OptionalbudgetOptionalbudgetOptionalconcurrencyhow many operations run at once; the budget still paces the requests inside them
OptionalcursorOptionalfailstop at the first failure instead of finishing and reporting
Optionaloncalled as each one finishes, for a progress line
OptionalonCalled with a copy of the cursor after every state change, so a caller can persist it.
A throw stops the apply and rejects with that error, as a failed durable write would.
how many actions to start before handing a cursor back