| //! Atomic types |
| //! |
| //! Atomic types provide primitive shared-memory communication between |
| //! threads, and are the building blocks of other concurrent |
| //! types. |
| //! |
| //! Rust atomics currently follow the same rules as [C++20 atomics][cpp], specifically `atomic_ref`. |
| //! Basically, creating a *shared reference* to one of the Rust atomic types corresponds to creating |
| //! an `atomic_ref` in C++; the `atomic_ref` is destroyed when the lifetime of the shared reference |
| //! ends. (A Rust atomic type that is exclusively owned or behind a mutable reference does *not* |
| //! correspond to an "atomic object" in C++, since it can be accessed via non-atomic operations.) |
| //! |
| //! This module defines atomic versions of a select number of primitive |
| //! types, including [`AtomicBool`], [`AtomicIsize`], [`AtomicUsize`], |
| //! [`AtomicI8`], [`AtomicU16`], etc. |
| //! Atomic types present operations that, when used correctly, synchronize |
| //! updates between threads. |
| //! |
| //! Each method takes an [`Ordering`] which represents the strength of |
| //! the memory barrier for that operation. These orderings are the |
| //! same as the [C++20 atomic orderings][1]. For more information see the [nomicon][2]. |
| //! |
| //! [cpp]: https://en.cppreference.com/w/cpp/atomic |
| //! [1]: https://en.cppreference.com/w/cpp/atomic/memory_order |
| //! [2]: ../../../nomicon/atomics.html |
| //! |
| //! Atomic variables are safe to share between threads (they implement [`Sync`]) |
| //! but they do not themselves provide the mechanism for sharing and follow the |
| //! [threading model](../../../std/thread/index.html#the-threading-model) of Rust. |
| //! The most common way to share an atomic variable is to put it into an [`Arc`][arc] (an |
| //! atomically-reference-counted shared pointer). |
| //! |
| //! [arc]: ../../../std/sync/struct.Arc.html |
| //! |
| //! Atomic types may be stored in static variables, initialized using |
| //! the constant initializers like [`AtomicBool::new`]. Atomic statics |
| //! are often used for lazy global initialization. |
| //! |
| //! # Portability |
| //! |
| //! All atomic types in this module are guaranteed to be [lock-free] if they're |
| //! available. This means they don't internally acquire a global mutex. Atomic |
| //! types and operations are not guaranteed to be wait-free. This means that |
| //! operations like `fetch_or` may be implemented with a compare-and-swap loop. |
| //! |
| //! Atomic operations may be implemented at the instruction layer with |
| //! larger-size atomics. For example some platforms use 4-byte atomic |
| //! instructions to implement `AtomicI8`. Note that this emulation should not |
| //! have an impact on correctness of code, it's just something to be aware of. |
| //! |
| //! The atomic types in this module might not be available on all platforms. The |
| //! atomic types here are all widely available, however, and can generally be |
| //! relied upon existing. Some notable exceptions are: |
| //! |
| //! * PowerPC and MIPS platforms with 32-bit pointers do not have `AtomicU64` or |
| //! `AtomicI64` types. |
| //! * ARM platforms like `armv5te` that aren't for Linux only provide `load` |
| //! and `store` operations, and do not support Compare and Swap (CAS) |
| //! operations, such as `swap`, `fetch_add`, etc. Additionally on Linux, |
| //! these CAS operations are implemented via [operating system support], which |
| //! may come with a performance penalty. |
| //! * ARM targets with `thumbv6m` only provide `load` and `store` operations, |
| //! and do not support Compare and Swap (CAS) operations, such as `swap`, |
| //! `fetch_add`, etc. |
| //! |
| //! [operating system support]: https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt |
| //! |
| //! Note that future platforms may be added that also do not have support for |
| //! some atomic operations. Maximally portable code will want to be careful |
| //! about which atomic types are used. `AtomicUsize` and `AtomicIsize` are |
| //! generally the most portable, but even then they're not available everywhere. |
| //! For reference, the `std` library requires `AtomicBool`s and pointer-sized atomics, although |
| //! `core` does not. |
| //! |
| //! The `#[cfg(target_has_atomic)]` attribute can be used to conditionally |
| //! compile based on the target's supported bit widths. It is a key-value |
| //! option set for each supported size, with values "8", "16", "32", "64", |
| //! "128", and "ptr" for pointer-sized atomics. |
| //! |
| //! [lock-free]: https://en.wikipedia.org/wiki/Non-blocking_algorithm |
| //! |
| //! # Examples |
| //! |
| //! A simple spinlock: |
| //! |
| //! ``` |
| //! use std::sync::Arc; |
| //! use std::sync::atomic::{AtomicUsize, Ordering}; |
| //! use std::{hint, thread}; |
| //! |
| //! fn main() { |
| //! let spinlock = Arc::new(AtomicUsize::new(1)); |
| //! |
| //! let spinlock_clone = Arc::clone(&spinlock); |
| //! let thread = thread::spawn(move|| { |
| //! spinlock_clone.store(0, Ordering::SeqCst); |
| //! }); |
| //! |
| //! // Wait for the other thread to release the lock |
| //! while spinlock.load(Ordering::SeqCst) != 0 { |
| //! hint::spin_loop(); |
| //! } |
| //! |
| //! if let Err(panic) = thread.join() { |
| //! println!("Thread had an error: {panic:?}"); |
| //! } |
| //! } |
| //! ``` |
| //! |
| //! Keep a global count of live threads: |
| //! |
| //! ``` |
| //! use std::sync::atomic::{AtomicUsize, Ordering}; |
| //! |
| //! static GLOBAL_THREAD_COUNT: AtomicUsize = AtomicUsize::new(0); |
| //! |
| //! let old_thread_count = GLOBAL_THREAD_COUNT.fetch_add(1, Ordering::SeqCst); |
| //! println!("live threads: {}", old_thread_count + 1); |
| //! ``` |
| |
| #![stable(feature = "rust1", since = "1.0.0")] |
| #![cfg_attr(not(target_has_atomic_load_store = "8"), allow(dead_code))] |
| #![cfg_attr(not(target_has_atomic_load_store = "8"), allow(unused_imports))] |
| #![rustc_diagnostic_item = "atomic_mod"] |
| |
| use self::Ordering::*; |
| |
| use crate::cell::UnsafeCell; |
| use crate::fmt; |
| use crate::intrinsics; |
| |
| use crate::hint::spin_loop; |
| |
| /// A boolean type which can be safely shared between threads. |
| /// |
| /// This type has the same in-memory representation as a [`bool`]. |
| /// |
| /// **Note**: This type is only available on platforms that support atomic |
| /// loads and stores of `u8`. |
| #[cfg(target_has_atomic_load_store = "8")] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_diagnostic_item = "AtomicBool"] |
| #[repr(C, align(1))] |
| pub struct AtomicBool { |
| v: UnsafeCell<u8>, |
| } |
| |
| #[cfg(target_has_atomic_load_store = "8")] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_const_unstable(feature = "const_default_impls", issue = "87864")] |
| impl const Default for AtomicBool { |
| /// Creates an `AtomicBool` initialized to `false`. |
| #[inline] |
| fn default() -> Self { |
| Self::new(false) |
| } |
| } |
| |
| // Send is implicitly implemented for AtomicBool. |
| #[cfg(target_has_atomic_load_store = "8")] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| unsafe impl Sync for AtomicBool {} |
| |
| /// A raw pointer type which can be safely shared between threads. |
| /// |
| /// This type has the same in-memory representation as a `*mut T`. |
| /// |
| /// **Note**: This type is only available on platforms that support atomic |
| /// loads and stores of pointers. Its size depends on the target pointer's size. |
| #[cfg(target_has_atomic_load_store = "ptr")] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg_attr(not(test), rustc_diagnostic_item = "AtomicPtr")] |
| #[cfg_attr(target_pointer_width = "16", repr(C, align(2)))] |
| #[cfg_attr(target_pointer_width = "32", repr(C, align(4)))] |
| #[cfg_attr(target_pointer_width = "64", repr(C, align(8)))] |
| pub struct AtomicPtr<T> { |
| p: UnsafeCell<*mut T>, |
| } |
| |
| #[cfg(target_has_atomic_load_store = "ptr")] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_const_unstable(feature = "const_default_impls", issue = "87864")] |
| impl<T> const Default for AtomicPtr<T> { |
| /// Creates a null `AtomicPtr<T>`. |
| fn default() -> AtomicPtr<T> { |
| AtomicPtr::new(crate::ptr::null_mut()) |
| } |
| } |
| |
| #[cfg(target_has_atomic_load_store = "ptr")] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| unsafe impl<T> Send for AtomicPtr<T> {} |
| #[cfg(target_has_atomic_load_store = "ptr")] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| unsafe impl<T> Sync for AtomicPtr<T> {} |
| |
| /// Atomic memory orderings |
| /// |
| /// Memory orderings specify the way atomic operations synchronize memory. |
| /// In its weakest [`Ordering::Relaxed`], only the memory directly touched by the |
| /// operation is synchronized. On the other hand, a store-load pair of [`Ordering::SeqCst`] |
| /// operations synchronize other memory while additionally preserving a total order of such |
| /// operations across all threads. |
| /// |
| /// Rust's memory orderings are [the same as those of |
| /// C++20](https://en.cppreference.com/w/cpp/atomic/memory_order). |
| /// |
| /// For more information see the [nomicon]. |
| /// |
| /// [nomicon]: ../../../nomicon/atomics.html |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)] |
| #[non_exhaustive] |
| #[rustc_diagnostic_item = "Ordering"] |
| pub enum Ordering { |
| /// No ordering constraints, only atomic operations. |
| /// |
| /// Corresponds to [`memory_order_relaxed`] in C++20. |
| /// |
| /// [`memory_order_relaxed`]: https://en.cppreference.com/w/cpp/atomic/memory_order#Relaxed_ordering |
| #[stable(feature = "rust1", since = "1.0.0")] |
| Relaxed, |
| /// When coupled with a store, all previous operations become ordered |
| /// before any load of this value with [`Acquire`] (or stronger) ordering. |
| /// In particular, all previous writes become visible to all threads |
| /// that perform an [`Acquire`] (or stronger) load of this value. |
| /// |
| /// Notice that using this ordering for an operation that combines loads |
| /// and stores leads to a [`Relaxed`] load operation! |
| /// |
| /// This ordering is only applicable for operations that can perform a store. |
| /// |
| /// Corresponds to [`memory_order_release`] in C++20. |
| /// |
| /// [`memory_order_release`]: https://en.cppreference.com/w/cpp/atomic/memory_order#Release-Acquire_ordering |
| #[stable(feature = "rust1", since = "1.0.0")] |
| Release, |
| /// When coupled with a load, if the loaded value was written by a store operation with |
| /// [`Release`] (or stronger) ordering, then all subsequent operations |
| /// become ordered after that store. In particular, all subsequent loads will see data |
| /// written before the store. |
| /// |
| /// Notice that using this ordering for an operation that combines loads |
| /// and stores leads to a [`Relaxed`] store operation! |
| /// |
| /// This ordering is only applicable for operations that can perform a load. |
| /// |
| /// Corresponds to [`memory_order_acquire`] in C++20. |
| /// |
| /// [`memory_order_acquire`]: https://en.cppreference.com/w/cpp/atomic/memory_order#Release-Acquire_ordering |
| #[stable(feature = "rust1", since = "1.0.0")] |
| Acquire, |
| /// Has the effects of both [`Acquire`] and [`Release`] together: |
| /// For loads it uses [`Acquire`] ordering. For stores it uses the [`Release`] ordering. |
| /// |
| /// Notice that in the case of `compare_and_swap`, it is possible that the operation ends up |
| /// not performing any store and hence it has just [`Acquire`] ordering. However, |
| /// `AcqRel` will never perform [`Relaxed`] accesses. |
| /// |
| /// This ordering is only applicable for operations that combine both loads and stores. |
| /// |
| /// Corresponds to [`memory_order_acq_rel`] in C++20. |
| /// |
| /// [`memory_order_acq_rel`]: https://en.cppreference.com/w/cpp/atomic/memory_order#Release-Acquire_ordering |
| #[stable(feature = "rust1", since = "1.0.0")] |
| AcqRel, |
| /// Like [`Acquire`]/[`Release`]/[`AcqRel`] (for load, store, and load-with-store |
| /// operations, respectively) with the additional guarantee that all threads see all |
| /// sequentially consistent operations in the same order. |
| /// |
| /// Corresponds to [`memory_order_seq_cst`] in C++20. |
| /// |
| /// [`memory_order_seq_cst`]: https://en.cppreference.com/w/cpp/atomic/memory_order#Sequentially-consistent_ordering |
| #[stable(feature = "rust1", since = "1.0.0")] |
| SeqCst, |
| } |
| |
| /// An [`AtomicBool`] initialized to `false`. |
| #[cfg(target_has_atomic_load_store = "8")] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[deprecated( |
| since = "1.34.0", |
| note = "the `new` function is now preferred", |
| suggestion = "AtomicBool::new(false)" |
| )] |
| pub const ATOMIC_BOOL_INIT: AtomicBool = AtomicBool::new(false); |
| |
| #[cfg(target_has_atomic_load_store = "8")] |
| impl AtomicBool { |
| /// Creates a new `AtomicBool`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::AtomicBool; |
| /// |
| /// let atomic_true = AtomicBool::new(true); |
| /// let atomic_false = AtomicBool::new(false); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_const_stable(feature = "const_atomic_new", since = "1.24.0")] |
| #[must_use] |
| pub const fn new(v: bool) -> AtomicBool { |
| AtomicBool { v: UnsafeCell::new(v as u8) } |
| } |
| |
| /// Returns a mutable reference to the underlying [`bool`]. |
| /// |
| /// This is safe because the mutable reference guarantees that no other threads are |
| /// concurrently accessing the atomic data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let mut some_bool = AtomicBool::new(true); |
| /// assert_eq!(*some_bool.get_mut(), true); |
| /// *some_bool.get_mut() = false; |
| /// assert_eq!(some_bool.load(Ordering::SeqCst), false); |
| /// ``` |
| #[inline] |
| #[stable(feature = "atomic_access", since = "1.15.0")] |
| pub fn get_mut(&mut self) -> &mut bool { |
| // SAFETY: the mutable reference guarantees unique ownership. |
| unsafe { &mut *(self.v.get() as *mut bool) } |
| } |
| |
| /// Get atomic access to a `&mut bool`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(atomic_from_mut)] |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let mut some_bool = true; |
| /// let a = AtomicBool::from_mut(&mut some_bool); |
| /// a.store(false, Ordering::Relaxed); |
| /// assert_eq!(some_bool, false); |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic_equal_alignment = "8")] |
