[ntp:hackers] Asynch resolver

Folkert van Heusden folkert at vanheusden.com
Mon May 8 14:10:34 UTC 2006


posix seems to define a (kludgy) ipc mechanism as well as shared memory

On Mon, May 08, 2006 at 02:05:26PM +0000, David L. Mills wrote:
> Paul,
> 
> For everything we do here NIS must be supported.
> 
> I have nothing against pipedreams, just asked for advice and got heavy 
> duty advocacy. The temporary file was the solution adopted some twenty 
> years ago. It was necessary in order to hold association data prior to 
> resolving the IP address and mobilizing the association. The problem of 
> course is the forked process doesn't see the syntax tree in the heap; a 
> suggested remedy is shared memory, but I don't know how portable that is.
> 
> Dave
> 
> Paul Vixie wrote:
> 
> >>I think that we really need to be careful here. Does eventlib really
> >>provide asynchronous naming services, even if it is not DNS in use?
> >
> >
> >no. eventlib is a framework and i/o scheduler inside which asynchrony
> >can be accomplished without calling select directly or creating threads.
> >
> >>What if the naming service is not reenterant or not idempotent?
> >
> >
> >the naming service has to be implemented in terms of eventlib primatives.
> >i offered to do this for dns lookups if ntp were to be converted from its
> >explicit select() and signalled I/O to be an eventlib app.
> >
> >>If eventlib handles these issues via a managed thread, is it really
> >>doing so in the same manner that a forked process would?
> >
> >
> >no. eventlib doesn't touch threads at all.
> >
> >>If we start using threads, we run into many of the same issues that
> >>we had with signaled I/O, namely, as all of the operations used by ntpd
> >>thread-safe?
> >
> >
> >if we really do have to run NIS as well, then eventlib is a non-starter
> >since NIS depends on Sun RPC and none of us are willing to re-implement
> >THAT in terms of eventlib primatives.
> >
> >dave, is there some problem with combining pipe(), fork(), and
> >gethostbyname()? i don't understand why we would need temporary files.
> 
> 
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Folkert van Heusden

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