unix domain socket support

[vividsnow]

support listening on unix socket, so one can run: plackup -E production -l /tmp/app.sock -s Feersum --pre-fork N app.psgi or feersum --native --listen /tmp/app.sock --pre-fork N ./app.feersum

[stash]

Hi @vividsnow ! Thanks for the PR! I haven't used or tested this module for years. The patch looks small so perhaps you can just walk me through it? Or, if we have a mutual friend, can you have them vouch for you and I'll just give you merge permission?

I am not sure why the socket file is getting unlinked if it exists (unlink $listen if -S $listen;) ... doesn't this cause a race condition between unlinking and opening it via IO::Socket::UNIX? Also, doesn't calling umask(0) make the file mode rwx by everyone? Would it be simpler, and less prone to race and permission issues, to just let IO::Socket::UNIX->new fail if permission isn't right?

Nice to have: if you could make the code the same as the IO::Socket::INET constructor below, that would be ideal.

[stash]

s/to just let/to not unlink and just let/

[stash]

Or I suppose we can wait for @audreyt to take a look (thank you so much for looking after Feersum!)

[vividsnow]

Hi, @stash @audreyt

• If socket file exists, then we will get 'Address already in use' error. I can add code which will attempt to cleanup socket file on shutdown and warn about unlink before bind
• yes, umask(0) makes unix socket accessible by everyone (haproxy, nginx..), just like opened tcp port

I fixed code style, but passing 'Blocking => 0' is currently unsupported by IO::Socket::UNIX, which is presumably a bug https://github.com/Perl/perl5/pull/17787

[audreyt]

This looks good to me. Would it be possible to write a unit test in t/ ?

[vividsnow]

Yes, it will be feasible by using Test::SharedFork

[audreyt]

This is now released in CPAN as 0.410.