| #[unstable(feature = "atomic_from_mut", issue = "76314")] |
| pub fn from_mut(v: &mut bool) -> &mut Self { |
| // SAFETY: the mutable reference guarantees unique ownership, and |
| // alignment of both `bool` and `Self` is 1. |
| unsafe { &mut *(v as *mut bool as *mut Self) } |
| } |
| |
| /// Get non-atomic access to a `&mut [AtomicBool]` slice. |
| /// |
| /// This is safe because the mutable reference guarantees that no other threads are |
| /// concurrently accessing the atomic data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(atomic_from_mut, inline_const)] |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let mut some_bools = [const { AtomicBool::new(false) }; 10]; |
| /// |
| /// let view: &mut [bool] = AtomicBool::get_mut_slice(&mut some_bools); |
| /// assert_eq!(view, [false; 10]); |
| /// view[..5].copy_from_slice(&[true; 5]); |
| /// |
| /// std::thread::scope(|s| { |
| /// for t in &some_bools[..5] { |
| /// s.spawn(move || assert_eq!(t.load(Ordering::Relaxed), true)); |
| /// } |
| /// |
| /// for f in &some_bools[5..] { |
| /// s.spawn(move || assert_eq!(f.load(Ordering::Relaxed), false)); |
| /// } |
| /// }); |
| /// ``` |
| #[inline] |
| #[unstable(feature = "atomic_from_mut", issue = "76314")] |
| pub fn get_mut_slice(this: &mut [Self]) -> &mut [bool] { |
| // SAFETY: the mutable reference guarantees unique ownership. |
| unsafe { &mut *(this as *mut [Self] as *mut [bool]) } |
| } |
| |
| /// Get atomic access to a `&mut [bool]` slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(atomic_from_mut)] |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let mut some_bools = [false; 10]; |
| /// let a = &*AtomicBool::from_mut_slice(&mut some_bools); |
| /// std::thread::scope(|s| { |
| /// for i in 0..a.len() { |
| /// s.spawn(move || a[i].store(true, Ordering::Relaxed)); |
| /// } |
| /// }); |
| /// assert_eq!(some_bools, [true; 10]); |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic_equal_alignment = "8")] |
| #[unstable(feature = "atomic_from_mut", issue = "76314")] |
| pub fn from_mut_slice(v: &mut [bool]) -> &mut [Self] { |
| // SAFETY: the mutable reference guarantees unique ownership, and |
| // alignment of both `bool` and `Self` is 1. |
| unsafe { &mut *(v as *mut [bool] as *mut [Self]) } |
| } |
| |
| /// Consumes the atomic and returns the contained value. |
| /// |
| /// This is safe because passing `self` by value guarantees that no other threads are |
| /// concurrently accessing the atomic data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::AtomicBool; |
| /// |
| /// let some_bool = AtomicBool::new(true); |
| /// assert_eq!(some_bool.into_inner(), true); |
| /// ``` |
| #[inline] |
| #[stable(feature = "atomic_access", since = "1.15.0")] |
| #[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")] |
| pub const fn into_inner(self) -> bool { |
| self.v.into_inner() != 0 |
| } |
| |
| /// Loads a value from the bool. |
| /// |
| /// `load` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. Possible values are [`SeqCst`], [`Acquire`] and [`Relaxed`]. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `order` is [`Release`] or [`AcqRel`]. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let some_bool = AtomicBool::new(true); |
| /// |
| /// assert_eq!(some_bool.load(Ordering::Relaxed), true); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn load(&self, order: Ordering) -> bool { |
| // SAFETY: any data races are prevented by atomic intrinsics and the raw |
| // pointer passed in is valid because we got it from a reference. |
| unsafe { atomic_load(self.v.get(), order) != 0 } |
| } |
| |
| /// Stores a value into the bool. |
| /// |
| /// `store` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. Possible values are [`SeqCst`], [`Release`] and [`Relaxed`]. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `order` is [`Acquire`] or [`AcqRel`]. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let some_bool = AtomicBool::new(true); |
| /// |
| /// some_bool.store(false, Ordering::Relaxed); |
| /// assert_eq!(some_bool.load(Ordering::Relaxed), false); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn store(&self, val: bool, order: Ordering) { |
| // SAFETY: any data races are prevented by atomic intrinsics and the raw |
| // pointer passed in is valid because we got it from a reference. |
| unsafe { |
| atomic_store(self.v.get(), val as u8, order); |
| } |
| } |
| |
| /// Stores a value into the bool, returning the previous value. |
| /// |
| /// `swap` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on `u8`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let some_bool = AtomicBool::new(true); |
| /// |
| /// assert_eq!(some_bool.swap(false, Ordering::Relaxed), true); |
| /// assert_eq!(some_bool.load(Ordering::Relaxed), false); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn swap(&self, val: bool, order: Ordering) -> bool { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_swap(self.v.get(), val as u8, order) != 0 } |
| } |
| |
| /// Stores a value into the [`bool`] if the current value is the same as the `current` value. |
| /// |
| /// The return value is always the previous value. If it is equal to `current`, then the value |
| /// was updated. |
| /// |
| /// `compare_and_swap` also takes an [`Ordering`] argument which describes the memory |
| /// ordering of this operation. Notice that even when using [`AcqRel`], the operation |
| /// might fail and hence just perform an `Acquire` load, but not have `Release` semantics. |
| /// Using [`Acquire`] makes the store part of this operation [`Relaxed`] if it |
| /// happens, and using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on `u8`. |
| /// |
| /// # Migrating to `compare_exchange` and `compare_exchange_weak` |
| /// |
| /// `compare_and_swap` is equivalent to `compare_exchange` with the following mapping for |
| /// memory orderings: |
| /// |
| /// Original | Success | Failure |
| /// -------- | ------- | ------- |
| /// Relaxed | Relaxed | Relaxed |
| /// Acquire | Acquire | Acquire |
| /// Release | Release | Relaxed |
| /// AcqRel | AcqRel | Acquire |
| /// SeqCst | SeqCst | SeqCst |
| /// |
| /// `compare_exchange_weak` is allowed to fail spuriously even when the comparison succeeds, |
| /// which allows the compiler to generate better assembly code when the compare and swap |
| /// is used in a loop. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let some_bool = AtomicBool::new(true); |
| /// |
| /// assert_eq!(some_bool.compare_and_swap(true, false, Ordering::Relaxed), true); |
| /// assert_eq!(some_bool.load(Ordering::Relaxed), false); |
| /// |
| /// assert_eq!(some_bool.compare_and_swap(true, true, Ordering::Relaxed), false); |
| /// assert_eq!(some_bool.load(Ordering::Relaxed), false); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[deprecated( |
| since = "1.50.0", |
| note = "Use `compare_exchange` or `compare_exchange_weak` instead" |
| )] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn compare_and_swap(&self, current: bool, new: bool, order: Ordering) -> bool { |
| match self.compare_exchange(current, new, order, strongest_failure_ordering(order)) { |
| Ok(x) => x, |
| Err(x) => x, |
| } |
| } |
| |
| /// Stores a value into the [`bool`] if the current value is the same as the `current` value. |
| /// |
| /// The return value is a result indicating whether the new value was written and containing |
| /// the previous value. On success this value is guaranteed to be equal to `current`. |
| /// |
| /// `compare_exchange` takes two [`Ordering`] arguments to describe the memory |
| /// ordering of this operation. `success` describes the required ordering for the |
| /// read-modify-write operation that takes place if the comparison with `current` succeeds. |
| /// `failure` describes the required ordering for the load operation that takes place when |
| /// the comparison fails. Using [`Acquire`] as success ordering makes the store part |
| /// of this operation [`Relaxed`], and using [`Release`] makes the successful load |
| /// [`Relaxed`]. The failure ordering can only be [`SeqCst`], [`Acquire`] or [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on `u8`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let some_bool = AtomicBool::new(true); |
| /// |
| /// assert_eq!(some_bool.compare_exchange(true, |
| /// false, |
| /// Ordering::Acquire, |
| /// Ordering::Relaxed), |
| /// Ok(true)); |
| /// assert_eq!(some_bool.load(Ordering::Relaxed), false); |
| /// |
| /// assert_eq!(some_bool.compare_exchange(true, true, |
| /// Ordering::SeqCst, |
| /// Ordering::Acquire), |
| /// Err(false)); |
| /// assert_eq!(some_bool.load(Ordering::Relaxed), false); |
| /// ``` |
| #[inline] |
| #[stable(feature = "extended_compare_and_swap", since = "1.10.0")] |
| #[doc(alias = "compare_and_swap")] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn compare_exchange( |
| &self, |
| current: bool, |
| new: bool, |
| success: Ordering, |
| failure: Ordering, |
| ) -> Result<bool, bool> { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| match unsafe { |
| atomic_compare_exchange(self.v.get(), current as u8, new as u8, success, failure) |
| } { |
| Ok(x) => Ok(x != 0), |
| Err(x) => Err(x != 0), |
| } |
| } |
| |
| /// Stores a value into the [`bool`] if the current value is the same as the `current` value. |
| /// |
| /// Unlike [`AtomicBool::compare_exchange`], this function is allowed to spuriously fail even when the |
| /// comparison succeeds, which can result in more efficient code on some platforms. The |
| /// return value is a result indicating whether the new value was written and containing the |
| /// previous value. |
| /// |
| /// `compare_exchange_weak` takes two [`Ordering`] arguments to describe the memory |
| /// ordering of this operation. `success` describes the required ordering for the |
| /// read-modify-write operation that takes place if the comparison with `current` succeeds. |
| /// `failure` describes the required ordering for the load operation that takes place when |
| /// the comparison fails. Using [`Acquire`] as success ordering makes the store part |
| /// of this operation [`Relaxed`], and using [`Release`] makes the successful load |
| /// [`Relaxed`]. The failure ordering can only be [`SeqCst`], [`Acquire`] or [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on `u8`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let val = AtomicBool::new(false); |
| /// |
| /// let new = true; |
| /// let mut old = val.load(Ordering::Relaxed); |
| /// loop { |
| /// match val.compare_exchange_weak(old, new, Ordering::SeqCst, Ordering::Relaxed) { |
| /// Ok(_) => break, |
| /// Err(x) => old = x, |
| /// } |
| /// } |
| /// ``` |
| #[inline] |
| #[stable(feature = "extended_compare_and_swap", since = "1.10.0")] |
| #[doc(alias = "compare_and_swap")] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn compare_exchange_weak( |
| &self, |
| current: bool, |
| new: bool, |
| success: Ordering, |
| failure: Ordering, |
| ) -> Result<bool, bool> { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| match unsafe { |
| atomic_compare_exchange_weak(self.v.get(), current as u8, new as u8, success, failure) |
| } { |
| Ok(x) => Ok(x != 0), |
| Err(x) => Err(x != 0), |
| } |
| } |
| |
| /// Logical "and" with a boolean value. |
| /// |
| /// Performs a logical "and" operation on the current value and the argument `val`, and sets |
| /// the new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_and` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on `u8`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let foo = AtomicBool::new(true); |
| /// assert_eq!(foo.fetch_and(false, Ordering::SeqCst), true); |
| /// assert_eq!(foo.load(Ordering::SeqCst), false); |
| /// |
| /// let foo = AtomicBool::new(true); |
| /// assert_eq!(foo.fetch_and(true, Ordering::SeqCst), true); |
| /// assert_eq!(foo.load(Ordering::SeqCst), true); |
| /// |
| /// let foo = AtomicBool::new(false); |
| /// assert_eq!(foo.fetch_and(false, Ordering::SeqCst), false); |
| /// assert_eq!(foo.load(Ordering::SeqCst), false); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_and(&self, val: bool, order: Ordering) -> bool { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_and(self.v.get(), val as u8, order) != 0 } |
| } |
| |
| /// Logical "nand" with a boolean value. |
| /// |
| /// Performs a logical "nand" operation on the current value and the argument `val`, and sets |
| /// the new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_nand` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on `u8`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let foo = AtomicBool::new(true); |
| /// assert_eq!(foo.fetch_nand(false, Ordering::SeqCst), true); |
| /// assert_eq!(foo.load(Ordering::SeqCst), true); |
| /// |
| /// let foo = AtomicBool::new(true); |
| /// assert_eq!(foo.fetch_nand(true, Ordering::SeqCst), true); |
| /// assert_eq!(foo.load(Ordering::SeqCst) as usize, 0); |
| /// assert_eq!(foo.load(Ordering::SeqCst), false); |
| /// |
| /// let foo = AtomicBool::new(false); |
| /// assert_eq!(foo.fetch_nand(false, Ordering::SeqCst), false); |
| /// assert_eq!(foo.load(Ordering::SeqCst), true); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_nand(&self, val: bool, order: Ordering) -> bool { |
| // We can't use atomic_nand here because it can result in a bool with |
| // an invalid value. This happens because the atomic operation is done |
| // with an 8-bit integer internally, which would set the upper 7 bits. |
| // So we just use fetch_xor or swap instead. |
| if val { |
| // !(x & true) == !x |
| // We must invert the bool. |
| self.fetch_xor(true, order) |
| } else { |
| // !(x & false) == true |
| // We must set the bool to true. |
| self.swap(true, order) |
| } |
| } |
| |
| /// Logical "or" with a boolean value. |
| /// |
| /// Performs a logical "or" operation on the current value and the argument `val`, and sets the |
| /// new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_or` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on `u8`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let foo = AtomicBool::new(true); |
| /// assert_eq!(foo.fetch_or(false, Ordering::SeqCst), true); |
| /// assert_eq!(foo.load(Ordering::SeqCst), true); |
| /// |
| /// let foo = AtomicBool::new(true); |
| /// assert_eq!(foo.fetch_or(true, Ordering::SeqCst), true); |
