Crate os_slab_vault 

os_slab_vault

A dependency-free, no_std-first generational slab / object pool.

What problem does it solve?

OS kernels frequently need to store “kernel objects” (tasks, threads, IPC endpoints, driver instances, capabilities, timers, file descriptors…) in a way that is:

• Deterministic: fixed upper bounds, predictable performance.
• Allocation-free: often the kernel cannot (or does not want to) rely on a heap.
• Safe: users of the structure should not accidentally dereference freed objects.

os_slab_vault provides a fixed-capacity Slab<T, N> with generation-checked handles (Key). Handles become stale when the referenced slot is freed and later reused, preventing a classic “use-after-free via index reuse” bug.

Design overview

The slab stores up to N values of type T. Each slot has:

• An occupied bit
• A generation counter
• Storage for T (using MaybeUninit<T> to avoid requiring T: Default)

A free-list is maintained for O(1) insertion into the next vacant slot.

Feature flags

• std: enables std for host-side tests/examples. The library remains no_std at its core.

Safety

This crate uses a small amount of unsafe internally to manage MaybeUninit<T> safely. Every unsafe block is documented with the invariants that make it correct. The public API is safe.

For a deeper dive, see the project docs in docs/, especially docs/SAFETY.md.

Structs

InsertError

Returned by Slab::insert when the slab is full.

Key

A stable handle to an element stored inside a Slab.

Slab

A fixed-capacity generational slab storing up to N values of type T.