UDP sockets

[Zunbeltz Izaola]

Hi

I'm porting a client writen in C++ to python. What is the way to get a
timeout in an select for one socket?
the c++ code is:
FD_ZERO(&fds);
FD_SET(fd_sock, &fds);
tv.tv_sec=2;
tv.tv_usec=0;
n = select(fd_sock+1,&fds,NULL,NULL,&tv);
sendto(...)

Thanks

Zunbeltz

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[Andrew Bennetts]

On Wed, Oct 22, 2003 at 11:15:35AM +0200, Zunbeltz Izaola wrote:

Hi

I'm porting a client writen in C++ to python. What is the way to get a
timeout in an select for one socket?
the c++ code is:
FD_ZERO(&fds);
FD_SET(fd_sock, &fds);
tv.tv_sec=2;
tv.tv_usec=0;
n = select(fd_sock+1,&fds,NULL,NULL,&tv);
sendto(...)

The python code is (assuming your socket.socket object is in a variable
called 'sock'):

import select
r, w, e = select.select([sock], [], [], 2)
if r:
sock.sendto(...)

-Andrew.

[Andrew Bennetts]

On Wed, Oct 22, 2003 at 10:02:00PM +1000, Andrew Bennetts wrote:

On Wed, Oct 22, 2003 at 11:15:35AM +0200, Zunbeltz Izaola wrote:

Hi

I'm porting a client writen in C++ to python. What is the way to get a
timeout in an select for one socket?
the c++ code is:
FD_ZERO(&fds);
FD_SET(fd_sock, &fds);
tv.tv_sec=2;
tv.tv_usec=0;
n = select(fd_sock+1,&fds,NULL,NULL,&tv);
sendto(...)

The python code is (assuming your socket.socket object is in a variable
called 'sock'):

import select
r, w, e = select.select([sock], [], [], 2)
if r:
sock.sendto(...)

Oh, I hurried too much and misread your code. You seem to want to always
call sendto, regardless of the result of the select call. In that case it's
even easier:

import select
select.select([sock], [], [], 2) # Just throw away the results :)
sock.sendto(...)

Anyway, hopefully it should be clear enough how to use select in python now
:)

-Andrew.

[Wojtek Walczak]

Dnia 22 Oct 2003 11:15:35 +0200, Zunbeltz Izaola napisa³(a):

I'm porting a client writen in C++ to python. What is the way to get a
timeout in an select for one socket?

Quote from the ,,7.3 select -- Waiting for I/O completion'':

The optional timeout argument specifies a time-out as a floating point
number in seconds.

So, it'll be something like this:

n = select.select([fds], [], [], 2)[0][0]

--
[ Wojtek Walczak - gminick (at) underground.org.pl ]
[ <http://gminick.linuxsecurity.pl/> ]
[ "...rozmaite zwroty, matowe od patyny dawnosci." ]

[Peter Hansen]

Wojtek Walczak wrote:

Dnia 22 Oct 2003 11:15:35 +0200, Zunbeltz Izaola napisa³(a):

I'm porting a client writen in C++ to python. What is the way to get a
timeout in an select for one socket?

Quote from the ,,7.3 select -- Waiting for I/O completion'':

The optional timeout argument specifies a time-out as a floating point
number in seconds.

So, it'll be something like this:

n = select.select([fds], [], [], 2)[0][0]

At first glance, this appears unsafe. What if the fds socket
is not ready after the timeout?

You will, I think, get an IndexError raised.

-Peter