Efficient passing of attrs during traversals

Two improvements:

Do not iterate through stack outputs when determining what attributes
to send as input_data to the next resources in a traversal; it is at
best extra processing and at worse results in extra attributes being
included in input_data.

Do not re-resolve attributes / re-calculate input_data when we already
have it. I.e., when a resource constructs input_data to send to a
requirer resource, that same input_data may be used for all other
requirer resources.

Change-Id: I64089fb0774c10f172d986c3f87090e91cb3f263
Closes-Bug: #1656125

heat/engine/check_resource.py

@@ -203,9 +203,13 @@ class CheckResource(object):
             # for the next traversal.
             graph_key = (rsrc.replaces, is_update)
 
-        def _get_input_data(req, fwd):
+        def _get_input_data(req, fwd, input_forward_data=None):
             if fwd:
+                if input_forward_data is None:
                     return construct_input_data(rsrc, stack)
+                else:
+                    # do not re-resolve attrs
+                    return input_forward_data
             else:
                 # Don't send data if initiating clean-up for self i.e.
                 # initiating delete of a replaced resource
@@ -217,8 +221,11 @@ class CheckResource(object):
             return None
 
         try:
+            input_forward_data = None
             for req, fwd in deps.required_by(graph_key):
-                input_data = _get_input_data(req, fwd)
+                input_data = _get_input_data(req, fwd, input_forward_data)
+                if fwd:
+                    input_forward_data = input_data
                 propagate_check_resource(
                     cnxt, self._rpc_client, req, current_traversal,
                     set(graph[(req, fwd)]), graph_key, input_data, fwd,
@@ -311,9 +318,7 @@ def _resolve_attributes(dep_attrs, rsrc):
 def construct_input_data(rsrc, curr_stack):
     dep_attrs = curr_stack.get_dep_attrs(
         six.itervalues(curr_stack.resources),
-        curr_stack.outputs,
-        rsrc.name,
-        curr_stack.t.OUTPUT_VALUE)
+        rsrc.name)
     input_data = {'id': rsrc.id,
                   'name': rsrc.name,
                   'reference_id': rsrc.get_reference_id(),

heat/engine/stack.py

@@ -462,17 +462,14 @@ class Stack(collections.Mapping):
             LOG.warning(_LW("Unable to set parameters StackId identifier"))
 
     @staticmethod
-    def get_dep_attrs(resources, outputs, resource_name, value_sec):
+    def get_dep_attrs(resources, resource_name):
         """Return the attributes of the specified resource that are referenced.
 
         Return an iterator over any attributes of the specified resource that
-        are referenced.
+        are referenced in resources.
         """
-        attr_lists = itertools.chain((res.dep_attrs(resource_name)
-                                      for res in resources),
-                                     (out.dep_attrs(resource_name)
-                                      for out in six.itervalues(outputs)))
-        return set(itertools.chain.from_iterable(attr_lists))
+        return set(itertools.chain.from_iterable(
+            res.dep_attrs(resource_name) for res in resources))
 
     def _get_dependencies(self, ignore_errors=True):
         """Return the dependency graph for a list of resources."""

heat/tests/test_stack_collect_attributes.py

@@ -192,8 +192,7 @@ class DepAttrsTest(common.HeatTestCase):
         ('one_res_several_attrs',
             dict(tmpl=tmpl3,
                  expected={'AResource': {'attr_A1', 'attr_A2', 'attr_A3',
-                                         'meta_A1', 'meta_A2', 'out_A1',
-                                         'out_A2'},
+                                         'meta_A1', 'meta_A2'},
                            'BResource': set()})),
         ('several_res_one_attr',
             dict(tmpl=tmpl4,
@@ -203,25 +202,19 @@ class DepAttrsTest(common.HeatTestCase):
                            'DResource': set()})),
         ('several_res_several_attrs',
             dict(tmpl=tmpl5,
-                 expected={'AResource': {'attr_A1', 'attr_A2', 'meta_A1',
-                                         'attr_A3', 'attr_A4'},
-                           'BResource': {'attr_B1', 'attr_B2', 'meta_B2',
-                                         'attr_B3'},
+                 expected={'AResource': {'attr_A1', 'attr_A2', 'meta_A1'},
+                           'BResource': {'attr_B1', 'attr_B2', 'meta_B2'},
                            'CResource': set()})),
         ('nested_attr',
             dict(tmpl=tmpl6,
-                 expected={'AResource': set([(u'flat_dict', u'key2'),
-                                             (u'list', 1),
-                                             (u'nested_dict', u'dict', u'b'),
-                                             (u'nested_dict', u'string')]),
-                           'BResource': set(['attr_B3'])})),
+                 expected={'AResource': set([(u'list', 1),
+                                             (u'nested_dict', u'dict', u'b')]),
+                           'BResource': set([])})),
         ('several_res_several_attrs_and_all_attrs',
             dict(tmpl=tmpl7,
-                 expected={'AResource': {'attr_A1', 'attr_A2', 'meta_A1',
-                                         'attr_A3', 'attr_A4'},
-                           'BResource': {'attr_B1', 'attr_B2', 'meta_B2',
-                                         'attr_B3'},
-                           'CResource': {'foo', 'Foo', 'show'}}))
+                 expected={'AResource': {'attr_A1', 'attr_A2', 'meta_A1'},
+                           'BResource': {'attr_B1', 'attr_B2', 'meta_B2'},
+                           'CResource': set()}))
     ]
 
     def setUp(self):
@@ -234,11 +227,8 @@ class DepAttrsTest(common.HeatTestCase):
                                  template.Template(parsed_tmpl))
 
         for res in six.itervalues(self.stack):
-            outputs = self.stack.outputs
             resources = six.itervalues(self.stack.resources)
             self.assertEqual(self.expected[res.name],
                              self.stack.get_dep_attrs(
                                  resources,
-                                 outputs,
-                                 res.name,
-                                 self.stack.t.OUTPUT_VALUE))
+                                 res.name))