Add convenience method for polling Task<>

crates/bevy_tasks/src/task.rs

@@ -1,7 +1,7 @@
 use std::{
     future::Future,
     pin::Pin,
-    task::{Context, Poll},
+    task::{Context, Poll, RawWaker, RawWakerVTable, Waker},
 };
 
 /// Wraps `async_executor::Task`, a spawned future.
@@ -40,6 +40,25 @@ impl<T> Task<T> {
     pub async fn cancel(self) -> Option<T> {
         self.0.cancel().await
     }
+
+    /// Check if the task has been completed, and if so, return the value.
+    pub fn check(&mut self) -> Option<T> {
+        const NOOP_WAKER_VTABLE: &RawWakerVTable = &RawWakerVTable::new(
+            |_| RawWaker::new(std::ptr::null::<()>(), NOOP_WAKER_VTABLE),
+            |_| {},
+            |_| {},
+            |_| {},
+        );
+
+        // SAFE: all vtable functions are always safe to call.
+        let waker =
+            unsafe { Waker::from_raw(RawWaker::new(std::ptr::null::<()>(), NOOP_WAKER_VTABLE)) };
+
+        match Pin::new(&mut self.0).poll(&mut Context::from_waker(&waker)) {
+            Poll::Ready(val) => Some(val),
+            Poll::Pending => None,
+        }
+    }
 }
 
 impl<T> Future for Task<T> {

examples/async_tasks/async_compute.rs

@@ -2,7 +2,6 @@ use bevy::{
     prelude::*,
     tasks::{AsyncComputeTaskPool, Task},
 };
-use futures_lite::future;
 use rand::Rng;
 use std::time::{Duration, Instant};
 
@@ -86,7 +85,7 @@ fn handle_tasks(
     box_material_handle: Res<BoxMaterialHandle>,
 ) {
     for (entity, mut task) in transform_tasks.iter_mut() {
-        if let Some(transform) = future::block_on(future::poll_once(&mut task.0)) {
+        if let Some(transform) = task.0.check() {
             // Add our new PbrBundle of components to our tagged entity
             commands.entity(entity).insert_bundle(PbrBundle {
                 mesh: box_mesh_handle.clone(),