(DBOS co-founder here) DBOS does exactly this! From the post:
DBOS has a special @DBOS.Transaction decorator. This runs the entire step inside a Postgres transaction. This guarantees exactly-once execution for databases transactional steps.
DBOS has a special @DBOS.Transaction decorator. This runs the entire step inside a Postgres transaction. This guarantees exactly-once execution for databases transactional steps.
@app.get("/background/{task_id}/{n}")
def launch_background_task(task_id: str, n: int) -> None:
with SetWorkflowID(task_id): # Set an idempotency key
DBOS.start_workflow(background_task, n) # Start the workflow in the background
Suppose you had an existing postgres-backed CRUD app with existing postgres transactions, and you want to add a feature to launch a workflow _atomically_ within an existing transaction, can you do that? (I.e. can the DBOS transaction be a nested transaction within a transaction defined outside the DBOS library?)
We don't currently support launching a workflow atomically from within an existing database transaction. I'd love to learn about the use case for that!
We do support calling a database transaction as a workflow step, which executes entirely atomically and exactly-once: https://docs.dbos.dev/python/tutorials/transaction-tutorial
(The background task may involve its own transactions when dequeued later, and spawn further background tasks, etc)
@app.get("/endpoint")
@DBOS.workflow()
def http_workflow():
synchronous_task() # Run the synchronous task
DBOS.start_workflow(background_task) # Start the background task asynchronously