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Re^3: Need Help With Alarm And Eval

by afoken (Parson)
on Dec 06, 2012 at 15:08 UTC ( #1007600=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Need Help With Alarm And Eval
in thread Need Help With Alarm And Eval

removed local and every thing worked perfectly

No, it doesn't. The On function sets the signal handler globally, for ever, even after eval has finished. You want local $SIG{'ALRM'} inside that eval.

The extra subs don't make your code any clearer. I think you should keep alarm and local $SIG{'ALRM'} inside the eval.

You could also consider writing a generic timeout function like this:

# untested sub withTimeout { my ($timeout,$worker,$timeouthandler)=@_; eval { local $SIG{'ALRM'}=sub { die "TIMEOUT" }; alarm($timeout); $worker->(); alarm(0); }; if ($@ and $@=~/TIMEOUT/) { $errorhandler->(); } }

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)


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Re^4: Need Help With Alarm And Eval
by PerlRocks6345 (Novice) on Dec 07, 2012 at 07:37 UTC

    Hey Thank you.My problem is ,I want subs to switch on and off my alarm so that i can call them when needed. Any suggestion how to do that ?

      I want subs to switch on and off my alarm so that i can call them when needed

      Why? The code you showed first is more or less the usual code for having a timeout in some long running code. (You do know the example in perlipc, right?) If you don't need a timeout, just don't mess with alarm and $SIG{'ALRM'} at all.

      In code:

      withTimeout(30,\&doSomething,sub { die 'Oooops, doSomething was too sl +ow' }); # <-- timeout after 30 seconds doSomething(); # <-- no timeout here

      If you still think that you need to "switch on and off", please explain your actual problem.

      Alexander

      --
      Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

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