From dfccc9e07db137a8a07c4170415b8b252c4d7bfd Mon Sep 17 00:00:00 2001
From: chris meyers <chris.meyers.fsu@gmail.com>
Date: Wed, 31 Oct 2018 16:13:19 -0400
Subject: [PATCH] rework wf cycle detection for convergence

---
 ...e.py => 0051_v340_workflow_convergence.py} |  2 +-
 awx/main/scheduler/dag_simple.py              | 24 +++++++++----------
 2 files changed, 12 insertions(+), 14 deletions(-)
 rename awx/main/migrations/{0050_v340_workflow_convergence.py => 0051_v340_workflow_convergence.py} (85%)

diff --git a/awx/main/migrations/0050_v340_workflow_convergence.py b/awx/main/migrations/0051_v340_workflow_convergence.py
similarity index 85%
rename from awx/main/migrations/0050_v340_workflow_convergence.py
rename to awx/main/migrations/0051_v340_workflow_convergence.py
index 2e6edd42d7..c874acb2e2 100644
--- a/awx/main/migrations/0050_v340_workflow_convergence.py
+++ b/awx/main/migrations/0051_v340_workflow_convergence.py
@@ -8,7 +8,7 @@ from django.db import migrations, models
 class Migration(migrations.Migration):
 
     dependencies = [
-        ('main', '0049_v330_validate_instance_capacity_adjustment'),
+        ('main', '0050_v340_drop_celery_tables'),
     ]
 
     operations = [
diff --git a/awx/main/scheduler/dag_simple.py b/awx/main/scheduler/dag_simple.py
index b82a7b808b..a8d96b4be6 100644
--- a/awx/main/scheduler/dag_simple.py
+++ b/awx/main/scheduler/dag_simple.py
@@ -123,26 +123,24 @@ class SimpleDAG(object):
 
     def has_cycle(self):
         node_objs = [node['node_object'] for node in self.get_root_nodes()]
-        nodes_visited = set([])
+        node_objs_visited = set([])
         path = set([])
         stack = node_objs
-        path_direction = 'DOWN'
 
         while stack:
             node_obj = stack.pop()
 
-            children = self.get_dependencies(node_obj)
-            for child in children:
-                if child['node_object'] not in nodes_visited:
-                    stack.append(child['node_object'])
-            if node_obj in path:
-                return True
+            children = [node['node_object'] for node in self.get_dependencies(node_obj)]
+            children_to_add = filter(lambda node_obj: node_obj not in node_objs_visited, children)
 
-            if not children:
-                path_direction = 'UP'
-
-            if path_direction == 'DOWN':
+            if children_to_add:
+                if node_obj in path:
+                    return True
                 path.add(node_obj)
-            elif path_direction == 'UP':
+                stack.append(node_obj)
+                stack.extend(children_to_add)
+            else:
+                node_objs_visited.add(node_obj)
                 path.discard(node_obj)
+
         return False