Do not refresh timestamp from database on read.

Doing a database refresh on timestamp read is causing errors
such as:
heat.openstack.common.rpc.amqp InvalidRequestError:
  Could not refresh instance '<Stack at 0x2c95a90>'

This has only been seen using postgres, possibly because the problem is
being masked on mysql due to the driver's lack of concurrency.

The database refresh seems to be unnecessary, as there appears to be
no logic which depends on timestamps being accurate (nor is there
any timestamp comparison logic at all)

Fixes bug: #1193132
Change-Id: I22c3c4546a0f44b76a95e473b68b6fbb2e423b90

diff --git a/heat/engine/timestamp.py b/heat/engine/timestamp.py
index c318cbefffc16628d22ff43c8101524705100e3e..5ec39fb26fd5b4edbd176beabd100d9a236b3a98 100644 (file)
--- a/heat/engine/timestamp.py
+++ b/heat/engine/timestamp.py
@@ -18,7 +18,7 @@ from heat.common import exception
 
 class Timestamp(object):
     '''
-    A descriptor for fetching an up-to-date timestamp from the database.
+    A descriptor for writing a timestamp to the database.
     '''
 
     def __init__(self, db_fetch, attribute):
@@ -32,13 +32,12 @@ class Timestamp(object):
 
     def __get__(self, obj, obj_class):
         '''
-        Get the latest data from the database for the given object and class.
+        Get timestamp for the given object and class.
         '''
         if obj is None or obj.id is None:
             return None
 
         o = self.db_fetch(obj.context, obj.id)
-        o.refresh(attrs=[self.attribute])
         return getattr(o, self.attribute)
 
     def __set__(self, obj, timestamp):