Currently when we set a single value we need
to call broadcast_to_all_shards to let observers on all
shards get notified of the new value.
However, the latter broadcasts all value to all shards
so it's terribly inefficient.
Instead, add async set_value_on_all_shards functions
to broadcast a value to all shards.
Use those in system_keyspace for db_config_table virtual table
and in task_manager_test to update the task_manager ttl.
Refs #7316
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
parent_data struct contains info that is common for each task,
not only in parent-child relationship context. To use it this way
without confusion, its name is changed to task_info.
In order to be able to widely and comfortably use task_info,
it is moved from tasks/task_manager.hh to tasks/types.hh
and slightly extended.
The implementation of a test api that helps testing task manager
api. It provides methods to simulate the operations that can happen
on modules and theirs task. Through the api user can: register
and unregister the test module and the tasks belonging to the module,
and finish the tasks with success or custom error.
