[scheduler] Consolidate host_info/passes steps in filter & weigher

Both host_info_requiring_instance_ids as well as host_passes/_weigh_object
had duplicated code for extracting the instance-ids needed
By consolidating them we reduce the code duplication.

Change-Id: Icfc1d3e554ff0834dec35d52772996284dc0a5da

nova/scheduler/filters/affinity_filter.py

@@ -32,7 +32,7 @@ class DifferentHostFilter(filters.BaseHostFilter):
     RUN_ON_REBUILD = False
 
     def host_passes(self, host_state, spec_obj):
-        affinity_uuids = spec_obj.get_scheduler_hint('different_host')
+        affinity_uuids = self.host_info_requiring_instance_ids(spec_obj)
         if affinity_uuids:
             overlap = utils.instance_uuids_overlap(host_state, affinity_uuids)
             return not overlap
@@ -53,7 +53,7 @@ class SameHostFilter(filters.BaseHostFilter):
     RUN_ON_REBUILD = False
 
     def host_passes(self, host_state, spec_obj):
-        affinity_uuids = spec_obj.get_scheduler_hint('same_host')
+        affinity_uuids = self.host_info_requiring_instance_ids(spec_obj)
         if affinity_uuids:
             overlap = utils.instance_uuids_overlap(host_state, affinity_uuids)
             return overlap
@@ -93,24 +93,25 @@ class _GroupAntiAffinityFilter(filters.BaseHostFilter):
     RUN_ON_REBUILD = False
 
     def host_passes(self, host_state, spec_obj):
-        # Only invoke the filter if 'anti-affinity' is configured
-        instance_group = spec_obj.instance_group
-        policy = instance_group.policy if instance_group else None
-        if self.policy_name != policy:
+        members = self.host_info_requiring_instance_ids(spec_obj)
+        # Only invoke the filter if 'anti-affinity' is configured,
+        # and there are any instances to consider
+        if not members:
             return True
 
         # NOTE(hanrong): Move operations like resize can check the same source
         # compute node where the instance is. That case, AntiAffinityFilter
         # must not return the source as a non-possible destination.
         if spec_obj.instance_uuid in host_state.instances.keys():
             return True
+
         # The list of instances UUIDs on the given host
         instances = set(host_state.instances.keys())
-        # The list of instances UUIDs which are members of this group
-        members = set(spec_obj.instance_group.members)
         # The set of instances on the host that are also members of this group
         servers_on_host = instances.intersection(members)
 
+        instance_group = spec_obj.instance_group
+
         rules = instance_group.rules
         if rules and 'max_server_per_host' in rules:
             max_server_per_host = rules['max_server_per_host']
@@ -137,9 +138,11 @@ def host_passes(self, host_state, spec_obj):
     def host_info_requiring_instance_ids(self, spec_obj):
         instance_group = spec_obj.instance_group
         policy = instance_group.policy if instance_group else None
+
         if self.policy_name != policy:
             return set()
 
+        # The list of instances UUIDs which are members of this group
         return set(spec_obj.instance_group.members)
 
 

nova/scheduler/weights/affinity.py

@@ -37,16 +37,11 @@ class _SoftAffinityWeigherBase(weights.BaseHostWeigher):
 
     def _weigh_object(self, host_state, request_spec):
         """Higher weights win."""
-        if not request_spec.instance_group:
-            return 0
-
-        policy = request_spec.instance_group.policy
-
-        if self.policy_name != policy:
+        members = self.host_info_requiring_instance_ids(request_spec)
+        if not members:
             return 0
 
         instances = set(host_state.instances.keys())
-        members = set(request_spec.instance_group.members)
         member_on_host = instances.intersection(members)
 
         return len(member_on_host)