Add IgnoreAttemptedHostsFilter to oslo

IgnoreAttemptedHostsFilter is RetryFilter that is using in nova and
cinder, so we can put it to oslo and then back port it to both nova
and cinder.

Change-Id: Ia355810b106fee14a55f48081301a310979befac
Implements part of bp oslo-more-filters

openstack/common/scheduler/filters/ignore_attempted_hosts_filter.py

@@ -0,0 +1,50 @@
+# Copyright (c) 2011 OpenStack Foundation.
+# 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.
+
+from openstack.common.gettextutils import _
+from openstack.common import log as logging
+from openstack.common.scheduler import filters
+
+LOG = logging.getLogger(__name__)
+
+
+class IgnoreAttemptedHostsFilter(filters.BaseHostFilter):
+    """Filter out previously attempted hosts
+
+    A host passes this filter if it has not already been attempted for
+    scheduling. The scheduler needs to add previously attempted hosts
+    to the 'attempted' key of filter_properties in order for this to work
+    correctly.
+    """
+
+    def host_passes(self, host_state, filter_properties):
+        """Skip nodes that have already been attempted."""
+        attempted = filter_properties.get('attempted', None)
+        if not attempted:
+            # Re-scheduling is disabled
+            LOG.debug(_("Re-scheduling is disabled"))
+            return True
+
+        hosts = attempted.get('hosts', [])
+        host = host_state.host
+
+        passes = host not in hosts
+        pass_msg = "passes" if passes else "fails"
+
+        LOG.debug(_("Host %(host)s %(pass_msg)s.  Previously tried hosts: "
+                    "%(hosts)s") % {'host': host,
+                                    'pass_msg': pass_msg,
+                                    'hosts': hosts})
+        return passes

setup.cfg

@@ -37,6 +37,7 @@ openstack.common.scheduler.filters =
     AvailabilityZoneFilter = openstack.common.scheduler.filters.availability_zone_filter:AvailabilityZoneFilter
     CapabilitiesFilter = openstack.common.scheduler.filters.capabilities_filter:CapabilitiesFilter
     JsonFilter = openstack.common.scheduler.filters.json_filter:JsonFilter
+    IgnoreAttemptedHostsFilter = openstack.common.scheduler.filters.ignore_attempted_hosts_filter:IgnoreAttemptedHostsFilter
 
 openstack.common.tests.fakes.weights =
     FakeWeigher1 = tests.unit.fakes:FakeWeigher1

tests/unit/scheduler/fake_hosts.py

@@ -47,5 +47,6 @@ class FakeHostManager(object):
 
 class FakeHostState(object):
     def __init__(self, host, attribute_dict):
+        self.host = host
         for (key, val) in six.iteritems(attribute_dict):
             setattr(self, key, val)

tests/unit/scheduler/test_host_filters.py

@@ -270,6 +270,7 @@ class HostFiltersTestCase(test.BaseTestCase):
         self.assertTrue('JsonFilter' in self.class_map)
         self.assertTrue('CapabilitiesFilter' in self.class_map)
         self.assertTrue('AvailabilityZoneFilter' in self.class_map)
+        self.assertTrue('IgnoreAttemptedHostsFilter' in self.class_map)
 
     def _do_test_type_filter_extra_specs(self, ecaps, especs, passes):
         filt_cls = self.class_map['CapabilitiesFilter']()
@@ -676,3 +677,26 @@ class HostFiltersTestCase(test.BaseTestCase):
         host = fakes.FakeHostState('host1',
                                    {'service': service})
         self.assertTrue(filt_cls.host_passes(host, request))
+
+    def test_ignore_attempted_hosts_filter_disabled(self):
+        # Test case where re-scheduling is disabled.
+        filt_cls = self.class_map['IgnoreAttemptedHostsFilter']()
+        host = fakes.FakeHostState('host1', {})
+        filter_properties = {}
+        self.assertTrue(filt_cls.host_passes(host, filter_properties))
+
+    def test_ignore_attempted_hosts_filter_pass(self):
+        # Node not previously tried.
+        filt_cls = self.class_map['IgnoreAttemptedHostsFilter']()
+        host = fakes.FakeHostState('host1', {})
+        attempted = dict(num_attempts=2, hosts=['host2'])
+        filter_properties = dict(attempted=attempted)
+        self.assertTrue(filt_cls.host_passes(host, filter_properties))
+
+    def test_ignore_attempted_hosts_filter_fail(self):
+        # Node was already tried.
+        filt_cls = self.class_map['IgnoreAttemptedHostsFilter']()
+        host = fakes.FakeHostState('host1', {})
+        attempted = dict(num_attempts=2, hosts=['host1'])
+        filter_properties = dict(attempted=attempted)
+        self.assertFalse(filt_cls.host_passes(host, filter_properties))