Make namespace deletion asynchronous

Instead of deleting a namespace synchronously as before, we now mark the namespace for deletion, disable it, and rename it. A worker then comes along and deletes the namespace in the background. This results in a *significantly* better user experience, as the namespace deletion operation now "completes" in under a second, where before it could take 10s of minutes at the worse.

Fixes https://jira.coreos.com/browse/QUAY-838

data/model/test/test_user.py

@@ -4,9 +4,11 @@ import pytest
 
 from mock import patch
 
-from data.database import EmailConfirmation
+from data.database import EmailConfirmation, User, DeletedNamespace
 from data.model.user import create_user_noverify, validate_reset_code, get_active_users
+from data.model.user import mark_namespace_for_deletion, delete_namespace_via_marker
 from util.timedeltastring import convert_to_timedelta
+from data.queue import WorkQueue
 from test.fixtures import *
 
 def test_create_user_with_expiration(initialized_db):
@@ -38,3 +40,46 @@ def test_get_active_users(disabled, initialized_db):
   for user in users:
     if not disabled:
       assert user.enabled
+
+def test_mark_namespace_for_deletion(initialized_db):
+  def create_transaction(db):
+    return db.transaction()
+
+  # Create a user and then mark it for deletion.
+  user = create_user_noverify('foobar', 'foo@example.com', email_required=False)
+
+  # Mark the user for deletion.
+  queue = WorkQueue('testgcnamespace', create_transaction)
+  mark_namespace_for_deletion(user, [], queue)
+
+  # Ensure the older user is still in the DB.
+  assert User.get(id=user.id).username != 'foobar'
+
+  # Ensure we can create a user with the same namespace again.
+  new_user = create_user_noverify('foobar', 'foo@example.com', email_required=False)
+  assert new_user.id != user.id
+
+  # Ensure the older user is still in the DB.
+  assert User.get(id=user.id).username != 'foobar'
+
+
+def test_delete_namespace_via_marker(initialized_db):
+  def create_transaction(db):
+    return db.transaction()
+
+  # Create a user and then mark it for deletion.
+  user = create_user_noverify('foobar', 'foo@example.com', email_required=False)
+
+  # Mark the user for deletion.
+  queue = WorkQueue('testgcnamespace', create_transaction)
+  marker_id = mark_namespace_for_deletion(user, [], queue)
+
+  # Delete the user.
+  delete_namespace_via_marker(marker_id, [])
+
+  # Ensure the user was actually deleted.
+  with pytest.raises(User.DoesNotExist):
+    User.get(id=user.id)
+
+  with pytest.raises(DeletedNamespace.DoesNotExist):
+    DeletedNamespace.get(id=marker_id)