Struct ConfigWatcher 

pub struct ConfigWatcher<T> { /* private fields */ }

A handle to a configuration that is automatically reloaded when any of its source files change.

• get returns the current snapshot without locking, cheap enough to call on every request;
• when a reload fails, the previous configuration stays active and the error is reported through on_error;
• dropping the watcher stops the background thread.

Created by ConfigBuilder::watch.

Implementations

impl<T> ConfigWatcher<T>

pub fn get(&self) -> Arc<T>

Returns the currently active configuration snapshot.

Lock-free (backed by arc-swap), so it can be called freely on hot paths and from any thread. The returned Arc stays valid even if the configuration is swapped out in the meantime.

pub fn on_change(&self, callback: impl Fn(Arc<T>) + Send + Sync + 'static)

Registers a callback invoked after each successful reload with the new configuration.

Callbacks may be registered multiple times and run on the background watcher thread — keep them short and non-blocking. A callback that panics will terminate that thread and stop hot reloading.

pub fn on_error(&self, callback: impl Fn(&Error) + Send + Sync + 'static)

Registers a callback invoked when a reload fails.

The previous configuration remains active in that case. Runs on the background watcher thread, same caveats as on_change.

Trait Implementations

impl<T> Drop for ConfigWatcher<T>

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.