Adding cache implementation for the programs api.

ECOM-2832

openedx/core/djangoapps/programs/migrations/0002_auto__add_field_programsapiconfig_cache_ttl.py

+# -*- coding: utf-8 -*-
+from south.utils import datetime_utils as datetime
+from south.db import db
+from south.v2 import SchemaMigration
+from django.db import models
+
+
+class Migration(SchemaMigration):
+
+    def forwards(self, orm):
+        # Adding field 'ProgramsApiConfig.cache_ttl'
+        db.add_column('programs_programsapiconfig', 'cache_ttl',
+                      self.gf('django.db.models.fields.PositiveIntegerField')(default=0),
+                      keep_default=False)
+
+
+    def backwards(self, orm):
+        # Deleting field 'ProgramsApiConfig.cache_ttl'
+        db.delete_column('programs_programsapiconfig', 'cache_ttl')
+
+
+    models = {
+        'auth.group': {
+            'Meta': {'object_name': 'Group'},
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '80'}),
+            'permissions': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Permission']", 'symmetrical': 'False', 'blank': 'True'})
+        },
+        'auth.permission': {
+            'Meta': {'ordering': "('content_type__app_label', 'content_type__model', 'codename')", 'unique_together': "(('content_type', 'codename'),)", 'object_name': 'Permission'},
+            'codename': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'content_type': ('django.db.models.fields.related.ForeignKey', [], {'to': "orm['contenttypes.ContentType']"}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '50'})
+        },
+        'auth.user': {
+            'Meta': {'object_name': 'User'},
+            'date_joined': ('django.db.models.fields.DateTimeField', [], {'default': 'datetime.datetime.now'}),
+            'email': ('django.db.models.fields.EmailField', [], {'max_length': '75', 'blank': 'True'}),
+            'first_name': ('django.db.models.fields.CharField', [], {'max_length': '30', 'blank': 'True'}),
+            'groups': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Group']", 'symmetrical': 'False', 'blank': 'True'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'is_active': ('django.db.models.fields.BooleanField', [], {'default': 'True'}),
+            'is_staff': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'is_superuser': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'last_login': ('django.db.models.fields.DateTimeField', [], {'default': 'datetime.datetime.now'}),
+            'last_name': ('django.db.models.fields.CharField', [], {'max_length': '30', 'blank': 'True'}),
+            'password': ('django.db.models.fields.CharField', [], {'max_length': '128'}),
+            'user_permissions': ('django.db.models.fields.related.ManyToManyField', [], {'to': "orm['auth.Permission']", 'symmetrical': 'False', 'blank': 'True'}),
+            'username': ('django.db.models.fields.CharField', [], {'unique': 'True', 'max_length': '30'})
+        },
+        'contenttypes.contenttype': {
+            'Meta': {'ordering': "('name',)", 'unique_together': "(('app_label', 'model'),)", 'object_name': 'ContentType', 'db_table': "'django_content_type'"},
+            'app_label': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'model': ('django.db.models.fields.CharField', [], {'max_length': '100'}),
+            'name': ('django.db.models.fields.CharField', [], {'max_length': '100'})
+        },
+        'programs.programsapiconfig': {
+            'Meta': {'ordering': "('-change_date',)", 'object_name': 'ProgramsApiConfig'},
+            'api_version_number': ('django.db.models.fields.IntegerField', [], {}),
+            'cache_ttl': ('django.db.models.fields.PositiveIntegerField', [], {'default': '0'}),
+            'change_date': ('django.db.models.fields.DateTimeField', [], {'auto_now_add': 'True', 'blank': 'True'}),
+            'changed_by': ('django.db.models.fields.related.ForeignKey', [], {'to': "orm['auth.User']", 'null': 'True', 'on_delete': 'models.PROTECT'}),
+            'enable_student_dashboard': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'enabled': ('django.db.models.fields.BooleanField', [], {'default': 'False'}),
+            'id': ('django.db.models.fields.AutoField', [], {'primary_key': 'True'}),
+            'internal_service_url': ('django.db.models.fields.URLField', [], {'max_length': '200'}),
+            'public_service_url': ('django.db.models.fields.URLField', [], {'max_length': '200'})
+        }
+    }
+
+    complete_apps = ['programs']

openedx/core/djangoapps/programs/models.py

@@ -6,6 +6,7 @@ from urlparse import urljoin
 
 from django.db.models import BooleanField, IntegerField, URLField
 from django.utils.translation import ugettext_lazy as _
+from django.db import models
 
 from config_models.models import ConfigurationModel
 
@@ -20,6 +21,15 @@ class ProgramsApiConfig(ConfigurationModel):
     public_service_url = URLField(verbose_name=_("Public Service URL"))
     api_version_number = IntegerField(verbose_name=_("API Version"))
     enable_student_dashboard = BooleanField(verbose_name=_("Enable Student Dashboard Displays"))
+    cache_ttl = models.PositiveIntegerField(
+        verbose_name=_("Cache Time To Live"),
+        default=0,
+        help_text=_(
+            "Specified in seconds. Enable caching by setting this to a value greater than 0."
+        )
+    )
+
+    PROGRAMS_API_CACHE_KEY = "programs.api.data"
 
     @property
     def internal_api_url(self):
@@ -42,3 +52,8 @@ class ProgramsApiConfig(ConfigurationModel):
         be enabled or not.
         """
         return self.enabled and self.enable_student_dashboard
+
+    @property
+    def is_cache_enabled(self):
+        """Whether responses from the Programs API will be cached."""
+        return self.enabled and self.cache_ttl > 0

openedx/core/djangoapps/programs/tests/test_models.py

 """
 Tests for models supporting Program-related functionality.
 """
-
+import ddt
 from mock import patch
-
 from django.test import TestCase
 
 from openedx.core.djangoapps.programs.models import ProgramsApiConfig
 from openedx.core.djangoapps.programs.tests.mixins import ProgramsApiConfigMixin
 
