protocol_socket.py 文件源码

def write(self, data):
        """\
        Output the given byte string over the serial port. Can block if the
        connection is blocked. May raise SerialException if the connection is
        closed.
        """
        if not self.is_open:
            raise portNotOpenError

        d = to_bytes(data)
        tx_len = length = len(d)
        timeout = Timeout(self._write_timeout)
        while tx_len > 0:
            try:
                n = self._socket.send(d)
                if timeout.is_non_blocking:
                    # Zero timeout indicates non-blocking - simply return the
                    # number of bytes of data actually written
                    return n
                elif not timeout.is_infinite:
                    # when timeout is set, use select to wait for being ready
                    # with the time left as timeout
                    if timeout.expired():
                        raise writeTimeoutError
                    _, ready, _ = select.select([], [self._socket], [], timeout.time_left())
                    if not ready:
                        raise writeTimeoutError
                else:
                    assert timeout.time_left() is None
                    # wait for write operation
                    _, ready, _ = select.select([], [self._socket], [], None)
                    if not ready:
                        raise SerialException('write failed (select)')
                d = d[n:]
                tx_len -= n
            except SerialException:
                raise
            except OSError as e:
                # this is for Python 3.x where select.error is a subclass of
                # OSError ignore BlockingIOErrors and EINTR. other errors are shown
                # https://www.python.org/dev/peps/pep-0475.
                if e.errno not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
                    raise SerialException('write failed: {}'.format(e))
            except select.error as e:
                # this is for Python 2.x
                # ignore BlockingIOErrors and EINTR. all errors are shown
                # see also http://www.python.org/dev/peps/pep-3151/#select
                if e[0] not in (errno.EAGAIN, errno.EALREADY, errno.EWOULDBLOCK, errno.EINPROGRESS, errno.EINTR):
                    raise SerialException('write failed: {}'.format(e))
            if not timeout.is_non_blocking and timeout.expired():
                raise writeTimeoutError
        return length - len(d)