daemon: drop listeners early in master on graceful shutdown

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.

diff --git a/lib/PublicInbox/Daemon.pm b/lib/PublicInbox/Daemon.pm
index 842ff1ccfd3424b677ca66eca8cd41c740fc29fc..9db472a19479b5fdfd271c6c60c6597116cadbe9 100644 (file)
--- 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;
                }