Provide a high level overview of task statuses
for a set of task ids, being the count in major categories of
PENDING, RUNNING, COMPLETE and ERROR.
rrq_task_overview(task_ids = NULL, controller = NULL)Optional character vector of task ids for which
you would like the overview. If not given (or NULL) then the
status of all task ids known to this rrq controller is used
(this might be fairly costly).
The controller to use. If not given (or NULL)
we'll use the controller registered with
rrq_default_controller_set().
A list with names corresponding to possible task status levels and values being the number of tasks in that state.