SocketBase.py 文件源码

def can_write(self, timeout=0):
        """
        Checks if there is data that can be written to the
        socket (if open). Returns True if writing is possible and
        False if not.

        It returns None if something very bad happens such as
        a dead connection (bad file descriptor), etc
        """

        # rs = Read Sockets
        # ws = Write Sockets
        # es = Error Sockets
        if self.socket is not None:
            try:
                _, ws, es = select([], [self.socket], [], timeout)
            except (SelectError, socket.error), e:
                if e[0] == errno.EBADF:
                    # Bad File Descriptor... hmm
                    self.close()
                    return None

            if len(es) > 0:
                # Bad File Descriptor
                self.close()
                return None

            return len(ws) > 0

        # no socket or no connection
        return None