On 12:29 pm, twisted-...@udmvt.ru wrote: >As far as I know, socket.recv() may raise socket.error exception >in case of error return from recv(2) system call. My system's (Linux >i386 2.6.32) >man page say there could be these error values: > > EAGAIN or EWOULDBLOCK > EBADF > ECONNREFUSED > EFAULT > EINTR > EINVAL > ENOMEM > ENOTCONN > ENOTSOCK > >Now, looking into twisted.internet.tcp, method doRead() on line 443, >(twisted 10.1.0) >we may find, that code: > try: > data = self.socket.recv(self.bufferSize) > except socket.error, se: > if se.args[0] == EWOULDBLOCK: > return > else: > return main.CONNECTION_LOST > if not data: > return main.CONNECTION_DONE > return self.protocol.dataReceived(data) > >This is the point in the twisted framework, that decides how TCP socket >will get closed, whether that be in "clean" or "non clean" fashion. > >But some error codes, besides EWOULDBLOCK, are not in any way related >to reporting a permanent error, that deserves closing the socket. > >Question to Python system library gurus: is socket.recv() supposed to >raise socket.error with EINTR code ? >In that case we should return None too, since that operation should be >restarted, >and reporting main.CONNECTION_LOST is a bug.
This particular socket.recv call should not fail with EINTR because it is a non-blocking receive. If you know of a condition which contradicts this, please let us know. > >What about ENOMEM case? Is system supposed to have destroyed the socket >after that event, >or it can safely recover later, so there is no sense in closing the >socket in twisted either? Python will turn an ENOMEM into a raised MemoryError. In general in Python, it is challenging to do anything useful in response to a MemoryError. It may be possible to recover and continue using the socket, or it may not be, there's no way to know in general (and even knowing in a particular case can be challenging). So, without an idea of what would be a better way to handle MemoryError, Twisted typically treats it the same way it treats any other unexpected exception. It will generally get logged and if it came from a socket.recv() call like the one above, that socket will be disconnected and the associated protocol object informed. Jean-Paul _______________________________________________ Twisted-Python mailing list Twisted-Python@twistedmatrix.com http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
