Deref deleted group immediately and then pass off the children and hosts

to be processed in the background.

Get rid of the child relative delete mechanism and merge the old concept
of delete on the /group/n endpoint with our new concept

awx/main/tasks.py

@@ -47,6 +47,46 @@ logger = logging.getLogger('awx.main.tasks')
 
 # FIXME: Cleanly cancel task when celery worker is stopped.
 
+@task()
+def bulk_inventory_element_delete(group_details):
+    def remove_host_from_group(host, group):
+        host.groups.remove(group)
+        host_inv_sources = host.inventory_sources.all()
+        for inv_source in group.inventory_sources.all():
+            if inv_source in host_inv_sources:
+                host.inventory_sources.remove(inv_source)
+        return host.groups.count() < 1
+    def mark_actual(group_details):
+        overall_parent = Group.objects.get(id=group_details['parent'])
+        linked_children = [(overall_parent , Group.objects.get(id=g['id'])) for g in group_details['children']]
+        initial_hosts = [Host.objects.get(id=h['id']) for h in group_details['hosts']]
+        marked_hosts = []
+        marked_groups = []
+        for host in initial_hosts:
+            last_group = remove_host_from_group(host, overall_parent)
+            if last_group:
+                marked_hosts.append(host)
+        for subgroup in linked_children:
+            parent, group = subgroup
+            if parent is not None:
+                group.parents.remove(parent)
+            if group.parents.count() > 0:
+                continue
+            for host in group.hosts.all():
+                last_group = remove_host_from_group(host, group)
+                if last_group:
+                    marked_hosts.append(host)
+            for childgroup in group.children.all():
+                linked_children.append((group, childgroup))
+            marked_groups.append(group)
+        for group in marked_groups:
+            group.mark_inactive()
+        for host in marked_hosts:
+            host.mark_inactive()
+    with ignore_inventory_computed_fields():
+        mark_actual(group_details)
+    update_inventory_computed_fields.delay(group_details['inventory'], True)
+
 @task(bind=True)
 def tower_periodic_scheduler(self):
     def get_last_run():