web/wsclient: reconnect automatically if disconnected

web/src/App.tsx

@@ -41,15 +41,41 @@ function App() {
 	}, [client])
 	useEffect(() => client.start(), [client])
 
-	if (connState?.error) {
-		return <div>
-			{`${connState.error} \u{1F63F}`}
+	const afterConnectError = Boolean(connState?.error && connState.reconnecting && clientState?.is_verified)
+	useEffect(() => {
+		if (afterConnectError) {
+			const cancelKeys = (evt: KeyboardEvent | MouseEvent) => evt.stopPropagation()
+			document.body.addEventListener("keydown", cancelKeys, { capture: true })
+			document.body.addEventListener("keyup", cancelKeys, { capture: true })
+			document.body.addEventListener("click", cancelKeys, { capture: true })
+			return () => {
+				document.body.removeEventListener("keydown", cancelKeys, { capture: true })
+				document.body.removeEventListener("keyup", cancelKeys, { capture: true })
+				document.body.removeEventListener("click", cancelKeys, { capture: true })
+			}
+		}
+	}, [afterConnectError])
+	const errorOverlay = connState?.error ? <div
+		className={`connection-error-wrapper ${afterConnectError ? "post-connect" : ""}`}
+		tabIndex={-1}
+	>
+		<div className="connection-error-inner">
+			<div>{connState.error} &#x1F63F;</div>
+			{connState.reconnecting && <div>
+				<ScaleLoader width="2rem" height="2rem" color="var(--primary-color)"/>
+				Reconnecting to backend...
+				{connState.nextAttempt ? <div><small>(next attempt at {connState.nextAttempt})</small></div> : null}
+			</div>}
 		</div>
-	} else if (!connState?.connected || !clientState) {
+	</div> : null
+
+	if (connState?.error && !afterConnectError) {
+		return errorOverlay
+	} else if ((!connState?.connected && !afterConnectError) || !clientState) {
 		const msg = connState?.connected ?
 			"Waiting for client state..." : "Connecting to backend..."
-		return <div>
-			<ScaleLoader/>
+		return <div className="pre-connect">
+			<ScaleLoader width="2rem" height="2rem" color="var(--primary-color)"/>
 			{msg}
 		</div>
 	} else if (!clientState.is_logged_in) {
@@ -61,6 +87,7 @@ function App() {
 			<LightboxWrapper>
 				<MainScreen/>
 			</LightboxWrapper>
+			{errorOverlay}
 		</ClientContext>
 	}
 }

web/src/api/client.ts

@@ -52,16 +52,16 @@ export default class Client {
 				method: "POST",
 				signal,
 			})
-			if (!resp.ok) {
+			if (!resp.ok && !signal.aborted) {
 				this.rpc.connect.emit({
 					connected: false,
-					error: new Error(`Authentication failed: ${resp.statusText}`),
+					reconnecting: false,
+					error: `Authentication failed: ${resp.statusText}`,
 				})
 				return
 			}
 		} catch (err) {
-			const error = err instanceof Error ? err : new Error(`${err}`)
-			this.rpc.connect.emit({ connected: false, error })
+			this.rpc.connect.emit({ connected: false, reconnecting: false, error: `Authentication failed: ${err}` })
 		}
 		if (signal.aborted) {
 			return

web/src/api/rpc.ts

@@ -42,7 +42,9 @@ import type {
 
 export interface ConnectionEvent {
 	connected: boolean
-	error: Error | null
+	reconnecting: boolean
+	error: string | null
+	nextAttempt?: string
 }
 
 export class ErrorResponse extends Error {

web/src/api/wailsclient.ts

@@ -39,7 +39,7 @@ export default class WailsClient extends RPCClient {
 			this.event.emit(evt.data[0])
 		})
 		this.#wails.Call.ByName("main.CommandHandler.Init")
-		this.connect.emit({ connected: true, error: null })
+		this.connect.emit({ connected: true, reconnecting: false, error: null })
 	}
 
 	async stop() {}

web/src/api/wsclient.ts

@@ -25,6 +25,9 @@ export default class WSClient extends RPCClient {
 	#pingInterval: number | null = null
 	#lastReceivedEvt: number = 0
 	#resumeRunID: string = ""
+	#stopped = false
+	#reconnectTimeout: number | null = null
+	#connectFailures: number = 0
 
 	constructor(readonly addr: string) {
 		super()
@@ -32,6 +35,7 @@ export default class WSClient extends RPCClient {
 
