Struct Slab 

pub struct Slab<'a, T: Pod + FixedLayout> { /* private fields */ }

A fixed-size slab allocator over a byte slice.

Tracks slot occupancy with an inline bitmap. Double-free, reads of freed slots, and writes to freed slots are all rejected.

Implementations

impl<'a, T: Pod + FixedLayout> Slab<'a, T>

pub fn from_bytes_mut(data: &'a mut [u8]) -> Result<Self, ProgramError>

Parse a slab from a mutable byte slice.

pub fn init(data: &mut [u8], capacity: usize) -> Result<(), ProgramError>

Initialize a slab with the given capacity.

Must be called on a zeroed buffer. Sets up the free list and clears the occupancy bitmap.

pub fn count(&self) -> u32

Number of allocated slots.

pub fn capacity(&self) -> usize

Total slot capacity.

pub fn is_full(&self) -> bool

Whether the slab is full.

pub fn is_slot_allocated(&self, index: u32) -> bool

Whether a slot index is currently allocated.

pub fn alloc(&mut self, value: T) -> Result<u32, ProgramError>

Allocate a slot and write the value. Returns the slot index.

pub fn free(&mut self, index: u32) -> Result<(), ProgramError>

Free a slot and return it to the free list.

Fails if the slot is not currently allocated (prevents double-free).

pub fn get(&self, index: u32) -> Result<T, ProgramError>

Read a value from a slot (copy).

Fails if the slot is not allocated.

pub fn get_ref(&self, index: u32) -> Result<&T, ProgramError>

Get a reference to a value in a slot.

Fails if the slot is not allocated.

pub fn get_mut(&mut self, index: u32) -> Result<&mut T, ProgramError>

Get a mutable reference to a value in a slot.

Fails if the slot is not allocated.

pub fn set(&mut self, index: u32, value: T) -> Result<(), ProgramError>

Write a value into an allocated slot.

Fails if the slot is not allocated.

pub const fn required_bytes(capacity: usize) -> usize

Bytes required for a slab of given capacity.