Merging upstream version 1.70.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

3 files changed, 74 insertions, 67 deletions

diff --git a/vendor/futures-executor/src/enter.rs b/vendor/futures-executor/src/enter.rs
index 5895a9efb..cb58c30bb 100644
--- a/vendor/futures-executor/src/enter.rs
+++ b/vendor/futures-executor/src/enter.rs
@@ -34,7 +34,7 @@ impl std::error::Error for EnterError {}
 /// executor.
 ///
 /// Executor implementations should call this function before beginning to
-/// execute a tasks, and drop the returned [`Enter`](Enter) value after
+/// execute a task, and drop the returned [`Enter`](Enter) value after
 /// completing task execution:
 ///
 /// ```
diff --git a/vendor/futures-executor/src/local_pool.rs b/vendor/futures-executor/src/local_pool.rs
index bee96d8db..8a9bc2fc9 100644
--- a/vendor/futures-executor/src/local_pool.rs
+++ b/vendor/futures-executor/src/local_pool.rs
@@ -63,7 +63,7 @@ thread_local! {
 impl ArcWake for ThreadNotify {
     fn wake_by_ref(arc_self: &Arc<Self>) {
         // Make sure the wakeup is remembered until the next `park()`.
-        let unparked = arc_self.unparked.swap(true, Ordering::Relaxed);
+        let unparked = arc_self.unparked.swap(true, Ordering::Release);
         if !unparked {
             // If the thread has not been unparked yet, it must be done
             // now. If it was actually parked, it will run again,
@@ -90,33 +90,21 @@ fn run_executor<T, F: FnMut(&mut Context<'_>) -> Poll<T>>(mut f: F) -> T {
             if let Poll::Ready(t) = f(&mut cx) {
                 return t;
             }
-            // Consume the wakeup that occurred while executing `f`, if any.
-            let unparked = thread_notify.unparked.swap(false, Ordering::Acquire);
-            if !unparked {
+
+            // Wait for a wakeup.
+            while !thread_notify.unparked.swap(false, Ordering::Acquire) {
                 // No wakeup occurred. It may occur now, right before parking,
                 // but in that case the token made available by `unpark()`
                 // is guaranteed to still be available and `park()` is a no-op.
                 thread::park();
-                // When the thread is unparked, `unparked` will have been set
-                // and needs to be unset before the next call to `f` to avoid
-                // a redundant loop iteration.
-                thread_notify.unparked.store(false, Ordering::Release);
             }
         }
     })
 }
 
-fn poll_executor<T, F: FnMut(&mut Context<'_>) -> T>(mut f: F) -> T {
-    let _enter = enter().expect(
-        "cannot execute `LocalPool` executor from within \
-         another executor",
-    );
-
-    CURRENT_THREAD_NOTIFY.with(|thread_notify| {
-        let waker = waker_ref(thread_notify);
-        let mut cx = Context::from_waker(&waker);
-        f(&mut cx)
-    })
+/// Check for a wakeup, but don't consume it.
+fn woken() -> bool {
+    CURRENT_THREAD_NOTIFY.with(|thread_notify| thread_notify.unparked.load(Ordering::Acquire))
 }
 
 impl LocalPool {
@@ -212,20 +200,26 @@ impl LocalPool {
     /// further use of one of the pool's run or poll methods.
     /// Though only one task will be completed, progress may be made on multiple tasks.
     pub fn try_run_one(&mut self) -> bool {
-        poll_executor(|ctx| {
+        run_executor(|cx| {
             loop {
-                let ret = self.poll_pool_once(ctx);
-
-                // return if we have executed a future
-                if let Poll::Ready(Some(_)) = ret {
-                    return true;
+                self.drain_incoming();
+
+                match self.pool.poll_next_unpin(cx) {
+                    // Success!
+                    Poll::Ready(Some(())) => return Poll::Ready(true),
+                    // The pool was empty.
+                    Poll::Ready(None) => return Poll::Ready(false),
+                    Poll::Pending => (),
                 }
 
-                // if there are no new incoming futures
-                // then there is no feature that can make progress
-                // and we can return without having completed a single future
-                if self.incoming.borrow().is_empty() {
-                    return false;
+                if !self.incoming.borrow().is_empty() {
+                    // New tasks were spawned; try again.
+                    continue;
+                } else if woken() {
+                    // The pool yielded to us, but there's more progress to be made.
+                    return Poll::Pending;
+                } else {
+                    return Poll::Ready(false);
                 }
             }
         })
@@ -257,44 +251,52 @@ impl LocalPool {
     /// of the pool's run or poll methods. While the function is running, all tasks
     /// in the pool will try to make progress.
     pub fn run_until_stalled(&mut self) {
-        poll_executor(|ctx| {
-            let _ = self.poll_pool(ctx);
+        run_executor(|cx| match self.poll_pool(cx) {
+            // The pool is empty.
+            Poll::Ready(()) => Poll::Ready(()),
+            Poll::Pending => {
+                if woken() {
+                    Poll::Pending
+                } else {
+                    // We're stalled for now.
+                    Poll::Ready(())
+                }
+            }
         });
     }
 
