realms: Add caching to the get_seat_count calculation for upload limit.

For simiplicty's sake, we can avoid trying to do cache invalidation in
the variety of events that can cause the seat count to change - since
having an up to 1 day delay between users being added and the upload
limit going up is quite reasonable.

corporate/lib/stripe.py

@@ -52,6 +52,7 @@ from corporate.models import (
     get_customer_by_remote_realm,
     get_customer_by_remote_server,
 )
+from zerver.lib.cache import cache_with_key, get_realm_seat_count_cache_key
 from zerver.lib.exceptions import JsonableError
 from zerver.lib.logging_util import log_to_file
 from zerver.lib.send_email import (
@@ -155,6 +156,14 @@ def get_latest_seat_count(realm: Realm) -> int:
     return get_seat_count(realm, extra_non_guests_count=0, extra_guests_count=0)
 
 
+@cache_with_key(lambda realm: get_realm_seat_count_cache_key(realm.id), timeout=3600 * 24)
+def get_cached_seat_count(realm: Realm) -> int:
+    # This is a cache value  we're intentionally okay with not invalidating.
+    # All that means is that this value will lag up to 24 hours before getting updated.
+    # We use this for calculating the uploaded files storage limit for paid Cloud organizations.
+    return get_latest_seat_count(realm)
+
+
 def get_seat_count(
     realm: Realm, extra_non_guests_count: int = 0, extra_guests_count: int = 0
 ) -> int:

zerver/lib/cache.py

@@ -486,6 +486,10 @@ def get_realm_used_upload_space_cache_key(realm_id: int) -> str:
     return f"realm_used_upload_space:{realm_id}"
 
 
+def get_realm_seat_count_cache_key(realm_id: int) -> str:
+    return f"realm_seat_count:{realm_id}"
+
+
 def active_user_ids_cache_key(realm_id: int) -> str:
     return f"active_user_ids:{realm_id}"
 

zerver/models/realms.py

@@ -847,11 +847,11 @@ class Realm(models.Model):  # type: ignore[django-manager-missing] # django-stub
         elif plan_type == Realm.PLAN_TYPE_STANDARD_FREE:
             return Realm.UPLOAD_QUOTA_STANDARD_FREE
         elif plan_type in [Realm.PLAN_TYPE_STANDARD, Realm.PLAN_TYPE_PLUS]:
-            from corporate.lib.stripe import get_seat_count
+            from corporate.lib.stripe import get_cached_seat_count
 
             # Paying customers with few users should get a reasonable minimum quota.
             return max(
-                get_seat_count(self) * settings.UPLOAD_QUOTA_PER_USER_GB,
+                get_cached_seat_count(self) * settings.UPLOAD_QUOTA_PER_USER_GB,
                 Realm.UPLOAD_QUOTA_STANDARD_FREE,
             )
         else: