tokio 0.3.0

#![warn(rust_2018_idioms)]
#![cfg(feature = "full")]
#![cfg(unix)]

use tokio::net::UnixDatagram;
use tokio::try_join;

use std::io;
use std::sync::Arc;

async fn echo_server(socket: UnixDatagram) -> io::Result<()> {
    let mut recv_buf = vec![0u8; 1024];
    loop {
        let (len, peer_addr) = socket.recv_from(&mut recv_buf[..]).await?;
        if let Some(path) = peer_addr.as_pathname() {
            socket.send_to(&recv_buf[..len], path).await?;
        }
    }
}

#[tokio::test]
async fn echo() -> io::Result<()> {
    let dir = tempfile::tempdir().unwrap();
    let server_path = dir.path().join("server.sock");
    let client_path = dir.path().join("client.sock");

    let server_socket = UnixDatagram::bind(server_path.clone())?;

    tokio::spawn(async move {
        if let Err(e) = echo_server(server_socket).await {
            eprintln!("Error in echo server: {}", e);
        }
    });

    {
        let socket = UnixDatagram::bind(&client_path).unwrap();
        socket.connect(server_path)?;
        socket.send(b"ECHO").await?;
        let mut recv_buf = [0u8; 16];
        let len = socket.recv(&mut recv_buf[..]).await?;
        assert_eq!(&recv_buf[..len], b"ECHO");
    }

    Ok(())
}

#[tokio::test]
async fn echo_from() -> io::Result<()> {
    let dir = tempfile::tempdir().unwrap();
    let server_path = dir.path().join("server.sock");
    let client_path = dir.path().join("client.sock");

    let server_socket = UnixDatagram::bind(server_path.clone())?;

    tokio::spawn(async move {
        if let Err(e) = echo_server(server_socket).await {
            eprintln!("Error in echo server: {}", e);
        }
    });

    {
        let socket = UnixDatagram::bind(&client_path).unwrap();
        socket.connect(&server_path)?;
        socket.send(b"ECHO").await?;
        let mut recv_buf = [0u8; 16];
        let (len, addr) = socket.recv_from(&mut recv_buf[..]).await?;
        assert_eq!(&recv_buf[..len], b"ECHO");
        assert_eq!(addr.as_pathname(), Some(server_path.as_path()));
    }

    Ok(())
}

// Even though we use sync non-blocking io we still need a reactor.
#[tokio::test]
async fn try_send_recv_never_block() -> io::Result<()> {
    let mut recv_buf = [0u8; 16];
    let payload = b"PAYLOAD";
    let mut count = 0;

    let (dgram1, dgram2) = UnixDatagram::pair()?;

    // Send until we hit the OS `net.unix.max_dgram_qlen`.
    loop {
        match dgram1.try_send(payload) {
            Err(err) => match err.kind() {
                io::ErrorKind::WouldBlock | io::ErrorKind::Other => break,
                _ => unreachable!("unexpected error {:?}", err),
            },
            Ok(len) => {
                assert_eq!(len, payload.len());
            }
        }
        count += 1;
    }

    // Read every dgram we sent.
    while count > 0 {
        let len = dgram2.try_recv(&mut recv_buf[..])?;
        assert_eq!(len, payload.len());
        assert_eq!(payload, &recv_buf[..len]);
        count -= 1;
    }

    let err = dgram2.try_recv(&mut recv_buf[..]).unwrap_err();
    match err.kind() {
        io::ErrorKind::WouldBlock => (),
        _ => unreachable!("unexpected error {:?}", err),
    }

    Ok(())
}

#[tokio::test]
async fn split() -> std::io::Result<()> {
    let dir = tempfile::tempdir().unwrap();
    let path = dir.path().join("split.sock");
    let s = Arc::new(UnixDatagram::bind(path.clone())?);
    let r = s.clone();

    let msg = b"hello";
    let ((), ()) = try_join! {
        async {
            s.send_to(msg, path).await?;
            io::Result::Ok(())
        },
        async {
            let mut recv_buf = [0u8; 32];
            let (len, _) = r.recv_from(&mut recv_buf[..]).await?;
            assert_eq!(&recv_buf[..len], msg);
            Ok(())
        },
    }?;

    Ok(())
}