From e2354943d7bca4e52fce923ff7709b7f84bd76e1 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Mark=20Jason=20Dominus=20=28=E9=99=B6=E6=95=8F=E4=BF=AE=29?=
 <mjd@plover.com>
Date: Sun, 30 Nov 2014 14:34:46 -0500
Subject: [PATCH 1/1] in debug mode, issue a warning before waiting for a lock

---
 IkiWiki.pm | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/IkiWiki.pm b/IkiWiki.pm
index 03f058ef7..a8e2865be 100644
--- a/IkiWiki.pm
+++ b/IkiWiki.pm
@@ -5,6 +5,7 @@ package IkiWiki;
 use warnings;
 use strict;
 use Encode;
+use Fcntl q{:flock};
 use URI::Escape q{uri_escape_utf8};
 use POSIX ();
 use Storable;
@@ -1813,8 +1814,11 @@ sub lockwiki () {
 	}
 	open($wikilock, '>', "$config{wikistatedir}/lockfile") ||
 		error ("cannot write to $config{wikistatedir}/lockfile: $!");
-	if (! flock($wikilock, 2)) { # LOCK_EX
-		error("failed to get lock");
+	if (! flock($wikilock, LOCK_EX | LOCK_NB)) {
+        	debug("failed to get lock; waiting...");
+		if (! flock($wikilock, LOCK_EX)) {
+			error("failed to get lock");
+		}
 	}
 	return 1;
 }
-- 
2.39.5