Comment 6 for bug 1841634

> Okay, so that part of dbCa changed in 3.16 without my realizing it

cf. https://code.launchpad.net/~epics-core/epics-base/dbscan-update/+merge/245680

I hide it right at the top of the diff?

> I see little point in processing the record more than once

Fine with me. I can't recall where the 5 times came from.

> modify onceTask to give it a more general callback mechanism

In terms of complexity, this seems not far away from callbackRequest().
Why not just use that? This would also have the side effect of making
.PRIO meaningful for CP links.