Re: Async DNS lookups

[Tom Tromey]

>>>>> "Lars" == Lars Magne Ingebrigtsen <address@hidden> writes:

Lars> I don't really see any easy fixes for this with Emacs' feature set at
Lars> the moment.  A process filter will block Emacs' "main thread", and it
Lars> needs to resolve the addresses, so...

Lars> 1) implement a C-level resolving functionality that has a callback that
Lars> will be called upon resolving the address.  This seems hard.

There is a GNU library for this:

http://directory.fsf.org/project/c-ares/


Apparently glibc already includes getaddrinfo_a for this.  It seems to
be undocumented, but this has some info & pointers:

http://bitsup.blogspot.com/2008/09/asynchronous-dns-lookups-on-linux-with.html


A couple other approaches come to mind as well.

You could run the synchronous resolver in a new thread, and have the
main thread run the event loop.

You could use a small helper program instead of calling the resolver
in-process.  That is basically the same as the previous idea,
substituting a process for a thread.

Tom