From 2dd0c177a6b33488dfcfff9041a3749b44484f34 Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@kitenet.net>
Date: Tue, 6 Jul 2010 13:57:17 -0400
Subject: [PATCH] aggregate: Write timestamp next aggregation can happen to
 .ikiwiki/aggregatetime, to allow for more sophisticated cron jobs.

---
 IkiWiki/Plugin/aggregate.pm | 18 ++++++++++++++++--
 debian/changelog            |  2 ++
 doc/plugins/aggregate.mdwn  | 15 ++++++++++++---
 3 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/IkiWiki/Plugin/aggregate.pm b/IkiWiki/Plugin/aggregate.pm
index 5a9eb433d..7789c4c2a 100644
--- a/IkiWiki/Plugin/aggregate.pm
+++ b/IkiWiki/Plugin/aggregate.pm
@@ -298,7 +298,7 @@ sub loadstate () {
 	return if $state_loaded;
 	$state_loaded=1;
 	if (-e "$config{wikistatedir}/aggregate") {
-		open(IN, "$config{wikistatedir}/aggregate") ||
+		open(IN, "<", "$config{wikistatedir}/aggregate") ||
 			die "$config{wikistatedir}/aggregate: $!";
 		while (<IN>) {
 			$_=IkiWiki::possibly_foolish_untaint($_);
@@ -335,7 +335,7 @@ sub savestate () {
 	garbage_collect();
 	my $newfile="$config{wikistatedir}/aggregate.new";
 	my $cleanup = sub { unlink($newfile) };
-	open (OUT, ">$newfile") || error("open $newfile: $!", $cleanup);
+	open (OUT, ">", $newfile) || error("open $newfile: $!", $cleanup);
 	foreach my $data (values %feeds, values %guids) {
 		my @line;
 		foreach my $field (keys %$data) {
@@ -356,6 +356,20 @@ sub savestate () {
 	close OUT || error("save $newfile: $!", $cleanup);
 	rename($newfile, "$config{wikistatedir}/aggregate") ||
 		error("rename $newfile: $!", $cleanup);
+
+	my $timestamp=undef;
+	foreach my $feed (keys %feeds) {
+		my $t=$feeds{$feed}->{lastupdate}+$feeds{$feed}->{updateinterval};
+		if (! defined $timestamp || $timestamp > $t) {
+			$timestamp=$t;
+		}
+	}
+	$newfile=~s/\.new$/time/;
+	open (OUT, ">", $newfile) || error("open $newfile: $!", $cleanup);
+	if (defined $timestamp) {
+		print OUT $timestamp."\n";
+	}
+	close OUT || error("save $newfile: $!", $cleanup);
 }
 
 sub garbage_collect () {
diff --git a/debian/changelog b/debian/changelog
index 18db7c0c2..9d88b5c9c 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -3,6 +3,8 @@ ikiwiki (3.20100705) UNRELEASED; urgency=low
   * img: Add a margin around images displayed by this directive.
   * comments: Added commentmoderation directive for easy linking to the
     comment moderation queue.
+  * aggregate: Write timestamp next aggregation can happen to
+    .ikiwiki/aggregatetime, to allow for more sophisticated cron jobs.
 
  -- Joey Hess <joeyh@debian.org>  Mon, 05 Jul 2010 13:59:42 -0400
 
diff --git a/doc/plugins/aggregate.mdwn b/doc/plugins/aggregate.mdwn
index bb828b05c..2925b6fba 100644
--- a/doc/plugins/aggregate.mdwn
+++ b/doc/plugins/aggregate.mdwn
@@ -5,9 +5,13 @@ This plugin allows content from other feeds to be aggregated into the
 wiki. To specify feeds to aggregate, use the
 [[ikiwiki/directive/aggregate]] [[ikiwiki/directive]].
 
-The [[meta]] and [[tag]] plugins are also recommended. Either the
-[[htmltidy]] or [[htmlbalance]] plugin is suggested, since feeds can easily
-contain html problems, some of which these plugins can fix.
+## requirements
+
+The [[meta]] and [[tag]] plugins are also recommended to be used with this
+one. Either the [[htmltidy]] or [[htmlbalance]] plugin is suggested, since
+feeds can easily contain html problems, some of which these plugins can fix.
+
+## triggering aggregation
 
 You will need to run ikiwiki periodically from a cron job, passing it the
 --aggregate parameter, to make it check for new posts. Here's an example
@@ -15,6 +19,11 @@ crontab entry:
 
 	*/15 * * * * ikiwiki --setup my.wiki --aggregate --refresh
 
+The plugin updates a file `.ikiwiki/aggregatetime` with the unix time stamp
+when the next aggregation run could occur. (The file may be empty, if no
+aggregation is required.) This can be integrated into more complex cron
+jobs or systems to trigger aggregation only when needed.
+
 Alternatively, you can allow `ikiwiki.cgi` to trigger the aggregation. You
 should only need this if for some reason you cannot use cron, and instead
 want to use a service such as [WebCron](http://webcron.org). To enable
-- 
2.39.5