 
+@ddt.ddt
 @patch('config_models.models.cache.get', return_value=None)  # during tests, make every cache get a miss.
 class ProgramsApiConfigTest(ProgramsApiConfigMixin, TestCase):
     """
@@ -70,3 +70,28 @@ class ProgramsApiConfigTest(ProgramsApiConfigMixin, TestCase):
 
         self.create_config(enabled=True, enable_student_dashboard=True)
         self.assertTrue(ProgramsApiConfig.current().is_student_dashboard_enabled)
+
+    @ddt.data(
+        (True, 0),
+        (False, 0),
+        (False, 1),
+    )
+    @ddt.unpack
+    def test_is_cache_enabled_returns_false(self, enabled, cache_ttl, _mock_cache):
+        """Verify that the method 'is_cache_enabled' returns false if
+        'cache_ttl' value is 0 or config is not enabled.
+        """
+        self.assertFalse(ProgramsApiConfig.current().is_cache_enabled)
+
+        self.create_config(
+            enabled=enabled,
+            cache_ttl=cache_ttl
+        )
+        self.assertFalse(ProgramsApiConfig.current().is_cache_enabled)
+
+    def test_is_cache_enabled_returns_true(self, _mock_cache):
+        """"Verify that is_cache_enabled returns True when Programs is enabled
+        and the cache TTL is greater than 0."
+        """
+        self.create_config(enabled=True, cache_ttl=10)
+        self.assertTrue(ProgramsApiConfig.current().is_cache_enabled)

openedx/core/djangoapps/programs/utils.py

 """
 Helper methods for Programs.
 """
+from django.core.cache import cache
 from edx_rest_api_client.client import EdxRestApiClient
 from openedx.core.djangoapps.programs.models import ProgramsApiConfig
 
@@ -20,3 +21,29 @@ def programs_api_client(api_url, jwt_access_token):
         api_url,
         jwt=jwt_access_token
     )
+
+
+def is_cache_enabled_for_programs():    # pylint: disable=invalid-name
+    """Returns a Boolean indicating whether responses from the Programs API
+    will be cached.
+    """
+    return ProgramsApiConfig.current().is_cache_enabled
+
+
+def set_cached_programs_response(programs_data):
+    """ Set cache value for the programs data with specific ttl.
+
+    Arguments:
+        programs_data (dict): Programs data in dictionary format
+    """
+    cache.set(
+        ProgramsApiConfig.PROGRAMS_API_CACHE_KEY,
+        programs_data,
+        ProgramsApiConfig.current().cache_ttl
+    )
+
+
+def get_cached_programs_response():
+    """ Get programs data from cache against cache key."""
+    cache_key = ProgramsApiConfig.PROGRAMS_API_CACHE_KEY
+    return cache.get(cache_key)

openedx/core/djangoapps/programs/views.py

@@ -6,7 +6,13 @@ import logging
 
 from openedx.core.djangoapps.util.helpers import get_id_token
 from openedx.core.djangoapps.programs.models import ProgramsApiConfig
-from openedx.core.djangoapps.programs.utils import programs_api_client, is_student_dashboard_programs_enabled
+from openedx.core.djangoapps.programs.utils import (
+    programs_api_client,
+    is_student_dashboard_programs_enabled,
+    is_cache_enabled_for_programs,
+    get_cached_programs_response,
+    set_cached_programs_response,
+)
 
 
 log = logging.getLogger(__name__)
@@ -37,6 +43,12 @@ def get_course_programs_for_dashboard(user, course_keys):   # pylint: disable=in
     # unicode-ify the course keys for efficient lookup
     course_keys = map(unicode, course_keys)
 
+    # If cache config is enabled then get the response from cache first.
+    if is_cache_enabled_for_programs():
+        cached_programs = get_cached_programs_response()
+        if cached_programs is not None:
+            return _get_user_course_programs(cached_programs, course_keys)
+
     # get programs slumber-based client 'EdxRestApiClient'
     try:
         api_client = programs_api_client(ProgramsApiConfig.current().internal_api_url, get_id_token(user, CLIENT_NAME))
@@ -56,14 +68,31 @@ def get_course_programs_for_dashboard(user, course_keys):   # pylint: disable=in
         log.warning("No programs found for the user '%s'.", user.id)
         return course_programs
 
+    # If cache config is enabled than set the cache.
+    if is_cache_enabled_for_programs():
+        set_cached_programs_response(programs)
+
+    return _get_user_course_programs(programs, course_keys)
+
+
+def _get_user_course_programs(programs, users_enrolled_course_keys):  # pylint: disable=invalid-name
+    """ Parse the raw programs according to the users enrolled courses and
+    return the matched course runs.
+
+    Arguments:
+        programs (list): List containing the programs data.
+        users_enrolled_course_keys (list) : List of course keys in which the user is enrolled.
+    """
+
     # reindex the result from pgm -> course code -> course run
-    #  to
+    # to
     # course run -> program, ignoring course runs not present in the dashboard enrollments
+    course_programs = {}
     for program in programs:
         try:
             for course_code in program['course_codes']:
                 for run in course_code['run_modes']:
-                    if run['course_key'] in course_keys:
+                    if run['course_key'] in users_enrolled_course_keys:
                         course_programs[run['course_key']] = program
         except KeyError:
             log.exception('Unable to parse Programs API response: %r', program)