/**
*
* @global wpdb $wpdb
* @staticvar boolean $init
* @return type
*/
function TryScanLock()
{
global $wpdb;
if (!self::$_scan_lock_init) {
self::$_scan_lock_init = true;
self::$_file_scan_locks = array();
self::$_cat_scan_locks = array();
register_shutdown_function(array(__CLASS__, '_removeScanLocks'));
}
if ($this->is_file) {
$sla =& self::$_file_scan_locks;
} else {
$sla =& self::$_cat_scan_locks;
}
$table = $this->is_file ? $wpdb->wpfilebase_files : $wpdb->wpfilebase_cats;
$prefix = $this->is_file ? 'file' : 'cat';
$slf = "{$prefix}_scan_lock";
$now = time();
$lock_time = $now + self::SCAN_LOCK_TIMEOUT;
$id = $this->GetId();
// first check if we own the lock and update if necessary
if (isset($sla[$id])) {
//echo "TryLock $this @".__LINE__." isset";
return $lock_time > $sla[$id] ? $wpdb->update($table, array($slf => $lock_time), array("{$prefix}_id" => $id, $slf => $sla[$id])) && ($sla[$id] = $this->{$slf} = $lock_time) : true;
}
// actually try to set the lock and store it in $sla if success
return $wpdb->query($wpdb->prepare("\n\t\t\tUPDATE `{$table}`\n\t\t\tSET `{$slf}` = %d\n\t\t\tWHERE (`{$prefix}_id` = %d) AND (`{$slf}` < %d)\n\t\t\t", $lock_time, $id, $now)) && ($sla[$id] = $this->{$slf} = $lock_time);
}
