Re: [cone] Automatic Refresh for local Maildir's mail counts?

[Linux-Fan <Ma_...@we...>]

[Sat, 31 Dec 2016 12:27:38 -0500] Sam Varshavchik
<mr...@co...> wrote:
> Linux-Fan writes:
> 
> > > If you do not have a folder open, but looking at the folder
> > > hierarchy, the message counts are not going to get updated in
> > > realtime. There's no facility to do that.

[...]

> > Is it possible/planned to add a means of updating the message counts
> > from the folder hierarchy view automatically as well (similar to
> > what I did upon receiving a SIGUSR1 for my proof-of-concept patch
> > from the previous mail)?
> 
> I'm open to such a feature; however this approach won't work. Signals

[...]

> The only safe way to do this: in addition to installing a signal
> handler, an internal pipe needs to be created, and put into
> nonblocking mode. The only thing the signal handler does is write a
> byte to the pipe, ignoring the results, and immediately terminating.
> 
> Then, on the folder screen only, in addition to handling all the
> regular events the read end of the pipe gets polled as well, and when
> something is read, what your patch does would happen.

OK. I am going to check this out when I find time to dig into the
source code again :) How about the other option: Just extending the (as
far as I understand it) existing event polling to also check for new
messages every NN seconds or such? I do not like polling that much but
in this case it sounds easier and probably more reliable?

> Even with that, things may not work 100%. All the code needs to be
> audited and verified that it'll correctly handle an interrupted
> system call.
>
> Correct signal handling is hard.

Yes it is :( Especially signal handling from within multithreaded
applications is probably asking for trouble, so I understand that might
not be the best solution here...

Thank you for the quick and thorough reply, I really appreciate it.

Happy new year to all list members :) !

Yours Sincerely
Linux-Fan

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