Re: asynchronous parsing

[Ted Zlatanov <tzz@lifelogs.com>]

On Wed, 12 Aug 2009 19:16:15 +0200 joakim@verona.se wrote: 

j> Ted Zlatanov <tzz@lifelogs.com> writes:
>> On Tue, 11 Aug 2009 12:04:20 -0400 Stefan Monnier <monnier@IRO.UMontreal.CA> wrote: 
>> 
>>>> I. Asynchronous parsing
SM> BTW, I'm interested in adding core-Emacs support for such parsing, so if
SM> you have any ideas about it, please share them.  The way I see it, there
SM> should be a table-based parsing engine written in C running in
SM> a spearate thread, so the question are "what should the tables look
SM> like?", "what should the output look like?", "what should the engine
SM> look like?", "how should the asynchronous code synchronize with the rest
SM> of Emacs?".  Any help along this effort would be welcome.
>> 
>> Maybe it would make sense to make this engine the first implementation
>> of an asynchronous process in Emacs.  We know we need general-purpose
>> asynchronous processes, it's been discussed many times.  Doing it with a
>> parser, a read-only process with internal state, would be a good start.
>> The difference from your suggestion is that rather than implementing a
>> one-off, the goal becomes the first cut of a general facility.
>> 
>> I bring this up because the need for asynchronous processes keeps coming
>> up in Gnus discussions...

j> Sounds very interesting, how would that work?

The same way Stefan's suggestion would work: a separate thread running
this parser.  The difference is that we don't just do one thread for the
parser and code especially for that purpose, but instead think of a
general thread facility the parser can use.  Once we prototype the
facility, we'll know better what works and what doesn't.

The specifics of the parser, if that's what you're curious about, are
not important to me (I don't plan to write such parsers or configure
them myself).  I just need the general threading facility for Gnus work.

Ted