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Re: Asynchronous callbacks from C

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Paul Johnson
July 5, 2001 08:04
Re: Asynchronous callbacks from C
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On Thu, Jul 05, 2001 at 03:12:25PM +0200, Artur Bergman wrote:
> 01-07-05 15.04, skrev David M. Lloyd på följande:
> > On Tue, 3 Jul 2001, Benjamin Stuhl wrote:
> > 
> >>> I have written an XS interface into a library that performs I/O and
> >>> then can asynchronously call a C function upon completion.  Is there a
> >>> SAFE way I can reflect an asynchronous callback into Perl?
> >> 
> >> AFAIK, only if the perl is built to expect such. In 5.8.0-to-be there
> >> is the PERL_ASYNC_CHECK which is used for safe signals. You would have
> >> to hack around a bit in the core to interface that to your XS, and
> >> even then it would only work with a perl built for it.
> >> 
> >> Maybe 5.8.0 should make PL_signal_pending or whatever it's called
> >> public and provide a way for modules to register a event-checking
> >> callback?
> > 
> > I can't help but be jealous of PHP/Zend in this respect.  I have a friend
> > who just wrote a signal handling *add-on* module (that is, there was no
> > hacking required of the core engine) because he was able to use an API
> > function to insert a C callback that is called between every opcode (or
> > whatever they call them... I think they have a subtly different name for
> > the same concept).
> > 
> > It would be awesome to have something like that in Perl.  I guess that the
> > performance hit associated with such a callback would be minimal... well
> > worth the added power.
> > 
> > - D
> Like Benjamin said, we have PERL_ASYNC_CHECK that checks between opcodes,
> this could added as a option to that.

Or you could use a plugable runops function.  Then you can do whatever
you want without hacking the core.  This sounds like just what you're

> How hard would it be for PERL_ASYNC_CHECK to call a C callback instead of a
> perl signal handler? And if that C callback did call_sv()...
> Artur

Paul Johnson -

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