async.rs

#[cfg(all(feature = "tokio-runtime", feature = "async-std-runtime"))]
compile_error!(
    "exactly one of the `tokio-runtime` and `async-std-runtime` features must be chosen"
);

#[cfg(all(not(feature = "tokio-runtime"), not(feature = "async-std-runtime")))]
compile_error!(
    "exactly one of the `tokio-runtime` and `async-std-runtime` features must be chosen"
);

use std::future::Future;

use mongodb::{error::Result, options::StreamAddress};

trait AsyncRuntimeHandle {
    type AsyncRead;
    type AsyncWrite;
    type Mutex;
    type MutexGuard;
    type TcpStream: AsyncRead + AsyncWrite;
    type ToSocketAddrs;

    fn new() -> Self;

    fn tcp_stream_new(
        addresses: impl IntoIterator<Item = StreamAddress>,
    ) -> Result<Self::TcpStream>;

    fn spawn_task<F, H, T>(future: F) -> H
    where
        H: Future<Output = T>,
        F: Future<Output = T> + Send + 'static,
        T: Send + 'static;
}

#[cfg(feature = "async-std-runtime")]
mod async_std;

#[cfg(feature = "tokio-runtime")]
mod tokio;

#[cfg(feature = "async-std-runtime")]
use async_std::AsyncRuntime;

#[cfg(feature = "tokio-runtime")]
use tokio::AsyncRuntime;