[PATCH 06/16] ipc: drop dynamic WQ process counts

[Eric Wong <e@80x24.org>]

In retrospect, I don't think it's needed; and trying to wire up
a user interface for lei to manage process counts doesn't seem
worthwhile.  It could be resurrected for public-facing daemon
use in the future, but that's what version control systems are for.

This also lets us automatically avoid setting up broadcast
sockets

Followup-to: 7b7939d47b336fb7 ("lei: lock worker counts")
---
 lib/PublicInbox/IPC.pm      | 69 ++++++-------------------------------
 lib/PublicInbox/LEI.pm      |  1 -
 lib/PublicInbox/LeiStore.pm |  1 -
 t/ipc.t                     | 13 +------
 4 files changed, 11 insertions(+), 73 deletions(-)

diff --git a/lib/PublicInbox/IPC.pm b/lib/PublicInbox/IPC.pm
index 92f35189..add5f3df 100644
--- a/lib/PublicInbox/IPC.pm
+++ b/lib/PublicInbox/IPC.pm
@@ -262,9 +262,10 @@ sub do_sock_stream { # via wq_io_do, for big requests
 sub wq_broadcast {
 	my ($self, $sub, @args) = @_;
 	if (my $wkr = $self->{-wq_workers}) {
+		my $buf = ipc_freeze([$sub, @args]);
 		for my $bcast1 (values %$wkr) {
-			my $buf = ipc_freeze([$sub, @args]);
-			send($bcast1, $buf, MSG_EOR) // croak "send: $!";
+			my $sock = $bcast1 // $self->{-wq_s1} // next;
+			send($sock, $buf, MSG_EOR) // croak "send: $!";
 			# XXX shouldn't have to deal with EMSGSIZE here...
 		}
 	} else {
@@ -336,11 +337,10 @@ sub wq_do {
 	}
 }
 
-sub _wq_worker_start ($$$) {
-	my ($self, $oldset, $fields) = @_;
+sub _wq_worker_start ($$$$) {
+	my ($self, $oldset, $fields, $one) = @_;
 	my ($bcast1, $bcast2);
-	$self->{-wq_no_bcast} or
-		socketpair($bcast1, $bcast2, AF_UNIX, $SEQPACKET, 0) or
+	$one or socketpair($bcast1, $bcast2, AF_UNIX, $SEQPACKET, 0) or
 							die "socketpair: $!";
 	my $seed = rand(0xffffffff);
 	my $pid = fork // die "fork: $!";
@@ -380,66 +380,17 @@ sub wq_workers_start {
 	socketpair($self->{-wq_s1}, $self->{-wq_s2}, AF_UNIX, $SEQPACKET, 0) or
 		die "socketpair: $!";
 	$self->ipc_atfork_prepare;
-	$nr_workers //= $self->{-wq_nr_workers};
+	$nr_workers //= $self->{-wq_nr_workers}; # was set earlier
 	my $sigset = $oldset // PublicInbox::DS::block_signals();
 	$self->{-wq_workers} = {};
 	$self->{-wq_ident} = $ident;
-	_wq_worker_start($self, $sigset, $fields) for (1..$nr_workers);
+	my $one = $nr_workers == 1;
+	$self->{-wq_nr_workers} = $nr_workers;
+	_wq_worker_start($self, $sigset, $fields, $one) for (1..$nr_workers);
 	PublicInbox::DS::sig_setmask($sigset) unless $oldset;
 	$self->{-wq_ppid} = $$;
 }
 
