unit)) { $this->exitCached(); } $this->setHeader('Last-Modified', time()); } }
/** * Get Cache Start * * Returns the unix timestamp of the If-Modified-Since HTTP header or the * current time if the header was not sent by the client. * * @access public * @return int unix timestamp */ function getCacheStart() { if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && !$this->isPost()) { return strtotime(current($array = explode(';', $_SERVER['HTTP_IF_MODIFIED_SINCE']))); } return time(); }
/** * Is Older Than * * You can call it like this: * <code> * $httpCache->isOlderThan(1, 'day'); * $httpCache->isOlderThan(47, 'days'); * * $httpCache->isOlderThan(1, 'week'); * $httpCache->isOlderThan(3, 'weeks'); * * $httpCache->isOlderThan(1, 'hour'); * $httpCache->isOlderThan(5, 'hours'); * * $httpCache->isOlderThan(1, 'minute'); * $httpCache->isOlderThan(15, 'minutes'); * * $httpCache->isOlderThan(1, 'second'); * $httpCache->isOlderThan(15); * </code> * * If you specify something greater than "weeks" as time untit, it just * works approximatly, because a month is taken to consist of 4.3 weeks. * * @access public * @return bool Returns true if requested page is older than specified. * @param int $time The amount of time. * @param string $unit The unit of the time amount - (year[s], month[s], * week[s], day[s], hour[s], minute[s], second[s]). */ function isOlderThan($time = 0, $unit = 'seconds') { if (!isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) || $this->isPost()) { return true; } if (!$time) { return false; } switch (strtolower($unit)) { case 'year': case 'years': $time *= 12; case 'month': case 'months': $time *= 4.3; case 'week': case 'weeks': $time *= 7; case 'day': case 'days': $time *= 24; case 'hour': case 'hours': $time *= 60; case 'minute': case 'minutes': $time *= 60; } return (time() - $this->getCacheStart()) > $time; }
/** * Is Cached * * Check whether we can consider to be cached on the client side. * * @access public * @return bool Whether the page/resource is considered to be cached. * @param int $lastModified Unix timestamp of last modification. */ function isCached($lastModified = 0) { if ($this->isPost()) { return false; } if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && !$lastModified) { return true; } if (!$seconds = time() - $lastModified) { return false; } return !$this->isOlderThan($seconds); } /** * Is Post * * Check if request method is "POST". * * @access public * @return bool */ function isPost() { return isset($_SERVER['REQUEST_METHOD']) and 'POST' == $_SERVER['REQUEST_METHOD']; } /** * Exit If Cached * * Exit with "HTTP 304 Not Modified" if we consider to be cached. * * @access public * @return void * @param int $lastModified Unix timestamp of last modification. */ function exitIfCached($lastModified = 0) { if ($this->isCached($lastModified)) { $this->exitCached(); } } /** * Exit Cached * * Exit with "HTTP 304 Not Modified". * * @access public * @return void */ function exitCached() { $this->sendHeaders(); $this->sendStatusCode(304); exit; } /** * Set Last Modified * * @access public * @return void * @param int $lastModified The unix timestamp of last modification. */ function setLastModified($lastModified = null) { $this->setHeader('Last-Modified', $lastModified); } } ?>
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