[Twisted-Python] advice sought - two database connections in a RunInteraction (adbapi.ConnectionPool)

[Jonathan Vanasco]

I've got some database transactional code running within a thread via RunInteraction (it needs to rollback on error).

One of the features on the logic is that it interacts with a 3rd party API, which may or may not have a ratelimit in effect.  Most 3rd party APIs i consume have a minute/hourly based limit -- so I just do a graceful fail on the transaction to requeue it, and set a local timeout.  

This particular API has a per-second meter in effect.  It is considerably more efficient to just sleep for a second and "try again" a second later.  I end up being able to process over twice as many API calls in a given period with that strategy.

The problem I ran into, is that I need a second database connection to note that a ratelimit has been created in the database -- and i'd like to pull that db connection out of the twisted connection pool to simplify my connection management.

- I can't do it within the existing connection, because I am in a transaction and the limit won't appear to other twisted jobs.  
- I can't use runInteraction() off the pool, because that will defer to a thread and I am in a thread, and the last time I did something like that... everything broke.
- the stopgap I have right now is just creating/closing a raw pscycopg2 connection and using that.  it works, but it requires a bit more management of postgres to ensure I can balance the right number of connections.

has anyone had a need like this before?  if so, what did you do?  

i basically just need to make two "INSERT" statements from a second connection.