Struct slabmalloc::SCAllocator

pub struct SCAllocator<'a, P: AllocablePage> { /* private fields */ }

A slab allocator allocates elements of a fixed size.

It maintains three internal lists of objects that implement AllocablePage from which it can allocate memory.

• empty_slabs: Is a list of pages that the SCAllocator maintains, but has 0 allocations in them, these can be given back to a requestor in case of reclamation.
• slabs: A list of pages partially allocated and still have room for more.
• full_slabs: A list of pages that are completely allocated.

On allocation we allocate memory from slabs, however if the list is empty we try to reclaim a page from empty_slabs before we return with an out-of-memory error. If a page becomes full after the allocation we move it from slabs to full_slabs.

Similarly, on dealloaction we might move a page from full_slabs to slabs or from slabs to empty_slabs after we deallocated an object.

If an allocation returns OutOfMemory a client using SCAllocator can refill it using the refill function.

Implementations

impl<'a, P: AllocablePage> SCAllocator<'a, P>

pub const fn new(size: usize) -> SCAllocator<'a, P>

Create a new SCAllocator.

pub fn size(&self) -> usize

Returns the maximum supported object size of this allocator.

pub fn try_reclaim_pages<F>(
    &mut self,
    to_reclaim: usize,
    dealloc: &mut F
) -> usize where
    F: FnMut(*mut P), 

pub unsafe fn refill(&mut self, page: &'a mut P)

Refill the SCAllocator

Safety

ObjectPage needs to be empty etc.

pub fn allocate(
    &mut self,
    layout: Layout
) -> Result<NonNull<u8>, AllocationError>

Allocates a block of memory descriped by layout.

Returns a pointer to a valid region of memory or an AllocationError.

The function may also move around pages between lists (empty -> partial or partial -> full).

pub fn deallocate(
    &self,
    ptr: NonNull<u8>,
    layout: Layout
) -> Result<(), AllocationError>

Deallocates a previously allocated ptr described by Layout.

May return an error in case an invalid layout is provided. The function may also move internal slab pages between lists partial -> empty or full -> partial lists.