fix(quick): cache entire project directory request

The projects don't change often, so we should be able to cache them for a while.
Additionally, every hour we will regenerate their cached values (take ~7m right now).

So the quick fix is two-fold:

 - cache the entire result and keep for an hour
 - regenerate per project cache every hour

Once the page cache expires, queries should take ~10-20 seconds, but only once until the next hour.

#4725: /rest/v1/project_directory performance

akvo/rest/views/project.py

@@ -7,6 +7,7 @@
 
 from django.db.models import Q
 from django.shortcuts import get_object_or_404
+from django.views.decorators.cache import cache_page
 from rest_framework.authentication import SessionAuthentication
 from rest_framework.decorators import api_view, authentication_classes, permission_classes
 from rest_framework.permissions import IsAuthenticated
@@ -15,7 +16,7 @@
 from geojson import Feature, Point, FeatureCollection
 
 from akvo.codelists.store.default_codelists import SECTOR_CATEGORY
-from akvo.rest.cache import serialized_project
+from akvo.rest.cache import PROJECT_DIRECTORY_CACHE, serialized_project
 from akvo.rest.serializers import (ProjectSerializer, ProjectExtraSerializer,
                                    ProjectExtraDeepSerializer,
                                    ProjectIatiExportSerializer,
@@ -262,6 +263,8 @@ class ProjectUpViewSet(ProjectViewSet):
 # Project directory
 ###############################################################################
 
+# Cache for one hour
+@cache_page(timeout=60 * 60, cache=PROJECT_DIRECTORY_CACHE)
 @api_view(['GET'])
 def project_directory(request):
     """Return the values for various project filters.

akvo/settings/90-finish.conf

@@ -105,5 +105,6 @@ CRONJOBS = [
     ('* * * * *', 'django.core.management.call_command', ['iati_import']),
     ('* * * * *', 'django.core.management.call_command', ['iati_export']),
     ('10 2 * * *', 'django.core.management.call_command', ['a4a_optimy_import']),
-    ('*/5 * * * *', 'django.core.management.call_command', ['perform_iati_checks'])
+    ('*/5 * * * *', 'django.core.management.call_command', ['perform_iati_checks']),
+    ('0 */1 * * *', 'django.core.management.call_command', ['populate_project_directory_cache']),
 ]