From 50f4af28b0f1fde03e1a57583bccc1387d6f08bf Mon Sep 17 00:00:00 2001
From: Emelia Smith <ThisIsMissEm@users.noreply.github.com>
Date: Fri, 28 Jul 2023 12:06:29 +0200
Subject: [PATCH] Fix: Streaming server memory leak in HTTP EventSource cleanup
 (#26228)

---
 streaming/index.js | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/streaming/index.js b/streaming/index.js
index 46e49524e..ab3a16030 100644
--- a/streaming/index.js
+++ b/streaming/index.js
@@ -227,9 +227,15 @@ const startWorker = async (workerId) => {
     callbacks.forEach(callback => callback(json));
   };
 
+  /**
+   * @callback SubscriptionListener
+   * @param {ReturnType<parseJSON>} json of the message
+   * @returns void
+   */
+
   /**
    * @param {string} channel
-   * @param {function(string): void} callback
+   * @param {SubscriptionListener} callback
    */
   const subscribe = (channel, callback) => {
     log.silly(`Adding listener for ${channel}`);
@@ -246,7 +252,7 @@ const startWorker = async (workerId) => {
 
   /**
    * @param {string} channel
-   * @param {function(Object<string, any>): void} callback
+   * @param {SubscriptionListener} callback
    */
   const unsubscribe = (channel, callback) => {
     log.silly(`Removing listener for ${channel}`);
@@ -618,9 +624,9 @@ const startWorker = async (workerId) => {
    * @param {string[]} ids
    * @param {any} req
    * @param {function(string, string): void} output
-   * @param {function(string[], function(string): void): void} attachCloseHandler
+   * @param {undefined | function(string[], SubscriptionListener): void} attachCloseHandler
    * @param {boolean=} needsFiltering
-   * @returns {function(object): void}
+   * @returns {SubscriptionListener}
    */
   const streamFrom = (ids, req, output, attachCloseHandler, needsFiltering = false) => {
     const accountId = req.accountId || req.remoteAddress;
@@ -703,7 +709,7 @@ const startWorker = async (workerId) => {
       subscribe(`${redisPrefix}${id}`, listener);
     });
 
-    if (attachCloseHandler) {
+    if (typeof attachCloseHandler === 'function') {
       attachCloseHandler(ids.map(id => `${redisPrefix}${id}`), listener);
     }
 
@@ -740,12 +746,13 @@ const startWorker = async (workerId) => {
   /**
    * @param {any} req
    * @param {function(): void} [closeHandler]
-   * @return {function(string[]): void}
+   * @returns {function(string[], SubscriptionListener): void}
    */
-  const streamHttpEnd = (req, closeHandler = undefined) => (ids) => {
+
+  const streamHttpEnd = (req, closeHandler = undefined) => (ids, listener) => {
     req.on('close', () => {
       ids.forEach(id => {
-        unsubscribe(id);
+        unsubscribe(id, listener);
       });
 
       if (closeHandler) {
@@ -956,7 +963,7 @@ const startWorker = async (workerId) => {
    * @typedef WebSocketSession
    * @property {any} socket
    * @property {any} request
-   * @property {Object.<string, { listener: function(string): void, stopHeartbeat: function(): void }>} subscriptions
+   * @property {Object.<string, { listener: SubscriptionListener, stopHeartbeat: function(): void }>} subscriptions
    */
 
   /**