CORD-1849 Split XOS code out of OLT and VTN repos

Change-Id: I307b2a9a54fdcdab14e6bf96d9a9b060ff421a77
diff --git a/xos/synchronizer/model_policies/model_policy_volttenant.py b/xos/synchronizer/model_policies/model_policy_volttenant.py
new file mode 100644
index 0000000..ef5ba4e
--- /dev/null
+++ b/xos/synchronizer/model_policies/model_policy_volttenant.py
@@ -0,0 +1,94 @@
+
+# Copyright 2017-present Open Networking Foundation
+#
+# 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 synchronizers.new_base.modelaccessor import *
+from synchronizers.new_base.policy import Policy
+
+class VOLTTenantPolicy(Policy):
+    model_name = "VOLTTenant"
+
+    def handle_create(self, tenant):
+        return self.handle_update(tenant)
+
+    def handle_update(self, tenant):
+        self.manage_vsg(tenant)
+        self.manage_subscriber(tenant)
+        self.cleanup_orphans(tenant)
+
+    def handle_delete(self, tenant):
+        if tenant.vcpe:
+            tenant.vcpe.delete()
+
+    def manage_vsg(self, tenant):
+        # Each VOLT object owns exactly one VCPE object
+
+        if tenant.deleted:
+            self.logger.info("MODEL_POLICY: volttenant %s deleted, deleting vsg" % tenant)
+            return
+
+        # Check to see if the wrong s-tag is set. This can only happen if the
+        # user changed the s-tag after the VoltTenant object was created.
+        if tenant.vcpe and tenant.vcpe.instance:
+            s_tags = Tag.objects.filter(content_type=tenant.vcpe.instance.self_content_type_id,
+                                        object_id=tenant.vcpe.instance.id, name="s_tag")
+            if s_tags and (s_tags[0].value != str(tenant.s_tag)):
+                self.logger.info("MODEL_POLICY: volttenant %s s_tag changed, deleting vsg" % tenant)
+                tenant.vcpe.delete()
+
+        if tenant.vcpe is None:
+            vsgServices = VSGService.objects.all()
+            if not vsgServices:
+                raise XOSConfigurationError("No VSG Services available")
+
+            self.logger.info("MODEL_POLICY: volttenant %s creating vsg" % tenant)
+
+            vcpe = VSGTenant(owner=vsgServices[0])
+            vcpe.creator = tenant.creator
+            vcpe.save()
+            link = ServiceInstanceLink(provider_service_instance = vcpe, subscriber_service_instance = tenant)
+            link.save()
+
+    def manage_subscriber(self, tenant):
+        # check for existing link to a root
+        links = tenant.provided_links.all()
+        for link in links:
+            roots = CordSubscriberRoot.objects.filter(id = link.subscriber_service_instance.id)
+            if roots:
+                return
+
+        subs = CordSubscriberRoot.objects.filter(service_specific_id = tenant.service_specific_id)
+        if subs:
+            self.logger.info("MODEL_POLICY: volttenant %s using existing subscriber root" % tenant)
+            sub = subs[0]
+        else:
+            self.logger.info("MODEL_POLICY: volttenant %s creating new subscriber root" % tenant)
+            sub = CordSubscriberRoot(service_specific_id = tenant.service_specific_id,
+                                     name = "autogenerated-for-vOLT-%s" % tenant.id)
+            sub.save()
+
+        link = ServiceInstanceLink(provider_service_instance = tenant, subscriber_service_instance = sub)
+        link.save()
+
+    def cleanup_orphans(self, tenant):
+        # ensure vOLT only has one vCPE
+        cur_vcpe = tenant.vcpe
+
+        links = tenant.subscribed_links.all()
+        for link in links:
+            vsgs = VSGTenant.objects.filter(id = link.provider_service_instance.id)
+            for vsg in vsgs:
+                if (not cur_vcpe) or (vsg.id != cur_vcpe.id):
+                    vsg.delete()