tokio: make try_io methods call mio's try_io internally

A user defined I/O closure should be called by mio's try_io to ensure
that the I/O receives more events if it hits a WouldBlock error.

Fixes: #4510

tokio/src/net/tcp/stream.rs

@@ -968,7 +968,7 @@ impl TcpStream {
         interest: Interest,
         f: impl FnOnce() -> io::Result<R>,
     ) -> io::Result<R> {
-        self.io.registration().try_io(interest, f)
+        self.io.registration().try_io(interest, || self.io.try_io(f))
     }
 
     /// Receives data on the socket from the remote address to which it is

tokio/src/net/udp.rs

@@ -1272,7 +1272,7 @@ impl UdpSocket {
         interest: Interest,
         f: impl FnOnce() -> io::Result<R>,
     ) -> io::Result<R> {
-        self.io.registration().try_io(interest, f)
+        self.io.registration().try_io(interest, || self.io.try_io(f))
     }
 
     /// Receives data from the socket, without removing it from the input queue.

tokio/src/net/unix/datagram/socket.rs

@@ -1241,7 +1241,7 @@ impl UnixDatagram {
         interest: Interest,
         f: impl FnOnce() -> io::Result<R>,
     ) -> io::Result<R> {
-        self.io.registration().try_io(interest, f)
+        self.io.registration().try_io(interest, || self.io.try_io(f))
     }
 
     /// Returns the local address that this socket is bound to.

tokio/src/net/unix/stream.rs

@@ -685,7 +685,7 @@ impl UnixStream {
         interest: Interest,
         f: impl FnOnce() -> io::Result<R>,
     ) -> io::Result<R> {
-        self.io.registration().try_io(interest, f)
+        self.io.registration().try_io(interest, || self.io.try_io(f))
     }
 
     /// Creates new `UnixStream` from a `std::os::unix::net::UnixStream`.