fix: resolve doubly linked list push issue (#3085)

* fix redis sentinel failover

* fix: resolve doubly linked list push issue

* fix semicolon syntax

* correctly set the removed node ref

* fix linked list node iterator

* revert push logic and refactor remove logic

* add linked list tests

packages/client/lib/client/linked-list.spec.ts

@@ -6,7 +6,7 @@ import {
 import { equal, deepEqual } from "assert/strict";
 
 describe("DoublyLinkedList", () => {
-  const list = new DoublyLinkedList();
+  const list = new DoublyLinkedList<number>();
 
   it("should start empty", () => {
     equal(list.length, 0);
@@ -96,6 +96,38 @@ describe("DoublyLinkedList", () => {
     }
     equal(count, 6);
   });
+
+  it("should handle remove on empty list", () => {
+    list.reset();
+    const node = list.push(1);
+    list.remove(node);
+    equal(list.length, 0);
+    deepEqual(Array.from(list), []);
+    list.remove(node);
+    equal(list.length, 0);
+    deepEqual(Array.from(list), []);
+  });
+
+
+  it("should safely remove nodes while iterating", () => {
+    list.reset();
+    list.push(1);
+    list.push(2);
+    list.push(3);
+    list.push(4);
+    list.push(5);
+    
+    const visited: number[] = [];
+    for (const node of list.nodes()) {
+      visited.push(node.value);
+      if (node.value % 2 === 0) {
+        list.remove(node);
+      }
+    }
+    deepEqual(visited, [1, 2, 3, 4, 5]);
+    equal(list.length, 3);
+    deepEqual(Array.from(list), [1, 3, 5]);
+  });
 });
 
 describe("SinglyLinkedList", () => {

packages/client/lib/client/linked-list.ts

@@ -29,7 +29,7 @@ export class DoublyLinkedList<T> {
     ++this.#length;
 
     if (this.#tail === undefined) {
-      return this.#tail = this.#head = {
+      return this.#head = this.#tail = {
         previous: this.#head,
         next: undefined,
         value
@@ -73,7 +73,7 @@ export class DoublyLinkedList<T> {
     --this.#length;
     const node = this.#head;
     if (node.next) {
-      node.next.previous = node.previous;
+      node.next.previous = undefined;
       this.#head = node.next;
       node.next = undefined;
     } else {
@@ -83,19 +83,23 @@ export class DoublyLinkedList<T> {
   }
 
   remove(node: DoublyLinkedNode<T>) {
+    if (this.#length === 0) return;
     --this.#length;
 
     if (this.#tail === node) {
       this.#tail = node.previous;
-    }
-
+    } 
     if (this.#head === node) {
       this.#head = node.next;
     } else {
-      node.previous!.next = node.next;
-      node.previous = undefined;
+      if (node.previous) {
+          node.previous.next = node.next;
+      }
+      if (node.next) {
+        node.next.previous = node.previous;
+      }
     }
-
+    node.previous = undefined;
     node.next = undefined;
   }
 
@@ -115,8 +119,9 @@ export class DoublyLinkedList<T> {
   *nodes() {
     let node = this.#head;
     while(node) {
+      const next = node.next
       yield node;
-      node = node.next;
+      node = next;
     }
   }
 }

packages/client/lib/sentinel/index.ts

@@ -928,6 +928,16 @@ class RedisSentinelInternal<
     }
   }
 
+  #handleSentinelFailure(node: RedisNode) {
+    const found = this.#sentinelRootNodes.findIndex(
+        (rootNode) => rootNode.host === node.host && rootNode.port === node.port
+    );
+    if (found !== -1) {
+        this.#sentinelRootNodes.splice(found, 1);
+    }
+    this.#reset();
+  }
+
   async close() {
     this.#destroy = true;
 
@@ -1197,8 +1207,9 @@ class RedisSentinelInternal<
           error: err
         };
         this.emit('client-error', event);
-        this.#reset();
-      });
+        this.#handleSentinelFailure(node);
+      })
+      .on('end', () => this.#handleSentinelFailure(node));
       this.#sentinelClient = client;
 
       this.#trace(`transform: adding sentinel client connect() to promise list`);