| /// assert_eq!(foo.load(Ordering::SeqCst), true); |
| /// |
| /// let foo = AtomicBool::new(false); |
| /// assert_eq!(foo.fetch_or(false, Ordering::SeqCst), false); |
| /// assert_eq!(foo.load(Ordering::SeqCst), false); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_or(&self, val: bool, order: Ordering) -> bool { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_or(self.v.get(), val as u8, order) != 0 } |
| } |
| |
| /// Logical "xor" with a boolean value. |
| /// |
| /// Performs a logical "xor" operation on the current value and the argument `val`, and sets |
| /// the new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_xor` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on `u8`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let foo = AtomicBool::new(true); |
| /// assert_eq!(foo.fetch_xor(false, Ordering::SeqCst), true); |
| /// assert_eq!(foo.load(Ordering::SeqCst), true); |
| /// |
| /// let foo = AtomicBool::new(true); |
| /// assert_eq!(foo.fetch_xor(true, Ordering::SeqCst), true); |
| /// assert_eq!(foo.load(Ordering::SeqCst), false); |
| /// |
| /// let foo = AtomicBool::new(false); |
| /// assert_eq!(foo.fetch_xor(false, Ordering::SeqCst), false); |
| /// assert_eq!(foo.load(Ordering::SeqCst), false); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_xor(&self, val: bool, order: Ordering) -> bool { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_xor(self.v.get(), val as u8, order) != 0 } |
| } |
| |
| /// Logical "not" with a boolean value. |
| /// |
| /// Performs a logical "not" operation on the current value, and sets |
| /// the new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_not` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on `u8`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(atomic_bool_fetch_not)] |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let foo = AtomicBool::new(true); |
| /// assert_eq!(foo.fetch_not(Ordering::SeqCst), true); |
| /// assert_eq!(foo.load(Ordering::SeqCst), false); |
| /// |
| /// let foo = AtomicBool::new(false); |
| /// assert_eq!(foo.fetch_not(Ordering::SeqCst), false); |
| /// assert_eq!(foo.load(Ordering::SeqCst), true); |
| /// ``` |
| #[inline] |
| #[unstable(feature = "atomic_bool_fetch_not", issue = "98485")] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_not(&self, order: Ordering) -> bool { |
| self.fetch_xor(true, order) |
| } |
| |
| /// Returns a mutable pointer to the underlying [`bool`]. |
| /// |
| /// Doing non-atomic reads and writes on the resulting integer can be a data race. |
| /// This method is mostly useful for FFI, where the function signature may use |
| /// `*mut bool` instead of `&AtomicBool`. |
| /// |
| /// Returning an `*mut` pointer from a shared reference to this atomic is safe because the |
| /// atomic types work with interior mutability. All modifications of an atomic change the value |
| /// through a shared reference, and can do so safely as long as they use atomic operations. Any |
| /// use of the returned raw pointer requires an `unsafe` block and still has to uphold the same |
| /// restriction: operations on it must be atomic. |
| /// |
| /// # Examples |
| /// |
| /// ```ignore (extern-declaration) |
| /// # fn main() { |
| /// use std::sync::atomic::AtomicBool; |
| /// extern "C" { |
| /// fn my_atomic_op(arg: *mut bool); |
| /// } |
| /// |
| /// let mut atomic = AtomicBool::new(true); |
| /// unsafe { |
| /// my_atomic_op(atomic.as_mut_ptr()); |
| /// } |
| /// # } |
| /// ``` |
| #[inline] |
| #[unstable(feature = "atomic_mut_ptr", reason = "recently added", issue = "66893")] |
| pub fn as_mut_ptr(&self) -> *mut bool { |
| self.v.get() as *mut bool |
| } |
| |
| /// Fetches the value, and applies a function to it that returns an optional |
| /// new value. Returns a `Result` of `Ok(previous_value)` if the function |
| /// returned `Some(_)`, else `Err(previous_value)`. |
| /// |
| /// Note: This may call the function multiple times if the value has been |
| /// changed from other threads in the meantime, as long as the function |
| /// returns `Some(_)`, but the function will have been applied only once to |
| /// the stored value. |
| /// |
| /// `fetch_update` takes two [`Ordering`] arguments to describe the memory |
| /// ordering of this operation. The first describes the required ordering for |
| /// when the operation finally succeeds while the second describes the |
| /// required ordering for loads. These correspond to the success and failure |
| /// orderings of [`AtomicBool::compare_exchange`] respectively. |
| /// |
| /// Using [`Acquire`] as success ordering makes the store part of this |
| /// operation [`Relaxed`], and using [`Release`] makes the final successful |
| /// load [`Relaxed`]. The (failed) load ordering can only be [`SeqCst`], |
| /// [`Acquire`] or [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on `u8`. |
| /// |
| /// # Considerations |
| /// |
| /// This method is not magic; it is not provided by the hardware. |
| /// It is implemented in terms of [`AtomicBool::compare_exchange_weak`], and suffers from the same drawbacks. |
| /// In particular, this method will not circumvent the [ABA Problem]. |
| /// |
| /// [ABA Problem]: https://en.wikipedia.org/wiki/ABA_problem |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| /// use std::sync::atomic::{AtomicBool, Ordering}; |
| /// |
| /// let x = AtomicBool::new(false); |
| /// assert_eq!(x.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |_| None), Err(false)); |
| /// assert_eq!(x.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |x| Some(!x)), Ok(false)); |
| /// assert_eq!(x.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |x| Some(!x)), Ok(true)); |
| /// assert_eq!(x.load(Ordering::SeqCst), false); |
| /// ``` |
| #[inline] |
| #[stable(feature = "atomic_fetch_update", since = "1.53.0")] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_update<F>( |
| &self, |
| set_order: Ordering, |
| fetch_order: Ordering, |
| mut f: F, |
| ) -> Result<bool, bool> |
| where |
| F: FnMut(bool) -> Option<bool>, |
| { |
| let mut prev = self.load(fetch_order); |
| while let Some(next) = f(prev) { |
| match self.compare_exchange_weak(prev, next, set_order, fetch_order) { |
| x @ Ok(_) => return x, |
| Err(next_prev) => prev = next_prev, |
| } |
| } |
| Err(prev) |
| } |
| } |
| |
| #[cfg(target_has_atomic_load_store = "ptr")] |
| impl<T> AtomicPtr<T> { |
| /// Creates a new `AtomicPtr`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::AtomicPtr; |
| /// |
| /// let ptr = &mut 5; |
| /// let atomic_ptr = AtomicPtr::new(ptr); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_const_stable(feature = "const_atomic_new", since = "1.24.0")] |
| pub const fn new(p: *mut T) -> AtomicPtr<T> { |
| AtomicPtr { p: UnsafeCell::new(p) } |
| } |
| |
| /// Returns a mutable reference to the underlying pointer. |
| /// |
| /// This is safe because the mutable reference guarantees that no other threads are |
| /// concurrently accessing the atomic data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let mut data = 10; |
| /// let mut atomic_ptr = AtomicPtr::new(&mut data); |
| /// let mut other_data = 5; |
| /// *atomic_ptr.get_mut() = &mut other_data; |
| /// assert_eq!(unsafe { *atomic_ptr.load(Ordering::SeqCst) }, 5); |
| /// ``` |
| #[inline] |
| #[stable(feature = "atomic_access", since = "1.15.0")] |
| pub fn get_mut(&mut self) -> &mut *mut T { |
| self.p.get_mut() |
| } |
| |
| /// Get atomic access to a pointer. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(atomic_from_mut)] |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let mut data = 123; |
| /// let mut some_ptr = &mut data as *mut i32; |
| /// let a = AtomicPtr::from_mut(&mut some_ptr); |
| /// let mut other_data = 456; |
| /// a.store(&mut other_data, Ordering::Relaxed); |
| /// assert_eq!(unsafe { *some_ptr }, 456); |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic_equal_alignment = "ptr")] |
| #[unstable(feature = "atomic_from_mut", issue = "76314")] |
| pub fn from_mut(v: &mut *mut T) -> &mut Self { |
| use crate::mem::align_of; |
| let [] = [(); align_of::<AtomicPtr<()>>() - align_of::<*mut ()>()]; |
| // SAFETY: |
| // - the mutable reference guarantees unique ownership. |
| // - the alignment of `*mut T` and `Self` is the same on all platforms |
| // supported by rust, as verified above. |
| unsafe { &mut *(v as *mut *mut T as *mut Self) } |
| } |
| |
| /// Get non-atomic access to a `&mut [AtomicPtr]` slice. |
| /// |
| /// This is safe because the mutable reference guarantees that no other threads are |
| /// concurrently accessing the atomic data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(atomic_from_mut, inline_const)] |
| /// use std::ptr::null_mut; |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let mut some_ptrs = [const { AtomicPtr::new(null_mut::<String>()) }; 10]; |
| /// |
| /// let view: &mut [*mut String] = AtomicPtr::get_mut_slice(&mut some_ptrs); |
| /// assert_eq!(view, [null_mut::<String>(); 10]); |
| /// view |
| /// .iter_mut() |
| /// .enumerate() |
| /// .for_each(|(i, ptr)| *ptr = Box::into_raw(Box::new(format!("iteration#{i}")))); |
| /// |
| /// std::thread::scope(|s| { |
| /// for ptr in &some_ptrs { |
| /// s.spawn(move || { |
| /// let ptr = ptr.load(Ordering::Relaxed); |
| /// assert!(!ptr.is_null()); |
| /// |
| /// let name = unsafe { Box::from_raw(ptr) }; |
| /// println!("Hello, {name}!"); |
| /// }); |
| /// } |
| /// }); |
| /// ``` |
| #[inline] |
| #[unstable(feature = "atomic_from_mut", issue = "76314")] |
| pub fn get_mut_slice(this: &mut [Self]) -> &mut [*mut T] { |
| // SAFETY: the mutable reference guarantees unique ownership. |
| unsafe { &mut *(this as *mut [Self] as *mut [*mut T]) } |
| } |
| |
| /// Get atomic access to a slice of pointers. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(atomic_from_mut)] |
| /// use std::ptr::null_mut; |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let mut some_ptrs = [null_mut::<String>(); 10]; |
| /// let a = &*AtomicPtr::from_mut_slice(&mut some_ptrs); |
| /// std::thread::scope(|s| { |
| /// for i in 0..a.len() { |
| /// s.spawn(move || { |
| /// let name = Box::new(format!("thread{i}")); |
| /// a[i].store(Box::into_raw(name), Ordering::Relaxed); |
| /// }); |
| /// } |
| /// }); |
| /// for p in some_ptrs { |
| /// assert!(!p.is_null()); |
| /// let name = unsafe { Box::from_raw(p) }; |
| /// println!("Hello, {name}!"); |
| /// } |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic_equal_alignment = "ptr")] |
| #[unstable(feature = "atomic_from_mut", issue = "76314")] |
| pub fn from_mut_slice(v: &mut [*mut T]) -> &mut [Self] { |
| // SAFETY: |
| // - the mutable reference guarantees unique ownership. |
| // - the alignment of `*mut T` and `Self` is the same on all platforms |
| // supported by rust, as verified above. |
| unsafe { &mut *(v as *mut [*mut T] as *mut [Self]) } |
| } |
| |
| /// Consumes the atomic and returns the contained value. |
| /// |
| /// This is safe because passing `self` by value guarantees that no other threads are |
| /// concurrently accessing the atomic data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::AtomicPtr; |
| /// |
| /// let mut data = 5; |
| /// let atomic_ptr = AtomicPtr::new(&mut data); |
| /// assert_eq!(unsafe { *atomic_ptr.into_inner() }, 5); |
| /// ``` |
| #[inline] |
| #[stable(feature = "atomic_access", since = "1.15.0")] |
| #[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")] |
| pub const fn into_inner(self) -> *mut T { |
| self.p.into_inner() |
| } |
| |
| /// Loads a value from the pointer. |
| /// |
| /// `load` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. Possible values are [`SeqCst`], [`Acquire`] and [`Relaxed`]. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `order` is [`Release`] or [`AcqRel`]. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let ptr = &mut 5; |
| /// let some_ptr = AtomicPtr::new(ptr); |
| /// |
| /// let value = some_ptr.load(Ordering::Relaxed); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn load(&self, order: Ordering) -> *mut T { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_load(self.p.get(), order) } |
| } |
| |
| /// Stores a value into the pointer. |
| /// |
| /// `store` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. Possible values are [`SeqCst`], [`Release`] and [`Relaxed`]. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `order` is [`Acquire`] or [`AcqRel`]. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let ptr = &mut 5; |
| /// let some_ptr = AtomicPtr::new(ptr); |
| /// |
| /// let other_ptr = &mut 10; |
| /// |
| /// some_ptr.store(other_ptr, Ordering::Relaxed); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn store(&self, ptr: *mut T, order: Ordering) { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { |
| atomic_store(self.p.get(), ptr, order); |
| } |
| } |
| |
| /// Stores a value into the pointer, returning the previous value. |
| /// |
| /// `swap` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on pointers. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let ptr = &mut 5; |
| /// let some_ptr = AtomicPtr::new(ptr); |
| /// |
| /// let other_ptr = &mut 10; |
| /// |
| /// let value = some_ptr.swap(other_ptr, Ordering::Relaxed); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[cfg(target_has_atomic = "ptr")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn swap(&self, ptr: *mut T, order: Ordering) -> *mut T { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_swap(self.p.get(), ptr, order) } |
| } |
| |
| /// Stores a value into the pointer if the current value is the same as the `current` value. |
| /// |
| /// The return value is always the previous value. If it is equal to `current`, then the value |
| /// was updated. |
| /// |
| /// `compare_and_swap` also takes an [`Ordering`] argument which describes the memory |
| /// ordering of this operation. Notice that even when using [`AcqRel`], the operation |
| /// might fail and hence just perform an `Acquire` load, but not have `Release` semantics. |
| /// Using [`Acquire`] makes the store part of this operation [`Relaxed`] if it |
| /// happens, and using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on pointers. |
| /// |
| /// # Migrating to `compare_exchange` and `compare_exchange_weak` |
| /// |
| /// `compare_and_swap` is equivalent to `compare_exchange` with the following mapping for |