-sub wq_worker_incr { # SIGTTIN handler
-	my ($self, $oldset, $fields) = @_;
-	$self->{-wq_s2} or return;
-	die "-wq_nr_workers locked" if defined $self->{-wq_nr_workers};
-	$self->ipc_atfork_prepare;
-	my $sigset = $oldset // PublicInbox::DS::block_signals();
-	_wq_worker_start($self, $sigset, $fields);
-	PublicInbox::DS::sig_setmask($sigset) unless $oldset;
-}
-
-sub wq_exit { # wakes up wq_worker_decr_wait
-	send($_[0]->{-wq_s2}, $$, MSG_EOR) // die "$$ send: $!";
-	exit;
-}
-
-sub wq_worker_decr { # SIGTTOU handler, kills first idle worker
-	my ($self) = @_;
-	return unless wq_workers($self);
-	die "-wq_nr_workers locked" if defined $self->{-wq_nr_workers};
-	$self->wq_io_do('wq_exit');
-	# caller must call wq_worker_decr_wait in main loop
-}
-
-sub wq_worker_decr_wait {
-	my ($self, $timeout, $cb, @args) = @_;
-	return if $self->{-wq_ppid} != $$; # can't reap siblings or parents
-	die "-wq_nr_workers locked" if defined $self->{-wq_nr_workers};
-	my $s1 = $self->{-wq_s1} // croak 'BUG: no wq_s1';
-	vec(my $rin = '', fileno($s1), 1) = 1;
-	select(my $rout = $rin, undef, undef, $timeout) or
-		croak 'timed out waiting for wq_exit';
-	recv($s1, my $pid, 64, 0) // croak "recv: $!";
-	my $workers = $self->{-wq_workers} // croak 'BUG: no wq_workers';
-	delete $workers->{$pid} // croak "BUG: PID:$pid invalid";
-	dwaitpid($pid, $cb // \&ipc_worker_reap, [ $self, @args ]);
-}
-
-# set or retrieve number of workers
-sub wq_workers {
-	my ($self, $nr, $cb, @args) = @_;
-	my $cur = $self->{-wq_workers} or return;
-	if (defined $nr) {
-		while (scalar(keys(%$cur)) > $nr) {
-			$self->wq_worker_decr;
-			$self->wq_worker_decr_wait(undef, $cb, @args);
-		}
-		$self->wq_worker_incr while scalar(keys(%$cur)) < $nr;
-	}
-	scalar(keys(%$cur));
-}
-
 sub wq_close {
 	my ($self, $nohang, $cb, @args) = @_;
 	delete @$self{qw(-wq_s1 -wq_s2)} or return;
diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index f62e82dc..def85ef1 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -627,7 +627,6 @@ sub workers_start {
 	my $end = $lei->pkt_op_pair;
 	my $ident = $wq->{-wq_ident} // "lei-$lei->{cmd} worker";
 	$flds->{lei} = $lei;
-	$wq->{-wq_nr_workers} //= $jobs; # lock, no incrementing
 	$wq->wq_workers_start($ident, $jobs, $lei->oldset, $flds);
 	delete $lei->{pkt_op_p};
 	my $op_c = delete $lei->{pkt_op_c};
diff --git a/lib/PublicInbox/LeiStore.pm b/lib/PublicInbox/LeiStore.pm
index 164a9f2d..b4f40912 100644
--- a/lib/PublicInbox/LeiStore.pm
+++ b/lib/PublicInbox/LeiStore.pm
@@ -565,7 +565,6 @@ sub write_prepare {
 		# Mail we import into lei are private, so headers filtered out
 		# by -mda for public mail are not appropriate
 		local @PublicInbox::MDA::BAD_HEADERS = ();
-		$self->{-wq_no_bcast} = 1;
 		$self->wq_workers_start("lei/store $dir", 1, $lei->oldset, {
 					lei => $lei,
 					-err_wr => $w,
diff --git a/t/ipc.t b/t/ipc.t
index 202b1cc6..ce89f94b 100644
--- a/t/ipc.t
+++ b/t/ipc.t
@@ -180,24 +180,13 @@ SKIP: {
 	is($warn[2], $warn[1], 'worker did not die');
 
 	$SIG{__WARN__} = 'DEFAULT';
-	is($ipc->wq_workers_start('wq', 1), $$, 'workers started again');
-	is($ipc->wq_workers, 1, '1 worker started');
-
-	$ipc->wq_worker_incr;
-	is($ipc->wq_workers, 2, 'worker count bumped');
-	$ipc->wq_worker_decr;
-	$ipc->wq_worker_decr_wait(10);
-	is($ipc->wq_workers, 1, 'worker count lowered');
-	is($ipc->wq_workers(2), 2, 'worker count set');
-	is($ipc->wq_workers, 2, 'worker count stayed set');
-
+	is($ipc->wq_workers_start('wq', 2), $$, 'workers started again');
 	$ipc->wq_broadcast('test_append_pid', "$tmpdir/append_pid");
 	$ipc->wq_close;
 	open my $fh, '<', "$tmpdir/append_pid" or BAIL_OUT "open: $!";
 	chomp(my @pids = <$fh>);
 	my %pids = map { $_ => 1 } grep(/\A[0-9]+\z/, @pids);
 	is(scalar keys %pids, 2, 'broadcast hit both PIDs');
-	is($ipc->wq_workers, undef, 'workers undef after close');
 }
 
 done_testing;