zb: Make use of futures_core::ready! marco

This makes writing manual async impls easier and will hopefully be part
of the [std](rust-lang/rust#81050) (maybe under
a different name though).

Author: zeenix

zbus/src/azync/connection.rs

@@ -28,7 +28,7 @@ use std::{
 };
 use zvariant::ObjectPath;
 
-use futures_core::{stream, Future};
+use futures_core::{ready, stream, Future};
 use futures_sink::Sink;
 use futures_util::{
     future::{select, Either},
@@ -857,10 +857,9 @@ impl Sink<Message> for Connection {
 
     fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>> {
         let mut raw_out_conn = self.inner.raw_out_conn.lock().expect("poisened lock");
-        match raw_out_conn.flush(cx) {
-            Poll::Ready(Ok(_)) => (),
-            Poll::Ready(Err(e)) => return Poll::Ready(Err(e)),
-            Poll::Pending => return Poll::Pending,
+        match ready!(raw_out_conn.flush(cx)) {
+            Ok(_) => (),
+            Err(e) => return Poll::Ready(Err(e)),
         }
 
         Poll::Ready(raw_out_conn.close())
@@ -876,7 +875,7 @@ impl stream::Stream for Connection {
         let err_fut = stream.error_receiver.next();
         let mut select_fut = select(msg_fut, err_fut);
 
-        match futures_core::ready!(Pin::new(&mut select_fut).poll(cx)) {
+        match ready!(Pin::new(&mut select_fut).poll(cx)) {
             Either::Left((msg, _)) => Poll::Ready(msg.map(Ok)),
             Either::Right((error, _)) => Poll::Ready(error.map(Err)),
         }
@@ -896,13 +895,10 @@ impl<'r, 's> Future for ReceiveMessage<'r, 's> {
         loop {
             match stream.raw_conn.try_receive_message() {
                 Err(Error::Io(e)) if e.kind() == ErrorKind::WouldBlock => {
-                    let poll = stream.raw_conn.socket().poll_readable(cx);
-
-                    match poll {
-                        Poll::Pending => return Poll::Pending,
+                    match ready!(stream.raw_conn.socket().poll_readable(cx)) {
                         // Guess socket became ready already so let's try it again.
-                        Poll::Ready(Ok(_)) => continue,
-                        Poll::Ready(Err(e)) => return Poll::Ready(Err(e.into())),
+                        Ok(_) => continue,
+                        Err(e) => return Poll::Ready(Err(e.into())),
                     }
                 }
                 m => return Poll::Ready(m),

zbus/src/azync/handshake.rs

@@ -1,4 +1,5 @@
 use async_io::Async;
+use futures_core::ready;
 
 use std::{
     fmt::Debug,
@@ -119,16 +120,15 @@ where
                 }
                 Err(Error::Io(e)) => {
                     if e.kind() == std::io::ErrorKind::WouldBlock {
-                        let poll = match handshake.next_io_operation() {
-                            IoOperation::Read => handshake.socket().poll_readable(cx),
-                            IoOperation::Write => handshake.socket().poll_writable(cx),
+                        let res = match handshake.next_io_operation() {
+                            IoOperation::Read => ready!(handshake.socket().poll_readable(cx)),
+                            IoOperation::Write => ready!(handshake.socket().poll_writable(cx)),
                             IoOperation::None => panic!("Invalid handshake state"),
                         };
-                        match poll {
-                            Poll::Pending => return Poll::Pending,
+                        match res {
                             // Guess socket became ready already so let's try it again.
-                            Poll::Ready(Ok(_)) => continue,
-                            Poll::Ready(Err(e)) => return Poll::Ready(Err(e.into())),
+                            Ok(_) => continue,
+                            Err(e) => return Poll::Ready(Err(e.into())),
                         }
                     } else {
                         return Poll::Ready(Err(Error::Io(e)));

zbus/src/azync/proxy.rs

@@ -164,9 +164,8 @@ where
         let m = self.get_mut();
         let (name, stream) = (m.name, m.stream.as_mut());
         // there must be a way to simplify the following code..
-        let p = stream::Stream::poll_next(stream, cx);
-        match p {
-            Poll::Ready(Some(item)) => {
+        match futures_core::ready!(stream::Stream::poll_next(stream, cx)) {
+            Some(item) => {
                 if item.0 == name {
                     if let Some(Ok(v)) = item.1.clone().map(T::try_from) {
                         Poll::Ready(Some(Some(v)))
@@ -177,8 +176,7 @@ where
                     Poll::Pending
                 }
             }
-            Poll::Ready(None) => Poll::Ready(None),
-            Poll::Pending => Poll::Pending,
+            None => Poll::Ready(None),
         }
     }
 }

zbus/src/raw/connection.rs

@@ -182,13 +182,10 @@ impl Connection<Async<Box<dyn Socket>>> {
                 Ok(()) => return Poll::Ready(Ok(())),
                 Err(e) => {
                     if e.kind() == ErrorKind::WouldBlock {
-                        let poll = self.socket().poll_writable(cx);
-
-                        match poll {
-                            Poll::Pending => return Poll::Pending,
+                        match futures_core::ready!(self.socket().poll_writable(cx)) {
                             // Guess socket became ready already so let's try it again.
-                            Poll::Ready(Ok(_)) => continue,
-                            Poll::Ready(Err(e)) => return Poll::Ready(Err(e.into())),
+                            Ok(_) => continue,
+                            Err(e) => return Poll::Ready(Err(e.into())),
                         }
                     } else {
                         return Poll::Ready(Err(crate::Error::Io(e)));