Workload prioritization was added in scylladb/scylladb#22031.
The functionality of updating service levels was implemented as
a lambda coroutine, leaving room for the lambda coroutine fiasco.
The problem was noticed and addressed in scylladb/scylladb#26404.
There are currently three functions that call switch_tenant:
- update_user_scheduling_group_v1 and update_user_scheduling_group_v2
use the deducing this (this auto self) to ensure the proper
lifecycle of the lambda capture.
- update_control_connection_scheduling_group doesn’t use the deducing
this, but the lambda captures only `this`, which is used before
the first possible coroutine preemption. Therefore, it doesn’t seem
that any memory corruption or undefined behavior is possible here.
Nevertheless, it seems better to start using the deducing this in
update_control_connection_scheduling_group as well, to avoid problems
in the future if someone modifies the code and forgets to add it.
Fixes: SCYLLADB-284
Closesscylladb/scylladb#28158
6eca7e4ff6