phpbb\install\helper\iohandler\ajax_iohandler::acquire_lock PHP Method

    public function acquire_lock()
    {
        $lock_file = $this->phpbb_root_path . 'store/io_lock.lock';
        $this->file_lock_pointer = @fopen($lock_file, 'w+');
        if ($this->file_lock_pointer) {
            flock($this->file_lock_pointer, LOCK_EX);
        }
    }