Delete all inventory has its own method DELETE

Previously we deleted all inventories for a resource provider
with a PUT method and empty payload.
With bp delete-inventories-placement-api implemented, scheduler's
client report now can use DELETE instead of PUT. To keep it
consistent across microversions, it should fallback to put method
if the delete attempt returns 406.

Change-Id: I626ca4a821b5ab0ebcaa79937a31771fbae5b8d9

nova/scheduler/client/report.py

@@ -241,10 +241,18 @@ def put(self, url, data):
             url, json=data,
             endpoint_filter=self.ks_filter, raise_exc=False)
 
-    def delete(self, url):
+    def delete(self, url, version=None):
+        kwargs = {}
+        if version is not None:
+            # TODO(mriedem): Perform some version discovery at some point.
+            kwargs = {
+                'headers': {
+                    'OpenStack-API-Version': 'placement %s' % version
+                },
+            }
         return self._client.delete(
             url,
-            endpoint_filter=self.ks_filter, raise_exc=False)
+            endpoint_filter=self.ks_filter, raise_exc=False, **kwargs)
 
     # TODO(sbauza): Change that poor interface into passing a rich versioned
     # object that would provide the ResourceProvider requirements.
@@ -602,6 +610,9 @@ def _update_inventory(self, rp_uuid, inv_data):
     def _delete_inventory(self, rp_uuid):
         """Deletes all inventory records for a resource provider with the
         supplied UUID.
+
+        First attempt to DELETE the inventory using microversion 1.5. If
+        this results in a 406, fail over to a PUT.
         """
         curr = self._get_inventory_and_update_provider_generation(rp_uuid)
 
@@ -617,50 +628,70 @@ def _delete_inventory(self, rp_uuid):
         LOG.info(msg, rp_uuid)
 
         url = '/resource_providers/%s/inventories' % rp_uuid
+        r = self.delete(url, version="1.5")
+        placement_req_id = get_placement_request_id(r)
         cur_rp_gen = self._resource_providers[rp_uuid]['generation']
-        payload = {
-            'resource_provider_generation': cur_rp_gen,
-            'inventories': {},
+        msg_args = {
+            'rp_uuid': rp_uuid,
+            'placement_req_id': placement_req_id,
         }
-        r = self.put(url, payload)
-        placement_req_id = get_placement_request_id(r)
-        if r.status_code == 200:
-            # Update our view of the generation for next time
-            updated_inv = r.json()
-            new_gen = updated_inv['resource_provider_generation']
-
-            self._resource_providers[rp_uuid]['generation'] = new_gen
-            msg_args = {
-                'rp_uuid': rp_uuid,
-                'generation': new_gen,
-                'placement_req_id': placement_req_id,
+        if r.status_code == 406:
+            # microversion 1.5 not available so try the earlier way
+            # TODO(cdent): When we're happy that all placement
+            # servers support microversion 1.5 we can remove this
+            # call and the associated code.
+            LOG.debug('Falling back to placement API microversion 1.0 '
+                      'for deleting all inventory for a resource provider.')
+            payload = {
+                'resource_provider_generation': cur_rp_gen,
+                'inventories': {},
             }
-            LOG.info(_LI('[%(placement_req_id)s] Deleted all inventory for '
-                         'resource provider %(rp_uuid)s at generation '
-                         '%(generation)i'),
+            r = self.put(url, payload)
+            placement_req_id = get_placement_request_id(r)
+            msg_args['placement_req_id'] = placement_req_id
+            if r.status_code == 200:
+                # Update our view of the generation for next time
+                updated_inv = r.json()
+                new_gen = updated_inv['resource_provider_generation']
+
+                self._resource_providers[rp_uuid]['generation'] = new_gen
+                msg_args['generation'] = new_gen
+                LOG.info(_LI("[%(placement_req_id)s] Deleted all inventory "
+                             "for resource provider %(rp_uuid)s at generation "
+                             "%(generation)i."),
+                         msg_args)
+                return
+
+        if r.status_code == 204:
+            self._resource_providers[rp_uuid]['generation'] = cur_rp_gen + 1
+            LOG.info(_LI("[%(placement_req_id)s] Deleted all inventory for "
+                         "resource provider %(rp_uuid)s."),
                      msg_args)
             return
+        elif r.status_code == 404:
+            # This can occur if another thread deleted the inventory and the
+            # resource provider already
+            LOG.debug("[%(placement_req_id)s] Resource provider %(rp_uuid)s "
+                      "deleted by another thread when trying to delete "
+                      "inventory. Ignoring.",
+                      msg_args)
+            self._resource_providers.pop(rp_uuid, None)
+            self._provider_aggregate_map.pop(rp_uuid, None)
+            return
         elif r.status_code == 409:
             rc_str = _extract_inventory_in_use(r.text)
             if rc_str is not None:
                 msg = _LW("[%(placement_req_id)s] We cannot delete inventory "
                           "%(rc_str)s for resource provider %(rp_uuid)s "
                           "because the inventory is in use.")
-                msg_args = {
-                    'rp_uuid': rp_uuid,
-                    'rc_str': rc_str,
-                    'placement_req_id': placement_req_id,
-                }
+                msg_args['rc_str'] = rc_str
                 LOG.warning(msg, msg_args)
                 return
 
         msg = _LE("[%(placement_req_id)s] Failed to delete inventory for "
-                  "resource provider %(rp_uuid)s. Got error response: %(err)s")
-        msg_args = {
-            'rp_uuid': rp_uuid,
-            'err': r.text,
-            'placement_req_id': placement_req_id,
-        }
+                  "resource provider %(rp_uuid)s. Got error response: "
+                  "%(err)s.")
+        msg_args['err'] = r.text
         LOG.error(msg, msg_args)
 
     def set_inventory_for_provider(self, rp_uuid, rp_name, inv_data):