Module collections 

Hash maps and sets for the whole kernel.

FastMap and FastSet are hashbrown tables hashed by foldhash with a fixed seed. The seed is what matters: a map’s iteration order is then a function of its insertions alone, the same in every run and every process, so a stage that walks a map cannot answer differently from one run to the next. The std tables seed themselves randomly and are refused by clippy (disallowed-types in clippy.toml) outside the few public signatures that already promised them.

A fixed seed gives up the defence against keys chosen to collide. The kernel hashes its own ids and coordinates, not adversarial strings.

The tables have no new or with_capacity: build them with FastMap::default(), collect(), or FastMap::with_capacity_and_hasher(n, FastHasher::default()).

Modules

hash_map

A hash map implemented with quadratic probing and SIMD lookup.

hash_set

A hash set implemented as a HashMap where the value is ().

Type Aliases

FastHasher

The hasher every FastMap and FastSet builds: foldhash, seeded the same way in every process.

FastMap

A hash map whose iteration order depends only on its contents and the order they were inserted in.

FastSet

A hash set whose iteration order depends only on its contents and the order they were inserted in.