From 72834f337058cecdb628dbb62043b2bbb16ac3e2 Mon Sep 17 00:00:00 2001
From: ageier <andreas.geier@holidaycheck.com>
Date: Thu, 21 Sep 2023 17:21:46 +0200
Subject: [PATCH 1/3] Return cache directly in getServerStylisCache

We are never using the accessor function that is returned.
In the code base later we access it like this:
`serverStylisCache[name]` and not like this `serverStylisCache(name)`

While we could change the access,
I'm not sure how we would write to the cache.
So I think we can just directly return the cache object.
---
 packages/cache/src/index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/cache/src/index.js b/packages/cache/src/index.js
index 39d66bf91..000163195 100644
--- a/packages/cache/src/index.js
+++ b/packages/cache/src/index.js
@@ -37,7 +37,7 @@ let getServerStylisCache = isBrowser
   : weakMemoize(() =>
       memoize(() => {
         let cache = {}
-        return name => cache[name]
+        return cache
       })
     )
 

From eaec045ccbd2a4c06a12d0990ba52067f3a5cc78 Mon Sep 17 00:00:00 2001
From: ageier <andreas.geier@holidaycheck.com>
Date: Thu, 21 Sep 2023 17:30:34 +0200
Subject: [PATCH 2/3] Move creation of stylisCache inside createCache function
 Currently we share caches even for multiple createCache() calls.

So if you have an SSR app that reates a cache on the server like this:

const cache = createCache({ key: 'custom' });

and you do this (like recommended) on every request, you still share a cache
between all requests. I also think this is currently a memory leak.
If you have a big application and maybe even lots of dynamic styles
the cache can get quite big and will never be garbage collected.
---
 packages/cache/src/index.js | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/packages/cache/src/index.js b/packages/cache/src/index.js
index 000163195..f1240043a 100644
--- a/packages/cache/src/index.js
+++ b/packages/cache/src/index.js
@@ -32,18 +32,18 @@ export type Options = {
   insertionPoint?: HTMLElement
 }
 
-let getServerStylisCache = isBrowser
-  ? undefined
-  : weakMemoize(() =>
-      memoize(() => {
-        let cache = {}
-        return cache
-      })
-    )
-
 const defaultStylisPlugins = [prefixer]
 
 let createCache = (options: Options): EmotionCache => {
+  let getServerStylisCache = isBrowser
+    ? undefined
+    : weakMemoize(() =>
+        memoize(() => {
+          let cache = {}
+          return cache
+        })
+      )
+
   let key = options.key
 
   if (process.env.NODE_ENV !== 'production' && !key) {

From c417aac5e3c5122480f6e959e1db01ce0abf29ae Mon Sep 17 00:00:00 2001
From: ageier <andreas.geier@holidaycheck.com>
Date: Thu, 21 Sep 2023 17:36:21 +0200
Subject: [PATCH 3/3] Add changeset

---
 .changeset/pink-dancers-wash.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/pink-dancers-wash.md

diff --git a/.changeset/pink-dancers-wash.md b/.changeset/pink-dancers-wash.md
new file mode 100644
index 000000000..50605e281
--- /dev/null
+++ b/.changeset/pink-dancers-wash.md
@@ -0,0 +1,5 @@
+---
+'@emotion/cache': patch
+---
+
+Ensure that caches are not reused for different createCache calls