Fix bug 1132961: Add cache to twitter feeds.

bedrock/mozorg/models.py

@@ -1,10 +1,33 @@
+from django.core.cache import cache
 from django.db import models
+from django.db.utils import DatabaseError
 
 from picklefield import PickledObjectField
 from django_extensions.db.fields import ModificationDateTimeField
 
 
+class TwitterCacheManager(models.Manager):
+    def get_tweets_for(self, account):
+        cache_key = 'tweets-for-' + str(account)
+        tweets = cache.get(cache_key)
+        if tweets is None:
+            try:
+                tweets = TwitterCache.objects.get(account=account).tweets
+            except (TwitterCache.DoesNotExist, DatabaseError):
+                # TODO: see if we should catch other errors
+                tweets = []
+
+            cache.set(cache_key, tweets, 60 * 60 * 6)  # 6 hours, same as cron
+
+        return tweets
+
+
 class TwitterCache(models.Model):
     account = models.CharField(max_length=100, db_index=True, unique=True)
     tweets = PickledObjectField(default=list)
     updated = ModificationDateTimeField()
+
+    objects = TwitterCacheManager()
+
+    def __unicode__(self):
+        return u'Tweets from @' + self.account

bedrock/mozorg/tests/test_models.py

@@ -0,0 +1,57 @@
+# -*- coding: utf-8 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from django.core.cache import cache
+from django.db.utils import DatabaseError
+
+from mock import patch
+
+from bedrock.mozorg.models import TwitterCache
+from bedrock.mozorg.tests import TestCase
+
+
+@patch.object(TwitterCache.objects, 'get')
+class TestTwitterCacheManager(TestCase):
+    def setUp(self):
+        cache.clear()
+
+    def test_results_cached(self, get_mock):
+        """Results from get_tweets_for() should be cached."""
+        get_mock.return_value.tweets = ['dude']
+
+        tweets = TwitterCache.objects.get_tweets_for('dude')
+        self.assertEqual(['dude'], tweets)
+
+        tweets = TwitterCache.objects.get_tweets_for('dude')
+        self.assertEqual(['dude'], tweets)
+
+        get_mock.assert_called_once_with(account='dude')
+
+        get_mock.return_value.tweets = ['donny']
+
+        tweets = TwitterCache.objects.get_tweets_for('donny')
+        self.assertEqual(['donny'], tweets)
+
+        tweets = TwitterCache.objects.get_tweets_for('donny')
+        self.assertEqual(['donny'], tweets)
+
+        self.assertEqual(get_mock.call_count, 2)
+
+    def test_errors_fail_silently(self, get_mock):
+        """Errors should return an empty list"""
+        get_mock.side_effect = TwitterCache.DoesNotExist
+        self.assertEqual(TwitterCache.objects.get_tweets_for('dude'), [])
+        self.assertEqual(TwitterCache.objects.get_tweets_for('dude'), [])
+
+        # and even errors should be cached
+        get_mock.assert_called_once_with(account='dude')
+
+        get_mock.reset_mock()
+        get_mock.side_effect = DatabaseError
+        self.assertEqual(TwitterCache.objects.get_tweets_for('walter'), [])
+        self.assertEqual(TwitterCache.objects.get_tweets_for('walter'), [])
+
+        # and even errors should be cached
+        get_mock.assert_called_once_with(account='walter')

bedrock/mozorg/tests/test_views.py

@@ -5,6 +5,8 @@
 
 from django.conf import settings
 from django.core import mail
+from django.core.cache import cache
+from django.db.utils import DatabaseError
 from django.test.client import RequestFactory
 from django.test.utils import override_settings
 from django.utils import simplejson
@@ -249,29 +251,30 @@ def setUp(self):
         self.rf = RequestFactory()
         self.get_req = self.rf.get('/')
         self.no_exist = views.TwitterCache.DoesNotExist()
+        cache.clear()
 
     @patch.object(views.l10n_utils, 'render')
-    @patch.object(views.TwitterCache, 'objects')
+    @patch.object(views.TwitterCache.objects, 'get')
     def test_db_exception_works(self, mock_manager, mock_render):
         """View should function properly without the DB."""
-        mock_manager.get.side_effect = views.DatabaseError
+        mock_manager.side_effect = DatabaseError
         views.contribute_studentambassadors_landing(self.get_req)
         mock_render.assert_called_with(ANY, ANY, {'tweets': []})
 
     @patch.object(views.l10n_utils, 'render')
-    @patch.object(views.TwitterCache, 'objects')
+    @patch.object(views.TwitterCache.objects, 'get')
     def test_no_db_row_works(self, mock_manager, mock_render):
         """View should function properly without data in the DB."""
-        mock_manager.get.side_effect = views.TwitterCache.DoesNotExist
+        mock_manager.side_effect = views.TwitterCache.DoesNotExist
         views.contribute_studentambassadors_landing(self.get_req)
         mock_render.assert_called_with(ANY, ANY, {'tweets': []})
 
     @patch.object(views.l10n_utils, 'render')
-    @patch.object(views.TwitterCache, 'objects')
+    @patch.object(views.TwitterCache.objects, 'get')
     def test_db_cache_works(self, mock_manager, mock_render):
         """View should use info returned by DB."""
         good_val = 'The Dude tweets, man.'
-        mock_manager.get.return_value.tweets = good_val
+        mock_manager.return_value.tweets = good_val
         views.contribute_studentambassadors_landing(self.get_req)
         mock_render.assert_called_with(ANY, ANY, {'tweets': good_val})
 

bedrock/mozorg/views.py

@@ -8,7 +8,6 @@
 from django.conf import settings
 from django.contrib.staticfiles.finders import find as find_static
 from django.core.context_processors import csrf
-from django.db.utils import DatabaseError
 from django.http import HttpResponseRedirect
 from django.views.decorators.csrf import csrf_exempt, csrf_protect
 from django.views.decorators.http import last_modified, require_safe
@@ -299,10 +298,7 @@ def plugincheck(request, template='mozorg/plugincheck.html'):
 
 @xframe_allow
 def contribute_studentambassadors_landing(request):
-    try:
-        tweets = TwitterCache.objects.get(account='mozstudents').tweets
-    except (TwitterCache.DoesNotExist, DatabaseError):
-        tweets = []
+    tweets = TwitterCache.objects.get_tweets_for('mozstudents')
     return l10n_utils.render(request,
                              'mozorg/contribute/studentambassadors/landing.html',
                              {'tweets': tweets})
@@ -395,10 +391,7 @@ def get_context_data(self, **kwargs):
 def home_tweets(locale):
     account = settings.HOMEPAGE_TWITTER_ACCOUNTS.get(locale)
     if account:
-        try:
-            return TwitterCache.objects.get(account=account).tweets
-        except (TwitterCache.DoesNotExist, DatabaseError):
-            pass  # TODO: see if we should catch other errors
+        return TwitterCache.objects.get_tweets_for(account)
     return []
 
 

bedrock/settings/__init__.py

@@ -38,6 +38,8 @@
 if len(sys.argv) > 1 and sys.argv[1] == 'test':
     # Using the CachedStaticFilesStorage for tests breaks all the things.
     STATICFILES_STORAGE = 'pipeline.storage.PipelineStorage'
+    # Turn off less compilation in tests
+    PIPELINE_ENABLED = True
     # TEMPLATE_DEBUG has to be True for jingo to call the template_rendered
     # signal which Django's test client uses to save away the contexts for your
     # test to look at later.