Re: cross platform alternative for signal.SIGALRM?

From	Cameron Simpson <cs@zip.com.au>
Newsgroups	comp.lang.python
Subject	Re: cross platform alternative for signal.SIGALRM?
Date	2015-11-12 16:20 +1100
Message-ID	<mailman.255.1447307382.16136.python-list@python.org> (permalink)
References	<n1vpl3$hrl$1@news2.informatik.uni-stuttgart.de>

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On 11Nov2015 16:16, Ulli Horlacher <framstag@rus.uni-stuttgart.de> wrote:
>I am rewriting a Perl program into Python (2.7).
>It must run on Linux and Windows.
>With Linux I have no problems, but Windows... :-(
>
>The current show stopper is signal.SIGALRM which is not available on
>Windows:
>
>  File "fexit.py", line 674, in formdata_post
>    signal.signal(signal.SIGALRM,timeout_handler)
>  AttributeError: 'module' object has no attribute 'SIGALRM'
>
>  https://docs.python.org/2/library/signal.html
>
>  signal.alarm(time) (...) Availability: Unix.
>
>Perl for Windows has had SIGALRM support (or some kind of emulation).
>
>Ok, I have to redesign this part of my code:
>
>  def timeout_handler(sig,frame):
>    raise ValueError("timeout!")
>
>  signal.signal(signal.SIGALRM,timeout_handler)
>
>  while True:
>    chunk = fileo.read(bs)
>    sock.sendall(chunk)
>    (...)
>
>What is the best practise for a cross platform timeout handler?

I suggest you look at the socket.settimeout function. Avoid SIGALRM altogether.  
Then (untested):

  import socket
  ...
  socket.settimeout(timeout_in_seconds)
  ...
  while True:
    ...
    chunk = fileo.read(bs)
    try:
      sock.sendall(chunk)
    except socket.timeout as e:
      ... complain about timeout, reciting "e" in the message ...

Cheers,
Cameron Simpson <cs@zip.com.au>

I think you're confusing "recognizing" and "understanding" with "caring".
The net is cruel, sometimes, but always fair.
        - Rick Gordon <rickg@crl.com>

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cross platform alternative for signal.SIGALRM? Ulli Horlacher <framstag@rus.uni-stuttgart.de> - 2015-11-11 16:16 +0000
  Re: cross platform alternative for signal.SIGALRM? Marko Rauhamaa <marko@pacujo.net> - 2015-11-11 18:30 +0200
    Re: cross platform alternative for signal.SIGALRM? Ulli Horlacher <framstag@rus.uni-stuttgart.de> - 2015-11-11 17:06 +0000
      Re: cross platform alternative for signal.SIGALRM? Marko Rauhamaa <marko@pacujo.net> - 2015-11-11 20:03 +0200
        Re: cross platform alternative for signal.SIGALRM? Ulli Horlacher <framstag@rus.uni-stuttgart.de> - 2015-11-11 22:42 +0000
      Re: cross platform alternative for signal.SIGALRM? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-11-11 19:42 -0500
  Re: cross platform alternative for signal.SIGALRM? Terry Reedy <tjreedy@udel.edu> - 2015-11-11 20:37 -0500
    Re: cross platform alternative for signal.SIGALRM? Marko Rauhamaa <marko@pacujo.net> - 2015-11-12 08:14 +0200
      Re: cross platform alternative for signal.SIGALRM? Christian Gollwitzer <auriocus@gmx.de> - 2015-11-12 07:43 +0100
        Re: cross platform alternative for signal.SIGALRM? Chris Angelico <rosuav@gmail.com> - 2015-11-12 18:37 +1100
        Re: cross platform alternative for signal.SIGALRM? Terry Reedy <tjreedy@udel.edu> - 2015-11-12 05:15 -0500
        Re: cross platform alternative for signal.SIGALRM? Chris Angelico <rosuav@gmail.com> - 2015-11-12 22:38 +1100
        Re: cross platform alternative for signal.SIGALRM? Terry Reedy <tjreedy@udel.edu> - 2015-11-12 09:01 -0500
      Re: cross platform alternative for signal.SIGALRM? Ulli Horlacher <framstag@rus.uni-stuttgart.de> - 2015-11-12 07:22 +0000
        Re: cross platform alternative for signal.SIGALRM? Marko Rauhamaa <marko@pacujo.net> - 2015-11-12 10:15 +0200
    Re: cross platform alternative for signal.SIGALRM? Ulli Horlacher <framstag@rus.uni-stuttgart.de> - 2015-11-12 06:58 +0000
  Re: cross platform alternative for signal.SIGALRM? Cameron Simpson <cs@zip.com.au> - 2015-11-12 16:20 +1100

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