Race condition in `submit.py:post`

[ponyisi]

We have, in

ServiceX/servicex_app/servicex_app/resources/transformation/submit.py

Lines 258 to 268 in 0b7f40c

	dataset_manager.refresh()
	# If this request has a fresh DID then submit the lookup request to the DID Finder
	if dataset_manager.is_lookup_required:
	dataset_manager.submit_lookup_request(
	self._generate_advertised_endpoint(
	"servicex/internal/transformation/"
	),
	self.celery_app,
	)
	request_rec.status = TransformStatus.lookup

, a check on dataset_manager.is_lookup_required and then potentially a lookup request submission which changes the value of that property to prevent further lookups. It seems that it is currently possible for multiple processes to hit this check simultaneously for a single dataset and trigger multiple lookups (which corrupts the file records). This block needs to do a row lock on the relevant dataset.