 	start() {
 		try {
+			this.#stopped = false
 			this.#lastMessage = Date.now()
 			const params = new URLSearchParams({
 				run_id: this.#resumeRunID,
@@ -44,9 +48,8 @@ export default class WSClient extends RPCClient {
 			this.#conn.onopen = this.#onOpen
 			this.#conn.onerror = this.#onError
 			this.#conn.onclose = this.#onClose
-			this.#pingInterval = setInterval(this.#pingLoop, PING_INTERVAL)
 		} catch (err) {
-			this.#dispatchConnectionStatus(false, err as Error)
+			this.#dispatchConnectionStatus(false, false, `Failed to create websocket: ${err}`)
 		}
 	}
 
@@ -66,8 +69,10 @@ export default class WSClient extends RPCClient {
 	}
 
 	stop() {
+		this.#stopped = true
 		if (this.#pingInterval !== null) {
 			clearInterval(this.#pingInterval)
+			this.#pingInterval = null
 		}
 		this.#conn?.close(1000, "Client closed")
 	}
@@ -105,13 +110,20 @@ export default class WSClient extends RPCClient {
 		this.onCommand(parsed)
 	}
 
-	#dispatchConnectionStatus(connected: boolean, error: Error | null) {
-		this.connect.emit({ connected, error })
+	#dispatchConnectionStatus(connected: boolean, reconnecting: boolean, error: string | null, nextAttempt?: number) {
+		this.connect.emit({
+			connected,
+			reconnecting,
+			error,
+			nextAttempt: nextAttempt ? new Date(nextAttempt).toLocaleTimeString() : undefined,
+		})
 	}
 
 	#onOpen = () => {
 		console.info("Websocket opened")
-		this.#dispatchConnectionStatus(true, null)
+		this.#dispatchConnectionStatus(true, false, null)
+		this.#connectFailures = 0
+		this.#pingInterval = setInterval(this.#pingLoop, PING_INTERVAL)
 	}
 
 	#clearPending = () => {
@@ -123,13 +135,33 @@ export default class WSClient extends RPCClient {
 
 	#onError = (ev: Event) => {
 		console.error("Websocket error:", ev)
-		this.#dispatchConnectionStatus(false, new Error("Websocket error"))
-		this.#clearPending()
 	}
 
 	#onClose = (ev: CloseEvent) => {
+		this.#connectFailures++
 		console.warn("Websocket closed:", ev)
-		this.#dispatchConnectionStatus(false, new Error(`Websocket closed: ${ev.code} ${ev.reason}`))
 		this.#clearPending()
+		if (this.#pingInterval !== null) {
+			clearInterval(this.#pingInterval)
+			this.#pingInterval = null
+		}
+		const willReconnect = !this.#stopped && !this.#reconnectTimeout
+		const backoff = Math.min(2 ** (this.#connectFailures - 4), 10) * 1000
+		this.#dispatchConnectionStatus(
+			false,
+			willReconnect,
+			`Websocket closed: ${ev.code} ${ev.reason}`,
+			Date.now() + backoff,
+		)
+		if (willReconnect) {
+			console.log("Attempting to reconnect in", backoff, "ms")
+			this.#reconnectTimeout = setTimeout(() => {
+				console.log("Reconnecting now")
+				this.#reconnectTimeout = null
+				this.start()
+			}, backoff)
+		} else {
+			console.log(`Not reconnecting (stopped=${this.#stopped}, reconnectTimeout=${this.#reconnectTimeout})`)
+		}
 	}
 }

web/src/index.css

@@ -206,6 +206,37 @@ button, a.button, span.button {
 	}
 }
 
+div.connection-error-wrapper {
+	position: fixed;
+	inset: 0;
+	z-index: 100;
+	display: flex;
+	align-items: center;
+	flex-direction: column;
+	justify-content: center;
+
+	&.post-connect {
+		background-color: var(--dimmed-overlay-background-color);
+	}
+
+	> div.connection-error-inner {
+		background-color: var(--background-color);
+		border: 2px solid var(--error-color);
+		border-radius: .5rem;
+		margin-top: 2rem;
+		padding: 1rem;
+		display: flex;
+		flex-direction: column;
+		align-items: center;
+		gap: 1rem;
+	}
+}
+
+div.pre-connect {
+	margin-top: 2rem;
+	text-align: center;
+}
+
 a {
 	text-decoration: none;
 	color: var(--link-text-color);