Module 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.

Structs

AreaInfo

Area descriptor handed to block visitors (mirrors mi_heap_area_t).

Heap

The heap.

PageQueue

A doubly-linked queue of pages serving one bin.

Stats

Always-on counters (plan §7.5 instrument #2): the primary evidence for sub-1% bricks and the work-parity check for every A/B.

Constants

MAX_DIRECT_BIN

Largest bin whose block size still fits the direct[] fast-path table.

MAX_NORMAL_BIN

Largest bin index actually reachable from a size (rest are M3 large pages).

Functions

visit_segment_blocks^⚠

Visit every live page of ONE segment; optionally each allocated block. tag_filter >= 0 skips pages with a different heap tag. owner selects exact snapshots (collect) vs read-only walks (abandoned segments).