Struct linked_list_allocator::Heap
source · [−]pub struct Heap { /* private fields */ }
Expand description
A fixed size heap backed by a linked list of free memory blocks.
Implementations
sourceimpl Heap
impl Heap
pub const fn empty() -> Heap
sourcepub unsafe fn init(&mut self, heap_bottom: *mut u8, heap_size: usize)
pub unsafe fn init(&mut self, heap_bottom: *mut u8, heap_size: usize)
Initializes an empty heap
Safety
This function must be called at most once and must only be used on an empty heap.
The bottom address must be valid and the memory in the
[heap_bottom, heap_bottom + heap_size)
range must not be used for anything else.
This function is unsafe because it can cause undefined behavior if the given address
is invalid.
The provided memory range must be valid for the 'static
lifetime.
sourcepub fn init_from_slice(&mut self, mem: &'static mut [MaybeUninit<u8>])
pub fn init_from_slice(&mut self, mem: &'static mut [MaybeUninit<u8>])
Initialize an empty heap with provided memory.
The caller is responsible for procuring a region of raw memory that may be utilized by the allocator. This might be done via any method such as (unsafely) taking a region from the program’s memory, from a mutable static, or by allocating and leaking such memory from another allocator.
The latter method may be especially useful if the underlying allocator does not perform deallocation (e.g. a simple bump allocator). Then the overlaid linked-list-allocator can provide memory reclamation.
Panics
This method panics if the heap is already initialized.
sourcepub unsafe fn new(heap_bottom: *mut u8, heap_size: usize) -> Heap
pub unsafe fn new(heap_bottom: *mut u8, heap_size: usize) -> Heap
Creates a new heap with the given bottom
and size
.
Safety
The bottom address must be valid and the memory in the
[heap_bottom, heap_bottom + heap_size)
range must not be used for anything else.
This function is unsafe because it can cause undefined behavior if the given address
is invalid.
The provided memory range must be valid for the 'static
lifetime.
sourcepub fn from_slice(mem: &'static mut [MaybeUninit<u8>]) -> Heap
pub fn from_slice(mem: &'static mut [MaybeUninit<u8>]) -> Heap
Creates a new heap from a slice of raw memory.
This has the same effect as [init_from_slice
] on an empty heap, but it is combined into a
single operation that can not panic.
sourcepub fn allocate_first_fit(&mut self, layout: Layout) -> Result<NonNull<u8>, ()>
pub fn allocate_first_fit(&mut self, layout: Layout) -> Result<NonNull<u8>, ()>
Allocates a chunk of the given size with the given alignment. Returns a pointer to the
beginning of that chunk if it was successful. Else it returns None
.
This function scans the list of free memory blocks and uses the first block that is big
enough. The runtime is in O(n) where n is the number of free blocks, but it should be
reasonably fast for small allocations.
sourcepub unsafe fn deallocate(&mut self, ptr: NonNull<u8>, layout: Layout)
pub unsafe fn deallocate(&mut self, ptr: NonNull<u8>, layout: Layout)
Frees the given allocation. ptr
must be a pointer returned
by a call to the allocate_first_fit
function with identical size and alignment.
This function walks the list of free memory blocks and inserts the freed block at the
correct place. If the freed block is adjacent to another free block, the blocks are merged
again. This operation is in O(n)
since the list needs to be sorted by address.
Safety
ptr
must be a pointer returned by a call to the [allocate_first_fit
] function with
identical layout. Undefined behavior may occur for invalid arguments.
Trait Implementations
Auto Trait Implementations
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more