Function maybe_spawn_encode

crates/client-api/src/routes/subscribe.rs:1775–1781

Run `encode` on Rayon when the payload is expected to be large. Small payloads stay on the async task to avoid Rayon scheduling overhead.

(is_large: bool, encode: impl FnOnce() -> T + Send + 'static)

///
/// Small payloads stay on the async task to avoid Rayon scheduling overhead.
async fn maybe_spawn_encode<T: Send + 'static>(is_large: bool, encode: impl FnOnce() -> T + Send + 'static) -> T {
    if is_large {
        spawn_rayon(encode).await
    } else {
        encode()
    }
}

/// Measure serialization/compression time for one websocket payload.
fn time_encode<T>(encode: impl FnOnce() -> (InUseSerializeBuffer, T)) -> (Duration, InUseSerializeBuffer, T) {