diff options
Diffstat (limited to 'vendor/crossbeam-epoch/src/atomic.rs')
| -rw-r--r-- | vendor/crossbeam-epoch/src/atomic.rs | 108 |
1 files changed, 104 insertions, 4 deletions
diff --git a/vendor/crossbeam-epoch/src/atomic.rs b/vendor/crossbeam-epoch/src/atomic.rs index b0b6a68e7..19bab4729 100644 --- a/vendor/crossbeam-epoch/src/atomic.rs +++ b/vendor/crossbeam-epoch/src/atomic.rs @@ -252,7 +252,7 @@ impl<T> Pointable for [MaybeUninit<T>] { let size = mem::size_of::<Array<T>>() + mem::size_of::<MaybeUninit<T>>() * len; let align = mem::align_of::<Array<T>>(); let layout = alloc::Layout::from_size_align(size, align).unwrap(); - let ptr = alloc::alloc(layout) as *mut Array<T>; + let ptr = alloc::alloc(layout).cast::<Array<T>>(); if ptr.is_null() { alloc::handle_alloc_error(layout); } @@ -305,6 +305,7 @@ impl<T> Atomic<T> { /// use crossbeam_epoch::Atomic; /// /// let a = Atomic::new(1234); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub fn new(init: T) -> Atomic<T> { Self::init(init) @@ -320,6 +321,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// use crossbeam_epoch::Atomic; /// /// let a = Atomic::<i32>::init(1234); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub fn init(init: T::Init) -> Atomic<T> { Self::from(Owned::init(init)) @@ -342,7 +344,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// /// let a = Atomic::<i32>::null(); /// ``` - #[cfg(all(crossbeam_const_fn_trait_bound, not(crossbeam_loom)))] + #[cfg(all(not(crossbeam_no_const_fn_trait_bound), not(crossbeam_loom)))] pub const fn null() -> Atomic<T> { Self { data: AtomicUsize::new(0), @@ -351,7 +353,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { } /// Returns a new null atomic pointer. - #[cfg(not(all(crossbeam_const_fn_trait_bound, not(crossbeam_loom))))] + #[cfg(not(all(not(crossbeam_no_const_fn_trait_bound), not(crossbeam_loom))))] pub fn null() -> Atomic<T> { Self { data: AtomicUsize::new(0), @@ -373,6 +375,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// let a = Atomic::new(1234); /// let guard = &epoch::pin(); /// let p = a.load(SeqCst, guard); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub fn load<'g>(&self, ord: Ordering, _: &'g Guard) -> Shared<'g, T> { unsafe { Shared::from_usize(self.data.load(ord)) } @@ -398,6 +401,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// let a = Atomic::new(1234); /// let guard = &epoch::pin(); /// let p = a.load_consume(guard); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub fn load_consume<'g>(&self, _: &'g Guard) -> Shared<'g, T> { unsafe { Shared::from_usize(self.data.load_consume()) } @@ -415,8 +419,10 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// use std::sync::atomic::Ordering::SeqCst; /// /// let a = Atomic::new(1234); + /// # unsafe { drop(a.load(SeqCst, &crossbeam_epoch::pin()).into_owned()); } // avoid leak /// a.store(Shared::null(), SeqCst); /// a.store(Owned::new(1234), SeqCst); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub fn store<P: Pointer<T>>(&self, new: P, ord: Ordering) { self.data.store(new.into_usize(), ord); @@ -437,6 +443,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// let a = Atomic::new(1234); /// let guard = &epoch::pin(); /// let p = a.swap(Shared::null(), SeqCst, guard); + /// # unsafe { drop(p.into_owned()); } // avoid leak /// ``` pub fn swap<'g, P: Pointer<T>>(&self, new: P, ord: Ordering, _: &'g Guard) -> Shared<'g, T> { unsafe { Shared::from_usize(self.data.swap(new.into_usize(), ord)) } @@ -471,6 +478,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// let curr = a.load(SeqCst, guard); /// let res1 = a.compare_exchange(curr, Shared::null(), SeqCst, SeqCst, guard); /// let res2 = a.compare_exchange(curr, Owned::new(5678), SeqCst, SeqCst, guard); + /// # unsafe { drop(curr.into_owned()); } // avoid leak /// ``` pub fn compare_exchange<'g, P>( &self, @@ -526,6 +534,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// /// let mut new = Owned::new(5678); /// let mut ptr = a.load(SeqCst, guard); + /// # unsafe { drop(a.load(SeqCst, guard).into_owned()); } // avoid leak /// loop { /// match a.compare_exchange_weak(ptr, new, SeqCst, SeqCst, guard) { /// Ok(p) => { @@ -546,6 +555,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// Err(err) => curr = err.current, /// } /// } + /// # unsafe { drop(curr.into_owned()); } // avoid leak /// ``` pub fn compare_exchange_weak<'g, P>( &self, @@ -608,6 +618,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// /// let res2 = a.fetch_update(SeqCst, SeqCst, guard, |x| None); /// assert!(res2.is_err()); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub fn fetch_update<'g, F>( &self, @@ -666,6 +677,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// let curr = a.load(SeqCst, guard); /// let res1 = a.compare_and_set(curr, Shared::null(), SeqCst, guard); /// let res2 = a.compare_and_set(curr, Owned::new(5678), SeqCst, guard); + /// # unsafe { drop(curr.into_owned()); } // avoid leak /// ``` // TODO: remove in the next major version. #[allow(deprecated)] @@ -723,6 +735,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// /// let mut new = Owned::new(5678); /// let mut ptr = a.load(SeqCst, guard); + /// # unsafe { drop(a.load(SeqCst, guard).into_owned()); } // avoid leak /// loop { /// match a.compare_and_set_weak(ptr, new, SeqCst, guard) { /// Ok(p) => { @@ -743,6 +756,7 @@ impl<T: ?Sized + Pointable> Atomic<T> { /// Err(err) => curr = err.current, /// } /// } + /// # unsafe { drop(curr.into_owned()); } // avoid leak /// ``` // TODO: remove in the next major version. #[allow(deprecated)] @@ -877,6 +891,52 @@ impl<T: ?Sized + Pointable> Atomic<T> { Owned::from_usize(self.data.into_inner()) } } + + /// Takes ownership of the pointee if it is non-null. + /// + /// This consumes the atomic and converts it into [`Owned`]. As [`Atomic`] doesn't have a + /// destructor and doesn't drop the pointee while [`Owned`] does, this is suitable for + /// destructors of data structures. + /// + /// # Safety + /// + /// This method may be called only if the pointer is valid and nobody else is holding a + /// reference to the same object, or the pointer is null. + /// + /// # Examples + /// + /// ```rust + /// # use std::mem; + /// # use crossbeam_epoch::Atomic; + /// struct DataStructure { + /// ptr: Atomic<usize>, + /// } + /// + /// impl Drop for DataStructure { + /// fn drop(&mut self) { + /// // By now the DataStructure lives only in our thread and we are sure we don't hold + /// // any Shared or & to it ourselves, but it may be null, so we have to be careful. + /// let old = mem::replace(&mut self.ptr, Atomic::null()); + /// unsafe { + /// if let Some(x) = old.try_into_owned() { + /// drop(x) + /// } + /// } + /// } + /// } + /// ``` + pub unsafe fn try_into_owned(self) -> Option<Owned<T>> { + // FIXME: See self.into_owned() + #[cfg(crossbeam_loom)] + let data = self.data.unsync_load(); + #[cfg(not(crossbeam_loom))] + let data = self.data.into_inner(); + if decompose_tag::<T>(data).0 == 0 { + None + } else { + Some(Owned::from_usize(data)) + } + } } impl<T: ?Sized + Pointable> fmt::Debug for Atomic<T> { @@ -925,6 +985,7 @@ impl<T: ?Sized + Pointable> From<Owned<T>> for Atomic<T> { /// use crossbeam_epoch::{Atomic, Owned}; /// /// let a = Atomic::<i32>::from(Owned::new(1234)); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` fn from(owned: Owned<T>) -> Self { let data = owned.data; @@ -1108,6 +1169,7 @@ impl<T: ?Sized + Pointable> Owned<T> { /// let o = Owned::new(1234); /// let guard = &epoch::pin(); /// let p = o.into_shared(guard); + /// # unsafe { drop(p.into_owned()); } // avoid leak /// ``` #[allow(clippy::needless_lifetimes)] pub fn into_shared<'g>(self, _: &'g Guard) -> Shared<'g, T> { @@ -1291,6 +1353,7 @@ impl<'g, T> Shared<'g, T> { /// let guard = &epoch::pin(); /// let p = a.load(SeqCst, guard); /// assert_eq!