slacktopic.pl: cache results of reading ChangeLog (save bandwidth)

1 files changed, 15 insertions, 2 deletions

diff --git a/slacktopic.pl b/slacktopic.pl
index 4471584..256db09 100644
--- a/slacktopic.pl
+++ b/slacktopic.pl
@@ -290,7 +290,7 @@ sub finish_update {
 	}
 
 	# Make sure this is a security fix update.
-	return unless is_security_update();
+	return unless is_security_update($new_date);
 
 	# Ask ChanServ to change the topic for us. We don't need +o in
 	# the channel, so long as we're logged in to services and have +t.
@@ -325,12 +325,24 @@ sub exec_update {
 			0); # last arg is unused
 }
 
+# Without %sec_check_cache, every non-security update would result in us
+# wasting bandwidth rechecking the ChangeLog every $update_frequency sec.
+our %sec_check_cache = ();
+
 # Return true if the first ChangeLog entry is a security update. Unlike
 # the regular check-for-update that happens periodically, this one blocks
 # for up to $cmd_timeout seconds. The updates only happen every few days,
 # I don't see this as a real problem that needs extra complexity to solve.
 sub is_security_update {
-	debugmsg("is_security_update() called");
+	my $date = shift;
+	debugmsg("is_security_update($date) called");
+
+	if(exists($sec_check_cache{$date})) {
+		debugmsg("already checked & got '$sec_check_cache{$date}' for $date");
+		return $sec_check_cache{$date};
+	}
+
+	debugmsg("getting start of ChangeLog");
 
 	my $result = 0;
 	my $lines = 0;
@@ -365,6 +377,7 @@ sub is_security_update {
 	}
 
 	debugmsg("read $lines lines from ChangeLog, returning $result");
+	$sec_check_cache{$date} = $result;
 	return $result;
 }