Re: Async DNS lookups

[Ken Raeburn <raeburn@raeburn.org>]

On Nov 1, 2010, at 12:09, Tom Tromey wrote:
> 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.

These would have the advantage that, rather than interacting with DNS directly, you can call getaddrinfo and use /etc/hosts or anything else configured by nsswitch or equivalent.  Assuming that all name-resolution calls should go straight to DNS (when you're not specifically looking for non-A/AAAA/PTR data) would be incorrect....

I think getaddrinfo_a looks nice, but I'd rather not use it unless we also have a workaround for non-glibc systems.  Presumably that would use your basic "spin off a thread that blocks in getaddrinfo and invokes a callback when done" approach, which (according to the blog Tom pointed to) is all getaddrinfo_a does anyways.  Maybe that means the code could be borrowed; maybe that means we should just implement the latter and not bother with getaddrinfo_a.

Ken