Struct std::sync::atomic::AtomicPtr

#[repr(C)]
pub struct AtomicPtr<T> { /* fields omitted */ }

A raw pointer type which can be safely shared between threads.

This type has the same in-memory representation as a *mut T.

Methods

impl<T> AtomicPtr<T>

pub const fn new(p: *mut T) -> AtomicPtr<T>

Creates a new AtomicPtr.

Examples

use std::sync::atomic::AtomicPtr;

let ptr = &mut 5;
let atomic_ptr  = AtomicPtr::new(ptr);

pub fn get_mut(&mut self) -> &mut *mut T

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 atomic_ptr = AtomicPtr::new(&mut 10);
*atomic_ptr.get_mut() = &mut 5;
assert_eq!(unsafe { *atomic_ptr.load(Ordering::SeqCst) }, 5);

pub fn into_inner(self) -> *mut T

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 atomic_ptr = AtomicPtr::new(&mut 5);
assert_eq!(unsafe { *atomic_ptr.into_inner() }, 5);

pub fn load(&self, order: Ordering) -> *mut T

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);

pub fn store(&self, ptr: *mut T, order: Ordering)

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);

pub fn swap(&self, ptr: *mut T, order: Ordering) -> *mut T

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.

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);

pub fn compare_and_swap(
    &self,
    current: *mut T,
    new: *mut T,
    order: Ordering
) -> *mut T

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.

Examples

use std::sync::atomic::{AtomicPtr, Ordering};

let ptr = &mut 5;
let some_ptr  = AtomicPtr::new(ptr);

let other_ptr   = &mut 10;
let another_ptr = &mut 10;

let value = some_ptr.compare_and_swap(other_ptr, another_ptr, Ordering::Relaxed);

pub fn compare_exchange(
    &self,
    current: *mut T,
    new: *mut T,
    success: Ordering,
    failure: Ordering
) -> Result<*mut T, *mut T>

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. The first describes the required ordering if the operation succeeds while the second describes the required ordering when the operation 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 and must be equivalent to or weaker than the success ordering.

Examples

use std::sync::atomic::{AtomicPtr, Ordering};

let ptr = &mut 5;
let some_ptr  = AtomicPtr::new(ptr);

let other_ptr   = &mut 10;
let another_ptr = &mut 10;

let value = some_ptr.compare_exchange(other_ptr, another_ptr,
                                      Ordering::SeqCst, Ordering::Relaxed);

pub fn compare_exchange_weak(
    &self,
    current: *mut T,
    new: *mut T,
    success: Ordering,
    failure: Ordering
) -> Result<*mut T, *mut T>

Stores a value into the pointer if the current value is the same as the current value.

Unlike 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. The first describes the required ordering if the operation succeeds while the second describes the required ordering when the operation 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 and must be equivalent to or weaker than the success ordering.

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,
    }
}

Trait Implementations

impl<T> Pointer for AtomicPtr<T>

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.

impl<T> Debug for AtomicPtr<T>

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.

impl<T> From<*mut T> for AtomicPtr<T>

fn from(p: *mut T) -> AtomicPtr<T>

Performs the conversion.

impl<T> Default for AtomicPtr<T>

fn default() -> AtomicPtr<T>

Creates a null AtomicPtr<T>.

impl<T> Sync for AtomicPtr<T>

impl<T> Send for AtomicPtr<T>

impl<T> RefUnwindSafe for AtomicPtr<T>