Caching for allowed_schema_ids, for performance.

ebpub/ebpub/db/constants.py

@@ -43,3 +43,6 @@
 # the optional pre-directional and/or post-directional (for example,
 # 'n', 'ne', 'n-w', '-sw').
 BLOCK_URL_REGEX = r'(\d{1,6})-(\d{1,6})([nsew]{1,2})?(?:-([nsew]{0,2}))?'
+
+# How long the Schema managers should cache allowed_schema_ids()
+ALLOWED_IDS_CACHE_TIME = 60 * 10

ebpub/ebpub/db/models.py

@@ -20,8 +20,10 @@
 from django.contrib.gis.db import models
 from django.contrib.gis.db.models import Count
 from django.core import urlresolvers
+from django.core.cache import cache
 from django.core.exceptions import ValidationError
 from django.db import connection, transaction
+from ebpub.db import constants
 from ebpub.geocoder.parser.parsing import normalize
 from ebpub.utils.geodjango import flatten_geomcollection
 from ebpub.utils.geodjango import ensure_valid
@@ -69,6 +71,16 @@ def field_mapping(schema_id_list):
 
 class SchemaManager(models.Manager):
 
+    _allowed_ids_cache_key = 'allowed_schema_ids__all'
+
+    def update(self, *args, **kwargs):
+        # Django doesn't provide pre/post_update signals, rats.
+        # See https://code.djangoproject.com/ticket/13021
+        # So we define one and send it here.
+        result = super(SchemaManager, self).update(*args, **kwargs)
+        post_update.send(sender=Schema)
+        return result
+
     def get_by_natural_key(self, slug):
         return self.get(slug=slug)
 
@@ -93,11 +105,16 @@ def allowed_schema_ids(self):
         Useful for filtering out schemas (or things related to
         schemas) based on the current Manager.
         """
-        return [s['id'] for s in self.all().values('id')]
-
+        ids = cache.get(self._allowed_ids_cache_key, None)
+        if ids is None:
+            ids = [s['id'] for s in self.all().values('id')]
+            cache.set(self._allowed_ids_cache_key, ids, constants.ALLOWED_IDS_CACHE_TIME)
+        return ids
 
 class SchemaPublicManager(SchemaManager):
 
+    _allowed_ids_cache_key = 'allowed_schema_ids__public'
+
     def get_query_set(self):
         return super(SchemaManager, self).get_query_set().filter(is_public=True)
 
@@ -1164,3 +1181,23 @@ def get_city_locations():
         return cities
     else:
         return Location.objects.filter(id=None)
+
+
+########################################################################
+# Signals
+
+# Django doesn't provide a pre_update() signal, rats.
+# See https://code.djangoproject.com/ticket/13021
+from django.dispatch import Signal
+from django.db.models.signals import post_save, post_delete
+
+post_update = Signal(providing_args=[])
+
+def clear_allowed_schema_ids_cache(sender, **kwargs):
+    cache.delete_many((SchemaPublicManager._allowed_ids_cache_key,
+                       SchemaManager._allowed_ids_cache_key))
+
+post_update.connect(clear_allowed_schema_ids_cache, sender=Schema)
+post_save.connect(clear_allowed_schema_ids_cache, sender=Schema)
+post_delete.connect(clear_allowed_schema_ids_cache, sender=Schema)
+

ebpub/ebpub/db/tests/test_models.py

@@ -216,6 +216,7 @@ def test_top_lookups__m2m(self):
         self.assertEqual(top_lookups[1]['count'], 2)
         self.assertEqual(top_lookups[1]['lookup'].slug, u'tag-2')
 
+
     def test_allowed_schema_ids(self):
         from ebpub.db.models import Schema
         self.assertEqual(Schema.objects.allowed_schema_ids(),