/**
  * Resets all clocks for all benchmarks.
  *
  * @param array $retain_benachmarks Optional. Numeric array containing benchmark-identifiers that should NOT get resetted.
  */
 public static function resetAll($retain_benchmarks = array())
 {
     // If no benchmarks should be retained
     if (count($retain_benchmarks) == 0) {
         self::$benchmark_results = array();
         return;
     }
     // Else reset all benchmarks BUT the retain_benachmarks
     @reset(self::$benchmark_results);
     while (list($identifier) = @each(self::$benchmark_results)) {
         if (!in_array($identifier, $retain_benchmarks)) {
             self::$benchmark_results[$identifier] = 0;
         }
     }
 }