perf: Optimize SSE communication between browser and container

- Add anti-buffering headers (X-Accel-Buffering, Content-Encoding)
- Reduce polling interval from 500ms to 250ms for faster updates
- Add heartbeat mechanism to keep connection alive
- Implement auto-reconnection on client side
- Disable Express response buffering for SSE endpoints
- Skip empty heartbeat messages on client
- Improve error handling and logging

admin/server.js

@@ -9,9 +9,22 @@ dotenv.config({ path: `.env.${ENV}` });
 const app = express();
 const PORT = process.env.PORT || 3002;
 
+// Disable Express poweredBy header for performance
+app.disable('x-powered-by');
+
 // Parse JSON bodies
 app.use(express.json());
 
+// Optimize Express for SSE performance
+app.use((req, res, next) => {
+    // Disable buffering for SSE endpoints
+    if (req.path === '/api/sse') {
+        res.setHeader('Cache-Control', 'no-cache');
+        res.setHeader('Connection', 'keep-alive');
+    }
+    next();
+});
+
 // Track SSE connections
 let sseConnections = 0;
 
@@ -41,16 +54,24 @@ app.get('/api/sse', (req, res) => {
     const connectionId = sseConnections;
     console.log(`[SSE] New connection #${connectionId} established. Total: ${sseConnections}`);
     
+    // Optimized headers for better performance
     res.writeHead(200, {
         'Content-Type': 'text/event-stream',
-        'Cache-Control': 'no-cache',
+        'Cache-Control': 'no-cache, no-store, must-revalidate',
         'Connection': 'keep-alive',
         'Access-Control-Allow-Origin': '*',
-        'Access-Control-Allow-Headers': 'Cache-Control'
+        'Access-Control-Allow-Headers': 'Cache-Control',
+        'X-Accel-Buffering': 'no', // Disable nginx buffering
+        'Content-Encoding': 'identity' // Disable compression
     });
 
     // Send initial connection message
     res.write('data: {"type": "connected", "message": "SSE connection established"}\n\n');
+    
+    // Send keepalive heartbeat every 30 seconds
+    const heartbeatInterval = setInterval(() => {
+        res.write(': heartbeat\n\n');
+    }, 30000);
 
     // Set up polling interval for game state updates
     const pollInterval = setInterval(async () => {
@@ -90,13 +111,14 @@ app.get('/api/sse', (req, res) => {
                 message: `Error fetching game stats: ${error.message}`
             })}\n\n`);
         }
-    }, 500); // Poll every 500ms
+    }, 250); // Poll every 250ms for faster updates
 
     // Clean up on client disconnect
     req.on('close', () => {
         sseConnections--;
         console.log(`[SSE] Connection #${connectionId} closed. Total: ${sseConnections}`);
         clearInterval(pollInterval);
+        clearInterval(heartbeatInterval);
     });
 });
 

admin/src/services/adminService.ts

@@ -47,6 +47,8 @@ class AdminService {
     await this.initializeServerUrl()
     
     this.callback = callback
+    
+    // Configure EventSource with better error handling
     this.eventSource = new EventSource('/api/sse')
 
     this.eventSource.onopen = () => {
@@ -57,11 +59,14 @@ class AdminService {
 
     this.eventSource.onmessage = (event) => {
       try {
+        // Skip heartbeat messages
+        if (event.data.trim() === '') return
+        
         const data = JSON.parse(event.data)
         console.log('[AdminService] SSE message received:', data.type, data.timestamp)
         this.callback?.(data)
       } catch (error) {
-        console.error('[AdminService] Error parsing SSE message:', error)
+        console.error('[AdminService] Error parsing SSE message:', error, 'Raw data:', event.data)
       }
     }
 
@@ -69,6 +74,14 @@ class AdminService {
       console.error('[AdminService] SSE connection error:', error)
       this.isConnected = false
       this.connectionCallback?.(false)
+      
+      // Auto-reconnect after 5 seconds
+      setTimeout(() => {
+        if (!this.isConnected) {
+          console.log('[AdminService] Attempting to reconnect...')
+          this.connect(this.callback!)
+        }
+      }, 5000)
     }
   }