Open a session on the slot.
If the 'auto reuse' setting is set, then this may be a recycled session with the same flags.
This call will return immediately and complete asynchronously.
| this |
The slot to open a session on. |
| options |
The options to open the new session with. |
| cancellable |
Optional cancellation object, or |
| callback |
Called when the operation completes. |
| user_data |
Data to pass to the callback. |