chore(docs): Add an example for the UnixListenerExt trait

util/src/mio/mio.rs

@@ -21,6 +21,44 @@ pub mod interest {
 }
 
 /// Extension trait providing additional functionality for Unix listener
+///
+/// # Example
+///
+/// ```rust
+/// use mio::net::{UnixListener, UnixStream};
+/// use rosenpass_util::mio::{UnixListenerExt, UnixStreamExt};
+///
+/// use std::os::unix::io::{AsRawFd, IntoRawFd, RawFd};
+/// use std::path::Path;
+///
+/// // This would be the UDS created by an external source
+/// let socket_path = "/tmp/rp_mio_uds_test_socket";
+/// if Path::new(socket_path).exists() {
+///     std::fs::remove_file(socket_path).expect("Failed to remove existing socket");
+/// }
+///
+/// // An extended MIO listener can then be created by claiming the existing socket
+/// // Note that the original descriptor is not reused, but copied before claiming it here
+/// let listener = UnixListener::bind(socket_path).unwrap();
+/// let listener_fd: RawFd = listener.as_raw_fd();
+/// let ext_listener = <UnixListener as UnixListenerExt>
+///     ::claim_fd(listener_fd).expect("Failed to claim_fd for ext_listener socket");
+///
+/// // Similarly, "client" connections can be established by claiming existing sockets
+/// // Note that in this case, the file descriptor will be reused (safety implications!)
+/// let stream = UnixStream::connect(socket_path).unwrap();
+/// let stream_fd = stream.into_raw_fd();
+/// let ext_stream = <UnixStream as UnixStreamExt>
+///     ::claim_fd_inplace(stream_fd).expect("Failed to claim_fd_inplace for ext_stream socket");
+///
+/// // Handle accepted connections...
+/// ext_listener.accept().expect("Failed to accept incoming connection");
+///
+/// // Send or receive messages ...
+///
+/// // Cleanup, shutdown etc. goes here ...
+/// std::fs::remove_file(socket_path).unwrap();
+/// ```
 pub trait UnixListenerExt: Sized {
     /// Creates a new Unix listener by claiming ownership of a raw file descriptor
     fn claim_fd(fd: RawFd) -> anyhow::Result<Self>;