| /// memory orderings: |
| /// |
| /// Original | Success | Failure |
| /// -------- | ------- | ------- |
| /// Relaxed | Relaxed | Relaxed |
| /// Acquire | Acquire | Acquire |
| /// Release | Release | Relaxed |
| /// AcqRel | AcqRel | Acquire |
| /// SeqCst | SeqCst | SeqCst |
| /// |
| /// `compare_exchange_weak` is allowed to fail spuriously even when the comparison succeeds, |
| /// which allows the compiler to generate better assembly code when the compare and swap |
| /// is used in a loop. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let ptr = &mut 5; |
| /// let some_ptr = AtomicPtr::new(ptr); |
| /// |
| /// let other_ptr = &mut 10; |
| /// |
| /// let value = some_ptr.compare_and_swap(ptr, other_ptr, Ordering::Relaxed); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[deprecated( |
| since = "1.50.0", |
| note = "Use `compare_exchange` or `compare_exchange_weak` instead" |
| )] |
| #[cfg(target_has_atomic = "ptr")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn compare_and_swap(&self, current: *mut T, new: *mut T, order: Ordering) -> *mut T { |
| match self.compare_exchange(current, new, order, strongest_failure_ordering(order)) { |
| Ok(x) => x, |
| Err(x) => x, |
| } |
| } |
| |
| /// Stores a value into the pointer if the current value is the same as the `current` value. |
| /// |
| /// The return value is a result indicating whether the new value was written and containing |
| /// the previous value. On success this value is guaranteed to be equal to `current`. |
| /// |
| /// `compare_exchange` takes two [`Ordering`] arguments to describe the memory |
| /// ordering of this operation. `success` describes the required ordering for the |
| /// read-modify-write operation that takes place if the comparison with `current` succeeds. |
| /// `failure` describes the required ordering for the load operation that takes place when |
| /// the comparison fails. Using [`Acquire`] as success ordering makes the store part |
| /// of this operation [`Relaxed`], and using [`Release`] makes the successful load |
| /// [`Relaxed`]. The failure ordering can only be [`SeqCst`], [`Acquire`] or [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on pointers. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let ptr = &mut 5; |
| /// let some_ptr = AtomicPtr::new(ptr); |
| /// |
| /// let other_ptr = &mut 10; |
| /// |
| /// let value = some_ptr.compare_exchange(ptr, other_ptr, |
| /// Ordering::SeqCst, Ordering::Relaxed); |
| /// ``` |
| #[inline] |
| #[stable(feature = "extended_compare_and_swap", since = "1.10.0")] |
| #[cfg(target_has_atomic = "ptr")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn compare_exchange( |
| &self, |
| current: *mut T, |
| new: *mut T, |
| success: Ordering, |
| failure: Ordering, |
| ) -> Result<*mut T, *mut T> { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_compare_exchange(self.p.get(), current, new, success, failure) } |
| } |
| |
| /// Stores a value into the pointer if the current value is the same as the `current` value. |
| /// |
| /// Unlike [`AtomicPtr::compare_exchange`], this function is allowed to spuriously fail even when the |
| /// comparison succeeds, which can result in more efficient code on some platforms. The |
| /// return value is a result indicating whether the new value was written and containing the |
| /// previous value. |
| /// |
| /// `compare_exchange_weak` takes two [`Ordering`] arguments to describe the memory |
| /// ordering of this operation. `success` describes the required ordering for the |
| /// read-modify-write operation that takes place if the comparison with `current` succeeds. |
| /// `failure` describes the required ordering for the load operation that takes place when |
| /// the comparison fails. Using [`Acquire`] as success ordering makes the store part |
| /// of this operation [`Relaxed`], and using [`Release`] makes the successful load |
| /// [`Relaxed`]. The failure ordering can only be [`SeqCst`], [`Acquire`] or [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on pointers. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let some_ptr = AtomicPtr::new(&mut 5); |
| /// |
| /// let new = &mut 10; |
| /// let mut old = some_ptr.load(Ordering::Relaxed); |
| /// loop { |
| /// match some_ptr.compare_exchange_weak(old, new, Ordering::SeqCst, Ordering::Relaxed) { |
| /// Ok(_) => break, |
| /// Err(x) => old = x, |
| /// } |
| /// } |
| /// ``` |
| #[inline] |
| #[stable(feature = "extended_compare_and_swap", since = "1.10.0")] |
| #[cfg(target_has_atomic = "ptr")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn compare_exchange_weak( |
| &self, |
| current: *mut T, |
| new: *mut T, |
| success: Ordering, |
| failure: Ordering, |
| ) -> Result<*mut T, *mut T> { |
| // SAFETY: This intrinsic is unsafe because it operates on a raw pointer |
| // but we know for sure that the pointer is valid (we just got it from |
| // an `UnsafeCell` that we have by reference) and the atomic operation |
| // itself allows us to safely mutate the `UnsafeCell` contents. |
| unsafe { atomic_compare_exchange_weak(self.p.get(), current, new, success, failure) } |
| } |
| |
| /// Fetches the value, and applies a function to it that returns an optional |
| /// new value. Returns a `Result` of `Ok(previous_value)` if the function |
| /// returned `Some(_)`, else `Err(previous_value)`. |
| /// |
| /// Note: This may call the function multiple times if the value has been |
| /// changed from other threads in the meantime, as long as the function |
| /// returns `Some(_)`, but the function will have been applied only once to |
| /// the stored value. |
| /// |
| /// `fetch_update` takes two [`Ordering`] arguments to describe the memory |
| /// ordering of this operation. The first describes the required ordering for |
| /// when the operation finally succeeds while the second describes the |
| /// required ordering for loads. These correspond to the success and failure |
| /// orderings of [`AtomicPtr::compare_exchange`] respectively. |
| /// |
| /// Using [`Acquire`] as success ordering makes the store part of this |
| /// operation [`Relaxed`], and using [`Release`] makes the final successful |
| /// load [`Relaxed`]. The (failed) load ordering can only be [`SeqCst`], |
| /// [`Acquire`] or [`Relaxed`]. |
| /// |
| /// **Note:** This method is only available on platforms that support atomic |
| /// operations on pointers. |
| /// |
| /// # Considerations |
| /// |
| /// This method is not magic; it is not provided by the hardware. |
| /// It is implemented in terms of [`AtomicPtr::compare_exchange_weak`], and suffers from the same drawbacks. |
| /// In particular, this method will not circumvent the [ABA Problem]. |
| /// |
| /// [ABA Problem]: https://en.wikipedia.org/wiki/ABA_problem |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| /// use std::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let ptr: *mut _ = &mut 5; |
| /// let some_ptr = AtomicPtr::new(ptr); |
| /// |
| /// let new: *mut _ = &mut 10; |
| /// assert_eq!(some_ptr.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |_| None), Err(ptr)); |
| /// let result = some_ptr.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |x| { |
| /// if x == ptr { |
| /// Some(new) |
| /// } else { |
| /// None |
| /// } |
| /// }); |
| /// assert_eq!(result, Ok(ptr)); |
| /// assert_eq!(some_ptr.load(Ordering::SeqCst), new); |
| /// ``` |
| #[inline] |
| #[stable(feature = "atomic_fetch_update", since = "1.53.0")] |
| #[cfg(target_has_atomic = "ptr")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_update<F>( |
| &self, |
| set_order: Ordering, |
| fetch_order: Ordering, |
| mut f: F, |
| ) -> Result<*mut T, *mut T> |
| where |
| F: FnMut(*mut T) -> Option<*mut T>, |
| { |
| let mut prev = self.load(fetch_order); |
| while let Some(next) = f(prev) { |
| match self.compare_exchange_weak(prev, next, set_order, fetch_order) { |
| x @ Ok(_) => return x, |
| Err(next_prev) => prev = next_prev, |
| } |
| } |
| Err(prev) |
| } |
| |
| /// Offsets the pointer's address by adding `val` (in units of `T`), |
| /// returning the previous pointer. |
| /// |
| /// This is equivalent to using [`wrapping_add`] to atomically perform the |
| /// equivalent of `ptr = ptr.wrapping_add(val);`. |
| /// |
| /// This method operates in units of `T`, which means that it cannot be used |
| /// to offset the pointer by an amount which is not a multiple of |
| /// `size_of::<T>()`. This can sometimes be inconvenient, as you may want to |
| /// work with a deliberately misaligned pointer. In such cases, you may use |
| /// the [`fetch_byte_add`](Self::fetch_byte_add) method instead. |
| /// |
| /// `fetch_ptr_add` takes an [`Ordering`] argument which describes the |
| /// memory ordering of this operation. All ordering modes are possible. Note |
| /// that using [`Acquire`] makes the store part of this operation |
| /// [`Relaxed`], and using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic |
| /// operations on [`AtomicPtr`]. |
| /// |
| /// [`wrapping_add`]: pointer::wrapping_add |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(strict_provenance_atomic_ptr, strict_provenance)] |
| /// use core::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let atom = AtomicPtr::<i64>::new(core::ptr::null_mut()); |
| /// assert_eq!(atom.fetch_ptr_add(1, Ordering::Relaxed).addr(), 0); |
| /// // Note: units of `size_of::<i64>()`. |
| /// assert_eq!(atom.load(Ordering::Relaxed).addr(), 8); |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic = "ptr")] |
| #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_ptr_add(&self, val: usize, order: Ordering) -> *mut T { |
| self.fetch_byte_add(val.wrapping_mul(core::mem::size_of::<T>()), order) |
| } |
| |
| /// Offsets the pointer's address by subtracting `val` (in units of `T`), |
| /// returning the previous pointer. |
| /// |
| /// This is equivalent to using [`wrapping_sub`] to atomically perform the |
| /// equivalent of `ptr = ptr.wrapping_sub(val);`. |
| /// |
| /// This method operates in units of `T`, which means that it cannot be used |
| /// to offset the pointer by an amount which is not a multiple of |
| /// `size_of::<T>()`. This can sometimes be inconvenient, as you may want to |
| /// work with a deliberately misaligned pointer. In such cases, you may use |
| /// the [`fetch_byte_sub`](Self::fetch_byte_sub) method instead. |
| /// |
| /// `fetch_ptr_sub` takes an [`Ordering`] argument which describes the memory |
| /// ordering of this operation. All ordering modes are possible. Note that |
| /// using [`Acquire`] makes the store part of this operation [`Relaxed`], |
| /// and using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic |
| /// operations on [`AtomicPtr`]. |
| /// |
| /// [`wrapping_sub`]: pointer::wrapping_sub |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(strict_provenance_atomic_ptr)] |
| /// use core::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let array = [1i32, 2i32]; |
| /// let atom = AtomicPtr::new(array.as_ptr().wrapping_add(1) as *mut _); |
| /// |
| /// assert!(core::ptr::eq( |
| /// atom.fetch_ptr_sub(1, Ordering::Relaxed), |
| /// &array[1], |
| /// )); |
| /// assert!(core::ptr::eq(atom.load(Ordering::Relaxed), &array[0])); |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic = "ptr")] |
| #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_ptr_sub(&self, val: usize, order: Ordering) -> *mut T { |
| self.fetch_byte_sub(val.wrapping_mul(core::mem::size_of::<T>()), order) |
| } |
| |
| /// Offsets the pointer's address by adding `val` *bytes*, returning the |
| /// previous pointer. |
| /// |
| /// This is equivalent to using [`wrapping_byte_add`] to atomically |
| /// perform `ptr = ptr.wrapping_byte_add(val)`. |
| /// |
| /// `fetch_byte_add` takes an [`Ordering`] argument which describes the |
| /// memory ordering of this operation. All ordering modes are possible. Note |
| /// that using [`Acquire`] makes the store part of this operation |
| /// [`Relaxed`], and using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic |
| /// operations on [`AtomicPtr`]. |
| /// |
| /// [`wrapping_byte_add`]: pointer::wrapping_byte_add |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(strict_provenance_atomic_ptr, strict_provenance)] |
| /// use core::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let atom = AtomicPtr::<i64>::new(core::ptr::null_mut()); |
| /// assert_eq!(atom.fetch_byte_add(1, Ordering::Relaxed).addr(), 0); |
| /// // Note: in units of bytes, not `size_of::<i64>()`. |
| /// assert_eq!(atom.load(Ordering::Relaxed).addr(), 1); |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic = "ptr")] |
| #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_byte_add(&self, val: usize, order: Ordering) -> *mut T { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_add(self.p.get(), core::ptr::invalid_mut(val), order).cast() } |
| } |
| |
| /// Offsets the pointer's address by subtracting `val` *bytes*, returning the |
| /// previous pointer. |
| /// |
| /// This is equivalent to using [`wrapping_byte_sub`] to atomically |
| /// perform `ptr = ptr.wrapping_byte_sub(val)`. |
| /// |
| /// `fetch_byte_sub` takes an [`Ordering`] argument which describes the |
| /// memory ordering of this operation. All ordering modes are possible. Note |
| /// that using [`Acquire`] makes the store part of this operation |
| /// [`Relaxed`], and using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic |
| /// operations on [`AtomicPtr`]. |
| /// |
| /// [`wrapping_byte_sub`]: pointer::wrapping_byte_sub |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(strict_provenance_atomic_ptr, strict_provenance)] |
| /// use core::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let atom = AtomicPtr::<i64>::new(core::ptr::invalid_mut(1)); |
| /// assert_eq!(atom.fetch_byte_sub(1, Ordering::Relaxed).addr(), 1); |
| /// assert_eq!(atom.load(Ordering::Relaxed).addr(), 0); |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic = "ptr")] |
| #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_byte_sub(&self, val: usize, order: Ordering) -> *mut T { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_sub(self.p.get(), core::ptr::invalid_mut(val), order).cast() } |
| } |
| |
| /// Performs a bitwise "or" operation on the address of the current pointer, |
| /// and the argument `val`, and stores a pointer with provenance of the |
