ds: introduce awaitpid, switch ProcessPipe users

awaitpid is the new API which will eventually replace dwaitpid.
It enables early registration of callback handlers.  Eventually
(once dwaitpid is gone) it'll be able to use fewer waitpid
calls.

The avoidance of waitpid(-1) in our earlier days was driven by
the belief that threads may eventually become relevant for Perl 5,
but that's extremely unlikely at this stage.  I will still
introduce optional threads via C, but they definitely won't be
spawning/reaping processes.

Argument order to callbacks is swapped (PID first) to allow
flattened multiple arguments more natrually.  The previous API
(allowing only a single argument, as influenced by
pthread_create(3)) was more tedious as it involved packing
multiple arguments into yet another array.

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index 7f61d8db..826ee508 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -365,9 +365,9 @@ sub popen_rd {
         $opt->{1} = fileno($w);
         my $pid = spawn($cmd, $env, $opt);
         return ($r, $pid) if wantarray;
-        my $ret = gensym;
-        tie *$ret, 'PublicInbox::ProcessPipe', $pid, $r, @$opt{qw(cb arg)};
-        $ret;
+        my $s = gensym;
+        tie *$s, 'PublicInbox::ProcessPipe', $pid, $r, @{$opt->{cb_arg} // []};
+        $s;
 }
 
 sub run_die ($;$$) {