# [−][src]Struct crossbeam::utils::CachePadded

    pub struct CachePadded<T> { /* fields omitted */ }

Pads and aligns a value to the length of a cache line.

In concurrent programming, sometimes it is desirable to make sure commonly accessed pieces of data are not placed into the same cache line. Updating an atomic value invalides the whole cache line it belongs to, which makes the next access to the same cache line slower for other CPU cores. Use `CachePadded` to ensure updating one piece of data doesn't invalidate other cached data.

Cache lines are assumed to be 64 bytes on all architectures.

# Size and alignment

The size of `CachePadded<T>` is the smallest multiple of 64 bytes large enough to accommodate a value of type `T`.

The alignment of `CachePadded<T>` is the maximum of 64 bytes and the alignment of `T`.

# Examples

Alignment and padding:

    use crossbeam_utils::CachePadded;

    let array = [CachePadded::new(1i32), CachePadded::new(2i32)];
    let addr1 = &*array[0] as *const i32 as usize;
    let addr2 = &*array[1] as *const i32 as usize;

    assert_eq!(addr2 - addr1, 64);
    assert_eq!(addr1 % 64, 0);
    assert_eq!(addr2 % 64, 0);

When building a concurrent queue with a head and a tail index, it is wise to place them in different cache lines so that concurrent threads pushing and popping elements don't invalidate each other's cache lines:

    use crossbeam_utils::CachePadded;
    use std::sync::atomic::AtomicUsize;

    struct Queue<T> {
        head: CachePadded<AtomicUsize>,
        tail: CachePadded<AtomicUsize>,
        buffer: *mut T,
    }

## Methods

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

#### `pub fn new(t: T) -> CachePadded<T>`[src]

Pads and aligns a value to the length of a cache line.

# Examples

    use crossbeam_utils::CachePadded;

    let padded_value = CachePadded::new(1);

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

Returns the value value.

# Examples

    use crossbeam_utils::CachePadded;

    let padded_value = CachePadded::new(7);
    let value = padded_value.into_inner();
    assert_eq!(value, 7);

## Trait Implementations

### `impl<T> Debug for CachePadded<T> where
T: Debug,` [src]

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

Formats the value using the given formatter. Read more

### `impl<T> Clone for CachePadded<T> where
T: Clone,` [src]

#### `fn clone(&self) -> CachePadded<T>`[src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`1.0.0[src]

Performs copy-assignment from `source`. Read more

### `impl<T> Default for CachePadded<T> where
T: Default,` [src]

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

Returns the "default value" for a type. Read more

### `impl<T> Hash for CachePadded<T> where
T: Hash,` [src]

#### `fn hash<__H>(&self, state: &mut __H) where
__H: Hasher,` [src]

Feeds this value into the given [`Hasher`]. Read more

#### `fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,` 1.3.0[src]

Feeds a slice of this type into the given [`Hasher`]. Read more

### `impl<T> Eq for CachePadded<T> where
T: Eq,` [src]

### `impl<T> Sync for CachePadded<T> where
T: Sync,` [src]

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

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

Performs the conversion.

### `impl<T> Deref for CachePadded<T>`[src]

#### `type Target = T`

The resulting type after dereferencing.

####
ⓘImportant traits for &'_ mut W

### Important traits for &'_ mut W

`impl<'_, W> Write for &'_ mut W where
W: Write + ?Sized, impl<'_, R> Read for &'_ mut R where
R: Read + ?Sized, impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;`
`fn deref(&self) -> &T`[src]

Dereferences the value.

### `impl<T> Send for CachePadded<T> where
T: Send,` [src]

### `impl<T> Copy for CachePadded<T> where
T: Copy,` [src]

### `impl<T> DerefMut for CachePadded<T>`[src]

####
ⓘImportant traits for &'_ mut W

### Important traits for &'_ mut W

`impl<'_, W> Write for &'_ mut W where
W: Write + ?Sized, impl<'_, R> Read for &'_ mut R where
R: Read + ?Sized, impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;`
`fn deref_mut(&mut self) -> &mut T`[src]

Mutably dereferences the value.

### `impl<T> PartialEq<CachePadded<T>> for CachePadded<T> where
T: PartialEq<T>,` [src]

#### `fn eq(&self, other: &CachePadded<T>) -> bool`[src]

This method tests for `self` and `other` values to be equal, and is used by `==`. Read more

#### `fn ne(&self, other: &CachePadded<T>) -> bool`[src]

This method tests for `!=`.

## Auto Trait Implementations

### `impl<T> Unpin for CachePadded<T> where
T: Unpin,`

### `impl<T> UnwindSafe for CachePadded<T> where
T: UnwindSafe,`

### `impl<T> RefUnwindSafe for CachePadded<T> where
T: RefUnwindSafe,`

## Blanket Implementations

### `impl<T> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `fn to_owned(&self) -> T`[src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `fn clone_into(&self, target: &mut T)`[src]

🔬 This is a nightly-only experimental API. (`toowned_clone_into`)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

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

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

Performs the conversion.

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

#### `fn from(t: T) -> T`[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.

#### `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.

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

Performs the conversion.

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

####
ⓘImportant traits for &'_ mut W

### Important traits for &'_ mut W

`impl<'_, W> Write for &'_ mut W where
W: Write + ?Sized, impl<'_, R> Read for &'_ mut R where
R: Read + ?Sized, impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;`
`fn borrow_mut(&mut self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

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

####
ⓘImportant traits for &'_ mut W

### Important traits for &'_ mut W

`impl<'_, W> Write for &'_ mut W where
W: Write + ?Sized, impl<'_, R> Read for &'_ mut R where
R: Read + ?Sized, impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;`
`fn borrow(&self) -> &T`[src]

Immutably borrows from an owned value. Read more

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

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

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

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