fix for retrieving leaf nodes in convergence stack delete

When generating the dependencies, the deletion order is already taken
care, hence we need not reverse the graph.

Change-Id: Iff158443f2281a07e3a136a4cf6f77f7be592d3f

heat/engine/dependencies.py

@@ -158,13 +158,6 @@ class Graph(collections.defaultdict):
         text = '{%s}' % ', '.join(pairs)
         return encodeutils.safe_decode(text)
 
-    def leaves(self):
-        '''
-        Return an iterator over all of the leaf nodes in the graph.
-        '''
-        return (requirer for requirer, required in self.items()
-                if not required)
-
     @staticmethod
     def toposort(graph):
         '''
@@ -256,6 +249,13 @@ class Dependencies(object):
 
         return Dependencies(edges)
 
+    def leaves(self):
+        '''
+        Return an iterator over all of the leaf nodes in the graph.
+        '''
+        return (requirer for requirer, required in self._graph.items()
+                if not required)
+
     def translate(self, transform):
         '''
         Translate all of the nodes using a transform function.

heat/engine/stack.py

@@ -960,11 +960,7 @@ class Stack(collections.Mapping):
                       self.convergence_dependencies.graph().edges()]}
         self.store()
 
-        leaves = (self.convergence_dependencies.graph(reverse=True).leaves()
-                  if self.action in (self.DELETE, self.SUSPEND)
-                  else self.convergence_dependencies.graph().leaves())
-
-        for rsrc_id, is_update in leaves:
+        for rsrc_id, is_update in self.convergence_dependencies.leaves():
             LOG.info(_LI("Triggering resource %(rsrc_id)s "
                          "for update=%(is_update)s"),
                      {'rsrc_id': rsrc_id, 'is_update': is_update})

heat/tests/test_dependencies.py

@@ -227,10 +227,10 @@ class dependenciesTest(common.HeatTestCase):
 
         self.assertRaises(KeyError, d.required_by, 'foo')
 
-    def test_graph_leaves(self):
+    def test_leaves(self):
         d = dependencies.Dependencies([('last1', 'mid'), ('last2', 'mid'),
                                        ('mid', 'first1'), ('mid', 'first2')])
 
-        leaves = sorted(list(d._graph.leaves()))
+        leaves = sorted(list(d.leaves()))
 
         self.assertEqual(['first1', 'first2'], leaves)

heat/tests/test_engine_service.py

@@ -236,9 +236,9 @@ resources:
 '''
 
 
-class StackConvergenceCreateUpdateTest(common.HeatTestCase):
+class StackConvergenceCreateUpdateDeleteTest(common.HeatTestCase):
     def setUp(self):
-        super(StackConvergenceCreateUpdateTest, self).setUp()
+        super(StackConvergenceCreateUpdateDeleteTest, self).setUp()
         cfg.CONF.set_override('convergence_engine', True)
 
     def test_conv_wordpress_single_instance_stack_create(self):