Groups > comp.programming.threads > #1111

Re: Safe accesses of global arrays in signal handlers?

From	Nobody <nobody@nowhere.com>
Subject	Re: Safe accesses of global arrays in signal handlers?
Date	2012-09-28 18:26 +0100
Message-Id	<pan.2012.09.28.17.26.06.856000@nowhere.com>
Newsgroups	comp.programming.threads, comp.unix.programmer
References	<accvmcFog2gU1@mid.individual.net> <pan.2012.09.25.11.15.59.228000@nowhere.com> <acik2gF3panU1@mid.individual.net> <pan.2012.09.27.12.35.52.872000@nowhere.com> <aclh4pFol46U1@mid.individual.net>
Organization	Zen Internet

Cross-posted to 2 groups.

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On Fri, 28 Sep 2012 13:48:40 +0200, Markus Elfring wrote:

>> Doing anything substantial in a signal handler is problematic.
> 
> Are the following approaches valid software design options for the
> discussed use case?
> 
> 1. "Self-pipe trick" that was described by Daniel J. Bernstein.
>    http://cr.yp.to/docs/selfpipe.html

Yes. write() is async-signal-safe, so one thread can do a blocking read()
and the signal handler can use write() to wake it.

> 2. Are lock-free algorithms applicable like an implementation is described
> in the article "Signal-Safe Locks"?

Lock-free algorithms require memory semantics beyond those specified in
the C and POSIX standards. E.g. they typically require the use of a memory
barrier (fence).

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Safe accesses of global arrays in signal handlers? Markus Elfring <Markus.Elfring@web.de> - 2012-09-25 08:01 +0200
  Re: Safe accesses of global arrays in signal handlers? Nobody <nobody@nowhere.com> - 2012-09-25 12:15 +0100
    Re: Safe accesses of global arrays in signal handlers? Markus Elfring <Markus.Elfring@web.de> - 2012-09-27 11:20 +0200
      Re: Safe accesses of global arrays in signal handlers? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-09-27 13:23 +0100
        Re: Safe accesses of global arrays in signal handlers? Markus Elfring <Markus.Elfring@web.de> - 2012-09-28 13:25 +0200
      Re: Safe accesses of global arrays in signal handlers? Nobody <nobody@nowhere.com> - 2012-09-27 13:35 +0100
        Re: Safe accesses of global arrays in signal handlers? Markus Elfring <Markus.Elfring@web.de> - 2012-09-28 13:48 +0200
          Re: Safe accesses of global arrays in signal handlers? Johann Klammer <klammerj@NOSPAM.a1.net> - 2012-09-28 18:34 +0200
            Re: Safe accesses of global arrays in signal handlers? scott@slp53.sl.home (Scott Lurndal) - 2012-09-28 17:54 +0000
          Re: Safe accesses of global arrays in signal handlers? Nobody <nobody@nowhere.com> - 2012-09-28 18:26 +0100
            Re: Safe accesses of global arrays in signal handlers? Markus Elfring <Markus.Elfring@web.de> - 2012-09-29 13:44 +0200
              Re: Safe accesses of global arrays in signal handlers? Nobody <nobody@nowhere.com> - 2012-09-29 20:37 +0100
                Re: Safe accesses of global arrays in signal handlers? William Ahern <william@wilbur.25thandClement.com> - 2012-09-29 17:31 -0700
                Signal handlers writing into pipes Markus Elfring <Markus.Elfring@web.de> - 2012-09-30 13:21 +0200
                Re: Safe accesses of global arrays in signal handlers? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-10-01 18:04 +0100
                Signal handlers writing into pipes Markus Elfring <Markus.Elfring@web.de> - 2012-10-03 16:36 +0200
                Re: Signal handlers writing into pipes Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-10-03 17:07 +0100
                Re: Safe accesses of global arrays in signal handlers? Markus Elfring <Markus.Elfring@web.de> - 2012-09-30 13:12 +0200
                Re: Safe accesses of global arrays in signal handlers? Nobody <nobody@nowhere.com> - 2012-09-30 20:46 +0100
        Re: Safe accesses of global arrays in signal handlers? Geoff Clare <geoff@clare.See-My-Signature.invalid> - 2012-09-28 13:39 +0100
        Re: Safe accesses of global arrays in signal handlers? Markus Elfring <Markus.Elfring@web.de> - 2012-09-29 13:15 +0200
          Re: Safe accesses of global arrays in signal handlers? William Ahern <william@wilbur.25thandClement.com> - 2012-09-29 17:42 -0700
            Re: Safe accesses of global arrays in signal handlers? Markus Elfring <Markus.Elfring@web.de> - 2012-09-30 14:04 +0200
  Re: Safe accesses of global arrays in signal handlers? Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-09-25 13:27 +0100

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