Create segment_host mapping after new segment

This adds logic to add segment to host mappings for agents
after a segment is created. The previous logic was doing this
only after an agent initially reported after the server started.
This meant that any segments created after the agent was running
would not get mappings to the agent's host.

Partially-Implements: blueprint routed-networks
Change-Id: Ibcd9964afb1c7ac3926447f90b3fd364fd4835ca

neutron/callbacks/resources.py

@@ -21,6 +21,7 @@ ROUTER_GATEWAY = 'router_gateway'
 ROUTER_INTERFACE = 'router_interface'
 SECURITY_GROUP = 'security_group'
 SECURITY_GROUP_RULE = 'security_group_rule'
+SEGMENT = 'segment'
 SUBNET = 'subnet'
 SUBNET_GATEWAY = 'subnet_gateway'
 SUBNETPOOL_ADDRESS_SCOPE = 'subnetpool_address_scope'

neutron/services/segments/db.py

@@ -33,6 +33,7 @@ from neutron.db import common_db_mixin
 from neutron.db import model_base
 from neutron.db import segments_db as db
 from neutron.extensions import segment as extension
+from neutron import manager
 from neutron.services.segments import exceptions
 
 
@@ -108,6 +109,8 @@ class SegmentDbMixin(common_db_mixin.CommonDbMixin):
                     db.SEGMENTATION_ID: segmentation_id}
             new_segment = db.NetworkSegment(**args)
             context.session.add(new_segment)
+            registry.notify(resources.SEGMENT, events.PRECOMMIT_CREATE, self,
+                            context=context, segment=new_segment)
 
         return self._make_segment_dict(new_segment)
 
@@ -219,6 +222,24 @@ def _update_segment_host_mapping_for_agent(resource, event, trigger,
     update_segment_host_mapping(context, host, current_segment_ids)
 
 
+def _add_segment_host_mapping_for_segment(resource, event, trigger,
+                                          context, segment):
+    if not segment.physical_network:
+        return
+    cp = manager.NeutronManager.get_plugin()
+    check_segment_for_agent = getattr(cp, 'check_segment_for_agent', None)
+    if not hasattr(cp, 'get_agents') or not check_segment_for_agent:
+        # not an agent-supporting plugin
+        registry.unsubscribe(_add_segment_host_mapping_for_segment,
+                             resources.SEGMENT, events.PRECOMMIT_CREATE)
+        return
+    hosts = {agent['host'] for agent in cp.get_agents(context)
+             if check_segment_for_agent(segment, agent)}
+    for host in hosts:
+        context.session.add(SegmentHostMapping(segment_id=segment.id,
+                                               host=host))
+
+
 def subscribe():
     registry.subscribe(_update_segment_host_mapping_for_agent,
                        resources.AGENT,
@@ -226,5 +247,7 @@ def subscribe():
     registry.subscribe(_update_segment_host_mapping_for_agent,
                        resources.AGENT,
                        events.AFTER_UPDATE)
+    registry.subscribe(_add_segment_host_mapping_for_segment,
+                       resources.SEGMENT, events.PRECOMMIT_CREATE)
 
 subscribe()

neutron/tests/unit/extensions/test_segment.py

@@ -389,6 +389,19 @@ class TestMl2HostSegmentMappingOVS(HostSegmentMappingTestCase):
                          segments_host_db[segment['id']]['segment_id'])
         self.assertEqual(host2, segments_host_db[segment['id']]['host'])
 
+    def test_new_segment_after_host_reg(self):
+        host1 = 'host1'
+        physical_network = 'phys_net1'
+        segment = self._test_one_segment_one_host(host1)
+        with self.network() as network:
+            network = network['network']
+        segment2 = self._test_create_segment(
+            network_id=network['id'], physical_network=physical_network,
+            segmentation_id=200, network_type=p_constants.TYPE_VLAN)['segment']
+        segments_host_db = self._get_segments_for_host(host1)
+        self.assertEqual(set((segment['id'], segment2['id'])),
+                         set(segments_host_db))
+
     def test_segment_deletion_removes_host_mapping(self):
         host = 'host1'
         segment = self._test_one_segment_one_host(host)