graceful handling of disconnects and page reloads

src/client.js

@@ -1,33 +1,28 @@
 const vid = document.querySelector('video');
 const wsProto = window.location.protocol === 'https:' ? 'wss' : 'ws';
-const socket = new WebSocket(`${wsProto}://${window.location.hostname}:${window.location.port}`);
-
-// if the new tms is within this margin of the current tms, then the change is ignored for smoother viewing
-const PLAYING_THRESH = 1;
-const PAUSED_THRESH = 0.01;
-
-// local state
-let video_playing = false;
-let last_updated = 0;
-let client_uid = null;
-
-// clocks sync variables
-const num_time_sync_cycles = 10;
-let over_estimates = new Array();
-let under_estimates = new Array();
-let over_estimate = 0;
-let under_estimate = 0;
-let correction = 0;
+let socket = null; // Initialize socket as null
+let retryInterval = 1000; // Initial retry interval in milliseconds
+const maxRetryInterval = 30000; // Maximum retry interval
 
+function createWebSocket() {
+	socket = new WebSocket(`${wsProto}://${window.location.hostname}:${window.location.port}`);
 
 	// Connection opened
 	socket.addEventListener('open', function (event) {
 		console.log('Connected to WS Server');
+		retryInterval = 1000; // Reset retry interval on successful connection
 	});
 
 	// Got message from the server
 	socket.addEventListener("message", (event) => {
 
+		// Reload the page if the server sends a reload request
+		if (event.data.startsWith("reload_request")) {
+			console.log("Reloading the page as requested by the server");
+			setTimeout(() => window.location.reload(), 1000);
+			return;
+		}
+
 		// Time syncing backward server-response
 		if (event.data.startsWith("time_sync_response_backward")) {
 			let time_at_server = Number(event.data.slice("time_sync_response_backward".length + 1));
@@ -82,14 +77,47 @@ socket.addEventListener("message", (event) => {
 		}
 	});
 
-
 	// Connection closed
 	socket.addEventListener('close', function (event) {
 		console.log('Disconnected from the WS Server');
 		client_uid = null;
-	setTimeout(() => window.location.reload(), 1000);
+		retryWebSocketConnection(); // Attempt to reconnect
 	});
 
+	// Connection error
+	socket.addEventListener('error', function (event) {
+		console.error('WebSocket error:', event);
+		socket.close(); // Ensure the socket is closed on error
+	});
+}
+
+function retryWebSocketConnection() {
+	console.log(`Attempting to reconnect in ${retryInterval / 1000} seconds...`);
+	setTimeout(() => {
+		retryInterval = Math.min(retryInterval * 2, maxRetryInterval); // Exponential backoff
+		createWebSocket(); // Recreate the WebSocket connection
+	}, retryInterval);
+}
+
+// Initial WebSocket connection
+createWebSocket();
+
+// if the new tms is within this margin of the current tms, then the change is ignored for smoother viewing
+const PLAYING_THRESH = 1;
+const PAUSED_THRESH = 0.01;
+
+// local state
+let video_playing = false;
+let last_updated = 0;
+let client_uid = null;
+
+// clocks sync variables
+const num_time_sync_cycles = 10;
+let over_estimates = new Array();
+let under_estimates = new Array();
+let over_estimate = 0;
+let under_estimate = 0;
+let correction = 0;
 
 // Send video state update to the server
 // event: the video event (ex: seeking, pause play) 
@@ -111,8 +139,10 @@ function state_change_handler(event) {
 		client_uid: client_uid
 	};
 
+	if (socket.readyState === WebSocket.OPEN) {
 		socket.send(`state_update_from_client ${JSON.stringify(state_image)}`);
 	}
+}
 
 // assigning event handlers
 vid.onseeking = state_change_handler;
@@ -213,3 +243,4 @@ document.addEventListener('DOMContentLoaded', function() {
 		style.textContent = `::cue { font-size: ${size} !important; }`;
 	});
 });
+

src/index.js

@@ -187,7 +187,10 @@ server.listen(settings.server_port, settings.server_ip,
 process.on('SIGINT', () => {
 	console.log("Shutting down server...");
 	// wss.close();
-	wss.clients.forEach(client => client.terminate());
+	wss.clients.forEach(client => {
+		client.send("reload_request");
+		client.terminate();
+	});
 	server.close(() => {
 		console.log("Server closed");
 		process.exit(0);