Rollup merge of #53068 - MajorBreakfast:spawn, r=cramertj

Rename Executor trait to Spawn

Renames the `Executor` trait to `Spawn` and the method on `Context` to `spawner`.

Note: Best only merge this after we've the alpha 3 announcement post ready.

r? @cramertj

src/liballoc/boxed.rs

@@ -67,7 +67,7 @@ use core::marker::{Unpin, Unsize};
 use core::mem::{self, PinMut};
 use core::ops::{CoerceUnsized, Deref, DerefMut, Generator, GeneratorState};
 use core::ptr::{self, NonNull, Unique};
-use core::task::{Context, Poll, Executor, SpawnErrorKind, SpawnObjError};
+use core::task::{Context, Poll, Spawn, SpawnErrorKind, SpawnObjError};
 
 use raw_vec::RawVec;
 use str::from_boxed_utf8_unchecked;
@@ -973,11 +973,14 @@ unsafe impl<'a, T, F> UnsafeFutureObj<'a, T> for PinBox<F>
 }
 
 #[unstable(feature = "futures_api", issue = "50547")]
-impl<E> Executor for Box<E>
-    where E: Executor + ?Sized
+impl<Sp> Spawn for Box<Sp>
+    where Sp: Spawn + ?Sized
 {
-    fn spawn_obj(&mut self, task: FutureObj<'static, ()>) -> Result<(), SpawnObjError> {
-        (**self).spawn_obj(task)
+    fn spawn_obj(
+        &mut self,
+        future: FutureObj<'static, ()>,
+    ) -> Result<(), SpawnObjError> {
+        (**self).spawn_obj(future)
     }
 
     fn status(&self) -> Result<(), SpawnErrorKind> {

src/libcore/task/context.rs

@@ -13,7 +13,7 @@
             issue = "50547")]
 
 use fmt;
-use super::{Executor, Waker, LocalWaker};
+use super::{Spawn, Waker, LocalWaker};
 
 /// Information about the currently-running task.
 ///
@@ -21,7 +21,7 @@ use super::{Executor, Waker, LocalWaker};
 /// when performing a single `poll` step on a task.
 pub struct Context<'a> {
     local_waker: &'a LocalWaker,
-    executor: &'a mut dyn Executor,
+    spawner: &'a mut dyn Spawn,
 }
 
 impl<'a> fmt::Debug for Context<'a> {
@@ -32,13 +32,14 @@ impl<'a> fmt::Debug for Context<'a> {
 }
 
 impl<'a> Context<'a> {
-    /// Create a new task `Context` with the provided `local_waker`, `waker`, and `executor`.
+    /// Create a new task `Context` with the provided `local_waker`, `waker`,
+    /// and `spawner`.
     #[inline]
-    pub fn new(local_waker: &'a LocalWaker, executor: &'a mut dyn Executor) -> Context<'a> {
-        Context {
-            local_waker,
-            executor,
-        }
+    pub fn new(
+        local_waker: &'a LocalWaker,
+        spawner: &'a mut dyn Spawn,
+    ) -> Context<'a> {
+        Context { local_waker, spawner }
     }
 
     /// Get the `LocalWaker` associated with the current task.
@@ -53,40 +54,45 @@ impl<'a> Context<'a> {
         unsafe { &*(self.local_waker as *const LocalWaker as *const Waker) }
     }
 
-    /// Get the default executor associated with this task.
+    /// Get the spawner associated with this task.
     ///
     /// This method is useful primarily if you want to explicitly handle
     /// spawn failures.
     #[inline]
-    pub fn executor(&mut self) -> &mut dyn Executor {
-        self.executor
+    pub fn spawner(&mut self) -> &mut dyn Spawn {
+        self.spawner
     }
 
-    /// Produce a context like the current one, but using the given waker instead.
+    /// Produce a context like the current one, but using the given waker
+    /// instead.
     ///
     /// This advanced method is primarily used when building "internal
     /// schedulers" within a task, where you want to provide some customized
     /// wakeup logic.
     #[inline]
-    pub fn with_waker<'b>(&'b mut self, local_waker: &'b LocalWaker) -> Context<'b> {
+    pub fn with_waker<'b>(
+        &'b mut self,
+        local_waker: &'b LocalWaker,
+    ) -> Context<'b> {
         Context {
             local_waker,
-            executor: self.executor,
+            spawner: self.spawner,
         }
     }
 
-    /// Produce a context like the current one, but using the given executor
+    /// Produce a context like the current one, but using the given spawner
     /// instead.
     ///
     /// This advanced method is primarily used when building "internal
     /// schedulers" within a task.
     #[inline]
-    pub fn with_executor<'b, E>(&'b mut self, executor: &'b mut E) -> Context<'b>
-        where E: Executor
-    {
+    pub fn with_spawner<'b, Sp: Spawn>(
+        &'b mut self,
+        spawner: &'b mut Sp,
+    ) -> Context<'b> {
         Context {
             local_waker: self.local_waker,
-            executor,
+            spawner,
         }
     }
 }

src/libcore/task/mod.rs

@@ -17,10 +17,8 @@
 mod context;
 pub use self::context::Context;
 
