daemon: periodically create stampfile

functions.php

@@ -1505,6 +1505,19 @@
 		}
 	}
 
+	function make_stampfile($filename) {
+		$fp = fopen($filename, "w");
+
+		if ($fp) {
+			fwrite($fp, time() . "\n");
+			fclose($fp);
+			return true;
+		} else {
+			return false;
+		}
+	}
+
+
 	function sql_random_function() {
 		if (DB_TYPE == "mysql") {
 			return "RAND()";

update_daemon.php

@@ -71,6 +71,11 @@
 
 	while (true) {
 
+		if (!make_stampfile('update_daemon.stamp')) {
+			print "error: unable to create stampfile";
+			die;
+		}
+
 		if (time() - $last_purge > PURGE_INTERVAL) {
 			_debug("Purging old posts (random 30 feeds)...");
 			global_purge_old_posts($link, true, 30);