Crate sefer_alloc 

sefer-alloc

A safe, handle-addressed region store. Instead of handing out raw pointers, a Region<T> hands out small generational Handle<T> values; the bytes live in a dense, cache-friendly backing store that the region is free to move. A stale handle never resolves to a live value — it returns None, never undefined behaviour.

The engine

The single-threaded core is a thin typed membrane over slotmap: Region<T> wraps a slotmap::SlotMap<DefaultKey, T> and Handle<T> is a newtype over a DefaultKey plus PhantomData<fn() -> T>, so handles stay generic-over-T and typed (which raw slotmap keys are not). slotmap’s audited unsafe owns the dense generational layout — the free list, generation bump on remove, and version-saturation retirement; this crate adds the typed boundary and stays #![forbid(unsafe_code)].

Region, Handle, and SyncRegion now live in the sefer-region crate alongside aligned-vmem / numa-shim / malloc-bench-rs. They are re-exported here for backward compatibility.

Scope (honest)

This is an application-level store, not a drop-in global allocator. For a process-wide allocator, use SeferMalloc (opt-in production feature) or reach for mimalloc.

See docs/INVARIANTS.md for the safety invariants this crate upholds and docs/DESIGN.md for the architecture.

Example

use sefer_alloc::Region;

let mut region = Region::new();
let a = region.insert("alpha");
let b = region.insert("beta");

assert_eq!(region.get(a), Some(&"alpha"));

region.remove(a);
assert_eq!(region.get(a), None); // stale handle → None, never UB
assert_eq!(region.get(b), Some(&"beta")); // others stay valid

Structs

Handle

An opaque, copyable reference to a value stored in a Region.

Region

A handle-addressed store of T.

SyncRegion

A thread-safe wrapper around Region<T> — the trusted concurrent baseline.