sync: change chan closed(&mut self) to closed(&self) (#2939)

tokio/src/sync/mpsc/bounded.rs

@@ -332,11 +332,11 @@ impl<T> Sender<T> {
     ///
     /// #[tokio::main]
     /// async fn main() {
-    ///     let (mut tx1, rx) = mpsc::channel::<()>(1);
-    ///     let mut tx2 = tx1.clone();
-    ///     let mut tx3 = tx1.clone();
-    ///     let mut tx4 = tx1.clone();
-    ///     let mut tx5 = tx1.clone();
+    ///     let (tx1, rx) = mpsc::channel::<()>(1);
+    ///     let tx2 = tx1.clone();
+    ///     let tx3 = tx1.clone();
+    ///     let tx4 = tx1.clone();
+    ///     let tx5 = tx1.clone();
     ///     tokio::spawn(async move {
     ///         drop(rx);
     ///     });
@@ -351,7 +351,7 @@ impl<T> Sender<T> {
     ////     println!("Receiver dropped");
     /// }
     /// ```
-    pub async fn closed(&mut self) {
+    pub async fn closed(&self) {
         self.chan.closed().await
     }
 

tokio/src/sync/mpsc/chan.rs

@@ -147,7 +147,7 @@ impl<T, S: Semaphore> Tx<T, S> {
         self.inner.semaphore.is_closed()
     }
 
-    pub(crate) async fn closed(&mut self) {
+    pub(crate) async fn closed(&self) {
         use std::future::Future;
         use std::pin::Pin;
         use std::task::Poll;

tokio/src/sync/mpsc/unbounded.rs

@@ -223,11 +223,11 @@ impl<T> UnboundedSender<T> {
     ///
     /// #[tokio::main]
     /// async fn main() {
-    ///     let (mut tx1, rx) = mpsc::unbounded_channel::<()>();
-    ///     let mut tx2 = tx1.clone();
-    ///     let mut tx3 = tx1.clone();
-    ///     let mut tx4 = tx1.clone();
-    ///     let mut tx5 = tx1.clone();
+    ///     let (tx1, rx) = mpsc::unbounded_channel::<()>();
+    ///     let tx2 = tx1.clone();
+    ///     let tx3 = tx1.clone();
+    ///     let tx4 = tx1.clone();
+    ///     let tx5 = tx1.clone();
     ///     tokio::spawn(async move {
     ///         drop(rx);
     ///     });
@@ -242,7 +242,7 @@ impl<T> UnboundedSender<T> {
     ////     println!("Receiver dropped");
     /// }
     /// ```
-    pub async fn closed(&mut self) {
+    pub async fn closed(&self) {
         self.chan.closed().await
     }
     /// Checks if the channel has been closed. This happens when the

tokio/src/sync/tests/loom_mpsc.rs

@@ -2,7 +2,9 @@ use crate::sync::mpsc;
 
 use futures::future::poll_fn;
 use loom::future::block_on;
+use loom::sync::Arc;
 use loom::thread;
+use tokio_test::assert_ok;
 
 #[test]
 fn closing_tx() {
@@ -43,8 +45,8 @@ fn closing_unbounded_tx() {
 #[test]
 fn closing_bounded_rx() {
     loom::model(|| {
-        let (mut tx1, rx) = mpsc::channel::<()>(16);
-        let mut tx2 = tx1.clone();
+        let (tx1, rx) = mpsc::channel::<()>(16);
+        let tx2 = tx1.clone();
         thread::spawn(move || {
             drop(rx);
         });
@@ -54,11 +56,38 @@ fn closing_bounded_rx() {
     });
 }
 
+#[test]
+fn closing_and_sending() {
+    loom::model(|| {
+        let (tx1, mut rx) = mpsc::channel::<()>(16);
+        let tx1 = Arc::new(tx1);
+        let tx2 = tx1.clone();
+
+        let th1 = thread::spawn(move || {
+            tx1.try_send(()).unwrap();
+        });
+
+        let th2 = thread::spawn(move || {
+            block_on(tx2.closed());
+        });
+
+        let th3 = thread::spawn(move || {
+            let v = block_on(rx.recv());
+            assert!(v.is_some());
+            drop(rx);
+        });
+
+        assert_ok!(th1.join());
+        assert_ok!(th2.join());
+        assert_ok!(th3.join());
+    });
+}
+
 #[test]
 fn closing_unbounded_rx() {
     loom::model(|| {
-        let (mut tx1, rx) = mpsc::unbounded_channel::<()>();
-        let mut tx2 = tx1.clone();
+        let (tx1, rx) = mpsc::unbounded_channel::<()>();
+        let tx2 = tx1.clone();
         thread::spawn(move || {
             drop(rx);
         });