Crate rusty_alloc 

rusty_alloc core — a pure-Rust remake of mimalloc v2.4.5.

Plan of record: docs/plans/rusty_alloc_v1.md. Module map mirrors upstream C files 1:1 (plan §6) so every diff-vs-oracle conversation has a shared map.

Milestone status: M4 — per-thread heaps, lock-free cross-thread frees (the loom-modeled xthread/delayed protocol), thread-exit abandonment and segment reclaim. No global lock anywhere on the alloc/free paths.

std note: M4’s TLS fast path uses thread_local! (const-init, !Drop — the R1 spike measured it at atomic-load parity). A no_std profile returns post-v1 with the nightly #[thread_local] or a platform TLS shim.

Re-exports

pub use bins::good_size;

Modules

alloc

Public allocation entry points (mirrors alloc.c/free.c routing).

arena

Arenas v1 (M6 subset of upstream arena.c): pre-reserved OS regions carved into SEGMENT-sized chunks that segment alloc/free recycles instead of round-tripping the OS. Upstream arenas allocate at slice granularity; ours are segment-granular (32 MiB chunks) — sufficient for the §5.9 API and the disallow_os_alloc / programmatic-memory use cases; slice-granular arenas are a post-v1 refinement.

bins

Size-class (bin) geometry, mirroring upstream page-queue.c mi_bin.

heap

The heap: per-bin page queues, the small-size direct table, the generic (heartbeat) allocation path, and free (mirrors heap.c + the hot parts of alloc.c/page.c). Since M4 there is NO global lock: every thread owns its own heap, free routes by the segment’s owner id, and cross-thread frees go through the loom-modeled 4-state protocol in page.rs.

init

Thread + heap lifecycle (mirrors upstream init.c + the abandonment side of arena-abandon.c).

options

Options table, environment parsing, and the registered hooks (mirrors options.c). Option INDICES are ABI: the enum matches the oracle v2.4.5 ordering exactly, deprecated slots included.

os

OS memory layer over crate::prim (mirrors upstream src/os.c).

page

Pages and their three sharded free lists (mirrors upstream page.c data side). A page is a slice-span inside a segment holding blocks of ONE size.

prim

OS primitive layer (mirrors upstream src/prim/*, plan §6). One backend per platform, selected at compile time; under miri a registry-backed [mock] stands in so the layers above stay testable where FFI cannot run (gate G4).

random

ChaCha8 CSPRNG (mirrors random.c): per-heap streams for free-list encoding keys, guarded-object sampling, and page-start randomization.

segment

Segments: 32 MiB-aligned reservations sliced into 64 KiB slices (M3 subset of upstream segment.c). The alignment IS the addressing scheme — ptr → segment is a mask, ptr → page two shifts and a table walk.

segment_map

Global segment map (mirrors upstream segment-map.c): one bit per 32 MiB address window, answering “does this pointer lie in memory we own?” — mi_is_in_heap_region, and the debug_checks foreign-free guard.

stats

Stats reporting (mirrors stats.c): per-heap counters live in crate::heap::Stats; this module aggregates them across the global heap registry, formats reports through the output hook, and queries process metrics (mi_process_info).

types

Core size constants, mirroring mimalloc v2.4.5 include/mimalloc/types.h.

Constants

MI_COMPAT_VERSION

The mimalloc version we are API- and ABI-compatible with, in mimalloc’s encoding (major·10⁴ + minor·10² + patch): v2.4.5. mi_version() reports this.

VERSION

Our own semantic version, from the crate manifest.

Functions

ptr_with_addr

Rebuild a pointer at addr keeping p’s provenance. Used wherever an address round-trips through an integer (atomic words, encoded links) — the thrice-learned law: provenance and reachability follow POINTERS.

version

mimalloc-encoded compat version, as reported by the C ABI mi_version().