before this change, alternator_timeout_in_ms is not live-updatable,
as after setting executor's default timeout right before creating
sharded executor instances, they never get updated with this option
anymore. but many users would like to set the driver timers based on
server timers. we need to enable them to configure timeout even
when the server is still running.
in this change,
* `alternator_timeout_in_ms` is marked as live-updateable
* `executor::_s_default_timeout` is changed to a thread_local variable,
so it can be updated by a per-shard updateable_value. and
it is now a updateable_value, so its variable name is updated
accordingly. this value is set in the ctor of executor, and
it is disconnected from the corresponding named_value<> option
in the dtor of executor.
* alternator_timeout_in_ms is passed to the constructor of
executor via sharded_parameter, so `executor::_timeout_in_ms` can
be initialized on per-shard basis
* `executor::set_default_timeout()` is dropped, as we already pass
the option to executor in its ctor.
Fixes#12232Closes#13300
* github.com:scylladb/scylladb:
alternator: split the param list of executor ctor into multi lines
alternator,config: make alternator_timeout_in_ms live-updateable
0cff0ffa08