Ensure cached conditions match stack

Ensure that the caching we do of conditions in TemplateCommon always
applies to the stack that has been passed in as an argument.

This was not the case previously, and in fact it was required not to be the
case because in the convergence path the new parameter values were not
copied into the stack at the start of an update. This patch rectifies that.

Change-Id: I942b53570222bf4e0d1bf78e584792d445c14090

heat/engine/stack.py

@@ -1200,6 +1200,8 @@ class Stack(collections.Mapping):
         if new_stack is not None:
             self.disable_rollback = new_stack.disable_rollback
             self.timeout_mins = new_stack.timeout_mins
+
+            self.parameters = new_stack.parameters
             self._set_param_stackid()
 
             self.tags = new_stack.tags
@@ -1455,7 +1457,6 @@ class Stack(collections.Mapping):
             updater = scheduler.TaskRunner(update_task)
 
             self.parameters = newstack.parameters
-            self.t._conditions = newstack.t.conditions(newstack)
             self.t.files = newstack.t.files
             self.t.env = newstack.t.env
             self.disable_rollback = newstack.disable_rollback

heat/engine/template.py

@@ -128,7 +128,6 @@ class Template(collections.Mapping):
         self.files = files or {}
         self.maps = self[self.MAPPINGS]
         self.env = env or environment.Environment({})
-        self._conditions = None
         self.merge_sections = [self.PARAMETERS]
 
         self.version = get_version(self.t, _template_classes.keys())

heat/engine/template_common.py

@@ -12,6 +12,7 @@
 #    under the License.
 
 import collections
+import weakref
 
 import six
 
@@ -30,6 +31,11 @@ class CommonTemplate(template.Template):
     classes from it do so at their own risk.
     """
 
+    def __init__(self, template, template_id=None, files=None, env=None):
+        super(CommonTemplate, self).__init__(template, template_id=template_id,
+                                             files=files, env=env)
+        self._conditions_cache = None, None
+
     @classmethod
     def validate_resource_key_type(cls, key, valid_types, typename,
                                    rsrc_name, rsrc_data):
@@ -91,21 +97,28 @@ class CommonTemplate(template.Template):
         return {}
 
     def conditions(self, stack):
-        if self._conditions is None:
-            raw_defs = self._get_condition_definitions()
-            if not isinstance(raw_defs, collections.Mapping):
-                message = _('Condition definitions must be a map. Found a '
-                            '%s instead') % type(raw_defs).__name__
-                raise exception.StackValidationFailed(
-                    error='Conditions validation error',
-                    message=message)
+        get_cache_stack, cached_conds = self._conditions_cache
+        if (cached_conds is not None and
+                get_cache_stack is not None and
+                get_cache_stack() is stack):
+            return cached_conds
 
-            parsed = {n: self.parse_condition(stack, c,
-                                              '.'.join([self.CONDITIONS, n]))
-                      for n, c in raw_defs.items()}
-            self._conditions = conditions.Conditions(parsed)
+        raw_defs = self._get_condition_definitions()
+        if not isinstance(raw_defs, collections.Mapping):
+            message = _('Condition definitions must be a map. Found a '
+                        '%s instead') % type(raw_defs).__name__
+            raise exception.StackValidationFailed(
+                error='Conditions validation error',
+                message=message)
 
-        return self._conditions
+        parsed = {n: self.parse_condition(stack, c,
+                                          '.'.join([self.CONDITIONS, n]))
+                  for n, c in raw_defs.items()}
+        conds = conditions.Conditions(parsed)
+
+        get_cache_stack = weakref.ref(stack) if stack is not None else None
+        self._conditions_cache = get_cache_stack, conds
+        return conds
 
     def outputs(self, stack):
         conds = self.conditions(stack)