[Python-Dev] Adding timeout to socket.py and httplib.py

Greg Ewing greg.ewing at canterbury.ac.nz
Tue Mar 20 23:51:00 CET 2007

Alan Kennedy wrote:

> The standard mechanism in C for doing a non-blocking connect is to
> issue the connect call, and check the return value for a non-zero
> error code. If this error code is errno.EAGAIN (code 10035), then the
> call succeeded, but you should check back later for completion of the
> operation.

Hmmm. I think that this case probably isn't what people
will have in mind when they specify a timeout for connecting.
More likely they mean "If the connection couldn't be successfully
established within this time, give up and let me know."

So it seems to me that a return value of EAGAIN should be
handled internally by re-issuing the connect call with a
suitably reduced timeout value. If the timeout gets down
to zero without a successful result, throw an exception.

An application that wants to do fully asynchronous connects
will have to take quite a different approach, so there
should probably be a different API for this.


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