| /// current pointer and the resulting address. |
| /// |
| /// This is equivalent to using [`map_addr`] to atomically perform |
| /// `ptr = ptr.map_addr(|a| a | val)`. This can be used in tagged |
| /// pointer schemes to atomically set tag bits. |
| /// |
| /// **Caveat**: This operation returns the previous value. To compute the |
| /// stored value without losing provenance, you may use [`map_addr`]. For |
| /// example: `a.fetch_or(val).map_addr(|a| a | val)`. |
| /// |
| /// `fetch_or` takes an [`Ordering`] argument which describes the memory |
| /// ordering of this operation. All ordering modes are possible. Note that |
| /// using [`Acquire`] makes the store part of this operation [`Relaxed`], |
| /// and using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic |
| /// operations on [`AtomicPtr`]. |
| /// |
| /// This API and its claimed semantics are part of the Strict Provenance |
| /// experiment, see the [module documentation for `ptr`][crate::ptr] for |
| /// details. |
| /// |
| /// [`map_addr`]: pointer::map_addr |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(strict_provenance_atomic_ptr, strict_provenance)] |
| /// use core::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let pointer = &mut 3i64 as *mut i64; |
| /// |
| /// let atom = AtomicPtr::<i64>::new(pointer); |
| /// // Tag the bottom bit of the pointer. |
| /// assert_eq!(atom.fetch_or(1, Ordering::Relaxed).addr() & 1, 0); |
| /// // Extract and untag. |
| /// let tagged = atom.load(Ordering::Relaxed); |
| /// assert_eq!(tagged.addr() & 1, 1); |
| /// assert_eq!(tagged.map_addr(|p| p & !1), pointer); |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic = "ptr")] |
| #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_or(&self, val: usize, order: Ordering) -> *mut T { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_or(self.p.get(), core::ptr::invalid_mut(val), order).cast() } |
| } |
| |
| /// Performs a bitwise "and" operation on the address of the current |
| /// pointer, and the argument `val`, and stores a pointer with provenance of |
| /// the current pointer and the resulting address. |
| /// |
| /// This is equivalent to using [`map_addr`] to atomically perform |
| /// `ptr = ptr.map_addr(|a| a & val)`. This can be used in tagged |
| /// pointer schemes to atomically unset tag bits. |
| /// |
| /// **Caveat**: This operation returns the previous value. To compute the |
| /// stored value without losing provenance, you may use [`map_addr`]. For |
| /// example: `a.fetch_and(val).map_addr(|a| a & val)`. |
| /// |
| /// `fetch_and` takes an [`Ordering`] argument which describes the memory |
| /// ordering of this operation. All ordering modes are possible. Note that |
| /// using [`Acquire`] makes the store part of this operation [`Relaxed`], |
| /// and using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic |
| /// operations on [`AtomicPtr`]. |
| /// |
| /// This API and its claimed semantics are part of the Strict Provenance |
| /// experiment, see the [module documentation for `ptr`][crate::ptr] for |
| /// details. |
| /// |
| /// [`map_addr`]: pointer::map_addr |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(strict_provenance_atomic_ptr, strict_provenance)] |
| /// use core::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let pointer = &mut 3i64 as *mut i64; |
| /// // A tagged pointer |
| /// let atom = AtomicPtr::<i64>::new(pointer.map_addr(|a| a | 1)); |
| /// assert_eq!(atom.fetch_or(1, Ordering::Relaxed).addr() & 1, 1); |
| /// // Untag, and extract the previously tagged pointer. |
| /// let untagged = atom.fetch_and(!1, Ordering::Relaxed) |
| /// .map_addr(|a| a & !1); |
| /// assert_eq!(untagged, pointer); |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic = "ptr")] |
| #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_and(&self, val: usize, order: Ordering) -> *mut T { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_and(self.p.get(), core::ptr::invalid_mut(val), order).cast() } |
| } |
| |
| /// Performs a bitwise "xor" operation on the address of the current |
| /// pointer, and the argument `val`, and stores a pointer with provenance of |
| /// the current pointer and the resulting address. |
| /// |
| /// This is equivalent to using [`map_addr`] to atomically perform |
| /// `ptr = ptr.map_addr(|a| a ^ val)`. This can be used in tagged |
| /// pointer schemes to atomically toggle tag bits. |
| /// |
| /// **Caveat**: This operation returns the previous value. To compute the |
| /// stored value without losing provenance, you may use [`map_addr`]. For |
| /// example: `a.fetch_xor(val).map_addr(|a| a ^ val)`. |
| /// |
| /// `fetch_xor` takes an [`Ordering`] argument which describes the memory |
| /// ordering of this operation. All ordering modes are possible. Note that |
| /// using [`Acquire`] makes the store part of this operation [`Relaxed`], |
| /// and using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic |
| /// operations on [`AtomicPtr`]. |
| /// |
| /// This API and its claimed semantics are part of the Strict Provenance |
| /// experiment, see the [module documentation for `ptr`][crate::ptr] for |
| /// details. |
| /// |
| /// [`map_addr`]: pointer::map_addr |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(strict_provenance_atomic_ptr, strict_provenance)] |
| /// use core::sync::atomic::{AtomicPtr, Ordering}; |
| /// |
| /// let pointer = &mut 3i64 as *mut i64; |
| /// let atom = AtomicPtr::<i64>::new(pointer); |
| /// |
| /// // Toggle a tag bit on the pointer. |
| /// atom.fetch_xor(1, Ordering::Relaxed); |
| /// assert_eq!(atom.load(Ordering::Relaxed).addr() & 1, 1); |
| /// ``` |
| #[inline] |
| #[cfg(target_has_atomic = "ptr")] |
| #[unstable(feature = "strict_provenance_atomic_ptr", issue = "99108")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_xor(&self, val: usize, order: Ordering) -> *mut T { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_xor(self.p.get(), core::ptr::invalid_mut(val), order).cast() } |
| } |
| } |
| |
| #[cfg(target_has_atomic_load_store = "8")] |
| #[stable(feature = "atomic_bool_from", since = "1.24.0")] |
| #[rustc_const_unstable(feature = "const_convert", issue = "88674")] |
| impl const From<bool> for AtomicBool { |
| /// Converts a `bool` into an `AtomicBool`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::AtomicBool; |
| /// let atomic_bool = AtomicBool::from(true); |
| /// assert_eq!(format!("{atomic_bool:?}"), "true") |
| /// ``` |
| #[inline] |
| fn from(b: bool) -> Self { |
| Self::new(b) |
| } |
| } |
| |
| #[cfg(target_has_atomic_load_store = "ptr")] |
| #[stable(feature = "atomic_from", since = "1.23.0")] |
| #[rustc_const_unstable(feature = "const_convert", issue = "88674")] |
| impl<T> const From<*mut T> for AtomicPtr<T> { |
| /// Converts a `*mut T` into an `AtomicPtr<T>`. |
| #[inline] |
| fn from(p: *mut T) -> Self { |
| Self::new(p) |
| } |
| } |
| |
| #[allow(unused_macros)] // This macro ends up being unused on some architectures. |
| macro_rules! if_not_8_bit { |
| (u8, $($tt:tt)*) => { "" }; |
| (i8, $($tt:tt)*) => { "" }; |
| ($_:ident, $($tt:tt)*) => { $($tt)* }; |
| } |
| |
| #[cfg(target_has_atomic_load_store = "8")] |
| macro_rules! atomic_int { |
| ($cfg_cas:meta, |
| $cfg_align:meta, |
| $stable:meta, |
| $stable_cxchg:meta, |
| $stable_debug:meta, |
| $stable_access:meta, |
| $stable_from:meta, |
| $stable_nand:meta, |
| $const_stable:meta, |
| $stable_init_const:meta, |
| $diagnostic_item:meta, |
| $s_int_type:literal, |
| $extra_feature:expr, |
| $min_fn:ident, $max_fn:ident, |
| $align:expr, |
| $atomic_new:expr, |
| $int_type:ident $atomic_type:ident $atomic_init:ident) => { |
| /// An integer type which can be safely shared between threads. |
| /// |
| /// This type has the same in-memory representation as the underlying |
| /// integer type, [` |
| #[doc = $s_int_type] |
| /// `]. For more about the differences between atomic types and |
| /// non-atomic types as well as information about the portability of |
| /// this type, please see the [module-level documentation]. |
| /// |
| /// **Note:** This type is only available on platforms that support |
| /// atomic loads and stores of [` |
| #[doc = $s_int_type] |
| /// `]. |
| /// |
| /// [module-level documentation]: crate::sync::atomic |
| #[$stable] |
| #[$diagnostic_item] |
| #[repr(C, align($align))] |
| pub struct $atomic_type { |
| v: UnsafeCell<$int_type>, |
| } |
| |
| /// An atomic integer initialized to `0`. |
| #[$stable_init_const] |
| #[deprecated( |
| since = "1.34.0", |
| note = "the `new` function is now preferred", |
| suggestion = $atomic_new, |
| )] |
| pub const $atomic_init: $atomic_type = $atomic_type::new(0); |
| |
| #[$stable] |
| #[rustc_const_unstable(feature = "const_default_impls", issue = "87864")] |
| impl const Default for $atomic_type { |
| #[inline] |
| fn default() -> Self { |
| Self::new(Default::default()) |
| } |
| } |
| |
| #[$stable_from] |
| #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")] |
| impl const From<$int_type> for $atomic_type { |
| #[doc = concat!("Converts an `", stringify!($int_type), "` into an `", stringify!($atomic_type), "`.")] |
| #[inline] |
| fn from(v: $int_type) -> Self { Self::new(v) } |
| } |
| |
| #[$stable_debug] |
| impl fmt::Debug for $atomic_type { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| fmt::Debug::fmt(&self.load(Ordering::Relaxed), f) |
| } |
| } |
| |
| // Send is implicitly implemented. |
| #[$stable] |
| unsafe impl Sync for $atomic_type {} |
| |
| impl $atomic_type { |
| /// Creates a new atomic integer. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::", stringify!($atomic_type), ";")] |
| /// |
| #[doc = concat!("let atomic_forty_two = ", stringify!($atomic_type), "::new(42);")] |
| /// ``` |
| #[inline] |
| #[$stable] |
| #[$const_stable] |
| #[must_use] |
| pub const fn new(v: $int_type) -> Self { |
| Self {v: UnsafeCell::new(v)} |
| } |
| |
| /// Returns a mutable reference to the underlying integer. |
| /// |
| /// This is safe because the mutable reference guarantees that no other threads are |
| /// concurrently accessing the atomic data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let mut some_var = ", stringify!($atomic_type), "::new(10);")] |
| /// assert_eq!(*some_var.get_mut(), 10); |
| /// *some_var.get_mut() = 5; |
| /// assert_eq!(some_var.load(Ordering::SeqCst), 5); |
| /// ``` |
| #[inline] |
| #[$stable_access] |
| pub fn get_mut(&mut self) -> &mut $int_type { |
| self.v.get_mut() |
| } |
| |
| #[doc = concat!("Get atomic access to a `&mut ", stringify!($int_type), "`.")] |
| /// |
| #[doc = if_not_8_bit! { |
| $int_type, |
| concat!( |
| "**Note:** This function is only available on targets where `", |
| stringify!($int_type), "` has an alignment of ", $align, " bytes." |
| ) |
| }] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(atomic_from_mut)] |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| /// let mut some_int = 123; |
| #[doc = concat!("let a = ", stringify!($atomic_type), "::from_mut(&mut some_int);")] |
| /// a.store(100, Ordering::Relaxed); |
| /// assert_eq!(some_int, 100); |
| /// ``` |
| /// |
| #[inline] |
| #[$cfg_align] |
| #[unstable(feature = "atomic_from_mut", issue = "76314")] |
| pub fn from_mut(v: &mut $int_type) -> &mut Self { |
| use crate::mem::align_of; |
| let [] = [(); align_of::<Self>() - align_of::<$int_type>()]; |
| // SAFETY: |
| // - the mutable reference guarantees unique ownership. |
| // - the alignment of `$int_type` and `Self` is the |
| // same, as promised by $cfg_align and verified above. |
| unsafe { &mut *(v as *mut $int_type as *mut Self) } |
| } |
| |
| #[doc = concat!("Get non-atomic access to a `&mut [", stringify!($atomic_type), "]` slice")] |
| /// |
| /// This is safe because the mutable reference guarantees that no other threads are |
| /// concurrently accessing the atomic data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(atomic_from_mut, inline_const)] |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let mut some_ints = [const { ", stringify!($atomic_type), "::new(0) }; 10];")] |
| /// |
| #[doc = concat!("let view: &mut [", stringify!($int_type), "] = ", stringify!($atomic_type), "::get_mut_slice(&mut some_ints);")] |
| /// assert_eq!(view, [0; 10]); |
| /// view |
| /// .iter_mut() |
| /// .enumerate() |
| /// .for_each(|(idx, int)| *int = idx as _); |
| /// |
| /// std::thread::scope(|s| { |
| /// some_ints |
| /// .iter() |
| /// .enumerate() |
| /// .for_each(|(idx, int)| { |
| /// s.spawn(move || assert_eq!(int.load(Ordering::Relaxed), idx as _)); |
| /// }) |
| /// }); |
| /// ``` |
| #[inline] |
| #[unstable(feature = "atomic_from_mut", issue = "76314")] |
| pub fn get_mut_slice(this: &mut [Self]) -> &mut [$int_type] { |
| // SAFETY: the mutable reference guarantees unique ownership. |
| unsafe { &mut *(this as *mut [Self] as *mut [$int_type]) } |
| } |
| |
| #[doc = concat!("Get atomic access to a `&mut [", stringify!($int_type), "]` slice.")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(atomic_from_mut)] |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| /// let mut some_ints = [0; 10]; |
| #[doc = concat!("let a = &*", stringify!($atomic_type), "::from_mut_slice(&mut some_ints);")] |
| /// std::thread::scope(|s| { |
| /// for i in 0..a.len() { |
| /// s.spawn(move || a[i].store(i as _, Ordering::Relaxed)); |
| /// } |
| /// }); |
| /// for (i, n) in some_ints.into_iter().enumerate() { |
| /// assert_eq!(i, n as usize); |
| /// } |
| /// ``` |
| #[inline] |
| #[$cfg_align] |
| #[unstable(feature = "atomic_from_mut", issue = "76314")] |
| pub fn from_mut_slice(v: &mut [$int_type]) -> &mut [Self] { |
| use crate::mem::align_of; |
| let [] = [(); align_of::<Self>() - align_of::<$int_type>()]; |
| // SAFETY: |
| // - the mutable reference guarantees unique ownership. |
| // - the alignment of `$int_type` and `Self` is the |
| // same, as promised by $cfg_align and verified above. |
| unsafe { &mut *(v as *mut [$int_type] as *mut [Self]) } |
| } |
| |
| /// Consumes the atomic and returns the contained value. |
| /// |
| /// This is safe because passing `self` by value guarantees that no other threads are |
| /// concurrently accessing the atomic data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::", stringify!($atomic_type), ";")] |
| /// |
| #[doc = concat!("let some_var = ", stringify!($atomic_type), "::new(5);")] |
