Move Spinlock to sync module

Author: k-nasa

src/rt/runtime.rs

@@ -12,8 +12,9 @@ use crossbeam_utils::thread::scope;
 use once_cell::unsync::OnceCell;
 
 use crate::rt::Reactor;
+use crate::sync::Spinlock;
 use crate::task::Runnable;
-use crate::utils::{abort_on_panic, random, Spinlock};
+use crate::utils::{abort_on_panic, random};
 
 thread_local! {
     /// A reference to the current machine, if the current thread runs tasks.

src/sync/mod.rs

@@ -178,9 +178,11 @@ pub use std::sync::{Arc, Weak};
 
 pub use mutex::{Mutex, MutexGuard};
 pub use rwlock::{RwLock, RwLockReadGuard, RwLockWriteGuard};
+pub(crate) use spin_lock::Spinlock;
 
 mod mutex;
 mod rwlock;
+mod spin_lock;
 
 cfg_unstable! {
     pub use barrier::{Barrier, BarrierWaitResult};

src/sync/spin_lock.rs

@@ -0,0 +1,96 @@
+use std::cell::UnsafeCell;
+use std::ops::{Deref, DerefMut};
+use std::sync::atomic::{AtomicBool, Ordering};
+
+use crossbeam_utils::Backoff;
+
+/// A simple spinlock.
+///
+/// ```
+/// # async_std::task::block_on(async {
+/// #
+/// use async_std::sync::{Arc, Spinlock};
+/// use async_std::task;
+///
+/// let m = Arc::new(Spinlock::new(0));
+/// let mut tasks = vec![];
+///
+/// for _ in 0..10 {
+///     let m = m.clone();
+///     tasks.push(task::spawn(async move {
+///         *m.lock() += 1;
+///     }));
+/// }
+///
+/// for t in tasks {
+///     t.await;
+/// }
+/// assert_eq!(*m.lock(), 10);
+/// #
+/// # })
+/// ```
+#[derive(Debug)]
+pub struct Spinlock<T> {
+    flag: AtomicBool,
+    value: UnsafeCell<T>,
+}
+
+unsafe impl<T: Send> Send for Spinlock<T> {}
+unsafe impl<T: Send> Sync for Spinlock<T> {}
+
+impl<T> Spinlock<T> {
+    /// Returns a new spinlock initialized with `value`.
+    pub const fn new(value: T) -> Spinlock<T> {
+        Spinlock {
+            flag: AtomicBool::new(false),
+            value: UnsafeCell::new(value),
+        }
+    }
+
+    /// Locks the spinlock.
+    pub fn lock(&self) -> SpinlockGuard<'_, T> {
+        let backoff = Backoff::new();
+        while self.flag.swap(true, Ordering::Acquire) {
+            backoff.snooze();
+        }
+        SpinlockGuard { parent: self }
+    }
+
+    /// Attempts to lock the spinlock.
+    pub fn try_lock(&self) -> Option<SpinlockGuard<'_, T>> {
+        if self.flag.swap(true, Ordering::Acquire) {
+            None
+        } else {
+            Some(SpinlockGuard { parent: self })
+        }
+    }
+}
+
+/// A guard holding a spinlock locked.
+#[derive(Debug)]
+pub struct SpinlockGuard<'a, T> {
+    parent: &'a Spinlock<T>,
+}
+
+unsafe impl<T: Send> Send for SpinlockGuard<'_, T> {}
+unsafe impl<T: Sync> Sync for SpinlockGuard<'_, T> {}
+
+impl<'a, T> Drop for SpinlockGuard<'a, T> {
+    fn drop(&mut self) {
+        self.parent.flag.store(false, Ordering::Release);
+    }
+}
+
+impl<'a, T> Deref for SpinlockGuard<'a, T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        unsafe { &*self.parent.value.get() }
+    }
+}
+
+impl<'a, T> DerefMut for SpinlockGuard<'a, T> {
+    fn deref_mut(&mut self) -> &mut T {
+        unsafe { &mut *self.parent.value.get() }
+    }
+}

src/utils.rs

@@ -293,76 +293,3 @@ macro_rules! extension_trait {
         extension_trait!($($tail)*);
     };
 }
-
-cfg_default! {
-    use std::cell::UnsafeCell;
-    use std::ops::{Deref, DerefMut};
-    use std::sync::atomic::{AtomicBool, Ordering};
-
-    use crossbeam_utils::Backoff;
-
-    /// A simple spinlock.
-    pub struct Spinlock<T> {
-        flag: AtomicBool,
-        value: UnsafeCell<T>,
-    }
-
-    unsafe impl<T: Send> Send for Spinlock<T> {}
-    unsafe impl<T: Send> Sync for Spinlock<T> {}
-
-    impl<T> Spinlock<T> {
-        /// Returns a new spinlock initialized with `value`.
-        pub const fn new(value: T) -> Spinlock<T> {
-            Spinlock {
-                flag: AtomicBool::new(false),
-                value: UnsafeCell::new(value),
-            }
-        }
-
-        /// Locks the spinlock.
-        pub fn lock(&self) -> SpinlockGuard<'_, T> {
-            let backoff = Backoff::new();
-            while self.flag.swap(true, Ordering::Acquire) {
-                backoff.snooze();
-            }
-            SpinlockGuard { parent: self }
-        }
-
-        /// Attempts to lock the spinlock.
-        pub fn try_lock(&self) -> Option<SpinlockGuard<'_, T>> {
-            if self.flag.swap(true, Ordering::Acquire) {
-                None
-            } else {
-                Some(SpinlockGuard { parent: self })
-            }
-        }
-    }
-
-    /// A guard holding a spinlock locked.
-    pub struct SpinlockGuard<'a, T> {
-        parent: &'a Spinlock<T>,
-    }
-
-    unsafe impl<T: Send> Send for SpinlockGuard<'_, T> {}
-    unsafe impl<T: Sync> Sync for SpinlockGuard<'_, T> {}
-
-    impl<'a, T> Drop for SpinlockGuard<'a, T> {
-        fn drop(&mut self) {
-            self.parent.flag.store(false, Ordering::Release);
-        }
-    }
-
-    impl<'a, T> Deref for SpinlockGuard<'a, T> {
-        type Target = T;
-
-        fn deref(&self) -> &T {
-            unsafe { &*self.parent.value.get() }
-        }
-    }
-
-    impl<'a, T> DerefMut for SpinlockGuard<'a, T> {
-        fn deref_mut(&mut self) -> &mut T {
-            unsafe { &mut *self.parent.value.get() }
-        }
-    }
-}