Enhance status with reporting maximum number of open files (sockets)

[michaelortmann]

Found by: michaelortmann
Patch by: michaelortmann
Fixes:

One-line summary:

Additional description (if needed):
While working on dns async code with threads and pipes it came to me, that enhancing .status with reporting maximum number of open files (sockets) could be useful. but i wanted the dns PR to be slim, so i copid the work for .status over to this new PR.

Test cases demonstrating functionality (if applicable):

.status
[...]
Socket table: 20/100
Memory table: 4421/8192 (54.0% full)
[...]

.status all
[...]
Socket table: 20/100
Maximum number of open files (sockets): soft limit 1024 hard limit 524288
Memory table: 4421/8192 (54.0% full)
[...]

[thommey]

LGTM

[vanosg]

Can we move this to .status all ? .status is becoming bloated.

[michaelortmann]

Can we move this to .status all ? .status is becoming bloated.

done. this makes this PR even more useful, because now we could easily hide more details, that are currently shown for .status and could be shown only for .status all. but this is future talk. the function tell_status() with its new parameter detail 0|1 would make it easy now.

[vanosg]

I like where your head is at and appreciate you roughing in code for future work, but I think we should either implement such a change completely, or don't. Looking over how this fits in larger code, I think I'd suggest we just leave it like it is but I'm open to other thoughts or reasons to move. I think anything we move from .status to .status all can just slide right into the existing tell_verbose_status(); the existing format (I think) was created the way it was because some of these functions are called from other sections of code. @thommey thoughts?

[michaelortmann]

@geo: done, the status boilerplate code is now unaltered. open files/sockets are only shown for .status **all** with minimal amount of code added.