[PATCH 2/2] daemon: drop listeners early in master on graceful shutdown

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

For users not relying on socket activation via systemd (or
similar), we want to drop listeners ASAP so another process
can bind to their address.  While we're at it, disable
TTIN and HUP handlers since we have no chance of starting
usable workers without listeners.
---
 lib/PublicInbox/Daemon.pm | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/lib/PublicInbox/Daemon.pm b/lib/PublicInbox/Daemon.pm
index 842ff1cc..9db472a1 100644
--- a/lib/PublicInbox/Daemon.pm
+++ b/lib/PublicInbox/Daemon.pm
@@ -462,23 +462,27 @@ sub unlink_pid_file_safe_ish ($$) {
 	}
 }
 
+sub master_quit ($) {
+	exit unless @listeners;
+	@listeners = ();
+	kill_workers($_[0]);
+}
+
 sub master_loop {
 	pipe(my ($p0, $p1)) or die "failed to create parent-pipe: $!";
 	# 1031: F_SETPIPE_SZ, 4096: page size
 	fcntl($p1, 1031, 4096) if $^O eq 'linux';
 	my $set_workers = $worker_processes;
 	reopen_logs();
-	my $quit = 0;
 	my $ignore_winch;
-	my $quit_cb = sub { exit if $quit++; kill_workers($_[0]) };
 	my $sig = {
 		USR1 => sub { reopen_logs(); kill_workers($_[0]); },
 		USR2 => \&upgrade,
-		QUIT => $quit_cb,
-		INT => $quit_cb,
-		TERM => $quit_cb,
+		QUIT => \&master_quit,
+		INT => \&master_quit,
+		TERM => \&master_quit,
 		WINCH => sub {
-			return if $ignore_winch;
+			return if $ignore_winch || !@listeners;
 			if (-t STDIN || -t STDOUT || -t STDERR) {
 				$ignore_winch = 1;
 				warn <<EOF;
@@ -489,10 +493,12 @@ EOF
 			}
 		},
 		HUP => sub {
+			return unless @listeners;
 			$worker_processes = $set_workers;
 			kill_workers($_[0]);
 		},
 		TTIN => sub {
+			return unless @listeners;
 			if ($set_workers > $worker_processes) {
 				++$worker_processes;
 			} else {
@@ -509,7 +515,7 @@ EOF
 	sig_setmask($oldset) if !$sigfd;
 	while (1) { # main loop
 		my $n = scalar keys %pids;
-		if ($quit) {
+		unless (@listeners) {
 			exit if $n == 0;
 			$set_workers = $worker_processes = $n = 0;
 		}