function shLoadURLCache()
{
global $shURLDiskCache, $shURLCacheFileName, $shURLTotalCount, $shURLMemCache, $shURLRam, $shCacheFileLocked;
static $shDiskCacheLoaded = false;
if (!$shDiskCacheLoaded) {
$shCacheFileLocked = false;
_log('Cache not loaded - trying to load ' . $shURLCacheFileName);
if (file_exists($shURLCacheFileName)) {
$startMem = function_exists('memory_get_usage') ? memory_get_usage() : 'unavailable';
_log('Including cache file (mem = ' . $startMem . ')');
$GLOBALS['shURLDiskCache'] = array();
// erase global, not local copy
$lock =& Shlock::getInstance();
// we try lock the cache file until the end of the request
// so as to avoid other concurrent requests writing to it
// while we have some pending data
if ($lock && $lock->acquire('shCacheContent')) {
$shCacheFileLocked = true;
}
include $shURLCacheFileName;
$endMem = function_exists('memory_get_usage') ? memory_get_usage() : 'unavailable';
$shURLRam = $startMem == 'unavailable' ? $startMem : $endMem - $startMem;
$shDiskCacheLoaded = !empty($shURLDiskCache);
$shURLTotalCount = !empty($shURLDiskCache) ? count($shURLDiskCache) : 0;
_log('Cache file included : ' . ($startMem == 'unavailable' ? $startMem : $endMem - $startMem) . ' bytes used, ' . $shURLTotalCount . ' URLs');
} else {
// cache file not there, create it
$now = time();
$sefConfig =& Sh404sefFactory::getConfig();
$cache = '<?php // shCache : URL cache file for sh404SEF
//' . $sefConfig->version . '
if (!defined(\'_JEXEC\')) die(\'Direct Access to this location is not allowed.\');
$shURLCacheCreationDate = ' . $now . ';' . "\n";
$cache .= "\n" . '?' . '>';
// lock cache file before using it
$lock =& Shlock::getInstance();
if ($lock && $lock->acquire('shCacheContent')) {
$shCacheFileLocked = true;
$cacheFile = fopen($shURLCacheFileName, 'ab');
if ($cacheFile) {
fwrite($cacheFile, $cache);
fclose($cacheFile);
}
}
$GLOBALS['shURLDiskCache'] = array();
$shDiskCacheLoaded = true;
// we don't want to try again if it failed first time
_log('Cache file does not exists');
}
}
}
function shWriteURLCacheToDisk()
{
global $shURLDiskCache, $shURLMemCache, $shURLCacheFileName, $shURLCacheCreationDate;
$sefConfig =& shRouter::shGetConfig();
if (!count($shURLMemCache)) {
return;
}
// nothing to do, no new URL to write to disk
$now = time();
if (!file_exists($shURLCacheFileName)) {
$cache = '<?php // shCache : URL cache file for sh404SEF
//' . $sefConfig->version . '
if (!defined(\'_JEXEC\')) die(\'Direct Access to this location is not allowed.\');
$shURLCacheCreationDate = ' . $now . ';' . "\n";
} else {
$cache = '<?php' . "\n";
// check cache TTL
if (empty($shURLCacheCreationDate)) {
// file exists, but creation date is missing : we are upgrading from a previous version
$status = stat($shURLCacheFileName);
// lets's read from file status : use last change date as creation date
if (!empty($status)) {
$shURLCacheCreationDate = $status[9];
$cache .= "\n" . '$shURLCacheCreationDate=' . $shURLCacheCreationDate . ";\n";
}
}
if (SH404SEF_URL_CACHE_TTL && mt_rand(1, SH404SEF_URL_CACHE_WRITES_TO_CHECK_TTL) == 1) {
// probability = 1/SH404SEF_WRITES_TO_CLEAN_LOGS
if (!empty($shURLCacheCreationDate)) {
// if we have a valid creation date, check TTL
if ($now - $shURLCacheCreationDate > SH404SEF_URL_CACHE_TTL * 86400) {
// cache must be cleared
$GLOBALS['shURLDiskCache'] = array();
unlink($shURLCacheFileName);
$shURLCacheCreationDate = $now;
$cache = '<?php // shCache : URL cache file for sh404SEF
//' . $sefConfig->version . '
if (!defined(\'_JEXEC\')) die(\'Direct Access to this location is not allowed.\');
$shURLCacheCreationDate = ' . $now . ';' . "\n";
}
}
}
}
$count = count($shURLDiskCache);
$cache .= sh_var_export($shURLMemCache, $count);
// only need to write memory cache, ie: those URL added since last read of cache from disk
$cache .= "\n" . '?' . '>';
// lock cache file before using it
$lock =& Shlock::getInstance();
if ($lock && $lock->acquire('shCacheContent')) {
$cacheFile = fopen($shURLCacheFileName, 'ab');
if ($cacheFile) {
fwrite($cacheFile, $cache);
fclose($cacheFile);
}
$lock->release('shCacheContent');
}
}
