code: public function read($uid) {
          if (!is_int($uid) && !is_numeric($uid)) {
              throw new Exception\RuntimeException('Segment type key must integer or numeric.');
          }
          $this->alloc();
          $strShm = shm_get_var($this->memory, $uid);
          $str = trim($strShm);
          if (!$str) {
              return false;
          }
          return $str;
      }
docs: Read datas with $uid key
  @param mixed $uid
  @return mixed