Module reload

Available on crate feature std only.

Wrapper for a Layer to allow it to be dynamically reloaded.

This module provides a Layer type implementing the Layer trait or Filter trait which wraps another type implementing the corresponding trait. This allows the wrapped type to be replaced with another instance of that type at runtime.

This can be used in cases where a subset of Layer or Filter functionality should be dynamically reconfigured, such as when filtering directives may change at runtime. Note that this layer introduces a (relatively small) amount of overhead, and should thus only be used as needed.

Examples

Reloading a global filtering layer:

use tracing_subscriber::{filter, fmt, reload, prelude::*};
let filter = filter::LevelFilter::WARN;
let (filter, reload_handle) = reload::Layer::new(filter);
tracing_subscriber::registry()
  .with(filter)
  .with(fmt::Layer::default())
  .init();
info!("This will be ignored");
reload_handle.modify(|filter| *filter = filter::LevelFilter::INFO);
info!("This will be logged");

Reloading a Filtered layer:

use tracing_subscriber::{filter, fmt, reload, prelude::*};
let filtered_layer = fmt::Layer::default().with_filter(filter::LevelFilter::WARN);
let (filtered_layer, reload_handle) = reload::Layer::new(filtered_layer);
tracing_subscriber::registry()
  .with(filtered_layer)
  .init();
info!("This will be ignored");
reload_handle.modify(|layer| *layer.filter_mut() = filter::LevelFilter::INFO);
info!("This will be logged");

Note

The Layer implementation is unable to implement downcasting functionality, so certain Layer will fail to downcast if wrapped in a reload::Layer.

If you only want to be able to dynamically change the Filter on a layer, prefer wrapping that Filter in the reload::Layer.

Structs

• Error
  Indicates that an error occurred when reloading a layer.
• Handle
  Allows reloading the state of an associated Layer.
• Layer
  Wraps a Layer or Filter, allowing it to be reloaded dynamically at runtime.