Add helper function to purge notifications

lib/www/server/lib/db/notify.js

@@ -1,6 +1,18 @@
 const { makeSubscriber, pool } = require('./connection');
 const { ALERT, ERROR, WARNING, NOTICE, INFO, DEBUG } = require('DOUGAL_ROOT/debug')(__filename);
 
+async function purge () {
+	DEBUG("Purging old notifications");
+	const client = await pool.connect();
+	try {
+		await client.query("CALL purge_notifications();");
+	} catch (err) {
+		ERROR(err);
+	} finally {
+		client.release();
+	}
+}
+
 async function fullPayload (payload) {
 
 	if (!payload.payload_id) {
@@ -58,5 +70,6 @@ async function listen (addChannels, callback) {
 }
 
 module.exports = {
-	listen
+	listen,
+	purge
 };