Struct BumpAllocator

pub struct BumpAllocator { /* private fields */ }

The bump allocator used as the default rust heap when running programs.

Implementations

impl BumpAllocator

pub unsafe fn new(arena: &mut [u8]) -> Self

Creates the allocator tied to a provided slice. This will not initialize the provided memory, except for the first bytes where the pointer is stored.

Safety

As long as BumpAllocator or any of its allocations are alive, writing into or deallocating the arena will cause UB.

Integer arithmetic in this global allocator implementation is safe when operating on the prescribed HEAP_START_ADDRESS and HEAP_LENGTH. Any other use may overflow and is thus unsupported and at one’s own risk.

pub const unsafe fn with_fixed_address_range(start: usize, len: usize) -> Self

Creates the allocator tied to specific range of addresses.

Safety

This is unsafe in most situations, unless you are totally sure that the provided start address and length can be written to by the allocator, and that the memory will be usable for the lifespan of the allocator.

For Solana on-chain programs, a certain address range is reserved, so the allocator can be given those addresses.

Trait Implementations

impl GlobalAlloc for BumpAllocator

Integer arithmetic in this global allocator implementation is safe when operating on the prescribed HEAP_START_ADDRESS and HEAP_LENGTH. Any other use may overflow and is thus unsupported and at one’s own risk.

unsafe fn alloc(&self, layout: Layout) -> *mut u8

Allocates memory as described by the given layout.

unsafe fn dealloc(&self, _: *mut u8, _: Layout)

Deallocates the block of memory at the given ptr pointer with the given layout.

unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8

Behaves like alloc, but also ensures that the contents are set to zero before being returned.

unsafe fn realloc( &self, ptr: *mut u8, layout: Layout, new_size: usize, ) -> *mut u8

Shrinks or grows a block of memory to the given new_size in bytes. The block is described by the given ptr pointer and layout.