From c969ae58c23938ef25e740cebf66fb60a1c91571 Mon Sep 17 00:00:00 2001
From: John McLear <john@mclear.co.uk>
Date: Sat, 6 Feb 2021 19:53:52 +0000
Subject: [PATCH] stats: activePads & lastDisconnected stats

---
 src/node/handler/PadMessageHandler.js | 13 +++++++++++++
 src/node/handler/SocketIORouter.js    |  6 ++++++
 2 files changed, 19 insertions(+)

diff --git a/src/node/handler/PadMessageHandler.js b/src/node/handler/PadMessageHandler.js
index 2a1f6385b..8c106c615 100644
--- a/src/node/handler/PadMessageHandler.js
+++ b/src/node/handler/PadMessageHandler.js
@@ -90,6 +90,19 @@ exports.handleConnect = (socket) => {
 
   // Initialize sessioninfos for this new session
   sessioninfos[socket.id] = {};
+
+  stats.gauge('activePads', () => {
+    const padIds = [];
+    for (const session of Object.keys(sessioninfos)) {
+      if(sessioninfos[session].padId) {
+        if(padIds.indexOf(sessioninfos[session].padId) === -1) {
+          padIds.push(sessioninfos[session].padId);
+        }
+      }
+    };
+    return padIds.length;
+  });
+
 };
 
 /**
diff --git a/src/node/handler/SocketIORouter.js b/src/node/handler/SocketIORouter.js
index 42d710a39..35325c072 100644
--- a/src/node/handler/SocketIORouter.js
+++ b/src/node/handler/SocketIORouter.js
@@ -22,6 +22,7 @@
 
 const log4js = require('log4js');
 const messageLogger = log4js.getLogger('message');
+const stats = require('../stats');
 
 /**
  * Saves all components
@@ -77,6 +78,11 @@ exports.setSocketIO = (_socket) => {
     });
 
     client.on('disconnect', () => {
+      // store the lastDisconnect as a timestamp, this is useful if you want to know
+      // when the last user disconnected.  If your activePads is 0 and totalUsers is 0
+      // you can say, if there has been no active pads or active users for 10 minutes
+      // this instance can be brought out of a scaling cluster.
+      stats.gauge('lastDisconnect', () => Date.now());
       // tell all components about this disconnect
       for (const i in components) {
         components[i].handleDisconnect(client);