Check instance lock in compute/api

This adds a check for the instance lock in compute/api.py, which:
1. Helps avoid the need to call into the manager just to be stopped
   by the lock there
2. Returns a failure to the user right away when an operation cannot
   be completed due to the lock
3. Avoids the potential for task_state to get into an unhappy state
   because a user unknowingly attempts an action whilst an instance
   is locked
4. Avoids the manager from having to re-do the lock check by
   stuffing a flag into RequestContext when the check has already
   been done by api.py

Various tests needed to be fixed up in order to pass fake instances
with the locked attribute. We could make the decorator ignore
instances without it, but I think it's more explicit to push that
requirement into the tests.

This fixes bug 872541

Change-Id: I1127e31d86a061a93a64ee1eb4a4d900d8bf49b5

1 files changed, 4 insertions, 2 deletions

diff --git a/nova/context.py b/nova/context.py
index 5712193fb..66697b567 100644
--- a/nova/context.py
+++ b/nova/context.py
@@ -45,7 +45,7 @@ class RequestContext(object):
                  roles=None, remote_address=None, timestamp=None,
                  request_id=None, auth_token=None, overwrite=True,
                  quota_class=None, user_name=None, project_name=None,
-                 service_catalog=None, **kwargs):
+                 service_catalog=None, instance_lock_checked=False, **kwargs):
         """
         :param read_deleted: 'no' indicates deleted records are hidden, 'yes'
             indicates deleted records are visible, 'only' indicates that
@@ -81,6 +81,7 @@ class RequestContext(object):
         self.request_id = request_id
         self.auth_token = auth_token
         self.service_catalog = service_catalog
+        self.instance_lock_checked = instance_lock_checked
 
         # NOTE(markmc): this attribute is currently only used by the
         # rs_limits turnstile pre-processor.
@@ -123,7 +124,8 @@ class RequestContext(object):
                 'quota_class': self.quota_class,
                 'user_name': self.user_name,
                 'service_catalog': self.service_catalog,
-                'project_name': self.project_name}
+                'project_name': self.project_name,
+                'instance_lock_checked': self.instance_lock_checked}
 
     @classmethod
     def from_dict(cls, values):