| /// assert_eq!(some_var.into_inner(), 5); |
| /// ``` |
| #[inline] |
| #[$stable_access] |
| #[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")] |
| pub const fn into_inner(self) -> $int_type { |
| self.v.into_inner() |
| } |
| |
| /// Loads a value from the atomic integer. |
| /// |
| /// `load` takes an [`Ordering`] argument which describes the memory ordering of this operation. |
| /// Possible values are [`SeqCst`], [`Acquire`] and [`Relaxed`]. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `order` is [`Release`] or [`AcqRel`]. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let some_var = ", stringify!($atomic_type), "::new(5);")] |
| /// |
| /// assert_eq!(some_var.load(Ordering::Relaxed), 5); |
| /// ``` |
| #[inline] |
| #[$stable] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn load(&self, order: Ordering) -> $int_type { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_load(self.v.get(), order) } |
| } |
| |
| /// Stores a value into the atomic integer. |
| /// |
| /// `store` takes an [`Ordering`] argument which describes the memory ordering of this operation. |
| /// Possible values are [`SeqCst`], [`Release`] and [`Relaxed`]. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `order` is [`Acquire`] or [`AcqRel`]. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let some_var = ", stringify!($atomic_type), "::new(5);")] |
| /// |
| /// some_var.store(10, Ordering::Relaxed); |
| /// assert_eq!(some_var.load(Ordering::Relaxed), 10); |
| /// ``` |
| #[inline] |
| #[$stable] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn store(&self, val: $int_type, order: Ordering) { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_store(self.v.get(), val, order); } |
| } |
| |
| /// Stores a value into the atomic integer, returning the previous value. |
| /// |
| /// `swap` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let some_var = ", stringify!($atomic_type), "::new(5);")] |
| /// |
| /// assert_eq!(some_var.swap(10, Ordering::Relaxed), 5); |
| /// ``` |
| #[inline] |
| #[$stable] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn swap(&self, val: $int_type, order: Ordering) -> $int_type { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_swap(self.v.get(), val, order) } |
| } |
| |
| /// Stores a value into the atomic integer if the current value is the same as |
| /// the `current` value. |
| /// |
| /// The return value is always the previous value. If it is equal to `current`, then the |
| /// value was updated. |
| /// |
| /// `compare_and_swap` also takes an [`Ordering`] argument which describes the memory |
| /// ordering of this operation. Notice that even when using [`AcqRel`], the operation |
| /// might fail and hence just perform an `Acquire` load, but not have `Release` semantics. |
| /// Using [`Acquire`] makes the store part of this operation [`Relaxed`] if it |
| /// happens, and using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Migrating to `compare_exchange` and `compare_exchange_weak` |
| /// |
| /// `compare_and_swap` is equivalent to `compare_exchange` with the following mapping for |
| /// memory orderings: |
| /// |
| /// Original | Success | Failure |
| /// -------- | ------- | ------- |
| /// Relaxed | Relaxed | Relaxed |
| /// Acquire | Acquire | Acquire |
| /// Release | Release | Relaxed |
| /// AcqRel | AcqRel | Acquire |
| /// SeqCst | SeqCst | SeqCst |
| /// |
| /// `compare_exchange_weak` is allowed to fail spuriously even when the comparison succeeds, |
| /// which allows the compiler to generate better assembly code when the compare and swap |
| /// is used in a loop. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let some_var = ", stringify!($atomic_type), "::new(5);")] |
| /// |
| /// assert_eq!(some_var.compare_and_swap(5, 10, Ordering::Relaxed), 5); |
| /// assert_eq!(some_var.load(Ordering::Relaxed), 10); |
| /// |
| /// assert_eq!(some_var.compare_and_swap(6, 12, Ordering::Relaxed), 10); |
| /// assert_eq!(some_var.load(Ordering::Relaxed), 10); |
| /// ``` |
| #[inline] |
| #[$stable] |
| #[deprecated( |
| since = "1.50.0", |
| note = "Use `compare_exchange` or `compare_exchange_weak` instead") |
| ] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn compare_and_swap(&self, |
| current: $int_type, |
| new: $int_type, |
| order: Ordering) -> $int_type { |
| match self.compare_exchange(current, |
| new, |
| order, |
| strongest_failure_ordering(order)) { |
| Ok(x) => x, |
| Err(x) => x, |
| } |
| } |
| |
| /// Stores a value into the atomic integer if the current value is the same as |
| /// the `current` value. |
| /// |
| /// The return value is a result indicating whether the new value was written and |
| /// containing the previous value. On success this value is guaranteed to be equal to |
| /// `current`. |
| /// |
| /// `compare_exchange` takes two [`Ordering`] arguments to describe the memory |
| /// ordering of this operation. `success` describes the required ordering for the |
| /// read-modify-write operation that takes place if the comparison with `current` succeeds. |
| /// `failure` describes the required ordering for the load operation that takes place when |
| /// the comparison fails. Using [`Acquire`] as success ordering makes the store part |
| /// of this operation [`Relaxed`], and using [`Release`] makes the successful load |
| /// [`Relaxed`]. The failure ordering can only be [`SeqCst`], [`Acquire`] or [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let some_var = ", stringify!($atomic_type), "::new(5);")] |
| /// |
| /// assert_eq!(some_var.compare_exchange(5, 10, |
| /// Ordering::Acquire, |
| /// Ordering::Relaxed), |
| /// Ok(5)); |
| /// assert_eq!(some_var.load(Ordering::Relaxed), 10); |
| /// |
| /// assert_eq!(some_var.compare_exchange(6, 12, |
| /// Ordering::SeqCst, |
| /// Ordering::Acquire), |
| /// Err(10)); |
| /// assert_eq!(some_var.load(Ordering::Relaxed), 10); |
| /// ``` |
| #[inline] |
| #[$stable_cxchg] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn compare_exchange(&self, |
| current: $int_type, |
| new: $int_type, |
| success: Ordering, |
| failure: Ordering) -> Result<$int_type, $int_type> { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_compare_exchange(self.v.get(), current, new, success, failure) } |
| } |
| |
| /// Stores a value into the atomic integer if the current value is the same as |
| /// the `current` value. |
| /// |
| #[doc = concat!("Unlike [`", stringify!($atomic_type), "::compare_exchange`],")] |
| /// this function is allowed to spuriously fail even |
| /// when the comparison succeeds, which can result in more efficient code on some |
| /// platforms. The return value is a result indicating whether the new value was |
| /// written and containing the previous value. |
| /// |
| /// `compare_exchange_weak` takes two [`Ordering`] arguments to describe the memory |
| /// ordering of this operation. `success` describes the required ordering for the |
| /// read-modify-write operation that takes place if the comparison with `current` succeeds. |
| /// `failure` describes the required ordering for the load operation that takes place when |
| /// the comparison fails. Using [`Acquire`] as success ordering makes the store part |
| /// of this operation [`Relaxed`], and using [`Release`] makes the successful load |
| /// [`Relaxed`]. The failure ordering can only be [`SeqCst`], [`Acquire`] or [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let val = ", stringify!($atomic_type), "::new(4);")] |
| /// |
| /// let mut old = val.load(Ordering::Relaxed); |
| /// loop { |
| /// let new = old * 2; |
| /// match val.compare_exchange_weak(old, new, Ordering::SeqCst, Ordering::Relaxed) { |
| /// Ok(_) => break, |
| /// Err(x) => old = x, |
| /// } |
| /// } |
| /// ``` |
| #[inline] |
| #[$stable_cxchg] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn compare_exchange_weak(&self, |
| current: $int_type, |
| new: $int_type, |
| success: Ordering, |
| failure: Ordering) -> Result<$int_type, $int_type> { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { |
| atomic_compare_exchange_weak(self.v.get(), current, new, success, failure) |
| } |
| } |
| |
| /// Adds to the current value, returning the previous value. |
| /// |
| /// This operation wraps around on overflow. |
| /// |
| /// `fetch_add` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let foo = ", stringify!($atomic_type), "::new(0);")] |
| /// assert_eq!(foo.fetch_add(10, Ordering::SeqCst), 0); |
| /// assert_eq!(foo.load(Ordering::SeqCst), 10); |
| /// ``` |
| #[inline] |
| #[$stable] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_add(&self, val: $int_type, order: Ordering) -> $int_type { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_add(self.v.get(), val, order) } |
| } |
| |
| /// Subtracts from the current value, returning the previous value. |
| /// |
| /// This operation wraps around on overflow. |
| /// |
| /// `fetch_sub` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let foo = ", stringify!($atomic_type), "::new(20);")] |
| /// assert_eq!(foo.fetch_sub(10, Ordering::SeqCst), 20); |
| /// assert_eq!(foo.load(Ordering::SeqCst), 10); |
| /// ``` |
| #[inline] |
| #[$stable] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_sub(&self, val: $int_type, order: Ordering) -> $int_type { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_sub(self.v.get(), val, order) } |
| } |
| |
| /// Bitwise "and" with the current value. |
| /// |
| /// Performs a bitwise "and" operation on the current value and the argument `val`, and |
| /// sets the new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_and` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let foo = ", stringify!($atomic_type), "::new(0b101101);")] |
| /// assert_eq!(foo.fetch_and(0b110011, Ordering::SeqCst), 0b101101); |
| /// assert_eq!(foo.load(Ordering::SeqCst), 0b100001); |
| /// ``` |
| #[inline] |
| #[$stable] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_and(&self, val: $int_type, order: Ordering) -> $int_type { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_and(self.v.get(), val, order) } |
| } |
| |
| /// Bitwise "nand" with the current value. |
| /// |
| /// Performs a bitwise "nand" operation on the current value and the argument `val`, and |
| /// sets the new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_nand` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let foo = ", stringify!($atomic_type), "::new(0x13);")] |
| /// assert_eq!(foo.fetch_nand(0x31, Ordering::SeqCst), 0x13); |
| /// assert_eq!(foo.load(Ordering::SeqCst), !(0x13 & 0x31)); |
| /// ``` |
| #[inline] |
| #[$stable_nand] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_nand(&self, val: $int_type, order: Ordering) -> $int_type { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_nand(self.v.get(), val, order) } |
| } |
| |
| /// Bitwise "or" with the current value. |
| /// |
| /// Performs a bitwise "or" operation on the current value and the argument `val`, and |
| /// sets the new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_or` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let foo = ", stringify!($atomic_type), "::new(0b101101);")] |
| /// assert_eq!(foo.fetch_or(0b110011, Ordering::SeqCst), 0b101101); |
| /// assert_eq!(foo.load(Ordering::SeqCst), 0b111111); |
| /// ``` |
| #[inline] |
| #[$stable] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_or(&self, val: $int_type, order: Ordering) -> $int_type { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_or(self.v.get(), val, order) } |
| } |
| |
| /// Bitwise "xor" with the current value. |
| /// |
| /// Performs a bitwise "xor" operation on the current value and the argument `val`, and |
| /// sets the new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_xor` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let foo = ", stringify!($atomic_type), "::new(0b101101);")] |
| /// assert_eq!(foo.fetch_xor(0b110011, Ordering::SeqCst), 0b101101); |
| /// assert_eq!(foo.load(Ordering::SeqCst), 0b011110); |
| /// ``` |
| #[inline] |
| #[$stable] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_xor(&self, val: $int_type, order: Ordering) -> $int_type { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { atomic_xor(self.v.get(), val, order) } |
| } |
| |
| /// Fetches the value, and applies a function to it that returns an optional |
| /// new value. Returns a `Result` of `Ok(previous_value)` if the function returned `Some(_)`, else |
| /// `Err(previous_value)`. |
| /// |
| /// Note: This may call the function multiple times if the value has been changed from other threads in |
| /// the meantime, as long as the function returns `Some(_)`, but the function will have been applied |
| /// only once to the stored value. |
| /// |
| /// `fetch_update` takes two [`Ordering`] arguments to describe the memory ordering of this operation. |
| /// The first describes the required ordering for when the operation finally succeeds while the second |
| /// describes the required ordering for loads. These correspond to the success and failure orderings of |
| #[doc = concat!("[`", stringify!($atomic_type), "::compare_exchange`]")] |
| /// respectively. |
| /// |
| /// Using [`Acquire`] as success ordering makes the store part |
| /// of this operation [`Relaxed`], and using [`Release`] makes the final successful load |
| /// [`Relaxed`]. The (failed) load ordering can only be [`SeqCst`], [`Acquire`] or [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Considerations |
| /// |
| /// This method is not magic; it is not provided by the hardware. |
| /// It is implemented in terms of |
| #[doc = concat!("[`", stringify!($atomic_type), "::compare_exchange_weak`],")] |
| /// and suffers from the same drawbacks. |
| /// In particular, this method will not circumvent the [ABA Problem]. |
| /// |
| /// [ABA Problem]: https://en.wikipedia.org/wiki/ABA_problem |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let x = ", stringify!($atomic_type), "::new(7);")] |
| /// assert_eq!(x.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |_| None), Err(7)); |
| /// assert_eq!(x.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |x| Some(x + 1)), Ok(7)); |
| /// assert_eq!(x.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |x| Some(x + 1)), Ok(8)); |
| /// assert_eq!(x.load(Ordering::SeqCst), 9); |
| /// ``` |
| #[inline] |
| #[stable(feature = "no_more_cas", since = "1.45.0")] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_update<F>(&self, |
