osdate_cache.php

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<?php
/* This is the main Page Caching mechanism of osdate.
 * Vijay Nair
 *
 * This caches following pags only and only if the user is not logged in.
 *
 * index.php
 *   index page for a visitor
 *   individual article and news item and stories display as part.
 *   terms of service page display
 *   faq page display
 *   privacy poliry
 *   services page
 *	 stories
 *	 allnews
 *   articles
 *   show one story
 *   show one news item
 *   show one article
 *   All saved pages
 *   login page
 *
 * showprofile.php
 *   profile of a member if popup is enabled as a full page
 *   profile of a member if popup is not enabled which works as part.
 *
 *
 * The expiry time of cache is limited by the value page_cache_expiry in Global
 *     settings. Default is 30 minutes.
 */
 function checkCache($query)
 {
 	global $config;
	/* Get hash file name for the query */
	$cached_file_name = generateCacheFilename($query);
	/* Now see if there is a hash for current query is svailable */
	$cached_data = getCachedData($cached_file_name);

	if (!$cached_data) { return false; }
	$cached_time = $cached_data['cached_time'];

	/* Convert the config['time_cache_expiry'] into seconds */
	$tm = time() - $config['page_cache_expiry']*60;

//	$tm = time() - (30*60);

	if ($cached_time < $tm) {
		removeCacheFile($cached_file_name);
		return false;
	}
	/* Cache is valid. return data */
	return $cached_data['saved_data'];
 }
 // }}}

// {{{ saveCache()
/*
 *	This function will update the cached_tables file with latest update time.
 *  This will write the file with updated time
 *  @param the SQL Query, result of query
 *
 *	@access internal
 *  @return none
 */
function saveCache($query, $result) {
	$cache_file = generateCacheFilename($query);
	$save_array = serialize(array(
		'cached_time' => get_micro_time(),
		'saved_data' => $result)
		);

	$fp = @fopen(CACHE_DIR.$cache_file,'wb');
	@flock($fp,LOCK_EX);
	@fwrite($fp,$save_array);
	@flock($fp,LOCK_UN);
	@fclose($fp);
}

// }}}

/* This function generates the file name for the cached item */
function generateCacheFilename($input)
{
	return 'pages_cache_'.md5($input).".dat";
}

/* Get microtime as table update time and cache time */
function get_micro_time()
{
/*		list($usec, $sec) = explode(" ", microtime());
	return (float)($usec + $sec);
	*/
	return time();
}

/* This function gets the cache file for a given cached_file_name  and returns
	data, and time of cache
*/
function getCachedData($cached_file_name){
	$cached_data = array();
	if (file_exists(CACHE_DIR.$cached_file_name)) {
		$cached_data = unserialize(file_get_contents(CACHE_DIR.$cached_file_name));
	}
	return $cached_data;
}

/* This function will remove the cacehd file from CACHE_DIR */
function removeCacheFile($cache_file_name) {

	unlink(CACHE_DIR.$cache_file_name);
}

?>