Stop using scheduler RPC API magic

If a scheduler RPC message isn't handled directly by a SchedulerManager
method, the __getattr__() fallback passes the message to a driver
method in the form of schedule_${method}() and, if that doesn't exist,
instead calls the schedule() method supplying the topic and method
args.

This is pretty bizarre stuff and we appear to only use it in two cases:

  1) live_migration - this is how the schedule_live_migration()
     method in the driver gets called, but the side-effect is that
     we require the client to pass a topic argument which is never
     used. This would be much more sanely handled with an explicit
     SchedulerManager.live_migration() method.

  2) create_volume - the volume API asks the scheduler to pick a
     target host for create_volume() using this method. This would
     be easily handled with an SchedulerManager.create_volume()
     method.

Change-Id: I1047489d85ac51d8d36fea1c4eb858df638ce349

nova/scheduler/multi.py

@@ -89,6 +89,9 @@ class MultiScheduler(driver.Scheduler):
     def schedule_prep_resize(self, *args, **kwargs):
         return self.drivers['compute'].schedule_prep_resize(*args, **kwargs)
 
+    def schedule_create_volume(self, *args, **kwargs):
+        return self.drivers['volume'].schedule_create_volume(*args, **kwargs)
+
     def update_service_capabilities(self, service_name, host, capabilities):
         # Multi scheduler is only a holder of sub-schedulers, so
         # pass the capabilities to the schedulers that matter

nova/scheduler/rpcapi.py

@@ -41,6 +41,7 @@ class SchedulerAPI(nova.openstack.common.rpc.proxy.RpcProxy):
         1.4 - Remove update_db from prep_resize
         1.5 - Add reservations argument to prep_resize()
         1.6 - Remove reservations argument to run_instance()
+        1.7 - Add create_volume() method, remove topic from live_migration()
     '''
 
     BASE_RPC_API_VERSION = '1.0'
@@ -73,14 +74,21 @@ class SchedulerAPI(nova.openstack.common.rpc.proxy.RpcProxy):
         return self.call(ctxt, self.make_msg('show_host_resources', host=host))
 
     def live_migration(self, ctxt, block_migration, disk_over_commit,
-            instance, dest, topic):
+            instance, dest):
         # NOTE(comstud): Call vs cast so we can get exceptions back, otherwise
         # this call in the scheduler driver doesn't return anything.
         instance_p = jsonutils.to_primitive(instance)
         return self.call(ctxt, self.make_msg('live_migration',
                 block_migration=block_migration,
                 disk_over_commit=disk_over_commit, instance=instance_p,
-                dest=dest, topic=topic), version='1.3')
+                dest=dest), version='1.7')
+
+    def create_volume(self, ctxt, volume_id, snapshot_id, reservations):
+        self.cast(ctxt,
+                  self.make_msg('create_volume',
+                                volume_id=volume_id, snapshot_id=snapshot_id,
+                                reservations=reservations),
+                  version='1.7')
 
     def update_service_capabilities(self, ctxt, service_name, host,
             capabilities):

nova/scheduler/simple.py

@@ -54,7 +54,8 @@ class SimpleScheduler(chance.ChanceScheduler):
         super(SimpleScheduler, self).schedule_run_instance(context,
                 request_spec, reservations, *_args, **_kwargs)
 
-    def schedule_create_volume(self, context, volume_id, *_args, **_kwargs):
+    def schedule_create_volume(self, context, volume_id, snapshot_id,
+                               reservations):
         """Picks a host that is up and has the fewest volumes."""
         deprecated.warn(_('nova-volume functionality is deprecated in Folsom '
                 'and will be removed in Grizzly.  Volumes are now handled '
@@ -72,7 +73,8 @@ class SimpleScheduler(chance.ChanceScheduler):
             if not utils.service_is_up(service):
                 raise exception.WillNotSchedule(host=host)
             driver.cast_to_volume_host(context, host, 'create_volume',
-                    volume_id=volume_id, **_kwargs)
+                    volume_id=volume_id, snapshot_id=snapshot_id,
+                    reservations=reservations)
             return None
 
         results = db.service_get_all_volume_sorted(elevated)
@@ -86,7 +88,8 @@ class SimpleScheduler(chance.ChanceScheduler):
                 raise exception.NoValidHost(reason=msg)
             if utils.service_is_up(service) and not service['disabled']:
                 driver.cast_to_volume_host(context, service['host'],
-                        'create_volume', volume_id=volume_id, **_kwargs)
+                        'create_volume', volume_id=volume_id,
+                        snapshot_id=snapshot_id, reservations=reservations)
                 return None
         msg = _("Is the appropriate service running?")
         raise exception.NoValidHost(reason=msg)

nova/tests/scheduler/test_multi_scheduler.py

@@ -46,9 +46,6 @@ class FakeVolumeScheduler(driver.Scheduler):
         super(FakeVolumeScheduler, self).__init__()
         self.is_update_caps_called = False
 
-    def schedule_create_volume(self, *args, **kwargs):
-        pass
-
     def schedule_create_volumes(self, *args, **kwargs):
         pass
 
@@ -97,7 +94,7 @@ class MultiDriverTestCase(test_scheduler.SchedulerTestCase):
 
         #no compute methods are proxied at this time
         test_methods = {compute_driver: [],
-                        volume_driver: ['create_volume', 'create_volumes']}
+                        volume_driver: ['create_volumes']}
 
         for driver, methods in test_methods.iteritems():
             for method in methods:

nova/tests/scheduler/test_rpcapi.py

@@ -86,10 +86,16 @@ class SchedulerRpcAPITestCase(test.TestCase):
         self._test_scheduler_api('live_migration', rpc_method='call',
                 block_migration='fake_block_migration',
                 disk_over_commit='fake_disk_over_commit',
-                instance='fake_instance', dest='fake_dest', topic='fake_topic',
-                version='1.3')
+                instance='fake_instance', dest='fake_dest',
+                version='1.7')
 
     def test_update_service_capabilities(self):
         self._test_scheduler_api('update_service_capabilities',
                 rpc_method='fanout_cast', service_name='fake_name',
                 host='fake_host', capabilities='fake_capabilities')
+
+    def test_create_volume(self):
+        self._test_scheduler_api('create_volume',
+                rpc_method='cast', volume_id="fake_volume",
+                snapshot_id="fake_snapshots", reservations=list('fake_res'),
+                version='1.7')