Handle unhandled errors in socket.reconnectStrategry (#2226)

* handle errors in reconnect strategy

* add test

* fix retries typo

* fix #2237 - flush queues on reconnect strategy error

* Update socket.ts

* Update socket.ts

packages/client/lib/client/socket.spec.ts

@@ -1,41 +1,63 @@
 import { strict as assert } from 'assert';
 import { SinonFakeTimers, useFakeTimers, spy } from 'sinon';
-import RedisSocket from './socket';
+import RedisSocket, { RedisSocketOptions } from './socket';
 
 describe('Socket', () => {
+    function createSocket(options: RedisSocketOptions): RedisSocket {
+        const socket = new RedisSocket(
+            () => Promise.resolve(),
+            options
+        );
+
+        socket.on('error', (err) => {
+            // ignore errors
+            console.log(err);
+        });
+
+        return socket;
+    }
+
     describe('reconnectStrategy', () => {
         let clock: SinonFakeTimers;
         beforeEach(() => clock = useFakeTimers());
         afterEach(() => clock.restore());
 
-        it('custom strategy', () => {
-            const reconnectStrategy = spy((retries: number): number | Error => {
+        it('custom strategy', async () => {
+            const reconnectStrategy = spy((retries: number) => {
                 assert.equal(retries + 1, reconnectStrategy.callCount);
 
-                if (retries === 50) {
-                    return Error('50');
-                }
+                if (retries === 50) return new Error('50');
 
                 const time = retries * 2;
                 queueMicrotask(() => clock.tick(time));
                 return time;
             });
 
-            const socket = new RedisSocket(
-                () => Promise.resolve(),
-                {
+            const socket = createSocket({
                 host: 'error',
                 reconnectStrategy
-                }
-            );
-
-            socket.on('error', () => {
-                // ignore errors
             });
 
-            return assert.rejects(socket.connect(), {
+            await assert.rejects(socket.connect(), {
                 message: '50'
             });
+
+            assert.equal(socket.isOpen, false);
+        });
+
+        it('should handle errors', async () => {
+            const socket = createSocket({
+                host: 'error',
+                reconnectStrategy(retries: number) {
+                    if (retries === 1) return new Error('done');
+                    queueMicrotask(() => clock.tick(500));
+                    throw new Error();
+                }
+            });
+
+            await assert.rejects(socket.connect());
+
+            assert.equal(socket.isOpen, false);
         });
     });
 });

packages/client/lib/client/socket.ts

@@ -44,10 +44,6 @@ export default class RedisSocket extends EventEmitter {
         return options;
     }
 
-    static #defaultReconnectStrategy(retries: number): number {
-        return Math.min(retries * 50, 500);
-    }
-
     static #isTlsSocket(options: RedisSocketOptions): options is RedisTlsSocketOptions {
         return (options as RedisTlsSocketOptions).tls === true;
     }
@@ -87,6 +83,23 @@ export default class RedisSocket extends EventEmitter {
         this.#options = RedisSocket.#initiateOptions(options);
     }
 
+    reconnectStrategy(retries: number): number | Error {
+        if (this.#options.reconnectStrategy) {
+            try {
+                const retryIn = this.#options.reconnectStrategy(retries);
+                if (typeof retryIn !== 'number' && !(retryIn instanceof Error)) {
+                    throw new TypeError('Reconnect strategy should return `number | Error`');
+                }
+
+                return retryIn;
+            } catch (err) {
+                this.emit('error', err);
+            }
+        }
+
+        return Math.min(retries * 50, 500);
+    }
+
     async connect(): Promise<void> {
         if (this.#isOpen) {
             throw new Error('Socket already opened');
@@ -116,14 +129,14 @@ export default class RedisSocket extends EventEmitter {
             this.#isReady = true;
             this.emit('ready');
         } catch (err) {
-            this.emit('error', err);
-
-            const retryIn = (this.#options?.reconnectStrategy ?? RedisSocket.#defaultReconnectStrategy)(retries);
+            const retryIn = this.reconnectStrategy(retries);
             if (retryIn instanceof Error) {
                 this.#isOpen = false;
+                this.emit('error', err);
                 throw new ReconnectStrategyError(retryIn, err);
             }
 
+            this.emit('error', err);
             await promiseTimeout(retryIn);
             return this.#connect(retries + 1);
         }