Refactor: extract method: driver_dict_from_config

Related to blueprint xenapi-volume-drivers

Extract method to create driver registries, so that it could be re-used
in xenapi for a similar purpose.

Change-Id: Ifd25d12335ac96a15dfea4c5ab7f315ff7ddfd8b

3 files changed, 75 insertions, 5 deletions

diff --git a/nova/tests/test_driver.py b/nova/tests/test_driver.py
new file mode 100644
index 000000000..2dee7725f
--- /dev/null
+++ b/nova/tests/test_driver.py
@@ -0,0 +1,60 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright (c) 2013 Citrix Systems, Inc.
+# Copyright 2013 OpenStack LLC.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from nova import test
+from nova.virt import driver
+
+
+class FakeDriver(object):
+    def __init__(self, *args, **kwargs):
+        self.args = args
+        self.kwargs = kwargs
+
+
+class FakeDriver2(FakeDriver):
+    pass
+
+
+class ToDriverRegistryTestCase(test.TestCase):
+
+    def assertDriverInstance(self, inst, class_, *args, **kwargs):
+        self.assertEquals(class_, inst.__class__)
+        self.assertEquals(args, inst.args)
+        self.assertEquals(kwargs, inst.kwargs)
+
+    def test_driver_dict_from_config(self):
+        drvs = driver.driver_dict_from_config(
+            [
+                'key1=nova.tests.test_driver.FakeDriver',
+                'key2=nova.tests.test_driver.FakeDriver2',
+            ], 'arg1', 'arg2', param1='value1', param2='value2'
+        )
+
+        self.assertEquals(
+            sorted(['key1', 'key2']),
+            sorted(drvs.keys())
+        )
+
+        self.assertDriverInstance(
+            drvs['key1'],
+            FakeDriver, 'arg1', 'arg2', param1='value1',
+            param2='value2')
+
+        self.assertDriverInstance(
+            drvs['key2'],
+            FakeDriver2, 'arg1', 'arg2', param1='value1',
+            param2='value2')
diff --git a/nova/virt/driver.py b/nova/virt/driver.py
index aa0439e74..f699d2011 100644
--- a/nova/virt/driver.py
+++ b/nova/virt/driver.py
@@ -49,6 +49,17 @@ CONF.register_opts(driver_opts)
 LOG = logging.getLogger(__name__)
 
 
+def driver_dict_from_config(named_driver_config, *args, **kwargs):
+    driver_registry = dict()
+
+    for driver_str in named_driver_config:
+        driver_type, _sep, driver = driver_str.partition('=')
+        driver_class = importutils.import_class(driver)
+        driver_registry[driver_type] = driver_class(*args, **kwargs)
+
+    return driver_registry
+
+
 def block_device_info_get_root(block_device_info):
     block_device_info = block_device_info or {}
     return block_device_info.get('root_device_name')
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index 597aa39a0..86afa1687 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -284,11 +284,10 @@ class LibvirtDriver(driver.ComputeDriver):
             self.virtapi,
             get_connection=self._get_connection)
         self.vif_driver = importutils.import_object(CONF.libvirt_vif_driver)
-        self.volume_drivers = {}
-        for driver_str in CONF.libvirt_volume_drivers:
-            driver_type, _sep, driver = driver_str.partition('=')
-            driver_class = importutils.import_class(driver)
-            self.volume_drivers[driver_type] = driver_class(self)
+
+        self.volume_drivers = driver.driver_dict_from_config(
+            CONF.libvirt_volume_drivers, self)
+
         self._host_state = None
 
         disk_prefix_map = {"lxc": "", "uml": "ubd", "xen": "sd"}