From e268efa5e78c71554717fcde3a6aa64f894516c3 Mon Sep 17 00:00:00 2001
From: Stephen Mitchell <scum@mac.com>
Date: Fri, 5 Jul 2024 21:31:10 -0400
Subject: [PATCH] [s3] Cache Cloudfront Signers (#1417)

---
 CHANGELOG.rst           | 2 ++
 storages/backends/s3.py | 9 ++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 0b0085fb..2a2045ec 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -10,6 +10,7 @@ S3
 - Pull ``AWS_SESSION_TOKEN`` from the environment (`#1399`_)
 - Fix newline handling for text mode files (`#1381`_)
 - Do not sign URLs when ``querystring_auth=False`` e.g public buckets or static files (`#1402`_)
+- Cache CloudFront Signers (`#1417`_)
 
 Azure
 -----
@@ -22,6 +23,7 @@ Azure
 .. _#1402: https://github.com/jschneier/django-storages/pull/1402
 .. _#1403: https://github.com/jschneier/django-storages/pull/1403
 .. _#1414: https://github.com/jschneier/django-storages/pull/1414
+.. _#1417: https://github.com/jschneier/django-storages/pull/1417
 
 
 1.14.3 (2024-05-04)
diff --git a/storages/backends/s3.py b/storages/backends/s3.py
index 3230f305..dbeb97e0 100644
--- a/storages/backends/s3.py
+++ b/storages/backends/s3.py
@@ -311,6 +311,8 @@ class S3Storage(CompressStorageMixin, BaseStorage):
     # settings/args are ignored.
     config = None
 
+    _signers = {}  # noqa: RUF012
+
     def __init__(self, **settings):
         omitted = object()
         if not hasattr(self, "cloudfront_signer"):
@@ -372,7 +374,12 @@ def __init__(self, **settings):
                 self.cloudfront_signer = None
 
     def get_cloudfront_signer(self, key_id, key):
-        return _cloud_front_signer_from_pem(key_id, key)
+        cache_key = f"{key_id}:{key}"
+        if cache_key not in self.__class__._signers:
+            self.__class__._signers[cache_key] = _cloud_front_signer_from_pem(
+                key_id, key
+            )
+        return self.__class__._signers[cache_key]
 
     def get_default_settings(self):
         return {