Cache sorting of countries

src/pretix/helpers/countries.py

@@ -0,0 +1,29 @@
+from django.core.cache import cache
+from django.utils.translation import get_language
+from django_countries import Countries
+
+
+class CachedCountries(Countries):
+    _cached_lists = {}
+
+    def __iter__(self):
+        """
+        Iterate through countries, sorted by name, but cache the results based on the locale.
+        django-countries performs a unicode-aware sorting based on pyuca which is incredibly
+        slow.
+        """
+        cache_key = "countries:all:{}".format(get_language())
+        if cache_key in self._cached_lists:
+            yield from self._cached_lists[cache_key]
+            return
+
+        val = cache.get(cache_key)
+        if val:
+            self._cached_lists[cache_key] = val
+            yield from val
+            return
+
+        val = list(super().__iter__())
+        self._cached_lists[cache_key] = val
+        cache.set(cache_key, val, 3600 * 24 * 30)
+        yield from val