-    // Make maximal progress on the entire pool of spawned task, returning `Ready`
-    // if the pool is empty and `Pending` if no further progress can be made.
+    /// Poll `self.pool`, re-filling it with any newly-spawned tasks.
+    /// Repeat until either the pool is empty, or it returns `Pending`.
+    ///
+    /// Returns `Ready` if the pool was empty, and `Pending` otherwise.
+    ///
+    /// NOTE: the pool may call `wake`, so `Pending` doesn't necessarily
+    /// mean that the pool can't make progress.
     fn poll_pool(&mut self, cx: &mut Context<'_>) -> Poll<()> {
-        // state for the FuturesUnordered, which will never be used
         loop {
-            let ret = self.poll_pool_once(cx);
+            self.drain_incoming();
 
-            // we queued up some new tasks; add them and poll again
+            let pool_ret = self.pool.poll_next_unpin(cx);
+
+            // We queued up some new tasks; add them and poll again.
             if !self.incoming.borrow().is_empty() {
                 continue;
             }
 
-            // no queued tasks; we may be done
-            match ret {
-                Poll::Pending => return Poll::Pending,
+            match pool_ret {
+                Poll::Ready(Some(())) => continue,
                 Poll::Ready(None) => return Poll::Ready(()),
-                _ => {}
+                Poll::Pending => return Poll::Pending,
             }
         }
     }
 
-    // Try make minimal progress on the pool of spawned tasks
-    fn poll_pool_once(&mut self, cx: &mut Context<'_>) -> Poll<Option<()>> {
-        // empty the incoming queue of newly-spawned tasks
-        {
-            let mut incoming = self.incoming.borrow_mut();
-            for task in incoming.drain(..) {
-                self.pool.push(task)
-            }
+    /// Empty the incoming queue of newly-spawned tasks.
+    fn drain_incoming(&mut self) {
+        let mut incoming = self.incoming.borrow_mut();
+        for task in incoming.drain(..) {
+            self.pool.push(task)
         }
-
-        // try to execute the next ready future
-        self.pool.poll_next_unpin(cx)
     }
 }
 
diff --git a/vendor/futures-executor/src/thread_pool.rs b/vendor/futures-executor/src/thread_pool.rs
index 5e1f586eb..537100895 100644
--- a/vendor/futures-executor/src/thread_pool.rs
+++ b/vendor/futures-executor/src/thread_pool.rs
@@ -108,12 +108,15 @@ impl ThreadPool {
     /// completion.
     ///
     /// ```
+    /// # {
     /// use futures::executor::ThreadPool;
     ///
     /// let pool = ThreadPool::new().unwrap();
     ///
     /// let future = async { /* ... */ };
     /// pool.spawn_ok(future);
+    /// # }
+    /// # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371
     /// ```
     ///
     /// > **Note**: This method is similar to `SpawnExt::spawn`, except that
@@ -346,9 +349,8 @@ impl fmt::Debug for Task {
 
 impl ArcWake for WakeHandle {
     fn wake_by_ref(arc_self: &Arc<Self>) {
-        match arc_self.mutex.notify() {
-            Ok(task) => arc_self.exec.state.send(Message::Run(task)),
-            Err(()) => {}
+        if let Ok(task) = arc_self.mutex.notify() {
+            arc_self.exec.state.send(Message::Run(task))
         }
     }
 }
@@ -360,16 +362,19 @@ mod tests {
 
     #[test]
     fn test_drop_after_start() {
-        let (tx, rx) = mpsc::sync_channel(2);
-        let _cpu_pool = ThreadPoolBuilder::new()
-            .pool_size(2)
-            .after_start(move |_| tx.send(1).unwrap())
-            .create()
-            .unwrap();
-
-        // After ThreadPoolBuilder is deconstructed, the tx should be dropped
-        // so that we can use rx as an iterator.
-        let count = rx.into_iter().count();
-        assert_eq!(count, 2);
+        {
+            let (tx, rx) = mpsc::sync_channel(2);
+            let _cpu_pool = ThreadPoolBuilder::new()
+                .pool_size(2)
+                .after_start(move |_| tx.send(1).unwrap())
+                .create()
+                .unwrap();
+
+            // After ThreadPoolBuilder is deconstructed, the tx should be dropped
+            // so that we can use rx as an iterator.
+            let count = rx.into_iter().count();
+            assert_eq!(count, 2);
+        }
+        std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371
     }
 }