Clear MiscConfig cache properly when saving/deleting the object; DMOJ…

…#1339

judge/signals.py

@@ -5,7 +5,7 @@
 from django.contrib.sites.models import Site
 from django.core.cache import cache
 from django.core.cache.utils import make_template_fragment_key
-from django.db.models.signals import post_delete, post_save
+from django.db.models.signals import post_delete, post_save, pre_save
 from django.dispatch import receiver
 
 from .caching import finished_submission
@@ -120,13 +120,33 @@ def organization_update(sender, instance, **kwargs):
 _misc_config_i18n.append('')
 
 
-@receiver(post_save, sender=MiscConfig)
-def misc_config_update(sender, instance, **kwargs):
-    cache.delete_many(['misc_config:%s:%s:%s' % (domain, lang, instance.key.split('.')[0])
+def misc_config_cache_delete(key):
+    cache.delete_many(['misc_config:%s:%s:%s' % (domain, lang, key.split('.')[0])
                        for lang in _misc_config_i18n
                        for domain in Site.objects.values_list('domain', flat=True)])
 
 
+@receiver(pre_save, sender=MiscConfig)
+def misc_config_pre_save(sender, instance, **kwargs):
+    try:
+        old_key = MiscConfig.objects.filter(id=instance.id).values_list('key').get()[0]
+    except MiscConfig.DoesNotExist:
+        old_key = None
+    instance._old_key = old_key
+
+
+@receiver(post_save, sender=MiscConfig)
+def misc_config_update(sender, instance, **kwargs):
+    misc_config_cache_delete(instance.key)
+    if instance._old_key is not None and instance._old_key != instance.key:
+        misc_config_cache_delete(instance._old_key)
+
+
+@receiver(post_delete, sender=MiscConfig)
+def misc_config_delete(sender, instance, **kwargs):
+    misc_config_cache_delete(instance.key)
+
+
 @receiver(post_save, sender=ContestSubmission)
 def contest_submission_update(sender, instance, **kwargs):
     Submission.objects.filter(id=instance.submission_id).update(contest_object_id=instance.participation.contest_id)