-mod executor;
-pub use self::executor::{
-  Executor, SpawnErrorKind, SpawnObjError, SpawnLocalObjError
-};
+mod spawn;
+pub use self::spawn::{Spawn, SpawnErrorKind, SpawnObjError, SpawnLocalObjError};
 
 mod poll;
 pub use self::poll::Poll;

src/libcore/task/spawn.rs

@@ -15,16 +15,13 @@
 use fmt;
 use future::{FutureObj, LocalFutureObj};
 
-/// A task executor.
+/// Spawns tasks that poll futures to completion onto its associated task
+/// executor.
 ///
-/// Futures are polled until completion by tasks, a kind of lightweight
-/// "thread". A *task executor* is responsible for the creation of these tasks
-/// and the coordination of their execution on real operating system threads. In
-/// particular, whenever a task signals that it can make further progress via a
-/// wake-up notification, it is the responsibility of the task executor to put
-/// the task into a queue to continue executing it, i.e. polling the future in
-/// it, later.
-pub trait Executor {
+/// The term "task" refers to a kind of lightweight "thread". Task executors
+/// are responsible for scheduling the execution of tasks on operating system
+/// threads.
+pub trait Spawn {
     /// Spawns a new task with the given future. The future will be polled until
     /// completion.
     ///

src/test/run-pass/async-await.rs

@@ -22,7 +22,7 @@ use std::sync::{
 use std::future::FutureObj;
 use std::task::{
     Context, Poll, Wake,
-    Executor, SpawnObjError,
+    Spawn, SpawnObjError,
     local_waker_from_nonlocal,
 };
 
@@ -36,8 +36,8 @@ impl Wake for Counter {
     }
 }
 
-struct NoopExecutor;
-impl Executor for NoopExecutor {
+struct NoopSpawner;
+impl Spawn for NoopSpawner {
     fn spawn_obj(&mut self, _: FutureObj<'static, ()>) -> Result<(), SpawnObjError> {
         Ok(())
     }
@@ -127,8 +127,8 @@ where
     let mut fut = PinBox::new(f(9));
     let counter = Arc::new(Counter { wakes: AtomicUsize::new(0) });
     let waker = local_waker_from_nonlocal(counter.clone());
-    let executor = &mut NoopExecutor;
-    let cx = &mut Context::new(&waker, executor);
+    let spawner = &mut NoopSpawner;
+    let cx = &mut Context::new(&waker, spawner);
 
     assert_eq!(0, counter.wakes.load(atomic::Ordering::SeqCst));
     assert_eq!(Poll::Pending, fut.as_pin_mut().poll(cx));

src/test/run-pass/futures-api.rs

@@ -23,7 +23,7 @@ use std::future::FutureObj;
 use std::task::{
     Context, Poll,
     Wake, Waker, LocalWaker,
-    Executor, SpawnObjError,
+    Spawn, SpawnObjError,
     local_waker, local_waker_from_nonlocal,
 };
 
@@ -42,9 +42,9 @@ impl Wake for Counter {
     }
 }
 
-struct NoopExecutor;
+struct NoopSpawner;
 
-impl Executor for NoopExecutor {
+impl Spawn for NoopSpawner {
     fn spawn_obj(&mut self, _: FutureObj<'static, ()>) -> Result<(), SpawnObjError> {
         Ok(())
     }
@@ -59,7 +59,7 @@ impl Future for MyFuture {
         cx.waker().wake();
         cx.waker().wake();
         cx.local_waker().wake();
-        cx.executor().spawn_obj(PinBox::new(MyFuture).into()).unwrap();
+        cx.spawner().spawn_obj(PinBox::new(MyFuture).into()).unwrap();
         Poll::Ready(())
     }
 }
@@ -70,8 +70,8 @@ fn test_local_waker() {
         nonlocal_wakes: AtomicUsize::new(0),
     });
     let waker = unsafe { local_waker(counter.clone()) };
-    let executor = &mut NoopExecutor;
-    let cx = &mut Context::new(&waker, executor);
+    let spawner = &mut NoopSpawner;
+    let cx = &mut Context::new(&waker, spawner);
     assert_eq!(Poll::Ready(()), PinMut::new(&mut MyFuture).poll(cx));
     assert_eq!(1, counter.local_wakes.load(atomic::Ordering::SeqCst));
     assert_eq!(2, counter.nonlocal_wakes.load(atomic::Ordering::SeqCst));
@@ -83,8 +83,8 @@ fn test_local_as_nonlocal_waker() {
         nonlocal_wakes: AtomicUsize::new(0),
     });
     let waker: LocalWaker = local_waker_from_nonlocal(counter.clone());
-    let executor = &mut NoopExecutor;
-    let cx = &mut Context::new(&waker, executor);
+    let spawner = &mut NoopSpawner;
+    let cx = &mut Context::new(&waker, spawner);
     assert_eq!(Poll::Ready(()), PinMut::new(&mut MyFuture).poll(cx));
     assert_eq!(0, counter.local_wakes.load(atomic::Ordering::SeqCst));
     assert_eq!(3, counter.nonlocal_wakes.load(atomic::Ordering::SeqCst));