* Change the aggregate plugin's locking strategy. Now it defers loading state

  until the wiki is building and already locked, unless it's aggregating.
  When aggregating, it does not wait for the lock if it cannot get it, and
  instead exits, to prevent aggregating processes from piling up.

4 files changed, 52 insertions, 27 deletions

diff --git a/IkiWiki.pm b/IkiWiki.pm
index a0b902794..31e175d2a 100644
--- a/IkiWiki.pm
+++ b/IkiWiki.pm
@@ -668,7 +668,8 @@ sub indexlink () { #{{{
 	return "<a href=\"$config{url}\">$config{wikiname}</a>";
 } #}}}
 
-sub lockwiki () { #{{{
+sub lockwiki (;$) { #{{{
+	my $wait=@_ ? shift : 1;
 	# Take an exclusive lock on the wiki to prevent multiple concurrent
 	# run issues. The lock will be dropped on program exit.
 	if (! -d $config{wikistatedir}) {
@@ -677,15 +678,22 @@ sub lockwiki () { #{{{
 	open(WIKILOCK, ">$config{wikistatedir}/lockfile") ||
 		error ("cannot write to $config{wikistatedir}/lockfile: $!");
 	if (! flock(WIKILOCK, 2 | 4)) { # LOCK_EX | LOCK_NB
-		debug("wiki seems to be locked, waiting for lock");
-		my $wait=600; # arbitrary, but don't hang forever to 
-		              # prevent process pileup
-		for (1..$wait) {
-			return if flock(WIKILOCK, 2 | 4);
-			sleep 1;
+		if ($wait) {
+			debug("wiki seems to be locked, waiting for lock");
+			my $wait=600; # arbitrary, but don't hang forever to 
+			              # prevent process pileup
+			for (1..$wait) {
+				return if flock(WIKILOCK, 2 | 4);
+				sleep 1;
+			}
+			error("wiki is locked; waited $wait seconds without lock being freed (possible stuck process or stale lock?)");
+		}
+		else {
+			debug("wiki is locked");
+			return 0;
 		}
-		error("wiki is locked; waited $wait seconds without lock being freed (possible stuck process or stale lock?)");
 	}
+	return 1;
 } #}}}
 
 sub unlockwiki () { #{{{
diff --git a/IkiWiki/Plugin/aggregate.pm b/IkiWiki/Plugin/aggregate.pm
index 78f8b409c..082290114 100644
--- a/IkiWiki/Plugin/aggregate.pm
+++ b/IkiWiki/Plugin/aggregate.pm
@@ -31,22 +31,26 @@ sub getopt () { #{{{
 } #}}}
 
 sub checkconfig () { #{{{
-	my $nolock=($config{post_commit} && ! IkiWiki::commit_hook_enabled());
-	IkiWiki::lockwiki() unless $nolock;
-	loadstate();
-	if ($config{aggregate} && ! $nolock) {
+	if ($config{aggregate} && ! ($config{post_commit} && 
+	                             IkiWiki::commit_hook_enabled())) {
+		# don't wait for the lock
+		IkiWiki::lockwiki(0) || exit 1;
+	
+		loadstate();
 		IkiWiki::loadindex();
 		aggregate();
 		expire();
 		savestate();
+
+		IkiWiki::unlockwiki();
 	}
-	IkiWiki::unlockwiki() unless $nolock;
 } #}}}
 
 sub filter (@) { #{{{
 	my %params=@_;
 	my $page=$params{page};
 
+	loadstate(); # if not already loaded
 	# Mark all feeds originating on this page as removable;
 	# preprocess will unmark those that still exist.
 	remove_feeds($page);
@@ -117,7 +121,9 @@ sub delete (@) { #{{{
 	}
 } #}}}
 
+my $state_loaded=0;
 sub loadstate () { #{{{
+	return if $state_loaded;
 	if (-e "$config{wikistatedir}/aggregate") {
 		open (IN, "$config{wikistatedir}/aggregate" ||
 			die "$config{wikistatedir}/aggregate: $!");
@@ -148,6 +154,8 @@ sub loadstate () { #{{{
 		}
 
 		close IN;
+		
+		$state_loaded=1;
 	}
 } #}}}
 
diff --git a/debian/changelog b/debian/changelog
index 10f5ef33f..87cf87087 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,12 @@
+ikiwiki (2.2) UNRELEASED; urgency=low
+
+  * Change the aggregate plugin's locking strategy. Now it defers loading state
+    until the wiki is building and already locked, unless it's aggregating.
+    When aggregating, it does not wait for the lock if it cannot get it, and
+    instead exits, to prevent aggregating processes from piling up.
+
+ -- Joey Hess <joeyh@debian.org>  Sun, 20 May 2007 22:23:09 -0400
+
 ikiwiki (2.1) unstable; urgency=low
 
   [ Joey Hess ]
diff --git a/po/ikiwiki.pot b/po/ikiwiki.pot
index d1431a910..d23c9d0bd 100644
--- a/po/ikiwiki.pot
+++ b/po/ikiwiki.pot
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2007-05-19 19:33-0400\n"
+"POT-Creation-Date: 2007-05-20 22:48-0400\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -67,62 +67,62 @@ msgstr ""
 msgid "login failed, perhaps you need to turn on cookies?"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:62
+#: ../IkiWiki/Plugin/aggregate.pm:66
 #, perl-format
 msgid "missing %s parameter"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:90
+#: ../IkiWiki/Plugin/aggregate.pm:94
 msgid "new feed"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:104
+#: ../IkiWiki/Plugin/aggregate.pm:108
 msgid "posts"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:106
+#: ../IkiWiki/Plugin/aggregate.pm:110
 msgid "new"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:212
+#: ../IkiWiki/Plugin/aggregate.pm:220
 #, perl-format
 msgid "expiring %s (%s days old)"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:219
+#: ../IkiWiki/Plugin/aggregate.pm:227
 #, perl-format
 msgid "expiring %s"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:242
+#: ../IkiWiki/Plugin/aggregate.pm:250
 #, perl-format
 msgid "processed ok at %s"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:247
+#: ../IkiWiki/Plugin/aggregate.pm:255
 #, perl-format
 msgid "checking feed %s ..."
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:252
+#: ../IkiWiki/Plugin/aggregate.pm:260
 #, perl-format
 msgid "could not find feed at %s"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:267
+#: ../IkiWiki/Plugin/aggregate.pm:275
 msgid "feed not found"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:278
+#: ../IkiWiki/Plugin/aggregate.pm:286
 #, perl-format
 msgid "(invalid UTF-8 stripped from feed)"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:283
+#: ../IkiWiki/Plugin/aggregate.pm:291
 msgid "feed crashed XML::Feed!"
 msgstr ""
 
-#: ../IkiWiki/Plugin/aggregate.pm:356
+#: ../IkiWiki/Plugin/aggregate.pm:364
 #, perl-format
 msgid "creating new page %s"
 msgstr ""