db/block_device_mapping/api: introduce update_or_create

introduce db.block_device_mapping_udpate_or_create() which
update the colume if exists. Create new column if not existed.
This api will be used later for block device mapping tracking.

2 files changed, 24 insertions, 1 deletions

diff --git a/nova/db/api.py b/nova/db/api.py
index 8f8e856b8..d77d0c352 100644
--- a/nova/db/api.py
+++ b/nova/db/api.py
@@ -936,10 +936,16 @@ def block_device_mapping_create(context, values):
 
 
 def block_device_mapping_update(context, bdm_id, values):
-    """Create an entry of block device mapping"""
+    """Update an entry of block device mapping"""
     return IMPL.block_device_mapping_update(context, bdm_id, values)
 
 
+def block_device_mapping_update_or_create(context, values):
+    """Update an entry of block device mapping.
+    If not existed, create a new entry"""
+    return IMPL.block_device_mapping_update_or_create(context, values)
+
+
 def block_device_mapping_get_all_by_instance(context, instance_id):
     """Get all block device mapping belonging to a instance"""
     return IMPL.block_device_mapping_get_all_by_instance(context, instance_id)
diff --git a/nova/db/sqlalchemy/api.py b/nova/db/sqlalchemy/api.py
index a2500a38d..7108c7a7a 100644
--- a/nova/db/sqlalchemy/api.py
+++ b/nova/db/sqlalchemy/api.py
@@ -1933,6 +1933,23 @@ def block_device_mapping_update(context, bdm_id, values):
 
 
 @require_context
+def block_device_mapping_update_or_create(context, values):
+    session = get_session()
+    with session.begin():
+        result = session.query(models.BlockDeviceMapping).\
+                 filter_by(instance_id=values['instance_id']).\
+                 filter_by(device_name=values['device_name']).\
+                 filter_by(deleted=False).\
+                 first()
+        if not result:
+            bdm_ref = models.BlockDeviceMapping()
+            bdm_ref.update(values)
+            bdm_ref.save(session=session)
+        else:
+            result.update(values)
+
+
+@require_context
 def block_device_mapping_get_all_by_instance(context, instance_id):
     session = get_session()
     result = session.query(models.BlockDeviceMapping).\