refactor(commands-queue): Improve push notification handling

- Replaced `setInvalidateCallback` with a more flexible `addPushHandler` method, allowing multiple handlers for push notifications.
- Introduced the `PushHandler` type to standardize push notification processing.
- Refactored `RedisCommandsQueue` to use a `#pushHandlers` array, enabling dynamic and modular handling of push notifications.
- Updated `RedisClient` to leverage the new handler mechanism for `invalidate` push notifications, simplifying and decoupling logic.

Author: nkaradzhov

packages/client/lib/client/commands-queue.ts

@@ -50,6 +50,13 @@ const RESP2_PUSH_TYPE_MAPPING = {
   [RESP_TYPES.SIMPLE_STRING]: Buffer
 };
 
+// Try to handle a push notification. Return whether you
+// successfully consumed the notification or not. This is
+// important in order for the queue to be able to pass the
+// notification to another handler if the current one did not
+// succeed.
+type PushHandler = (pushItems: Array<any>) => boolean;
+
 export default class RedisCommandsQueue {
   readonly #respVersion;
   readonly #maxLength;
@@ -60,12 +67,11 @@ export default class RedisCommandsQueue {
   readonly decoder;
   readonly #pubSub = new PubSub();
 
+  #pushHandlers: PushHandler[] = [this.#onPush.bind(this)];
   get isPubSubActive() {
     return this.#pubSub.isActive;
   }
 
-  #invalidateCallback?: (key: RedisArgument | null) => unknown;
-
   constructor(
     respVersion: RespVersions,
     maxLength: number | null | undefined,
@@ -107,6 +113,7 @@ export default class RedisCommandsQueue {
       }
       return true;
     }
+    return false
   }
 
   #getTypeMapping() {
@@ -119,30 +126,16 @@ export default class RedisCommandsQueue {
       onErrorReply: err => this.#onErrorReply(err),
       //TODO: we can shave off a few cycles by not adding onPush handler at all if CSC is not used
       onPush: push => {
-        if (!this.#onPush(push)) {
-          // currently only supporting "invalidate" over RESP3 push messages
-          switch (push[0].toString()) {
-            case "invalidate": {
-              if (this.#invalidateCallback) {
-                if (push[1] !== null) {
-                  for (const key of push[1]) {
-                    this.#invalidateCallback(key);
-                  }
-                } else {
-                  this.#invalidateCallback(null);
-                }
-              }
-              break;
-            }
-          }
+        for(const pushHandler of this.#pushHandlers) {
+          if(pushHandler(push)) return
         }
       },
       getTypeMapping: () => this.#getTypeMapping()
     });
   }
 
-  setInvalidateCallback(callback?: (key: RedisArgument | null) => unknown) {
-    this.#invalidateCallback = callback;
+  addPushHandler(handler: PushHandler): void {
+    this.#pushHandlers.push(handler);
   }
 
   addCommand<T>(
@@ -432,7 +425,7 @@ export default class RedisCommandsQueue {
   }
 
   static #removeTimeoutListener(command: CommandToWrite) {
-    command.timeout!.signal.removeEventListener('abort', command.timeout!.listener);
+    command.timeout?.signal.removeEventListener('abort', command.timeout!.listener);
   }
 
   static #flushToWrite(toBeSent: CommandToWrite, err: Error) {

packages/client/lib/client/index.ts

@@ -464,7 +464,19 @@ export default class RedisClient<
         const cscConfig = options.clientSideCache;
         this.#clientSideCache = new BasicClientSideCache(cscConfig);
       }
-      this.#queue.setInvalidateCallback(this.#clientSideCache.invalidate.bind(this.#clientSideCache));
+      this.#queue.addPushHandler((push: Array<any>): boolean => {
+        if (push[0].toString() !== 'invalidate') return false;
+
+        if (push[1] !== null) {
+          for (const key of push[1]) {
+            this.#clientSideCache?.invalidate(key)
+          }
+        } else {
+          this.#clientSideCache?.invalidate(null)
+        }
+
+        return true
+      });
     }
   }