diff options
Diffstat (limited to 'compiler/rustc_data_structures/src/atomic_ref.rs')
-rw-r--r-- | compiler/rustc_data_structures/src/atomic_ref.rs | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/compiler/rustc_data_structures/src/atomic_ref.rs b/compiler/rustc_data_structures/src/atomic_ref.rs new file mode 100644 index 000000000..eeb1b3092 --- /dev/null +++ b/compiler/rustc_data_structures/src/atomic_ref.rs @@ -0,0 +1,26 @@ +use std::marker::PhantomData; +use std::sync::atomic::{AtomicPtr, Ordering}; + +/// This is essentially an `AtomicPtr` but is guaranteed to always be valid +pub struct AtomicRef<T: 'static>(AtomicPtr<T>, PhantomData<&'static T>); + +impl<T: 'static> AtomicRef<T> { + pub const fn new(initial: &'static T) -> AtomicRef<T> { + AtomicRef(AtomicPtr::new(initial as *const T as *mut T), PhantomData) + } + + pub fn swap(&self, new: &'static T) -> &'static T { + // We never allow storing anything but a `'static` reference so it's safe to + // return it for the same. + unsafe { &*self.0.swap(new as *const T as *mut T, Ordering::SeqCst) } + } +} + +impl<T: 'static> std::ops::Deref for AtomicRef<T> { + type Target = T; + fn deref(&self) -> &Self::Target { + // We never allow storing anything but a `'static` reference so it's safe to lend + // it out for any amount of time. + unsafe { &*self.0.load(Ordering::SeqCst) } + } +} |