Type Alias PrometheusUpdateCallback 

pub type PrometheusUpdateCallback = Arc<dyn Fn() -> Result<()> + Send + Sync + 'static>;

Type alias for runtime callback functions to reduce complexity

This type represents an Arc-wrapped callback function that can be:

• Shared efficiently across multiple threads and contexts
• Cloned without duplicating the underlying closure
• Used in generic contexts requiring ’static lifetime

The Arc wrapper is included in the type to make sharing explicit.

Aliased Type

pub struct PrometheusUpdateCallback { /* private fields */ }