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.
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?
Sorry, if that is a non-issue, or already tracked, I'm just curious.
--
Alexey.
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