Merge "Add randomness to physical host selection"

blazar/plugins/oshosts/host_plugin.py

@@ -15,6 +15,7 @@
 # under the License.
 
 import datetime
+from random import Random
 
 from novaclient import exceptions as nova_exceptions
 from oslo_config import cfg
@@ -64,6 +65,9 @@ plugin_opts = [
                help='Interval (minutes) of reservation healing. '
                     'If 0 is specified, the interval is infinite and all the '
                     'reservations in the future is healed at one time.'),
+    cfg.BoolOpt('randomize_host_selection',
+                default=False,
+                help='Allocate hosts for reservations randomly.'),
 ]
 
 CONF = cfg.CONF
@@ -593,9 +597,13 @@ class PhysicalHostPlugin(base.BasePlugin, nova.NovaClientWrapper):
             ]:
                 allocated_host_ids.append(host['id'])
         if len(not_allocated_host_ids) >= int(min_host):
+            if CONF[self.resource_type].randomize_host_selection:
+                Random.shuffle(not_allocated_host_ids)
             return not_allocated_host_ids[:int(max_host)]
         all_host_ids = allocated_host_ids + not_allocated_host_ids
         if len(all_host_ids) >= int(min_host):
+            if CONF[self.resource_type].randomize_host_selection:
+                Random.shuffle(all_host_ids)
             return all_host_ids[:int(max_host)]
         else:
             return []

blazar/tests/plugins/oshosts/test_physical_host_plugin.py

@@ -22,6 +22,7 @@ from novaclient import client as nova_client
 from novaclient import exceptions as nova_exceptions
 from oslo_config import cfg
 from oslo_config import fixture as conf_fixture
+import random
 import testtools
 
 from blazar import context
@@ -2333,8 +2334,115 @@ class PhysicalHostPluginTestCase(tests.TestCase):
             '[]', '[]', '3-3',
             datetime.datetime(2013, 12, 19, 20, 00),
             datetime.datetime(2013, 12, 19, 21, 00))
+        self.addCleanup(CONF.clear_override, 'cleaning_time')
         self.assertEqual(['host1', 'host2', 'host3'], result)
 
+    @mock.patch.object(random.Random, "shuffle")
+    def test_random_matching_hosts_not_allocated_hosts(self, mock_shuffle):
+        def host_allocation_get_all_by_values(**kwargs):
+            if kwargs['compute_host_id'] == 'host1':
+                return True
+        self.cfg.CONF.set_override('randomize_host_selection', True,
+                                   group=plugin.RESOURCE_TYPE)
+        host_get = self.patch(
+            self.db_api,
+            'reservable_host_get_all_by_queries')
+        host_get.return_value = [
+            {'id': 'host1'},
+            {'id': 'host2'},
+            {'id': 'host3'},
+        ]
+        host_get = self.patch(
+            self.db_api,
+            'host_allocation_get_all_by_values')
+        host_get.side_effect = host_allocation_get_all_by_values
+        host_get = self.patch(
+            self.db_utils,
+            'get_free_periods')
+        host_get.return_value = [
+            (datetime.datetime(2013, 12, 19, 20, 00),
+             datetime.datetime(2013, 12, 19, 21, 00)),
+        ]
+        self.fake_phys_plugin._matching_hosts(
+            '[]', '[]', '1-3',
+            datetime.datetime(2013, 12, 19, 20, 00),
+            datetime.datetime(2013, 12, 19, 21, 00))
+        self.addCleanup(CONF.clear_override, 'randomize_host_selection',
+                        group=plugin.RESOURCE_TYPE)
+        mock_shuffle.assert_called_once_with(['host2', 'host3'])
+
+    @mock.patch.object(random.Random, "shuffle")
+    def test_random_matching_hosts_allocated_hosts(self, mock_shuffle):
+        def host_allocation_get_all_by_values(**kwargs):
+            if kwargs['compute_host_id'] == 'host1':
+                return True
+        self.cfg.CONF.set_override('randomize_host_selection', True,
+                                   group=plugin.RESOURCE_TYPE)
+        host_get = self.patch(
+            self.db_api,
+            'reservable_host_get_all_by_queries')
+        host_get.return_value = [
+            {'id': 'host1'},
+            {'id': 'host2'},
+            {'id': 'host3'},
+        ]
+        host_get = self.patch(
+            self.db_api,
+            'host_allocation_get_all_by_values')
+        host_get.side_effect = host_allocation_get_all_by_values
+        host_get = self.patch(
+            self.db_utils,
+            'get_free_periods')
+        host_get.return_value = [
+            (datetime.datetime(2013, 12, 19, 20, 00),
+             datetime.datetime(2013, 12, 19, 21, 00)),
+        ]
+        self.fake_phys_plugin._matching_hosts(
+            '[]', '[]', '3-3',
+            datetime.datetime(2013, 12, 19, 20, 00),
+            datetime.datetime(2013, 12, 19, 21, 00))
+        self.addCleanup(CONF.clear_override, 'randomize_host_selection',
+                        group=plugin.RESOURCE_TYPE)
+        mock_shuffle.assert_called_once_with(['host1', 'host2', 'host3'])
+
+    @mock.patch.object(random.Random, "shuffle")
+    def test_random_matching_hosts_allocated_cleaning_time(self, mock_shuffle):
+        def host_allocation_get_all_by_values(**kwargs):
+            if kwargs['compute_host_id'] == 'host1':
+                return True
+        self.cfg.CONF.set_override('randomize_host_selection', True,
+                                   group=plugin.RESOURCE_TYPE)
+        self.cfg.CONF.set_override('cleaning_time', '5')
+        host_get = self.patch(
+            self.db_api,
+            'reservable_host_get_all_by_queries')
+        host_get.return_value = [
+            {'id': 'host1'},
+            {'id': 'host2'},
+            {'id': 'host3'},
+        ]
+        host_get = self.patch(
+            self.db_api,
+            'host_allocation_get_all_by_values')
+        host_get.side_effect = host_allocation_get_all_by_values
+        host_get = self.patch(
+            self.db_utils,
+            'get_free_periods')
+        host_get.return_value = [
+            (datetime.datetime(2013, 12, 19, 20, 00)
+             - datetime.timedelta(minutes=5),
+             datetime.datetime(2013, 12, 19, 21, 00)
+             + datetime.timedelta(minutes=5))
+        ]
+        self.fake_phys_plugin._matching_hosts(
+            '[]', '[]', '3-3',
+            datetime.datetime(2013, 12, 19, 20, 00),
+            datetime.datetime(2013, 12, 19, 21, 00))
+        self.addCleanup(CONF.clear_override, 'randomize_host_selection',
+                        group=plugin.RESOURCE_TYPE)
+        self.addCleanup(CONF.clear_override, 'cleaning_time')
+        mock_shuffle.assert_called_once_with(['host1', 'host2', 'host3'])
+
     def test_matching_hosts_not_matching(self):
         host_get = self.patch(
             self.db_api,

releasenotes/notes/option-for-randomising-host-selection-101e95baab67dd88.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Adds optional randomness to physical host allocation. This is disabled by
+    default and can be enabled with the configuration option
+    ``[physical:host]/randomize_host_selection``.