Function spawn_controlled 

pub fn spawn_controlled<T>(t: T) -> ControlledHandle
where
    T: Future + Send + 'static,
    T::Output: Send + 'static,

Spawns a new task returning an abort handle for it.

It is similar to tokio::task::spawn but instad of returning a JoinHandle it will return an ControlledHandle. The ControlledHandle can be used to directly abort the task that was spawned. ControlledHandle can be cloned resulting in a new handle to the same underlying task. Dropping all ControlledHandle instances pointing to a given task will result in the abort of that task.

The use case this function is tasks that “run in the background” and are tied to a specific object. We attach the ControlledHandle to the object in question so that the background task is “dropped” (aborted) when the object is dropped.