AtomicIsize in std::sync::atomic - Rust (original) (raw)

Struct AtomicIsize

1.0.0 · Source


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

pub struct AtomicIsize { /* private fields */ }

Expand description

An integer type which can be safely shared between threads.

This type has the same size and bit validity as the underlying integer type, isize. However, the alignment of this type is always equal to its size, even on targets where isize has a lesser alignment.

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 isize.

Source §

1.0.0 (const: 1.24.0) · Source

Creates a new atomic integer.

§Examples

use std::sync::atomic::AtomicIsize;

let atomic_forty_two = AtomicIsize::new(42);

1.75.0 (const: 1.84.0) · Source

Creates a new reference to an atomic integer from a pointer.

§Examples

use std::sync::atomic::{self, AtomicIsize};

// Get a pointer to an allocated value
let ptr: *mut isize = Box::into_raw(Box::new(0));

assert!(ptr.cast::<AtomicIsize>().is_aligned());

{
    // Create an atomic view of the allocated value
    let atomic = unsafe {AtomicIsize::from_ptr(ptr) };

    // Use `atomic` for atomic operations, possibly share it with other threads
    atomic.store(1, atomic::Ordering::Relaxed);
}

// It's ok to non-atomically access the value behind `ptr`,
// since the reference to the atomic ended its lifetime in the block above
assert_eq!(unsafe { *ptr }, 1);

// Deallocate the value
unsafe { drop(Box::from_raw(ptr)) }

§Safety

ptr must be aligned toalign_of::<AtomicIsize>()(note that on some platforms this can be bigger than align_of::<isize>()).
ptr must be valid for both reads and writes for the whole lifetime 'a.
You must adhere to the Memory model for atomic accesses. In particular, it is not allowed to mix atomic and non-atomic accesses, or atomic accesses of different sizes, without synchronization.

1.15.0 · Source

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

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

let mut some_var = AtomicIsize::new(10);
assert_eq!(*some_var.get_mut(), 10);
*some_var.get_mut() = 5;
assert_eq!(some_var.load(Ordering::SeqCst), 5);

Source

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

Get atomic access to a &mut isize.

Note: This function is only available on targets where AtomicIsize has the same alignment as isize.

§Examples

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

let mut some_int = 123;
let a = AtomicIsize::from_mut(&mut some_int);
a.store(100, Ordering::Relaxed);
assert_eq!(some_int, 100);

Source

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

Get non-atomic access to a &mut [AtomicIsize] slice

This is safe because the mutable reference guarantees that no other threads are concurrently accessing the atomic data.

§Examples

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

let mut some_ints = [const { AtomicIsize::new(0) }; 10];

let view: &mut [isize] = AtomicIsize::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 _));
        })
});

Source

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

Get atomic access to a &mut [isize] slice.

§Examples

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

let mut some_ints = [0; 10];
let a = &*AtomicIsize::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);
}

1.15.0 (const: 1.79.0) · Source

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::AtomicIsize;

let some_var = AtomicIsize::new(5);
assert_eq!(some_var.into_inner(), 5);

1.0.0 · Source

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

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

let some_var = AtomicIsize::new(5);

assert_eq!(some_var.load(Ordering::Relaxed), 5);

1.0.0 · Source

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

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

let some_var = AtomicIsize::new(5);

some_var.store(10, Ordering::Relaxed);
assert_eq!(some_var.load(Ordering::Relaxed), 10);

1.0.0 · Source

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 usingAcquire 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 onisize.

§Examples

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

let some_var = AtomicIsize::new(5);

assert_eq!(some_var.swap(10, Ordering::Relaxed), 5);

1.0.0 · Source

👎Deprecated since 1.50.0: Use compare_exchange or compare_exchange_weak instead

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 onisize.

§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_and_swap and compare_exchange also differ in their return type. You can usecompare_exchange(...).unwrap_or_else(|x| x) to recover the behavior of compare_and_swap, but in most cases it is more idiomatic to check whether the return value is Ok or Errrather than to infer success vs failure based on the value that was read.

During migration, consider whether it makes sense to use compare_exchange_weak instead.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::{AtomicIsize, Ordering};

let some_var = AtomicIsize::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);

1.10.0 · Source

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 tocurrent.

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 loadRelaxed. The failure ordering can only be SeqCst, Acquire or Relaxed.

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

§Examples

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

let some_var = AtomicIsize::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);

1.10.0 · Source

Stores a value into the atomic integer if the current value is the same as the current value.

Unlike AtomicIsize::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 loadRelaxed. The failure ordering can only be SeqCst, Acquire or Relaxed.

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

§Examples

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

let val = AtomicIsize::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,
    }
}

1.0.0 · Source

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 usingAcquire 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 onisize.