| set_order: Ordering, |
| fetch_order: Ordering, |
| mut f: F) -> Result<$int_type, $int_type> |
| where F: FnMut($int_type) -> Option<$int_type> { |
| let mut prev = self.load(fetch_order); |
| while let Some(next) = f(prev) { |
| match self.compare_exchange_weak(prev, next, set_order, fetch_order) { |
| x @ Ok(_) => return x, |
| Err(next_prev) => prev = next_prev |
| } |
| } |
| Err(prev) |
| } |
| |
| /// Maximum with the current value. |
| /// |
| /// Finds the maximum of the current value and the argument `val`, and |
| /// sets the new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_max` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let foo = ", stringify!($atomic_type), "::new(23);")] |
| /// assert_eq!(foo.fetch_max(42, Ordering::SeqCst), 23); |
| /// assert_eq!(foo.load(Ordering::SeqCst), 42); |
| /// ``` |
| /// |
| /// If you want to obtain the maximum value in one step, you can use the following: |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let foo = ", stringify!($atomic_type), "::new(23);")] |
| /// let bar = 42; |
| /// let max_foo = foo.fetch_max(bar, Ordering::SeqCst).max(bar); |
| /// assert!(max_foo == 42); |
| /// ``` |
| #[inline] |
| #[stable(feature = "atomic_min_max", since = "1.45.0")] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_max(&self, val: $int_type, order: Ordering) -> $int_type { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { $max_fn(self.v.get(), val, order) } |
| } |
| |
| /// Minimum with the current value. |
| /// |
| /// Finds the minimum of the current value and the argument `val`, and |
| /// sets the new value to the result. |
| /// |
| /// Returns the previous value. |
| /// |
| /// `fetch_min` takes an [`Ordering`] argument which describes the memory ordering |
| /// of this operation. All ordering modes are possible. Note that using |
| /// [`Acquire`] makes the store part of this operation [`Relaxed`], and |
| /// using [`Release`] makes the load part [`Relaxed`]. |
| /// |
| /// **Note**: This method is only available on platforms that support atomic operations on |
| #[doc = concat!("[`", $s_int_type, "`].")] |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let foo = ", stringify!($atomic_type), "::new(23);")] |
| /// assert_eq!(foo.fetch_min(42, Ordering::Relaxed), 23); |
| /// assert_eq!(foo.load(Ordering::Relaxed), 23); |
| /// assert_eq!(foo.fetch_min(22, Ordering::Relaxed), 23); |
| /// assert_eq!(foo.load(Ordering::Relaxed), 22); |
| /// ``` |
| /// |
| /// If you want to obtain the minimum value in one step, you can use the following: |
| /// |
| /// ``` |
| #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")] |
| /// |
| #[doc = concat!("let foo = ", stringify!($atomic_type), "::new(23);")] |
| /// let bar = 12; |
| /// let min_foo = foo.fetch_min(bar, Ordering::SeqCst).min(bar); |
| /// assert_eq!(min_foo, 12); |
| /// ``` |
| #[inline] |
| #[stable(feature = "atomic_min_max", since = "1.45.0")] |
| #[$cfg_cas] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fetch_min(&self, val: $int_type, order: Ordering) -> $int_type { |
| // SAFETY: data races are prevented by atomic intrinsics. |
| unsafe { $min_fn(self.v.get(), val, order) } |
| } |
| |
| /// Returns a mutable pointer to the underlying integer. |
| /// |
| /// Doing non-atomic reads and writes on the resulting integer can be a data race. |
| /// This method is mostly useful for FFI, where the function signature may use |
| #[doc = concat!("`*mut ", stringify!($int_type), "` instead of `&", stringify!($atomic_type), "`.")] |
| /// |
| /// Returning an `*mut` pointer from a shared reference to this atomic is safe because the |
| /// atomic types work with interior mutability. All modifications of an atomic change the value |
| /// through a shared reference, and can do so safely as long as they use atomic operations. Any |
| /// use of the returned raw pointer requires an `unsafe` block and still has to uphold the same |
| /// restriction: operations on it must be atomic. |
| /// |
| /// # Examples |
| /// |
| /// ```ignore (extern-declaration) |
| /// # fn main() { |
| #[doc = concat!($extra_feature, "use std::sync::atomic::", stringify!($atomic_type), ";")] |
| /// |
| /// extern "C" { |
| #[doc = concat!(" fn my_atomic_op(arg: *mut ", stringify!($int_type), ");")] |
| /// } |
| /// |
| #[doc = concat!("let mut atomic = ", stringify!($atomic_type), "::new(1);")] |
| /// |
| // SAFETY: Safe as long as `my_atomic_op` is atomic. |
| /// unsafe { |
| /// my_atomic_op(atomic.as_mut_ptr()); |
| /// } |
| /// # } |
| /// ``` |
| #[inline] |
| #[unstable(feature = "atomic_mut_ptr", |
| reason = "recently added", |
| issue = "66893")] |
| pub fn as_mut_ptr(&self) -> *mut $int_type { |
| self.v.get() |
| } |
| } |
| } |
| } |
| |
| #[cfg(target_has_atomic_load_store = "8")] |
| atomic_int! { |
| cfg(target_has_atomic = "8"), |
| cfg(target_has_atomic_equal_alignment = "8"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicI8"), |
| "i8", |
| "", |
| atomic_min, atomic_max, |
| 1, |
| "AtomicI8::new(0)", |
| i8 AtomicI8 ATOMIC_I8_INIT |
| } |
| #[cfg(target_has_atomic_load_store = "8")] |
| atomic_int! { |
| cfg(target_has_atomic = "8"), |
| cfg(target_has_atomic_equal_alignment = "8"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicU8"), |
| "u8", |
| "", |
| atomic_umin, atomic_umax, |
| 1, |
| "AtomicU8::new(0)", |
| u8 AtomicU8 ATOMIC_U8_INIT |
| } |
| #[cfg(target_has_atomic_load_store = "16")] |
| atomic_int! { |
| cfg(target_has_atomic = "16"), |
| cfg(target_has_atomic_equal_alignment = "16"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicI16"), |
| "i16", |
| "", |
| atomic_min, atomic_max, |
| 2, |
| "AtomicI16::new(0)", |
| i16 AtomicI16 ATOMIC_I16_INIT |
| } |
| #[cfg(target_has_atomic_load_store = "16")] |
| atomic_int! { |
| cfg(target_has_atomic = "16"), |
| cfg(target_has_atomic_equal_alignment = "16"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicU16"), |
| "u16", |
| "", |
| atomic_umin, atomic_umax, |
| 2, |
| "AtomicU16::new(0)", |
| u16 AtomicU16 ATOMIC_U16_INIT |
| } |
| #[cfg(target_has_atomic_load_store = "32")] |
| atomic_int! { |
| cfg(target_has_atomic = "32"), |
| cfg(target_has_atomic_equal_alignment = "32"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicI32"), |
| "i32", |
| "", |
| atomic_min, atomic_max, |
| 4, |
| "AtomicI32::new(0)", |
| i32 AtomicI32 ATOMIC_I32_INIT |
| } |
| #[cfg(target_has_atomic_load_store = "32")] |
| atomic_int! { |
| cfg(target_has_atomic = "32"), |
| cfg(target_has_atomic_equal_alignment = "32"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicU32"), |
| "u32", |
| "", |
| atomic_umin, atomic_umax, |
| 4, |
| "AtomicU32::new(0)", |
| u32 AtomicU32 ATOMIC_U32_INIT |
| } |
| #[cfg(target_has_atomic_load_store = "64")] |
| atomic_int! { |
| cfg(target_has_atomic = "64"), |
| cfg(target_has_atomic_equal_alignment = "64"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicI64"), |
| "i64", |
| "", |
| atomic_min, atomic_max, |
| 8, |
| "AtomicI64::new(0)", |
| i64 AtomicI64 ATOMIC_I64_INIT |
| } |
| #[cfg(target_has_atomic_load_store = "64")] |
| atomic_int! { |
| cfg(target_has_atomic = "64"), |
| cfg(target_has_atomic_equal_alignment = "64"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| stable(feature = "integer_atomics_stable", since = "1.34.0"), |
| rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicU64"), |
| "u64", |
| "", |
| atomic_umin, atomic_umax, |
| 8, |
| "AtomicU64::new(0)", |
| u64 AtomicU64 ATOMIC_U64_INIT |
| } |
| #[cfg(target_has_atomic_load_store = "128")] |
| atomic_int! { |
| cfg(target_has_atomic = "128"), |
| cfg(target_has_atomic_equal_alignment = "128"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicI128"), |
| "i128", |
| "#![feature(integer_atomics)]\n\n", |
| atomic_min, atomic_max, |
| 16, |
| "AtomicI128::new(0)", |
| i128 AtomicI128 ATOMIC_I128_INIT |
| } |
| #[cfg(target_has_atomic_load_store = "128")] |
| atomic_int! { |
| cfg(target_has_atomic = "128"), |
| cfg(target_has_atomic_equal_alignment = "128"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"), |
| unstable(feature = "integer_atomics", issue = "99069"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicU128"), |
| "u128", |
| "#![feature(integer_atomics)]\n\n", |
| atomic_umin, atomic_umax, |
| 16, |
| "AtomicU128::new(0)", |
| u128 AtomicU128 ATOMIC_U128_INIT |
| } |
| |
| macro_rules! atomic_int_ptr_sized { |
| ( $($target_pointer_width:literal $align:literal)* ) => { $( |
| #[cfg(target_has_atomic_load_store = "ptr")] |
| #[cfg(target_pointer_width = $target_pointer_width)] |
| atomic_int! { |
| cfg(target_has_atomic = "ptr"), |
| cfg(target_has_atomic_equal_alignment = "ptr"), |
| stable(feature = "rust1", since = "1.0.0"), |
| stable(feature = "extended_compare_and_swap", since = "1.10.0"), |
| stable(feature = "atomic_debug", since = "1.3.0"), |
| stable(feature = "atomic_access", since = "1.15.0"), |
| stable(feature = "atomic_from", since = "1.23.0"), |
| stable(feature = "atomic_nand", since = "1.27.0"), |
| rustc_const_stable(feature = "const_ptr_sized_atomics", since = "1.24.0"), |
| stable(feature = "rust1", since = "1.0.0"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicIsize"), |
| "isize", |
| "", |
| atomic_min, atomic_max, |
| $align, |
| "AtomicIsize::new(0)", |
| isize AtomicIsize ATOMIC_ISIZE_INIT |
| } |
| #[cfg(target_has_atomic_load_store = "ptr")] |
| #[cfg(target_pointer_width = $target_pointer_width)] |
| atomic_int! { |
| cfg(target_has_atomic = "ptr"), |
| cfg(target_has_atomic_equal_alignment = "ptr"), |
| stable(feature = "rust1", since = "1.0.0"), |
| stable(feature = "extended_compare_and_swap", since = "1.10.0"), |
| stable(feature = "atomic_debug", since = "1.3.0"), |
| stable(feature = "atomic_access", since = "1.15.0"), |
| stable(feature = "atomic_from", since = "1.23.0"), |
| stable(feature = "atomic_nand", since = "1.27.0"), |
| rustc_const_stable(feature = "const_ptr_sized_atomics", since = "1.24.0"), |
| stable(feature = "rust1", since = "1.0.0"), |
| cfg_attr(not(test), rustc_diagnostic_item = "AtomicUsize"), |
| "usize", |
| "", |
| atomic_umin, atomic_umax, |
| $align, |
| "AtomicUsize::new(0)", |
| usize AtomicUsize ATOMIC_USIZE_INIT |
| } |
| )* }; |
| } |
| |
| atomic_int_ptr_sized! { |
| "16" 2 |
| "32" 4 |
| "64" 8 |
| } |
| |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| fn strongest_failure_ordering(order: Ordering) -> Ordering { |
| match order { |
| Release => Relaxed, |
| Relaxed => Relaxed, |
| SeqCst => SeqCst, |
| Acquire => Acquire, |
| AcqRel => Acquire, |
| } |
| } |
| |
| #[inline] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_store<T: Copy>(dst: *mut T, val: T, order: Ordering) { |
| // SAFETY: the caller must uphold the safety contract for `atomic_store`. |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_store_relaxed(dst, val), |
| Release => intrinsics::atomic_store_release(dst, val), |
| SeqCst => intrinsics::atomic_store_seqcst(dst, val), |
| Acquire => panic!("there is no such thing as an acquire store"), |
| AcqRel => panic!("there is no such thing as an acquire-release store"), |
| } |
| } |
| } |
| |
| #[inline] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_load<T: Copy>(dst: *const T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_load`. |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_load_relaxed(dst), |
| Acquire => intrinsics::atomic_load_acquire(dst), |
| SeqCst => intrinsics::atomic_load_seqcst(dst), |
| Release => panic!("there is no such thing as a release load"), |
| AcqRel => panic!("there is no such thing as an acquire-release load"), |
| } |
| } |
| } |
| |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_swap<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_swap`. |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_xchg_relaxed(dst, val), |
| Acquire => intrinsics::atomic_xchg_acquire(dst, val), |
| Release => intrinsics::atomic_xchg_release(dst, val), |
| AcqRel => intrinsics::atomic_xchg_acqrel(dst, val), |
| SeqCst => intrinsics::atomic_xchg_seqcst(dst, val), |
| } |
| } |
| } |
| |
| /// Returns the previous value (like __sync_fetch_and_add). |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_add<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_add`. |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_xadd_relaxed(dst, val), |
| Acquire => intrinsics::atomic_xadd_acquire(dst, val), |
| Release => intrinsics::atomic_xadd_release(dst, val), |
| AcqRel => intrinsics::atomic_xadd_acqrel(dst, val), |
| SeqCst => intrinsics::atomic_xadd_seqcst(dst, val), |
| } |
| } |
| } |
| |
| /// Returns the previous value (like __sync_fetch_and_sub). |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_sub<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_sub`. |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_xsub_relaxed(dst, val), |
| Acquire => intrinsics::atomic_xsub_acquire(dst, val), |
| Release => intrinsics::atomic_xsub_release(dst, val), |
| AcqRel => intrinsics::atomic_xsub_acqrel(dst, val), |
| SeqCst => intrinsics::atomic_xsub_seqcst(dst, val), |
| } |
| } |
| } |
| |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_compare_exchange<T: Copy>( |
| dst: *mut T, |
| old: T, |
| new: T, |
| success: Ordering, |
| failure: Ordering, |
| ) -> Result<T, T> { |
| // SAFETY: the caller must uphold the safety contract for `atomic_compare_exchange`. |
| let (val, ok) = unsafe { |
| match (success, failure) { |
| (Relaxed, Relaxed) => intrinsics::atomic_cxchg_relaxed_relaxed(dst, old, new), |
| (Relaxed, Acquire) => intrinsics::atomic_cxchg_relaxed_acquire(dst, old, new), |
| (Relaxed, SeqCst) => intrinsics::atomic_cxchg_relaxed_seqcst(dst, old, new), |
| (Acquire, Relaxed) => intrinsics::atomic_cxchg_acquire_relaxed(dst, old, new), |
| (Acquire, Acquire) => intrinsics::atomic_cxchg_acquire_acquire(dst, old, new), |
| (Acquire, SeqCst) => intrinsics::atomic_cxchg_acquire_seqcst(dst, old, new), |
| (Release, Relaxed) => intrinsics::atomic_cxchg_release_relaxed(dst, old, new), |
| (Release, Acquire) => intrinsics::atomic_cxchg_release_acquire(dst, old, new), |
| (Release, SeqCst) => intrinsics::atomic_cxchg_release_seqcst(dst, old, new), |
| (AcqRel, Relaxed) => intrinsics::atomic_cxchg_acqrel_relaxed(dst, old, new), |
| (AcqRel, Acquire) => intrinsics::atomic_cxchg_acqrel_acquire(dst, old, new), |
