remind user to restart c3nav if no external cache is configured

src/c3nav/mapdata/management/commands/clearmapcache.py

@@ -1,4 +1,6 @@
+from django.conf import settings
 from django.core.management.base import BaseCommand
+from django.utils.translation import ugettext_lazy as _
 
 
 class Command(BaseCommand):
@@ -7,3 +9,6 @@ class Command(BaseCommand):
     def handle(self, *args, **options):
         from c3nav.mapdata.models import MapUpdate
         MapUpdate.objects.create(type='management')
+
+        if not settings.HAS_REAL_CACHE:
+            print(_('You have no external cache configured, so don\'t forget to restart your c3nav instance!'))

src/c3nav/mapdata/management/commands/processupdates.py

@@ -1,4 +1,6 @@
+from django.conf import settings
 from django.core.management.base import BaseCommand
+from django.utils.translation import ugettext_lazy as _
 
 from c3nav.mapdata.tasks import process_map_updates
 
@@ -8,3 +10,6 @@ class Command(BaseCommand):
 
     def handle(self, *args, **options):
         process_map_updates()
+
+        if not settings.HAS_REAL_CACHE:
+            print(_('You have no external cache configured, so don\'t forget to restart your c3nav instance!'))

src/c3nav/settings.py

@@ -118,11 +118,13 @@ CACHES = {
         'LOCATION': 'unique-snowflake',
     }
 }
+HAS_REAL_CACHE = False
 
 SESSION_ENGINE = "django.contrib.sessions.backends.db"
 
 HAS_MEMCACHED = config.has_option('memcached', 'location')
 if HAS_MEMCACHED:
+    HAS_REAL_CACHE = True
     CACHES['default'] = {
         'BACKEND': 'django.core.cache.backends.memcached.PyLibMCCache',
         'LOCATION': config.get('memcached', 'location'),
@@ -131,6 +133,7 @@ if HAS_MEMCACHED:
 
 HAS_REDIS = config.has_option('redis', 'location')
 if HAS_REDIS:
+    HAS_REAL_CACHE = True
     CACHES['redis'] = {
         "BACKEND": "django_redis.cache.RedisCache",
         "LOCATION": config.get('redis', 'location'),