From c83a66f3cfc29560873256736ac45c65f9fb4bfb Mon Sep 17 00:00:00 2001
From: "Kyle J. McKay" <mackyle@gmail.com>
Date: Sat, 26 Nov 2016 22:56:54 -0800
Subject: [PATCH] jobd.pl: support graceful restart

If the string "restart" is written to jobd's lock file, then
restart the next time the queue is about to be run.

This allows a graceful restart of jobd.pl to be scheduled
by an update install.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>
---
 jobd/jobd.pl | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/jobd/jobd.pl b/jobd/jobd.pl
index e2ad822..75b112c 100755
--- a/jobd/jobd.pl
+++ b/jobd/jobd.pl
@@ -18,6 +18,7 @@ use Girocco::Project;
 use Girocco::User;
 use Girocco::Util;
 BEGIN {noFatalsToBrowser}
+use Girocco::ExecUtil;
 
 # Options
 my $quiet;
@@ -465,15 +466,27 @@ sub run_perpetually {
 	close LOCK;
 	$locked = 1;
 
+	my $result = "";
 	while ($perpetual) {
 		# touch ctime of lockfile to prevent it from being removed by /tmp cleaning
-		chmod 0444, $lockfile;
+		chmod 0640, $lockfile;
 		chmod 0644, $lockfile;
+		# check for restart request
+		open LOCK, '<', $lockfile || die "Lock file '$lockfile' has disappeared!";
+		my $request = <LOCK>;
+		close LOCK;
+		chomp $request if defined($request);
+		if (defined($request) && $request eq "restart") {
+			$result = $request;
+			last;
+		}
 		queue_all();
 		run_queue();
 		sleep($restart_delay) if $perpetual; # Let the system breathe for a moment
 	}
 	unlink $lockfile;
+	$locked = 0;
+	return $result;
 }
 
 ######### Helpers {{{1
@@ -491,6 +504,7 @@ sub fatal($) {
 
 ######### Main {{{1
 
+my $reexec = Girocco::ExecUtil->new;
 chdir "/";
 close(DATA) if fileno(DATA);
 # Parse options
@@ -531,7 +545,15 @@ if ($all_once) {
 	exit;
 }
 
-run_perpetually();
+{
+	if (run_perpetually() eq "restart") {
+		error("Restarting in response to restart request... ");
+		$reexec->reexec;
+		error("Continuing after failed restart: $!");
+		chdir "/";
+		redo;
+	}
+}
 
 ########## Documentation {{{1
 
-- 
2.11.4.GIT