| (AcqRel, SeqCst) => intrinsics::atomic_cxchg_acqrel_seqcst(dst, old, new), |
| (SeqCst, Relaxed) => intrinsics::atomic_cxchg_seqcst_relaxed(dst, old, new), |
| (SeqCst, Acquire) => intrinsics::atomic_cxchg_seqcst_acquire(dst, old, new), |
| (SeqCst, SeqCst) => intrinsics::atomic_cxchg_seqcst_seqcst(dst, old, new), |
| (_, AcqRel) => panic!("there is no such thing as an acquire-release failure ordering"), |
| (_, Release) => panic!("there is no such thing as a release failure ordering"), |
| } |
| }; |
| if ok { Ok(val) } else { Err(val) } |
| } |
| |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_compare_exchange_weak<T: Copy>( |
| dst: *mut T, |
| old: T, |
| new: T, |
| success: Ordering, |
| failure: Ordering, |
| ) -> Result<T, T> { |
| // SAFETY: the caller must uphold the safety contract for `atomic_compare_exchange_weak`. |
| let (val, ok) = unsafe { |
| match (success, failure) { |
| (Relaxed, Relaxed) => intrinsics::atomic_cxchgweak_relaxed_relaxed(dst, old, new), |
| (Relaxed, Acquire) => intrinsics::atomic_cxchgweak_relaxed_acquire(dst, old, new), |
| (Relaxed, SeqCst) => intrinsics::atomic_cxchgweak_relaxed_seqcst(dst, old, new), |
| (Acquire, Relaxed) => intrinsics::atomic_cxchgweak_acquire_relaxed(dst, old, new), |
| (Acquire, Acquire) => intrinsics::atomic_cxchgweak_acquire_acquire(dst, old, new), |
| (Acquire, SeqCst) => intrinsics::atomic_cxchgweak_acquire_seqcst(dst, old, new), |
| (Release, Relaxed) => intrinsics::atomic_cxchgweak_release_relaxed(dst, old, new), |
| (Release, Acquire) => intrinsics::atomic_cxchgweak_release_acquire(dst, old, new), |
| (Release, SeqCst) => intrinsics::atomic_cxchgweak_release_seqcst(dst, old, new), |
| (AcqRel, Relaxed) => intrinsics::atomic_cxchgweak_acqrel_relaxed(dst, old, new), |
| (AcqRel, Acquire) => intrinsics::atomic_cxchgweak_acqrel_acquire(dst, old, new), |
| (AcqRel, SeqCst) => intrinsics::atomic_cxchgweak_acqrel_seqcst(dst, old, new), |
| (SeqCst, Relaxed) => intrinsics::atomic_cxchgweak_seqcst_relaxed(dst, old, new), |
| (SeqCst, Acquire) => intrinsics::atomic_cxchgweak_seqcst_acquire(dst, old, new), |
| (SeqCst, SeqCst) => intrinsics::atomic_cxchgweak_seqcst_seqcst(dst, old, new), |
| (_, AcqRel) => panic!("there is no such thing as an acquire-release failure ordering"), |
| (_, Release) => panic!("there is no such thing as a release failure ordering"), |
| } |
| }; |
| if ok { Ok(val) } else { Err(val) } |
| } |
| |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_and<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_and` |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_and_relaxed(dst, val), |
| Acquire => intrinsics::atomic_and_acquire(dst, val), |
| Release => intrinsics::atomic_and_release(dst, val), |
| AcqRel => intrinsics::atomic_and_acqrel(dst, val), |
| SeqCst => intrinsics::atomic_and_seqcst(dst, val), |
| } |
| } |
| } |
| |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_nand<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_nand` |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_nand_relaxed(dst, val), |
| Acquire => intrinsics::atomic_nand_acquire(dst, val), |
| Release => intrinsics::atomic_nand_release(dst, val), |
| AcqRel => intrinsics::atomic_nand_acqrel(dst, val), |
| SeqCst => intrinsics::atomic_nand_seqcst(dst, val), |
| } |
| } |
| } |
| |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_or<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_or` |
| unsafe { |
| match order { |
| SeqCst => intrinsics::atomic_or_seqcst(dst, val), |
| Acquire => intrinsics::atomic_or_acquire(dst, val), |
| Release => intrinsics::atomic_or_release(dst, val), |
| AcqRel => intrinsics::atomic_or_acqrel(dst, val), |
| Relaxed => intrinsics::atomic_or_relaxed(dst, val), |
| } |
| } |
| } |
| |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_xor<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_xor` |
| unsafe { |
| match order { |
| SeqCst => intrinsics::atomic_xor_seqcst(dst, val), |
| Acquire => intrinsics::atomic_xor_acquire(dst, val), |
| Release => intrinsics::atomic_xor_release(dst, val), |
| AcqRel => intrinsics::atomic_xor_acqrel(dst, val), |
| Relaxed => intrinsics::atomic_xor_relaxed(dst, val), |
| } |
| } |
| } |
| |
| /// returns the max value (signed comparison) |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_max<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_max` |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_max_relaxed(dst, val), |
| Acquire => intrinsics::atomic_max_acquire(dst, val), |
| Release => intrinsics::atomic_max_release(dst, val), |
| AcqRel => intrinsics::atomic_max_acqrel(dst, val), |
| SeqCst => intrinsics::atomic_max_seqcst(dst, val), |
| } |
| } |
| } |
| |
| /// returns the min value (signed comparison) |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_min<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_min` |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_min_relaxed(dst, val), |
| Acquire => intrinsics::atomic_min_acquire(dst, val), |
| Release => intrinsics::atomic_min_release(dst, val), |
| AcqRel => intrinsics::atomic_min_acqrel(dst, val), |
| SeqCst => intrinsics::atomic_min_seqcst(dst, val), |
| } |
| } |
| } |
| |
| /// returns the max value (unsigned comparison) |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_umax<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_umax` |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_umax_relaxed(dst, val), |
| Acquire => intrinsics::atomic_umax_acquire(dst, val), |
| Release => intrinsics::atomic_umax_release(dst, val), |
| AcqRel => intrinsics::atomic_umax_acqrel(dst, val), |
| SeqCst => intrinsics::atomic_umax_seqcst(dst, val), |
| } |
| } |
| } |
| |
| /// returns the min value (unsigned comparison) |
| #[inline] |
| #[cfg(target_has_atomic = "8")] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| unsafe fn atomic_umin<T: Copy>(dst: *mut T, val: T, order: Ordering) -> T { |
| // SAFETY: the caller must uphold the safety contract for `atomic_umin` |
| unsafe { |
| match order { |
| Relaxed => intrinsics::atomic_umin_relaxed(dst, val), |
| Acquire => intrinsics::atomic_umin_acquire(dst, val), |
| Release => intrinsics::atomic_umin_release(dst, val), |
| AcqRel => intrinsics::atomic_umin_acqrel(dst, val), |
| SeqCst => intrinsics::atomic_umin_seqcst(dst, val), |
| } |
| } |
| } |
| |
| /// An atomic fence. |
| /// |
| /// Depending on the specified order, a fence prevents the compiler and CPU from |
| /// reordering certain types of memory operations around it. |
| /// That creates synchronizes-with relationships between it and atomic operations |
| /// or fences in other threads. |
| /// |
| /// A fence 'A' which has (at least) [`Release`] ordering semantics, synchronizes |
| /// with a fence 'B' with (at least) [`Acquire`] semantics, if and only if there |
| /// exist operations X and Y, both operating on some atomic object 'M' such |
| /// that A is sequenced before X, Y is sequenced before B and Y observes |
| /// the change to M. This provides a happens-before dependence between A and B. |
| /// |
| /// ```text |
| /// Thread 1 Thread 2 |
| /// |
| /// fence(Release); A -------------- |
| /// x.store(3, Relaxed); X --------- | |
| /// | | |
| /// | | |
| /// -------------> Y if x.load(Relaxed) == 3 { |
| /// |-------> B fence(Acquire); |
| /// ... |
| /// } |
| /// ``` |
| /// |
| /// Atomic operations with [`Release`] or [`Acquire`] semantics can also synchronize |
| /// with a fence. |
| /// |
| /// A fence which has [`SeqCst`] ordering, in addition to having both [`Acquire`] |
| /// and [`Release`] semantics, participates in the global program order of the |
| /// other [`SeqCst`] operations and/or fences. |
| /// |
| /// Accepts [`Acquire`], [`Release`], [`AcqRel`] and [`SeqCst`] orderings. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `order` is [`Relaxed`]. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::atomic::AtomicBool; |
| /// use std::sync::atomic::fence; |
| /// use std::sync::atomic::Ordering; |
| /// |
| /// // A mutual exclusion primitive based on spinlock. |
| /// pub struct Mutex { |
| /// flag: AtomicBool, |
| /// } |
| /// |
| /// impl Mutex { |
| /// pub fn new() -> Mutex { |
| /// Mutex { |
| /// flag: AtomicBool::new(false), |
| /// } |
| /// } |
| /// |
| /// pub fn lock(&self) { |
| /// // Wait until the old value is `false`. |
| /// while self |
| /// .flag |
| /// .compare_exchange_weak(false, true, Ordering::Relaxed, Ordering::Relaxed) |
| /// .is_err() |
| /// {} |
| /// // This fence synchronizes-with store in `unlock`. |
| /// fence(Ordering::Acquire); |
| /// } |
| /// |
| /// pub fn unlock(&self) { |
| /// self.flag.store(false, Ordering::Release); |
| /// } |
| /// } |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_diagnostic_item = "fence"] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn fence(order: Ordering) { |
| // SAFETY: using an atomic fence is safe. |
| unsafe { |
| match order { |
| Acquire => intrinsics::atomic_fence_acquire(), |
| Release => intrinsics::atomic_fence_release(), |
| AcqRel => intrinsics::atomic_fence_acqrel(), |
| SeqCst => intrinsics::atomic_fence_seqcst(), |
| Relaxed => panic!("there is no such thing as a relaxed fence"), |
| } |
| } |
| } |
| |
| /// A compiler memory fence. |
| /// |
| /// `compiler_fence` does not emit any machine code, but restricts the kinds |
| /// of memory re-ordering the compiler is allowed to do. Specifically, depending on |
| /// the given [`Ordering`] semantics, the compiler may be disallowed from moving reads |
| /// or writes from before or after the call to the other side of the call to |
| /// `compiler_fence`. Note that it does **not** prevent the *hardware* |
| /// from doing such re-ordering. This is not a problem in a single-threaded, |
| /// execution context, but when other threads may modify memory at the same |
| /// time, stronger synchronization primitives such as [`fence`] are required. |
| /// |
| /// The re-ordering prevented by the different ordering semantics are: |
| /// |
| /// - with [`SeqCst`], no re-ordering of reads and writes across this point is allowed. |
| /// - with [`Release`], preceding reads and writes cannot be moved past subsequent writes. |
| /// - with [`Acquire`], subsequent reads and writes cannot be moved ahead of preceding reads. |
| /// - with [`AcqRel`], both of the above rules are enforced. |
| /// |
| /// `compiler_fence` is generally only useful for preventing a thread from |
| /// racing *with itself*. That is, if a given thread is executing one piece |
| /// of code, and is then interrupted, and starts executing code elsewhere |
| /// (while still in the same thread, and conceptually still on the same |
| /// core). In traditional programs, this can only occur when a signal |
| /// handler is registered. In more low-level code, such situations can also |
| /// arise when handling interrupts, when implementing green threads with |
| /// pre-emption, etc. Curious readers are encouraged to read the Linux kernel's |
| /// discussion of [memory barriers]. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `order` is [`Relaxed`]. |
| /// |
| /// # Examples |
| /// |
| /// Without `compiler_fence`, the `assert_eq!` in following code |
| /// is *not* guaranteed to succeed, despite everything happening in a single thread. |
| /// To see why, remember that the compiler is free to swap the stores to |
| /// `IMPORTANT_VARIABLE` and `IS_READY` since they are both |
| /// `Ordering::Relaxed`. If it does, and the signal handler is invoked right |
| /// after `IS_READY` is updated, then the signal handler will see |
| /// `IS_READY=1`, but `IMPORTANT_VARIABLE=0`. |
| /// Using a `compiler_fence` remedies this situation. |
| /// |
| /// ``` |
| /// use std::sync::atomic::{AtomicBool, AtomicUsize}; |
| /// use std::sync::atomic::Ordering; |
| /// use std::sync::atomic::compiler_fence; |
| /// |
| /// static IMPORTANT_VARIABLE: AtomicUsize = AtomicUsize::new(0); |
| /// static IS_READY: AtomicBool = AtomicBool::new(false); |
| /// |
| /// fn main() { |
| /// IMPORTANT_VARIABLE.store(42, Ordering::Relaxed); |
| /// // prevent earlier writes from being moved beyond this point |
| /// compiler_fence(Ordering::Release); |
| /// IS_READY.store(true, Ordering::Relaxed); |
| /// } |
| /// |
| /// fn signal_handler() { |
| /// if IS_READY.load(Ordering::Relaxed) { |
| /// assert_eq!(IMPORTANT_VARIABLE.load(Ordering::Relaxed), 42); |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// [memory barriers]: https://www.kernel.org/doc/Documentation/memory-barriers.txt |
| #[inline] |
| #[stable(feature = "compiler_fences", since = "1.21.0")] |
| #[rustc_diagnostic_item = "compiler_fence"] |
| #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces |
| pub fn compiler_fence(order: Ordering) { |
| // SAFETY: using an atomic fence is safe. |
| unsafe { |
| match order { |
| Acquire => intrinsics::atomic_singlethreadfence_acquire(), |
| Release => intrinsics::atomic_singlethreadfence_release(), |
| AcqRel => intrinsics::atomic_singlethreadfence_acqrel(), |
| SeqCst => intrinsics::atomic_singlethreadfence_seqcst(), |
| Relaxed => panic!("there is no such thing as a relaxed compiler fence"), |
| } |
| } |
| } |
| |
| #[cfg(target_has_atomic_load_store = "8")] |
| #[stable(feature = "atomic_debug", since = "1.3.0")] |
| impl fmt::Debug for AtomicBool { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| fmt::Debug::fmt(&self.load(Ordering::Relaxed), f) |
| } |
| } |
| |
| #[cfg(target_has_atomic_load_store = "ptr")] |
| #[stable(feature = "atomic_debug", since = "1.3.0")] |
| impl<T> fmt::Debug for AtomicPtr<T> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| fmt::Debug::fmt(&self.load(Ordering::Relaxed), f) |
| } |
| } |
| |
| #[cfg(target_has_atomic_load_store = "ptr")] |
| #[stable(feature = "atomic_pointer", since = "1.24.0")] |
| impl<T> fmt::Pointer for AtomicPtr<T> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| fmt::Pointer::fmt(&self.load(Ordering::SeqCst), f) |
| } |
| } |
| |
| /// Signals the processor that it is inside a busy-wait spin-loop ("spin lock"). |
| /// |
| /// This function is deprecated in favor of [`hint::spin_loop`]. |
| /// |
| /// [`hint::spin_loop`]: crate::hint::spin_loop |
| #[inline] |
| #[stable(feature = "spin_loop_hint", since = "1.24.0")] |
| #[deprecated(since = "1.51.0", note = "use hint::spin_loop instead")] |
| pub fn spin_loop_hint() { |
| spin_loop() |
| } |