allow scheduling topics to multiple drivers

3 files changed, 98 insertions, 4 deletions

diff --git a/nova/scheduler/manager.py b/nova/scheduler/manager.py
index c8b16b622..13c0bf22a 100644
--- a/nova/scheduler/manager.py
+++ b/nova/scheduler/manager.py
@@ -34,12 +34,13 @@ from nova.scheduler import zone_manager
 LOG = logging.getLogger('nova.scheduler.manager')
 FLAGS = flags.FLAGS
 flags.DEFINE_string('scheduler_driver',
-                    'nova.scheduler.chance.ChanceScheduler',
-                    'Driver to use for the scheduler')
+                    'nova.scheduler.multi.MultiScheduler',
+                    'Default driver to use for the scheduler')
 
 
 class SchedulerManager(manager.Manager):
     """Chooses a host to run instances on."""
+
     def __init__(self, scheduler_driver=None, *args, **kwargs):
         self.zone_manager = zone_manager.ZoneManager()
         if not scheduler_driver:
diff --git a/nova/scheduler/multi.py b/nova/scheduler/multi.py
new file mode 100644
index 000000000..b1578033c
--- /dev/null
+++ b/nova/scheduler/multi.py
@@ -0,0 +1,73 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright (c) 2010 Openstack, LLC.
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+#
+#    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.
+
+"""
+Scheduler that allows routing some calls to one driver and others to another.
+"""
+
+from nova import flags
+from nova import utils
+from nova.scheduler import driver
+
+
+FLAGS = flags.FLAGS
+flags.DEFINE_string('compute_scheduler_driver',
+                    'nova.scheduler.chance.ChanceScheduler',
+                    'Driver to use for scheduling compute calls')
+flags.DEFINE_string('volume_scheduler_driver',
+                    'nova.scheduler.chance.ChanceScheduler',
+                    'Driver to use for scheduling volume calls')
+
+
+# A mapping of methods to topics so we can figure out which driver to use.
+_METHOD_MAP = {'run_instance': 'compute',
+               'start_instance': 'compute',
+               'create_volume': 'volume'}
+
+
+class MultiScheduler(driver.Scheduler):
+    """A scheduler that holds multiple sub-schedulers.
+
+    This exists to allow flag-driven composibility of schedulers, allowing
+    third parties to integrate custom schedulers more easily.
+
+    """
+
+    def __init__(self):
+        super(MultiScheduler, self).__init__()
+        compute_driver = utils.import_object(FLAGS.compute_scheduler_driver)
+        volume_driver = utils.import_object(FLAGS.volume_scheduler_driver)
+
+        self.drivers = {'compute': compute_driver,
+                        'volume': volume_driver}
+
+    def __getattr__(self, key):
+        if not key.startswith('schedule_'):
+            raise AttributeError(key)
+        method = key[len('schedule_'):]
+        if method not in _METHOD_MAP:
+            raise AttributeError(key)
+        return getattr(self.drivers[_METHOD_MAP[method]], key)
+
+    def set_zone_manager(self, zone_manager):
+        for k, v in self.drivers.iteritems():
+            v.set_zone_manager(zone_manager)
+
+    def schedule(self, context, topic, *_args, **_kwargs):
+        return self.drivers[topic].schedule(context, topic, *_args, **_kwargs)
diff --git a/nova/tests/scheduler/test_scheduler.py b/nova/tests/scheduler/test_scheduler.py
index 7a26fd1bb..d70a6779f 100644
--- a/nova/tests/scheduler/test_scheduler.py
+++ b/nova/tests/scheduler/test_scheduler.py
@@ -36,8 +36,9 @@ from nova import test
 from nova import rpc
 from nova import utils
 from nova.scheduler import api
-from nova.scheduler import manager
 from nova.scheduler import driver
+from nova.scheduler import manager
+from nova.scheduler import multi
 from nova.compute import power_state
 
 
@@ -391,7 +392,7 @@ class SimpleDriverTestCase(test.TestCase):
         compute1.kill()
         compute2.kill()
 
-    def test_wont_sechedule_if_specified_host_is_down_no_queue(self):
+    def test_wont_schedule_if_specified_host_is_down_no_queue(self):
         compute1 = service.Service('host1',
                                    'nova-compute',
                                    'compute',
@@ -903,6 +904,25 @@ class SimpleDriverTestCase(test.TestCase):
         db.service_destroy(self.context, s_ref2['id'])
 
 
+class MultiDriverTestCase(SimpleDriverTestCase):
+    """Test case for multi driver."""
+
+    def setUp(self):
+        super(MultiDriverTestCase, self).setUp()
+        self.flags(connection_type='fake',
+                   stub_network=True,
+                   max_cores=4,
+                   max_gigabytes=4,
+                   network_manager='nova.network.manager.FlatManager',
+                   volume_driver='nova.volume.driver.FakeISCSIDriver',
+                   compute_scheduler_driver=('nova.scheduler.simple'
+                                             '.SimpleScheduler'),
+                   volume_scheduler_driver=('nova.scheduler.simple'
+                                            '.SimpleScheduler'),
+                   scheduler_driver='nova.scheduler.multi.MultiScheduler')
+        self.scheduler = manager.SchedulerManager()
+
+
 class FakeZone(object):
     def __init__(self, id, api_url, username, password):
         self.id = id