Move AtomicWaker from futures-core to futures-task

Author: taiki-e

futures-channel/Cargo.toml

@@ -28,6 +28,7 @@ cfg-target-has-atomic = ["futures-core-preview/cfg-target-has-atomic"]
 
 [dependencies]
 futures-core-preview = { path = "../futures-core", version = "=0.3.0-alpha.19", default-features = false }
+futures-task-preview = { path = "../futures-task", version = "=0.3.0-alpha.19", default-features = false }
 futures-sink-preview = { path = "../futures-sink", version = "=0.3.0-alpha.19", default-features = false, optional = true }
 
 [dev-dependencies]

futures-channel/src/mpsc/mod.rs

@@ -80,7 +80,7 @@
 
 use futures_core::stream::{FusedStream, Stream};
 use futures_core::task::{Context, Poll, Waker};
-use futures_core::task::__internal::AtomicWaker;
+use futures_task::AtomicWaker;
 use std::fmt;
 use std::pin::Pin;
 use std::sync::{Arc, Mutex};

futures-core/src/task/poll.rs renamed to futures-core/src/task.rs

@@ -1,3 +1,7 @@
+//! Task notification.
+
+pub use core::task::{Context, Poll, Waker, RawWaker, RawWakerVTable};
+
 /// Extracts the successful type of a `Poll<T>`.
 ///
 /// This macro bakes in propagation of `Pending` signals by returning early.

futures-core/src/task/__internal/mod.rs

@@ -19,5 +19,11 @@ default = ["std"]
 std = ["alloc"]
 alloc = []
 
+# Unstable features
+# These features are outside of the normal semver guarantees and require the
+# `unstable` feature as an explicit opt-in to unstable API.
+unstable = []
+cfg-target-has-atomic = []
+
 [dependencies]
 futures-core-preview = { path = "../futures-core", version = "=0.3.0-alpha.19" }

futures-core/src/task/mod.rs

@@ -1,8 +1,8 @@
-use core::fmt;
 use core::cell::UnsafeCell;
+use core::fmt;
 use core::sync::atomic::AtomicUsize;
 use core::sync::atomic::Ordering::{Acquire, Release, AcqRel};
-use crate::task::Waker;
+use core::task::Waker;
 
 /// A synchronization primitive for task wakeup.
 ///

futures-task/Cargo.toml

@@ -1,5 +1,7 @@
 //! Tools for working with tasks.
 
+#![cfg_attr(feature = "cfg-target-has-atomic", feature(cfg_target_has_atomic))]
+
 #![cfg_attr(not(feature = "std"), no_std)]
 
 #![warn(missing_docs, missing_debug_implementations, rust_2018_idioms, unreachable_pub)]
@@ -11,10 +13,18 @@
 
 #![doc(html_root_url = "https://docs.rs/futures-task-preview/0.3.0-alpha.19")]
 
+#[cfg(all(feature = "cfg-target-has-atomic", not(feature = "unstable")))]
+compile_error!("The `cfg-target-has-atomic` feature requires the `unstable` feature as an explicit opt-in to unstable features");
+
 #[cfg(feature = "alloc")]
 extern crate alloc;
 
 mod spawn;
 pub use crate::spawn::{Spawn, SpawnError, LocalSpawn};
 
+#[cfg_attr(feature = "cfg-target-has-atomic", cfg(target_has_atomic = "ptr"))]
+mod atomic_waker;
+#[cfg_attr(feature = "cfg-target-has-atomic", cfg(target_has_atomic = "ptr"))]
+pub use crate::atomic_waker::AtomicWaker;
+
 pub use futures_core::future::{FutureObj, LocalFutureObj};

futures-core/src/task/__internal/atomic_waker.rs renamed to futures-task/src/atomic_waker.rs

@@ -16,7 +16,7 @@ cfg_target_has_atomic! {
     #[cfg(feature = "alloc")]
     pub use self::waker_ref::{waker_ref, WakerRef};
 
-    pub use futures_core::task::__internal::AtomicWaker;
+    pub use futures_task::AtomicWaker;
 }
 
 mod noop_waker;