From d0644858af875d995d365d012537920565aa74aa Mon Sep 17 00:00:00 2001
From: cha0s <git@cha0s.io>
Date: Wed, 7 Aug 2024 14:29:05 -0500
Subject: [PATCH] feat: heartbeat/rtt

---
 app/net/client.js                 | 10 +++++--
 app/net/packets/heartbeat.js      |  3 +++
 app/react/components/devtools.jsx |  5 ++--
 app/server/engine.js              | 43 +++++++++++++++++++++++++------
 4 files changed, 49 insertions(+), 12 deletions(-)
 create mode 100644 app/net/packets/heartbeat.js

diff --git a/app/net/client.js b/app/net/client.js
index f7be2a1..9e71108 100644
--- a/app/net/client.js
+++ b/app/net/client.js
@@ -1,8 +1,9 @@
-import {CLIENT_LATENCY} from '@/util/constants.js';
+import {CLIENT_LATENCY, CLIENT_PREDICTION} from '@/util/constants.js';
 import EventEmitter from '@/util/event-emitter.js';
 
 export default class Client {
   emitter = new EventEmitter();
+  rtt = 0;
   throughput = {$$down: 0, down: 0, $$up: 0, up: 0};
   constructor() {
     setInterval(() => {
@@ -13,6 +14,11 @@ export default class Client {
     }, 250);
   }
   accept(packet) {
+    if ('Heartbeat' === packet.type) {
+      this.rtt = packet.payload.rtt;
+      this.send(packet);
+      return;
+    }
     this.emitter.invoke(packet.type, packet.payload);
   }
   addPacketListener(type, listener) {
@@ -22,7 +28,7 @@ export default class Client {
     this.emitter.removeListener(type, listener);
   }
   send(packet) {
-    if (CLIENT_LATENCY > 0) {
+    if (CLIENT_LATENCY > 0 && !CLIENT_PREDICTION) {
       setTimeout(() => {
         this.transmit(packet);
       }, CLIENT_LATENCY);
diff --git a/app/net/packets/heartbeat.js b/app/net/packets/heartbeat.js
new file mode 100644
index 0000000..f50a1c2
--- /dev/null
+++ b/app/net/packets/heartbeat.js
@@ -0,0 +1,3 @@
+import Packet from '@/net/packet.js';
+
+export default class Heartbeat extends Packet {}
diff --git a/app/react/components/devtools.jsx b/app/react/components/devtools.jsx
index 4896bbd..42fc095 100644
--- a/app/react/components/devtools.jsx
+++ b/app/react/components/devtools.jsx
@@ -34,8 +34,9 @@ export default function Devtools({
           <div className={styles.dashboard}>
             <form>
               <div className={styles.engineBar}>
-                <div>{Math.round(((client.throughput.down * 8) / 1024) * 10) / 10}kb/s</div>
-                <div>{Math.round(((client.throughput.up * 8) / 1024) * 10) / 10}kb/s</div>
+                <div>{Math.round(client.rtt * 100) / 100}rtt</div>
+                <div>{Math.round(((client.throughput.down * 8) / 1024) * 10) / 10}kb/s down</div>
+                <div>{Math.round(((client.throughput.up * 8) / 1024) * 10) / 10}kb/s up</div>
               </div>
             </form>
             <pre><code><small>{mainEntityJson}</small></code></pre>
diff --git a/app/server/engine.js b/app/server/engine.js
index 797fca1..305fdcd 100644
--- a/app/server/engine.js
+++ b/app/server/engine.js
@@ -117,6 +117,24 @@ export default class Engine {
       }
       this.incomingActions.get(connection).push(payload);
     });
+    this.server.addPacketListener('Heartbeat', (connection) => {
+      const playerData = this.connectedPlayers.get(connection);
+      const {distance} = playerData;
+      const now = performance.now();
+      distance.rtt = (now - distance.last) / 1000;
+      playerData.heartbeat = setTimeout(() => {
+        distance.last = performance.now();
+        this.server.send(
+          connection,
+          {
+            type: 'Heartbeat',
+            payload: {
+              rtt: distance.rtt,
+            },
+          },
+        );
+      }, 1000);
+    });
   }
 
   acceptActions() {
@@ -239,18 +257,26 @@ export default class Engine {
     }
     const ecs = this.ecses[entityJson.Ecs.path];
     const entity = ecs.get(await ecs.create(entityJson));
-    entity.Player.id = id
-    this.connectedPlayers.set(
+    entity.Player.id = id;
+    const playerData = {
+      distance: {last: performance.now(), rtt: 0},
+      entity,
+      id,
+      memory: {
+        chunks: new Map(),
+        nearby: new Set(),
+      },
+    };
+    this.server.send(
       connection,
       {
-        entity,
-        id,
-        memory: {
-          chunks: new Map(),
-          nearby: new Set(),
+        type: 'Heartbeat',
+        payload: {
+          rtt: 0,
         },
       },
     );
+    this.connectedPlayers.set(connection, playerData);
   }
 
   createEcs() {
@@ -264,7 +290,8 @@ export default class Engine {
     }
     this.connectedPlayers.delete(connection);
     this.incomingActions.delete(connection);
-    const {entity, id} = connectedPlayer;
+    const {entity, heartbeat, id} = connectedPlayer;
+    clearTimeout(heartbeat);
     const json = entity.toJSON();
     const ecs = this.ecses[entity.Ecs.path];
     return Promise.all([