# Struct std::sync::atomic::AtomicPtr 1.0.0[−][src]

    #[repr(C, align(8))]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`.

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.

## Implementations

### `impl<T> AtomicPtr<T>`[src]

#### `pub const fn new(p: *mut T) -> AtomicPtr<T>`1.0.0 (const: 1.32.0)[src]

Creates a new `AtomicPtr`.

# Examples

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

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

Run

#### `pub fn get_mut(&mut self) -> &mut *mut T` 1.15.0[src]

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);

Run

#### `pub fn from_mut(v: &mut *mut T) -> &AtomicPtr<T>`[src]

🔬 This is a nightly-only experimental API. (`atomic_from_mut` #76314)

Get atomic access to a pointer.

# Examples

    #![feature(atomic_from_mut)]
    use std::sync::atomic::{AtomicPtr, Ordering};

    let mut some_ptr = &mut 123 as *mut i32;
    let a = AtomicPtr::from_mut(&mut some_ptr);
    a.store(&mut 456, Ordering::Relaxed);
    assert_eq!(unsafe { *some_ptr }, 456);

Run

#### `pub fn into_inner(self) -> *mut T` 1.15.0[src]

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);

Run

#### `pub fn load(&self, order: Ordering) -> *mut T`[src]

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);

Run

#### `pub fn store(&self, ptr: *mut T, order: Ordering)`[src]

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);

Run

#### `pub fn swap(&self, ptr: *mut T, order: Ordering) -> *mut T`[src]

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);

Run

#### `pub fn compare_and_swap(
&self,
current: *mut T,
new: *mut T,
order: Ordering
) -> *mut T`[src]

👎 Deprecated since 1.50.0:

Use `compare_exchange` or `compare_exchange_weak` instead

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);

Run

#### `pub fn compare_exchange(
&self,
current: *mut T,
new: *mut T,
success: Ordering,
failure: Ordering
) -> Result<*mut T, *mut T>`1.10.0[src]

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` and must be equivalent to or weaker than the success ordering.

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);

Run

#### `pub fn compare_exchange_weak(
&self,
current: *mut T,
new: *mut T,
success: Ordering,
failure: Ordering
) -> Result<*mut T, *mut T>`1.10.0[src]

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` and must be equivalent to or weaker than the success ordering.

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,
        }
    }

Run

#### `pub fn fetch_update<F>(
&self,
set_order: Ordering,
fetch_order: Ordering,
f: F
) -> Result<*mut T, *mut T> where
F: FnMut(*mut T) -> Option<*mut T>,` [src]

🔬 This is a nightly-only experimental API. (`atomic_fetch_update` #78639)

recently added

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` and must be equivalent to or weaker than the success ordering.

Note: This method is only available on platforms that support atomic operations on pointers.

# Examples

    #![feature(atomic_fetch_update)]
    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);

Run

## Trait Implementations

### `impl<T> Debug for AtomicPtr<T>`1.3.0[src]

#### `pub fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>`[src]

Formats the value using the given formatter. Read more

### `impl<T> Default for AtomicPtr<T>`[src]

#### `pub fn default() -> AtomicPtr<T>`[src]

Creates a null `AtomicPtr<T>`.

### `impl<T> From<*mut T> for AtomicPtr<T>`1.23.0[src]

#### `pub fn from(p: *mut T) -> AtomicPtr<T>`[src]

Performs the conversion.

### `impl<T> Pointer for AtomicPtr<T>`1.24.0[src]

#### `pub fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>`[src]

Formats the value using the given formatter.

### `impl<T> RefUnwindSafe for AtomicPtr<T>`1.14.0[src]

### `impl<T> Send for AtomicPtr<T>`[src]

### `impl<T> Sync for AtomicPtr<T>`[src]

## Auto Trait Implementations

### `impl<T> Unpin for AtomicPtr<T>`[src]

### `impl<T> UnwindSafe for AtomicPtr<T> where
T: RefUnwindSafe,` [src]

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId`[src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &Tⓘ

### Notable traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<R: Read + ?Sized> Read for &mut Rimpl<W: Write + ?Sized> Write for &mut W`
`[src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut Tⓘ

### Notable traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<R: Read + ?Sized> Read for &mut Rimpl<W: Write + ?Sized> Write for &mut W`
`[src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T`[src]

#### `pub fn from(t: T) -> T`[src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U`[src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>`[src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>`[src]

Performs the conversion.