Trait MailboxDepthObserver 

pub trait MailboxDepthObserver:
    Send
    + Sync
    + 'static {
    // Required method
    fn on_depth_change(&self, queued_messages: usize);
}

Observer notified whenever a Mailbox implementation observes a change in its queue depth.

Installed on a mailbox via Mailbox::set_depth_observer. Backends that cannot cheaply report depth on every enqueue may return false from that method, in which case consumers must fall back to periodic polling via Mailbox::status.

The observer is called synchronously from the enqueue code path; implementations should therefore keep their work short (typically a bounded try_send into a channel). Implementations must not block the enqueue path and must tolerate missed notifications.

Required Methods

fn on_depth_change(&self, queued_messages: usize)

Called after an enqueue completes, carrying the post-enqueue queued-message count.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors