// so we allocate immediately, but defer release.
// On commit we best-effort release the deferred releases.
// On rollback we best-effort release any allocations we did.
//
// Pattern for use:
//
//	op := StartPortAllocationOperation(...)
//	defer op.Finish
//	...
//	write(updatedOwner)
//
// /  op.Commit()
type PortAllocationOperation struct {
	pa              Interface
	allocated       []int
	releaseDeferred []int