Do not populate unused stack and watch rule objects

These fields are lazy loaded, so cause extra unnecessary database
access.

The watch rules are needed when formatting every watch data metric for
the cloudwatch API, so an id->name map of all rules is built to avoid
repeated lazy loading of every rule.

Change-Id: I36dd43172ccd402f08a45b254ae47e208b7b8c08
Related-Bug: #1479723

heat/engine/api.py

@@ -463,7 +463,7 @@ def format_watch(watch):
     return result
 
 
-def format_watch_data(wd):
+def format_watch_data(wd, rule_names):
 
     # Demangle DB format data into something more easily used in the API
     # We are expecting a dict with exactly two items, Namespace and
@@ -477,7 +477,7 @@ def format_watch_data(wd):
         return
 
     result = {
-        rpc_api.WATCH_DATA_ALARM: wd.watch_rule.name,
+        rpc_api.WATCH_DATA_ALARM: rule_names.get(wd.watch_rule_id),
         rpc_api.WATCH_DATA_METRIC: metric_name,
         rpc_api.WATCH_DATA_TIME: wd.created_at.isoformat(),
         rpc_api.WATCH_DATA_NAMESPACE: namespace,

heat/engine/service.py

@@ -2063,11 +2063,14 @@ class EngineService(service.Service):
 
         try:
             wds = watch_data.WatchData.get_all(cnxt)
+            rule_names = {
+                r.id: r.name for r in watch_rule.WatchRule.get_all(cnxt)
+            }
         except Exception as ex:
             LOG.warning(_LW('show_metric (all) db error %s'), ex)
             return
 
-        result = [api.format_watch_data(w) for w in wds]
+        result = [api.format_watch_data(w, rule_names) for w in wds]
         return result
 
     @context.request_context

heat/objects/watch_data.py

@@ -31,22 +31,14 @@ class WatchData(
         'id': fields.IntegerField(),
         'data': heat_fields.JsonField(nullable=True),
         'watch_rule_id': fields.StringField(),
-        'watch_rule': fields.ObjectField('WatchRule'),
         'created_at': fields.DateTimeField(read_only=True),
         'updated_at': fields.DateTimeField(nullable=True),
     }
 
     @staticmethod
     def _from_db_object(context, rule, db_data):
-        from heat.objects import watch_rule
         for field in rule.fields:
-            if field == 'watch_rule':
-                rule[field] = watch_rule.WatchRule._from_db_object(
-                    context,
-                    watch_rule.WatchRule(),
-                    db_data['watch_rule'])
-            else:
-                rule[field] = db_data[field]
+            rule[field] = db_data[field]
         rule._context = context
         rule.obj_reset_changes()
         return rule

heat/objects/watch_rule.py

@@ -20,7 +20,6 @@ from oslo_versionedobjects import fields
 from heat.db import api as db_api
 from heat.objects import base as heat_base
 from heat.objects import fields as heat_fields
-from heat.objects import stack
 from heat.objects import watch_data
 
 
@@ -36,7 +35,6 @@ class WatchRule(
         'state': fields.StringField(nullable=True),
         'last_evaluated': fields.DateTimeField(nullable=True),
         'stack_id': fields.StringField(),
-        'stack': fields.ObjectField(stack.Stack),
         'watch_data': fields.ListOfObjectsField(watch_data.WatchData),
         'created_at': fields.DateTimeField(read_only=True),
         'updated_at': fields.DateTimeField(nullable=True),
@@ -45,10 +43,7 @@ class WatchRule(
     @staticmethod
     def _from_db_object(context, rule, db_rule):
         for field in rule.fields:
-            if field == 'stack':
-                rule[field] = stack.Stack._from_db_object(
-                    context, stack.Stack(), db_rule[field])
-            elif field == 'watch_data':
+            if field == 'watch_data':
                 rule[field] = watch_data.WatchData.get_all_by_watch_rule_id(
                     context, db_rule['id'])
             else: