From b189f2a67d3a05985926bc42be44ac9a2284273d Mon Sep 17 00:00:00 2001
From: Russell Bryant <rbryant@redhat.com>
Date: Fri, 11 Jan 2013 14:11:08 -0500
Subject: [PATCH] Handle waiting for conductor in nova.service.

Previously we were waiting for conductor to respond to a ping() in the
compute manager.  This patch moves this down to the base Service class.
A nova service binary can indicate that db access is not allowed and if
so, as soon as the service gets created, it will block while waiting for
conductor to respond.

The compute service has been updated to use this.  This should not
result in any real functional difference.

The reason for this is that there is some database access that needs to
be avoided down at this level.  This allows us to divert these actions
to conductor if needed.

Part of bp no-db-compute.

Change-Id: Idd6387b9428e3f9f4e4dbfe51293693238b2daf0
---
 bin/nova-compute |  3 ++-
 nova/service.py  | 13 ++++++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/bin/nova-compute b/bin/nova-compute
index d93ddb5bd..8826015d4 100755
--- a/bin/nova-compute
+++ b/bin/nova-compute
@@ -55,6 +55,7 @@ if __name__ == '__main__':
     logging.setup('nova')
     utils.monkey_patch()
     server = service.Service.create(binary='nova-compute',
-                                    topic=CONF.compute_topic)
+                                    topic=CONF.compute_topic,
+                                    db_allowed=False)
     service.serve(server)
     service.wait()
diff --git a/nova/service.py b/nova/service.py
index 86f022f61..05049d464 100644
--- a/nova/service.py
+++ b/nova/service.py
@@ -30,6 +30,7 @@ import time
 import eventlet
 import greenlet
 
+from nova import conductor
 from nova import context
 from nova import db
 from nova import exception
@@ -38,6 +39,7 @@ from nova.openstack.common import eventlet_backdoor
 from nova.openstack.common import importutils
 from nova.openstack.common import log as logging
 from nova.openstack.common import rpc
+from nova.openstack.common.rpc import common as rpc_common
 from nova import servicegroup
 from nova import utils
 from nova import version
@@ -392,7 +394,7 @@ class Service(object):
 
     def __init__(self, host, binary, topic, manager, report_interval=None,
                  periodic_enable=None, periodic_fuzzy_delay=None,
-                 periodic_interval_max=None,
+                 periodic_interval_max=None, db_allowed=True,
                  *args, **kwargs):
         self.host = host
         self.binary = binary
@@ -407,6 +409,9 @@ class Service(object):
         self.saved_args, self.saved_kwargs = args, kwargs
         self.timers = []
         self.backdoor_port = None
+        self.db_allowed = db_allowed
+        self.conductor_api = conductor.API(use_local=db_allowed)
+        self.conductor_api.wait_until_ready(context.get_admin_context())
         self.servicegroup_api = servicegroup.API()
 
     def start(self):
@@ -481,7 +486,8 @@ class Service(object):
     @classmethod
     def create(cls, host=None, binary=None, topic=None, manager=None,
                report_interval=None, periodic_enable=None,
-               periodic_fuzzy_delay=None, periodic_interval_max=None):
+               periodic_fuzzy_delay=None, periodic_interval_max=None,
+               db_allowed=True):
         """Instantiates class and passes back application object.
 
         :param host: defaults to CONF.host
@@ -514,7 +520,8 @@ class Service(object):
                           report_interval=report_interval,
                           periodic_enable=periodic_enable,
                           periodic_fuzzy_delay=periodic_fuzzy_delay,
-                          periodic_interval_max=periodic_interval_max)
+                          periodic_interval_max=periodic_interval_max,
+                          db_allowed=db_allowed)
 
         return service_obj