#hash-map #lru-cache #no-std #data-structures #key-value #back #fork

no-std veilid-hashlink

Temporary fork of hashlink. HashMap-like containers that hold their key-value pairs in a user controllable order

1 unstable release

0.1.0 Sep 3, 2023

#165 in Caching

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Used in 7 crates (via veilid-core)



hashlink -- HashMap-like containers that hold their key-value pairs in a user controllable order

Build Status Latest Version API Documentation

This crate is a fork of linked-hash-map that builds on top of hashbrown to implement more up to date versions of LinkedHashMap LinkedHashSet, and LruCache.

One important API change is that when a LinkedHashMap is used as a LRU cache, it allows you to easily retrieve an entry and move it to the back OR produce a new entry at the back without needlessly repeating key hashing and lookups:

let mut lru_cache = LinkedHashMap::new();
let key = "key".to_owned();
// Try to find my expensive to construct and hash key
let _cached_val = match lru_cache.raw_entry_mut().from_key(&key) {
    RawEntryMut::Occupied(mut occupied) => {
        // Cache hit, move entry to the back.
    RawEntryMut::Vacant(vacant) => {
        // Insert expensive to construct key and expensive to compute value,
        // automatically inserted at the back.
        vacant.insert(key.clone(), 42).1

Or, a simpler way to do the same thing:

let mut lru_cache = LinkedHashMap::new();
let key = "key".to_owned();
let _cached_val = lru_cache
    .or_insert_with(|| (key.clone(), 42));

This crate contains a decent amount of unsafe code from handling its internal linked list, and the unsafe code has diverged quite a lot from the original linked-hash-map implementation. It currently passes tests under miri and sanitizers, but it should probably still receive more review and testing, and check for test code coverage.


There is a huge amount of code in this crate that is copied verbatim from linked-hash-map and hashbrown, especially tests, associated types like iterators, and things like Debug impls.


This library is licensed the same as linked-hash-map and hashbrown, it is licensed under either of:

at your option.


~26K SLoC