arti: use 128 KB socket buffers for proxy sockets

        );

    }

    // We don't (yet) use any custom options on the listening socket.

    let listen_options = Default::default();

    // Our proxy sockets will use a small-ish fixed kernel socket buffer size.

    // Tor streams are slow relative to a pair of loopback sockets,

    // so don't need socket buffers as large as what Linux provides by default

    // (sometimes several MBs).

    //

    // This has a few advantages over the defaults:

    // - Less buffer bloat.

    // - Better ability to make congestion/flow control decisions.

    // - Disables TCP autotuning, which means behaviour will better match Shadow sims.

    // - Easier to reason about stream performance when the buffer size isn't dynamic.

    //

    // See https://gitlab.torproject.org/tpo/core/arti/-/work_items/2500.

    let mut listen_options = tor_rtcompat::TcpListenOptions::builder();

    listen_options

        .common()

        .send_buffer_size(Some(128_000))

        .recv_buffer_size(Some(128_000));

    let listen_options = listen_options.build()?;

    let mut listeners = Vec::new();