Struct SubAllocator 

pub struct SubAllocator { /* private fields */ }

Bump-pointer sub-allocator that partitions a single large backing buffer into smaller regions.

Allocation is O(1); individual free is O(n) over live allocations; defrag compacts the live allocations to the front of the buffer, reclaiming all freed space.

Implementations

impl SubAllocator

pub fn new(backing_size: u64, alignment: u64) -> Self

Create a new SubAllocator backed by a buffer of backing_size bytes, with all offsets aligned to alignment bytes.

alignment is clamped to at least 1.

pub fn alloc(&mut self, size: u64) -> Option<SubAllocation>

Allocate size bytes from the backing buffer.

Returns Some(SubAllocation) if there is room, None if the backing buffer is exhausted.

pub fn free(&mut self, id: u64)

Mark the allocation with the given id as freed.

Freed allocations are not reclaimed until defrag is called.

pub fn defrag(&mut self)

Compact all live allocations to the front of the backing buffer, reclaiming the space left by freed allocations.

After defragmentation the bump pointer is set to just after the last live allocation, making that space available for future alloc calls.

pub fn utilization(&self) -> f64

Fraction of the backing buffer that is currently occupied by live allocations (0.0 = empty, 1.0 = full).

pub fn allocation_count(&self) -> usize

Number of live allocations.

pub fn current_offset(&self) -> u64

Current value of the bump pointer (first unassigned byte offset).

pub fn capacity(&self) -> u64

Total backing buffer size in bytes.

pub fn alignment(&self) -> u64

Alignment used for all allocations.

Trait Implementations

impl Debug for SubAllocator

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.