After SERVER-98084 and SERVER-98126, we will now have access to a session registry and also concurrency control to make it safe for us to access these sessions and find the correct one. After finding the correct session we handle the rollback request on that session from the rollback event handler. WiredTiger prohibits calling into the API from an event handler. To get around this we can fire off a background task in the server to process the rollback request.

Testing considerations:

• Ensure the right session is rolled back. 

• Mock a testing environment to make this predictable, e.g  having server call the event handler in place of WT's calls and testing this way.