db: Remove unnecessary use of '_mapping'

Now that we've addressed the SQLAlchemy 2.0 issues, we can focus on
cleaning things up. Replace uses of '_mapping' with explicit references
to the fields.

Change-Id: I3da80bebac4a2013a3c7cbf128615c19eb836735
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

placement/objects/allocation.py

@@ -163,12 +163,11 @@ def _check_capacity_exceeded(ctx, allocs):
     usage_map = {}
     provs_with_inv = set()
     for record in records:
-        record = record._mapping
-        map_key = (record['uuid'], record['resource_class_id'])
+        map_key = (record.uuid, record.resource_class_id)
         if map_key in usage_map:
             raise KeyError("%s already in usage_map, bad query" % str(map_key))
         usage_map[map_key] = record
-        provs_with_inv.add(record["uuid"])
+        provs_with_inv.add(record.uuid)
     # Ensure that all providers have existing inventory
     missing_provs = provider_uuids - provs_with_inv
     if missing_provs:
@@ -199,10 +198,10 @@ def _check_capacity_exceeded(ctx, allocs):
             raise exception.InvalidInventory(
                 resource_class=alloc.resource_class,
                 resource_provider=rp_uuid)
-        allocation_ratio = usage['allocation_ratio']
-        min_unit = usage['min_unit']
-        max_unit = usage['max_unit']
-        step_size = usage['step_size']
+        allocation_ratio = usage.allocation_ratio
+        min_unit = usage.min_unit
+        max_unit = usage.max_unit
+        step_size = usage.step_size
 
         # check min_unit, max_unit, step_size
         if (amount_needed < min_unit or amount_needed > max_unit or
@@ -222,9 +221,9 @@ def _check_capacity_exceeded(ctx, allocs):
                 resource_class=alloc.resource_class,
                 resource_provider=rp_uuid)
 
-        # usage["used"] can be returned as None
-        used = usage['used'] or 0
-        capacity = (usage['total'] - usage['reserved']) * allocation_ratio
+        # usage.used can be returned as None
+        used = usage.used or 0
+        capacity = (usage.total - usage.reserved) * allocation_ratio
         if (capacity < (used + amount_needed) or
                 capacity < (used + rp_resource_class_sum[rp_uuid][rc_id])):
             LOG.warning(

placement/objects/allocation_candidate.py

@@ -526,8 +526,7 @@ def _build_provider_summaries(context, rw_ctx, root_ids, prov_traits):
     # ProviderSummary objects containing one or more ProviderSummaryResource
     # objects representing the resources the provider has inventory for.
     for usage in usages:
-        usage = usage._mapping
-        rp_id = usage['resource_provider_id']
+        rp_id = usage.resource_provider_id
         summary = rw_ctx.summaries_by_id.get(rp_id)
         if not summary:
             pids = provider_ids[rp_id]
@@ -550,7 +549,7 @@ def _build_provider_summaries(context, rw_ctx, root_ids, prov_traits):
             summary.traits = prov_traits[rp_id]
             rw_ctx.summaries_by_id[rp_id] = summary
 
-        rc_id = usage['resource_class_id']
+        rc_id = usage.resource_class_id
         if rc_id is None:
             # NOTE(tetsuro): This provider doesn't have any inventory itself.
             # But we include this provider in summaries since another
@@ -558,20 +557,20 @@ def _build_provider_summaries(context, rw_ctx, root_ids, prov_traits):
             # Let's skip the following and leave "ProviderSummary.resources"
             # field empty.
             continue
-        # NOTE(jaypipes): usage['used'] may be None due to the LEFT JOIN of
+        # NOTE(jaypipes): usage.used may be None due to the LEFT JOIN of
         # the usages subquery, so we coerce NULL values to 0 here. It may
         # also be a Decimal, as that's the type that mysql tends to return
         # when func.sum is used in a query. We need an int, otherwise later
         # JSON serialization will not work.
-        used = int(usage['used'] or 0)
-        allocation_ratio = usage['allocation_ratio']
-        cap = int((usage['total'] - usage['reserved']) * allocation_ratio)
+        used = int(usage.used or 0)
+        allocation_ratio = usage.allocation_ratio
+        cap = int((usage.total - usage.reserved) * allocation_ratio)
         rc_name = context.rc_cache.string_from_id(rc_id)
         rpsr = ProviderSummaryResource(
             resource_class=rc_name,
             capacity=cap,
             used=used,
-            max_unit=usage['max_unit'],
+            max_unit=usage.max_unit,
         )
         # Construct a dict, keyed by resource provider + resource class, of
         # ProviderSummaryResource. This will be used to do a final capacity
@@ -945,5 +944,5 @@ def _provider_ids_from_root_ids(context, root_ids):
 
     ret = {}
     for r in context.session.execute(sel, {'root_ids': list(root_ids)}):
-        ret[r._mapping['id']] = r
+        ret[r.id] = r
     return ret

placement/objects/resource_class.py

@@ -68,9 +68,14 @@ class ResourceClass(object):
 
         :raises: ResourceClassNotFound if no such resource class was found
         """
-        rc = context.rc_cache.all_from_string(name)._mapping
-        obj = cls(context, id=rc['id'], name=rc['name'],
-                  updated_at=rc['updated_at'], created_at=rc['created_at'])
+        rc = context.rc_cache.all_from_string(name)
+        obj = cls(
+            context,
+            id=rc.id,
+            name=rc.name,
+            updated_at=rc.updated_at,
+            created_at=rc.created_at,
+        )
         return obj
 
     @staticmethod

placement/objects/resource_provider.py

@@ -140,10 +140,12 @@ def _update_inventory_for_provider(ctx, rp, inv_list, to_update):
             sa.and_(
                 _ALLOC_TBL.c.resource_provider_id == rp.id,
                 _ALLOC_TBL.c.resource_class_id == rc_id))
-        allocations = ctx.session.execute(allocation_query).first()._mapping
-        if (allocations and
-                allocations['usage'] is not None and
-                allocations['usage'] > inv_record.capacity):
+        allocations = ctx.session.execute(allocation_query).first()
+        if (
+            allocations and
+            allocations.usage is not None and
+            allocations.usage > inv_record.capacity
+        ):
             exceeded.append((rp.uuid, rc_str))
         upd_stmt = _INV_TBL.update().where(
             sa.and_(