Enum Finalizer 

pub enum Finalizer {
    Sync(Box<dyn FnOnce() + Send>),
    Async(Pin<Box<dyn Future<Output = ()> + Send>>),
}

A finalizer that runs during region close.

Finalizers are stored in a stack and executed LIFO when a region transitions to the Finalizing state. This ensures resources are released in the reverse order they were acquired.

Variants

Sync(Box<dyn FnOnce() + Send>)

Synchronous finalizer (runs directly on scheduler thread).

Use for lightweight cleanup that doesn’t need to await.

Async(Pin<Box<dyn Future<Output = ()> + Send>>)

Asynchronous finalizer (runs as masked task).

Use for cleanup that needs to perform async operations. Runs under a cancel mask to prevent interruption.

Trait Implementations

impl Debug for Finalizer

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.