Refactor nova.volume.cinder.API to reduce roundtrips with Cinder

Make cinder.API methods accept volume_id instead of the whole volume object.
This will remove redundant roundtrip to get the volume before
passing it to other methods as in fact they only need the id.

Fixes bug 1172297

Change-Id: I5e7f944c1c29b2f211ece2ef86c0959c81e806df

2 files changed, 27 insertions, 37 deletions

diff --git a/nova/compute/api.py b/nova/compute/api.py
index 9d73c3055..1d392c7b5 100644
--- a/nova/compute/api.py
+++ b/nova/compute/api.py
@@ -1182,18 +1182,17 @@ class API(base.Base):
         # cleanup volumes
         for bdm in bdms:
             if bdm['volume_id']:
-                volume = self.volume_api.get(context, bdm['volume_id'])
                 # NOTE(vish): We don't have access to correct volume
                 #             connector info, so just pass a fake
                 #             connector. This can be improved when we
                 #             expose get_volume_connector to rpc.
                 connector = {'ip': '127.0.0.1', 'initiator': 'iqn.fake'}
                 self.volume_api.terminate_connection(context,
-                                                     volume,
+                                                     bdm['volume_id'],
                                                      connector)
-                self.volume_api.detach(elevated, volume)
+                self.volume_api.detach(elevated, bdm['volume_id'])
                 if bdm['delete_on_termination']:
-                    self.volume_api.delete(context, volume)
+                    self.volume_api.delete(context, bdm['volume_id'])
             self.db.block_device_mapping_destroy(context, bdm['id'])
         instance = self._instance_update(context,
                                          instance_uuid,
@@ -1613,7 +1612,7 @@ class API(base.Base):
                 #                 short time, it doesn't matter for now.
                 name = _('snapshot for %s') % image_meta['name']
                 snapshot = self.volume_api.create_snapshot_force(
-                    context, volume, name, volume['display_description'])
+                    context, volume['id'], name, volume['display_description'])
                 bdm['snapshot_id'] = snapshot['id']
                 del bdm['volume_id']
 
@@ -2306,7 +2305,7 @@ class API(base.Base):
         try:
             volume = self.volume_api.get(context, volume_id)
             self.volume_api.check_attach(context, volume, instance=instance)
-            self.volume_api.reserve_volume(context, volume)
+            self.volume_api.reserve_volume(context, volume_id)
             self.compute_rpcapi.attach_volume(context, instance=instance,
                     volume_id=volume_id, mountpoint=device)
         except Exception:
@@ -2321,7 +2320,7 @@ class API(base.Base):
         it easier for cells version to override.
         """
         self.volume_api.check_detach(context, volume)
-        self.volume_api.begin_detaching(context, volume)
+        self.volume_api.begin_detaching(context, volume['id'])
         self.compute_rpcapi.detach_volume(context, instance=instance,
                 volume_id=volume['id'])
 
diff --git a/nova/compute/manager.py b/nova/compute/manager.py
index 16ea63f9f..4f32e5132 100755
--- a/nova/compute/manager.py
+++ b/nova/compute/manager.py
@@ -793,7 +793,7 @@ class ComputeManager(manager.SchedulerDependentManager):
             if bdm['volume_id'] is not None:
                 volume = self.volume_api.get(context, bdm['volume_id'])
                 self.volume_api.check_attach(context, volume,
-                                                      instance=instance)
+                                             instance=instance)
                 cinfo = self._attach_volume_boot(context,
                                                  instance,
                                                  volume,
@@ -1316,12 +1316,11 @@ class ComputeManager(manager.SchedulerDependentManager):
             try:
                 # NOTE(vish): actual driver detach done in driver.destroy, so
                 #             just tell nova-volume that we are done with it.
-                volume = self.volume_api.get(context, bdm['volume_id'])
                 connector = self.driver.get_volume_connector(instance)
                 self.volume_api.terminate_connection(context,
-                                                     volume,
+                                                     bdm['volume_id'],
                                                      connector)
-                self.volume_api.detach(context, volume)
+                self.volume_api.detach(context, bdm['volume_id'])
             except exception.DiskNotFound as exc:
                 LOG.warn(_('Ignoring DiskNotFound: %s') % exc,
                          instance=instance)
@@ -1336,8 +1335,7 @@ class ComputeManager(manager.SchedulerDependentManager):
             LOG.debug(_("terminating bdm %s") % bdm,
                       instance_uuid=instance_uuid)
             if bdm['volume_id'] and bdm['delete_on_termination']:
-                volume = self.volume_api.get(context, bdm['volume_id'])
-                self.volume_api.delete(context, volume)
+                self.volume_api.delete(context, bdm['volume_id'])
             # NOTE(vish): bdms will be deleted on instance destroy
 
     @hooks.add_hook("delete_instance")
@@ -1652,8 +1650,7 @@ class ComputeManager(manager.SchedulerDependentManager):
             # NOTE(sirp): this detach is necessary b/c we will reattach the
             # volumes in _prep_block_devices below.
             for bdm in self._get_volume_bdms(bdms):
-                volume = self.volume_api.get(context, bdm['volume_id'])
-                self.volume_api.detach(context, volume)
+                self.volume_api.detach(context, bdm['volume_id'])
 
             if not recreate:
                 block_device_info = self._get_volume_block_device_info(
@@ -1726,7 +1723,7 @@ class ComputeManager(manager.SchedulerDependentManager):
                 LOG.info(_("Detaching from volume api: %s") % volume_id)
                 volume = self.volume_api.get(context, volume_id)
                 self.volume_api.check_detach(context, volume)
-                self.volume_api.begin_detaching(context, volume)
+                self.volume_api.begin_detaching(context, volume_id)
 
