[−][src]Struct static_alloc::slab::Level
Specifies an amount of consumed space of a slab.
Each allocation of the Slab
increases the current level as they must not be empty. By
ensuring that an allocation is performed at a specific level it is thus possible to check that
multiple allocations happened in succession without other intermediate allocations. This
ability in turns makes it possible to group allocations together, for example to initialize a
#[repr(C)]
struct member-by-member or to extend a slice.
Usage
The main use is successively allocating a slice without requiring all data to be present at
once. Other similar interface often require an internal locking mechanism but Level
leaves
the choice to the user. This is not yet encapsulate in a safe API yet Level
makes it easy to
reason about.
static SLAB: Slab<[u64; 4]> = Slab::uninit(); /// Gathers as much data as possible. /// /// An arbitrary amount of data, can't stack allocate! fn gather_data(mut iter: impl Iterator<Item=u64>) -> &'static mut [u64] { let first = match iter.next() { Some(item) => item, None => return &mut [], }; let mut level: Level = SLAB.level(); let mut begin: *mut u64; let mut count; match SLAB.leak_at(first, level) { Ok((first, first_level)) => { begin = first; level = first_level; count = 1; }, _ => return &mut [], } let _ = iter.try_for_each(|value: u64| { match SLAB.leak_at(value, level) { Err(err) => return Err(err), Ok((_, new_level)) => level = new_level, }; count += 1; Ok(()) }); unsafe { // SAFETY: all `count` allocations are contiguous, begin is well aligned and no // reference is currently pointing at any of the values. The lifetime is `'static` as // the SLAB itself is static. slice::from_raw_parts_mut(begin, count) } } fn main() { // There is no other thread running, so this succeeds. let slice = gather_data(0..=3); assert_eq!(slice, [0, 1, 2, 3]); }
Trait Implementations
impl Debug for Level
[src]
impl PartialEq<Level> for Level
[src]
impl Eq for Level
[src]
impl Ord for Level
[src]
fn cmp(&self, other: &Level) -> Ordering
[src]
fn max(self, other: Self) -> Self
1.21.0[src]
Compares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self
1.21.0[src]
Compares and returns the minimum of two values. Read more
fn clamp(self, min: Self, max: Self) -> Self
[src]
clamp
)Restrict a value to a certain interval. Read more
impl PartialOrd<Level> for Level
[src]
fn partial_cmp(&self, other: &Level) -> Option<Ordering>
[src]
fn lt(&self, other: &Level) -> bool
[src]
fn le(&self, other: &Level) -> bool
[src]
fn gt(&self, other: &Level) -> bool
[src]
fn ge(&self, other: &Level) -> bool
[src]
impl Hash for Level
[src]
fn hash<__H: Hasher>(&self, state: &mut __H)
[src]
fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,
1.3.0[src]
H: Hasher,
Feeds a slice of this type into the given [Hasher
]. Read more
impl Copy for Level
[src]
impl Clone for Level
[src]
Auto Trait Implementations
Blanket Implementations
impl<T, U> TryFrom<U> for T where
U: Into<T>,
[src]
U: Into<T>,
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]
impl<T, U> Into<U> for T where
U: From<T>,
[src]
U: From<T>,
impl<T> From<T> for T
[src]
impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
[src]
U: TryFrom<T>,
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]
impl<T> Borrow<T> for T where
T: ?Sized,
[src]
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
[src]
T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
[src]
impl<T> Any for T where
T: 'static + ?Sized,
[src]
T: 'static + ?Sized,