sync: Barrier doc should use task, not thread (#3780)

tokio/src/sync/barrier.rs

@@ -2,7 +2,7 @@ use crate::sync::watch;
 
 use std::sync::Mutex;
 
-/// A barrier enables multiple threads to synchronize the beginning of some computation.
+/// A barrier enables multiple tasks to synchronize the beginning of some computation.
 ///
 /// ```
 /// # #[tokio::main]
@@ -52,10 +52,10 @@ struct BarrierState {
 }
 
 impl Barrier {
-    /// Creates a new barrier that can block a given number of threads.
+    /// Creates a new barrier that can block a given number of tasks.
     ///
-    /// A barrier will block `n`-1 threads which call [`Barrier::wait`] and then wake up all
+    /// A barrier will block `n`-1 tasks which call [`Barrier::wait`] and then wake up all
-    /// threads at once when the `n`th thread calls `wait`.
+    /// tasks at once when the `n`th task calls `wait`.
     pub fn new(mut n: usize) -> Barrier {
         let (waker, wait) = crate::sync::watch::channel(0);
 
@@ -79,11 +79,11 @@ impl Barrier {
 
     /// Does not resolve until all tasks have rendezvoused here.
     ///
-    /// Barriers are re-usable after all threads have rendezvoused once, and can
+    /// Barriers are re-usable after all tasks have rendezvoused once, and can
     /// be used continuously.
     ///
     /// A single (arbitrary) future will receive a [`BarrierWaitResult`] that returns `true` from
-    /// [`BarrierWaitResult::is_leader`] when returning from this function, and all other threads
+    /// [`BarrierWaitResult::is_leader`] when returning from this function, and all other tasks
     /// will receive a result that will return `false` from `is_leader`.
     pub async fn wait(&self) -> BarrierWaitResult {
         // NOTE: we are taking a _synchronous_ lock here.
@@ -129,14 +129,14 @@ impl Barrier {
     }
 }
 
-/// A `BarrierWaitResult` is returned by `wait` when all threads in the `Barrier` have rendezvoused.
+/// A `BarrierWaitResult` is returned by `wait` when all tasks in the `Barrier` have rendezvoused.
 #[derive(Debug, Clone)]
 pub struct BarrierWaitResult(bool);
 
 impl BarrierWaitResult {
-    /// Returns `true` if this thread from wait is the "leader thread".
+    /// Returns `true` if this task from wait is the "leader task".
     ///
-    /// Only one thread will have `true` returned from their result, all other threads will have
+    /// Only one task will have `true` returned from their result, all other tasks will have
     /// `false` returned.
     pub fn is_leader(&self) -> bool {
         self.0