                 # Manager-detach
                 self.detach_volume(context, volume_id, instance)
@@ -2209,9 +2206,8 @@ class ComputeManager(manager.SchedulerDependentManager):
         connector = self.driver.get_volume_connector(instance)
 
         for bdm in bdms:
-            volume = self.volume_api.get(context, bdm['volume_id'])
             cinfo = self.volume_api.initialize_connection(
-                    context, volume, connector)
+                    context, bdm['volume_id'], connector)
 
             self.conductor_api.block_device_mapping_update(
                 context, bdm['id'],
@@ -2473,9 +2469,8 @@ class ComputeManager(manager.SchedulerDependentManager):
         if bdms:
             connector = self.driver.get_volume_connector(instance)
             for bdm in bdms:
-                volume = self.volume_api.get(context, bdm['volume_id'])
-                self.volume_api.terminate_connection(context, volume,
-                        connector)
+                self.volume_api.terminate_connection(context, bdm['volume_id'],
+                                                     connector)
 
     def _finish_resize(self, context, instance, migration, disk_info,
                        image):
@@ -2880,9 +2875,9 @@ class ComputeManager(manager.SchedulerDependentManager):
                   locals(), context=context, instance=instance)
         connector = self.driver.get_volume_connector(instance)
         connection_info = self.volume_api.initialize_connection(context,
-                                                                volume,
+                                                                volume_id,
                                                                 connector)
-        self.volume_api.attach(context, volume, instance_uuid, mountpoint)
+        self.volume_api.attach(context, volume_id, instance_uuid, mountpoint)
         return connection_info
 
     @exception.wrap_exception(notifier=notifier, publisher_id=publisher_id())
@@ -2925,14 +2920,13 @@ class ComputeManager(manager.SchedulerDependentManager):
                         context, instance, mountpoint)
 
     def _attach_volume(self, context, volume_id, mountpoint, instance):
-        volume = self.volume_api.get(context, volume_id)
         context = context.elevated()
         LOG.audit(_('Attaching volume %(volume_id)s to %(mountpoint)s'),
                   locals(), context=context, instance=instance)
         try:
             connector = self.driver.get_volume_connector(instance)
             connection_info = self.volume_api.initialize_connection(context,
-                                                                    volume,
+                                                                    volume_id,
                                                                     connector)
         except Exception:  # pylint: disable=W0702
             with excutils.save_and_reraise_exception():
@@ -2940,7 +2934,7 @@ class ComputeManager(manager.SchedulerDependentManager):
                         "while attaching at %(mountpoint)s")
                 LOG.exception(msg % locals(), context=context,
                               instance=instance)
-                self.volume_api.unreserve_volume(context, volume)
+                self.volume_api.unreserve_volume(context, volume_id)
 
         if 'serial' not in connection_info:
             connection_info['serial'] = volume_id
@@ -2956,11 +2950,11 @@ class ComputeManager(manager.SchedulerDependentManager):
                 LOG.exception(msg % locals(), context=context,
                               instance=instance)
                 self.volume_api.terminate_connection(context,
-                                                     volume,
+                                                     volume_id,
                                                      connector)
 
         self.volume_api.attach(context,
-                               volume,
+                               volume_id,
                                instance['uuid'],
                                mountpoint)
         values = {
@@ -3001,8 +2995,7 @@ class ComputeManager(manager.SchedulerDependentManager):
                 msg = _("Failed to detach volume %(volume_id)s from %(mp)s")
                 LOG.exception(msg % locals(), context=context,
                               instance=instance)
-                volume = self.volume_api.get(context, volume_id)
-                self.volume_api.roll_detaching(context, volume)
+                self.volume_api.roll_detaching(context, volume_id)
 
     @exception.wrap_exception(notifier=notifier, publisher_id=publisher_id())
     @reverts_task_state
@@ -3031,10 +3024,9 @@ class ComputeManager(manager.SchedulerDependentManager):
                                                     update_totals=True)
 
         self._detach_volume(context, instance, bdm)
-        volume = self.volume_api.get(context, volume_id)
         connector = self.driver.get_volume_connector(instance)
-        self.volume_api.terminate_connection(context, volume, connector)
-        self.volume_api.detach(context.elevated(), volume)
+        self.volume_api.terminate_connection(context, volume_id, connector)
+        self.volume_api.detach(context.elevated(), volume_id)
         self.conductor_api.block_device_mapping_destroy_by_instance_and_volume(
             context, instance, volume_id)
 
@@ -3047,9 +3039,8 @@ class ComputeManager(manager.SchedulerDependentManager):
         try:
             bdm = self._get_instance_volume_bdm(context, instance, volume_id)
             self._detach_volume(context, instance, bdm)
-            volume = self.volume_api.get(context, volume_id)
             connector = self.driver.get_volume_connector(instance)
-            self.volume_api.terminate_connection(context, volume, connector)
+            self.volume_api.terminate_connection(context, volume_id, connector)
         except exception.NotFound:
             pass
 
@@ -3271,8 +3262,8 @@ class ComputeManager(manager.SchedulerDependentManager):
 
             # remove the volume connection without detaching from hypervisor
             # because the instance is not running anymore on the current host
-            volume = self.volume_api.get(ctxt, bdm['volume_id'])
-            self.volume_api.terminate_connection(ctxt, volume, connector)
+            self.volume_api.terminate_connection(ctxt, bdm['volume_id'],
+                                                 connector)
 
         # Releasing vlan.
         # (not necessary in current implementation?)