TCP读取为空的问题

if ($buffer === '' || $buffer === false) {
            if ($check_eof && (feof($socket) || !is_resource($socket) || $buffer === false)) {
                $this->destroy();
                return;
            }
        } else {
            $this->bytesRead += strlen($buffer);
            $this->_recvBuffer .= $buffer;
        }