Refactor async runtimes support (#88)

* refactor async runtimes support

ntex-async-std/src/lib.rs

@@ -0,0 +1,64 @@
+use std::{io::Result, net, net::SocketAddr};
+
+use ntex_bytes::PoolRef;
+use ntex_io::Io;
+
+mod io;
+mod signals;
+
+pub use self::signals::{signal, Signal};
+
+#[derive(Clone)]
+struct TcpStream(async_std::net::TcpStream);
+
+#[cfg(unix)]
+#[derive(Clone)]
+struct UnixStream(async_std::os::unix::net::UnixStream);
+
+/// Opens a TCP connection to a remote host.
+pub async fn tcp_connect(addr: SocketAddr) -> Result<Io> {
+    let sock = async_std::net::TcpStream::connect(addr).await?;
+    sock.set_nodelay(true)?;
+    Ok(Io::new(TcpStream(sock)))
+}
+
+/// Opens a TCP connection to a remote host and use specified memory pool.
+pub async fn tcp_connect_in(addr: SocketAddr, pool: PoolRef) -> Result<Io> {
+    let sock = async_std::net::TcpStream::connect(addr).await?;
+    sock.set_nodelay(true)?;
+    Ok(Io::with_memory_pool(TcpStream(sock), pool))
+}
+
+#[cfg(unix)]
+/// Opens a unix stream connection.
+pub async fn unix_connect<P>(addr: P) -> Result<Io>
+where
+    P: AsRef<async_std::path::Path>,
+{
+    let sock = async_std::os::unix::net::UnixStream::connect(addr).await?;
+    Ok(Io::new(UnixStream(sock)))
+}
+
+#[cfg(unix)]
+/// Opens a unix stream connection and specified memory pool.
+pub async fn unix_connect_in<P>(addr: P, pool: PoolRef) -> Result<Io>
+where
+    P: AsRef<async_std::path::Path>,
+{
+    let sock = async_std::os::unix::net::UnixStream::connect(addr).await?;
+    Ok(Io::with_memory_pool(UnixStream(sock), pool))
+}
+
+/// Convert std TcpStream to async-std's TcpStream
+pub fn from_tcp_stream(stream: net::TcpStream) -> Result<Io> {
+    stream.set_nonblocking(true)?;
+    stream.set_nodelay(true)?;
+    Ok(Io::new(TcpStream(async_std::net::TcpStream::from(stream))))
+}
+
+#[cfg(unix)]
+/// Convert std UnixStream to async-std's UnixStream
+pub fn from_unix_stream(stream: std::os::unix::net::UnixStream) -> Result<Io> {
+    stream.set_nonblocking(true)?;
+    Ok(Io::new(UnixStream(From::from(stream))))
+}