Struct static_alloc::bump::Level [−][src]
pub struct Level(_);
Expand description
Specifies an amount of consumed space of a slab.
Each allocation of the Bump
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 BUMP: Bump<[u64; 4]> = Bump::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 = BUMP.level(); let mut begin: *mut u64; let mut count; match BUMP.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 BUMP.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 BUMP 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 Ord for Level
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impl Ord for Level
[src]impl PartialOrd<Level> for Level
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impl PartialOrd<Level> for Level
[src]fn partial_cmp(&self, other: &Level) -> Option<Ordering>
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fn partial_cmp(&self, other: &Level) -> Option<Ordering>
[src]This method returns an ordering between self
and other
values if one exists. Read more
#[must_use]fn lt(&self, other: &Rhs) -> bool
1.0.0[src]
#[must_use]fn lt(&self, other: &Rhs) -> bool
1.0.0[src]This method tests less than (for self
and other
) and is used by the <
operator. Read more
#[must_use]fn le(&self, other: &Rhs) -> bool
1.0.0[src]
#[must_use]fn le(&self, other: &Rhs) -> bool
1.0.0[src]This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
impl Copy for Level
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impl Eq for Level
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impl StructuralEq for Level
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impl StructuralPartialEq for Level
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Auto Trait Implementations
Blanket Implementations
impl<T> BorrowMut<T> for T where
T: ?Sized,
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impl<T> BorrowMut<T> for T where
T: ?Sized,
[src]pub fn borrow_mut(&mut self) -> &mut T
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pub fn borrow_mut(&mut self) -> &mut T
[src]Mutably borrows from an owned value. Read more
impl<T> ToOwned for T where
T: Clone,
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impl<T> ToOwned for T where
T: Clone,
[src]type Owned = T
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn to_owned(&self) -> T
[src]Creates owned data from borrowed data, usually by cloning. Read more
pub fn clone_into(&self, target: &mut T)
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pub 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