Add user_get_image_count() to DB API

This adds an efficient query method for getting a count of a user's
non-deleted images. It can be used by subsequent patches to enforce
the image count quota.

Partially-implements: blueprint glance-unified-quotas

Change-Id: I4d6e071b8d48862032f36c80ee19632a3fe85009

glance/db/sqlalchemy/api.py

@@ -781,6 +781,13 @@ def _image_get_staging_usage_by_owner(owner, session):
                                                copying_images))
 
 
+def _image_get_count_by_owner(owner, session):
+    query = session.query(models.Image)
+    query = query.filter(models.Image.owner == owner)
+    query = query.filter(~models.Image.status.in_(['killed', 'deleted']))
+    return query.count()
+
+
 def _validate_image(values, mandatory_status=True):
     """
     Validates the incoming data and raises a Invalid exception
@@ -1594,6 +1601,11 @@ def user_get_staging_usage(context, owner_id, session=None):
     return _image_get_staging_usage_by_owner(owner_id, session)
 
 
+def user_get_image_count(context, owner_id, session=None):
+    session = session or get_session()
+    return _image_get_count_by_owner(owner_id, session)
+
+
 def _task_info_format(task_info_ref):
     """Format a task info ref for consumption outside of this module"""
     if task_info_ref is None:

glance/tests/functional/db/test_sqlalchemy.py

@@ -418,3 +418,10 @@ class TestImageStorageUsage(base.TestDriver,
             # Each user has two active images of size 100 each, but only one
             # has an active location.
             self.assertEqual(100, usage)
+
+    def test_get_image_count(self):
+        for owner, ctxt in self.contexts.items():
+            count = self.db_api.user_get_image_count(ctxt, ctxt.owner)
+            # Each user has two active images, two staged images, two
+            # importing, and two queued images
+            self.assertEqual(8, count)