§Examples

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

let foo = AtomicIsize::new(0);
assert_eq!(foo.fetch_add(10, Ordering::SeqCst), 0);
assert_eq!(foo.load(Ordering::SeqCst), 10);

1.0.0 · Source

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 usingAcquire 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 onisize.

§Examples

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

let foo = AtomicIsize::new(20);
assert_eq!(foo.fetch_sub(10, Ordering::SeqCst), 20);
assert_eq!(foo.load(Ordering::SeqCst), 10);

1.0.0 · Source

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 usingAcquire 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 onisize.

§Examples

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

let foo = AtomicIsize::new(0b101101);
assert_eq!(foo.fetch_and(0b110011, Ordering::SeqCst), 0b101101);
assert_eq!(foo.load(Ordering::SeqCst), 0b100001);

1.27.0 · Source

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 usingAcquire 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 onisize.

§Examples

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

let foo = AtomicIsize::new(0x13);
assert_eq!(foo.fetch_nand(0x31, Ordering::SeqCst), 0x13);
assert_eq!(foo.load(Ordering::SeqCst), !(0x13 & 0x31));

1.0.0 · Source

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 usingAcquire 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 onisize.

§Examples

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

let foo = AtomicIsize::new(0b101101);
assert_eq!(foo.fetch_or(0b110011, Ordering::SeqCst), 0b101101);
assert_eq!(foo.load(Ordering::SeqCst), 0b111111);

1.0.0 · Source

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 usingAcquire 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 onisize.

§Examples

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

let foo = AtomicIsize::new(0b101101);
assert_eq!(foo.fetch_xor(0b110011, Ordering::SeqCst), 0b101101);
assert_eq!(foo.load(Ordering::SeqCst), 0b011110);

1.45.0 · Source

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(_), elseErr(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 ofAtomicIsize::compare_exchangerespectively.

Using Acquire as success ordering makes the store part of this operation Relaxed, and using Release makes the final successful loadRelaxed. The (failed) load ordering can only be SeqCst, Acquire or Relaxed.

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

§Considerations

This method is not magic; it is not provided by the hardware. It is implemented in terms ofAtomicIsize::compare_exchange_weak, and suffers from the same drawbacks. In particular, this method will not circumvent the ABA Problem.

§Examples

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

let x = AtomicIsize::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);

Source

🔬This is a nightly-only experimental API. (atomic_try_update #135894)

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(_), elseErr(previous_value).

§Considerations

§Examples

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

let x = AtomicIsize::new(7);
assert_eq!(x.try_update(Ordering::SeqCst, Ordering::SeqCst, |_| None), Err(7));
assert_eq!(x.try_update(Ordering::SeqCst, Ordering::SeqCst, |x| Some(x + 1)), Ok(7));
assert_eq!(x.try_update(Ordering::SeqCst, Ordering::SeqCst, |x| Some(x + 1)), Ok(8));
assert_eq!(x.load(Ordering::SeqCst), 9);

Source

🔬This is a nightly-only experimental API. (atomic_try_update #135894)

Fetches the value, applies a function to it that it return a new value. The new value is stored and the old value is returned.

§Considerations

§Examples

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

let x = AtomicIsize::new(7);
assert_eq!(x.update(Ordering::SeqCst, Ordering::SeqCst, |x| x + 1), 7);
assert_eq!(x.update(Ordering::SeqCst, Ordering::SeqCst, |x| x + 1), 8);
assert_eq!(x.load(Ordering::SeqCst), 9);

1.45.0 · Source

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 usingAcquire 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 onisize.

§Examples

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

let foo = AtomicIsize::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:

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

let foo = AtomicIsize::new(23);
let bar = 42;
let max_foo = foo.fetch_max(bar, Ordering::SeqCst).max(bar);
assert!(max_foo == 42);

1.45.0 · Source

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 usingAcquire 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 onisize.

§Examples

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

let foo = AtomicIsize::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:

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

let foo = AtomicIsize::new(23);
let bar = 12;
let min_foo = foo.fetch_min(bar, Ordering::SeqCst).min(bar);
assert_eq!(min_foo, 12);

1.70.0 (const: 1.70.0) · Source

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*mut isize instead of &AtomicIsize.

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

ⓘ

use std::sync::atomic::AtomicIsize;

extern "C" {
    fn my_atomic_op(arg: *mut isize);
}

let atomic = AtomicIsize::new(1);

// SAFETY: Safe as long as `my_atomic_op` is atomic.
unsafe {
    my_atomic_op(atomic.as_ptr());
}

AtomicIsize in std::sync::atomic - Rust (original) (raw)

Struct AtomicIsize

§Examples

§Examples

§Safety

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§Panics

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§Panics

§Examples

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§Migrating to compare_exchange and compare_exchange_weak

§Examples

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§Considerations

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§Considerations

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§Considerations

§Examples

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§Migrating to `compare_exchange` and `compare_exchange_weak`