def _update_counters(self, ti_status):
        """
        
        """
        for key, ti in list(ti_status.running.items()):
            ti.refresh_from_db()
            if ti.state == State.SUCCESS:
                ti_status.succeeded.add(key)
                self.log.debug("Task instance %s succeeded. Don't rerun.", ti)
                ti_status.running.pop(key)
                continue
            elif ti.state == State.SKIPPED:
                ti_status.skipped.add(key)
                self.log.debug("Task instance %s skipped. Don't rerun.", ti)
                ti_status.running.pop(key)
                continue
            elif ti.state == State.FAILED:
                self.log.error("Task instance %s failed", ti)
                ti_status.failed.add(key)
                ti_status.running.pop(key)
                continue
            # special case: if the task needs to run again put it back
            elif ti.state == State.UP_FOR_RETRY:
                self.log.warning("Task instance %s is up for retry", ti)
                ti_status.running.pop(key)
                ti_status.to_run[key] = ti
            # special case: if the task needs to be rescheduled put it back
            elif ti.state == State.UP_FOR_RESCHEDULE:
                self.log.warning("Task instance %s is up for reschedule", ti)
                ti_status.running.pop(key)
                ti_status.to_run[key] = ti
            # special case: The state of the task can be set to NONE by the task itself
            # when it reaches concurrency limits. It could also happen when the state
            # is changed externally, e.g. by clearing tasks from the ui. We need to cover
            # for that as otherwise those tasks would fall outside of the scope of
            # the backfill suddenly.
            elif ti.state == State.NONE:
                self.log.warning(
                    "FIXME: task instance %s state was set to none externally or "
                    "reaching concurrency limits. Re-adding task to queue.",
                    ti
                )
                ti.set_state(State.SCHEDULED)
                ti_status.running.pop(key)
                ti_status.to_run[key] = ti