(p.as_raw(), raw); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub fn as_raw(&self) -> *const T { let (raw, _) = decompose_tag::<T>(self.data); @@ -1329,6 +1392,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> { /// assert!(a.load(SeqCst, guard).is_null()); /// a.store(Owned::new(1234), SeqCst); /// assert!(!a.load(SeqCst, guard).is_null()); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub fn is_null(&self) -> bool { let (raw, _) = decompose_tag::<T>(self.data); @@ -1365,6 +1429,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> { /// unsafe { /// assert_eq!(p.deref(), &1234); /// } + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub unsafe fn deref(&self) -> &'g T { let (raw, _) = decompose_tag::<T>(self.data); @@ -1406,6 +1471,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> { /// unsafe { /// assert_eq!(p.deref(), &vec![1, 2, 3, 4, 5]); /// } + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub unsafe fn deref_mut(&mut self) -> &'g mut T { let (raw, _) = decompose_tag::<T>(self.data); @@ -1442,6 +1508,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> { /// unsafe { /// assert_eq!(p.as_ref(), Some(&1234)); /// } + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub unsafe fn as_ref(&self) -> Option<&'g T> { let (raw, _) = decompose_tag::<T>(self.data); @@ -1481,6 +1548,36 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> { Owned::from_usize(self.data) } + /// Takes ownership of the pointee if it is not null. + /// + /// # Safety + /// + /// This method may be called only if the pointer is valid and nobody else is holding a + /// reference to the same object, or if the pointer is null. + /// + /// # Examples + /// + /// ``` + /// use crossbeam_epoch::{self as epoch, Atomic}; + /// use std::sync::atomic::Ordering::SeqCst; + /// + /// let a = Atomic::new(1234); + /// unsafe { + /// let guard = &epoch::unprotected(); + /// let p = a.load(SeqCst, guard); + /// if let Some(x) = p.try_into_owned() { + /// drop(x); + /// } + /// } + /// ``` + pub unsafe fn try_into_owned(self) -> Option<Owned<T>> { + if self.is_null() { + None + } else { + Some(Owned::from_usize(self.data)) + } + } + /// Returns the tag stored within the pointer. /// /// # Examples @@ -1493,6 +1590,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> { /// let guard = &epoch::pin(); /// let p = a.load(SeqCst, guard); /// assert_eq!(p.tag(), 2); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub fn tag(&self) -> usize { let (_, tag) = decompose_tag::<T>(self.data); @@ -1516,6 +1614,7 @@ impl<'g, T: ?Sized + Pointable> Shared<'g, T> { /// assert_eq!(p1.tag(), 0); /// assert_eq!(p2.tag(), 2); /// assert_eq!(p1.as_raw(), p2.as_raw()); + /// # unsafe { drop(a.into_owned()); } // avoid leak /// ``` pub fn with_tag(&self, tag: usize) -> Shared<'g, T> { unsafe { Self::from_usize(compose_tag::<T>(self.data, tag)) } @@ -1536,6 +1635,7 @@ impl<T> From<*const T> for Shared<'_, T> { /// /// let p = Shared::from(Box::into_raw(Box::new(1234)) as *const _); /// assert!(!p.is_null()); + /// # unsafe { drop(p.into_owned()); } // avoid leak /// ``` fn from(raw: *const T) -> Self { let raw = raw as usize; @@ -1612,7 +1712,7 @@ mod tests { #[test] fn array_init() { let owned = Owned::<[MaybeUninit<usize>]>::init(10); - let arr: &[MaybeUninit<usize>] = &*owned; + let arr: &[MaybeUninit<usize>] = &owned; assert_eq!(arr.len(), 10); } } |