Read the documentation.

tinyset

tinyset contains a few collections that are optimized to scale in size well for small numbers of elements, while still scaling well in time (and size) for numbers of elements. We now have just a few types that you might care for.

1. [Set64] is a set for types that are 64 bits in size or less and are Copy, intended for essentially integer types. This is our most efficient type, since it can store small sets with just the size of one pointer, with no heap storage.

2. [SetU64] just holds u64 items, and is the internal storage of [Set64].

3. [SetU32] just holds u32 items, and uses a bit less memory than [SetU64].

4. [SetUsize] holds usize items, and uses either [SetU64] or [SetU32] internally.

All of these set types will do no heap allocation for small sets of small elements. TinySet will store up to 16 bytes of elements before doing any heap allocation, while Set stores sets up to size 8 without allocation. Set64 will store up to 22 bytes of elements, and if all your elements are small (e.g. 0..22 as u64 it will store them in as few bytes as possible.

These sets all differ from the standard sets in that they iterate over items rather than references to items, because they do not store values directly in a way that can be referenced. All of the type-specific sets further differ in that remove and contains accept values rather than references.

Benchmarks

To run the benchmark suite, run

cargo bench

This will give you loads of timings and storage requirements for a wide variety of set types.