Commit transactions as soon no longer needed

We think that holding open database transactions while we go and do
something else is causing us to have poor performance.

Because we’re not serialising everything as soon as we pull it out of
the database we can guarantee that we don’t need to go back to the
database again.

So let’s see if explicitly closing the transaction helps with
performance.

app/serialised_models.py

@@ -7,7 +7,7 @@ import cachetools
 from notifications_utils.clients.redis import RequestCache
 from werkzeug.utils import cached_property
 
-from app import redis_store
+from app import db, redis_store
 
 from app.dao import templates_dao
 from app.dao.api_key_dao import get_model_api_keys
@@ -109,6 +109,7 @@ class SerialisedTemplate(SerialisedModel):
         )
 
         template_dict = template_schema.dump(fetched_template).data
+        db.session.commit()
 
         return {'data': template_dict}
 
@@ -132,7 +133,10 @@ class SerialisedService(SerialisedModel):
     def get_dict(service_id):
         from app.schemas import service_schema
 
-        return service_schema.dump(dao_fetch_service_by_id(service_id)).data
+        service_dict = service_schema.dump(dao_fetch_service_by_id(service_id)).data
+        db.session.commit()
+
+        return service_dict
 
     @cached_property
     def api_keys(self):
@@ -153,7 +157,9 @@ class SerialisedAPIKeyCollection(SerialisedModelCollection):
 
     @classmethod
     def from_service_id(cls, service_id):
-        return cls([
+        keys = [
             {k: getattr(key, k) for k in SerialisedAPIKey.ALLOWED_PROPERTIES}
             for key in get_model_api_keys(service_id)
-        ])
+        ]
+        db.session.commit()
+        return cls(keys)