Crate kioku

Kioku is a memory arena allocator for Rust.

The arena works by internally allocating memory in large-ish blocks of memory one-at-a-time, and doling out memory from the current block in linear order until its space runs out.

Additionally, it attempts to minimize wasted space through some heuristics based on a configurable maximum waste percentage.

Some contrived example usage:

let arena = Arena::new().with_block_size(1024);

let integer = arena.alloc(42);
let array1 = arena.copy_slice(&[1, 2, 3, 4, 5, 42]);
assert_eq!(*integer, array1[5]);

*integer = 16;
array1[1] = 16;
assert_eq!(*integer, array1[1]);

let character = arena.alloc('A');
let array2 = arena.alloc_array('A', 42);
assert_eq!(array2.len(), 42);
assert_eq!(*character, array2[20]);

*character = '学';
array2[30] = '学';
assert_eq!(*character, array2[30]);

Large Allocations

Allocations larger than the block size are handled by just allocating them separately. Those large allocations are also owned by the arena, just like all other arena allocations, and will be freed when it gets dropped.

Custom Alignment

All methods with a custom alignment parameter require the alignment to be greater than zero and a power of two. Moreover, the alignment parameter can only increase the strictness of the alignment, and will be ignored if less strict than the natural alignment of the type being allocated.

Array allocation methods with alignment parameters only align the head of the array to that alignment, and otherwise follow standard array memory layout.

Zero Sized Types

Zero-sized types such as () are unsupported. All allocations will panic if T is zero-sized.

However, you can allocate zero length arrays using the array allocation methods. Only T itself must be non-zero-sized.

Structs

Arena

A memory arena allocator.

Enums

GrowthStrategy

Strategy for determining the size of new blocks.