How it compares to rustc's hash function

[yyy33]

The rust compiler has an fxhash, which seems to be unencrypted as well, how does the speed of xxhash compare to its

[DoumanAsh]

Generally Rust's hash interface is not very good for performance of xxhash due to it re-creating state every time. But on large input (i.e. 1kb) it would generally out perform fxhash.

If you're only concerned with usage within hash map I believe default hasher would suit you more than enough as most of the time your input will be fairly small keys.

But if you need high performance outside hash map I recommend to not use default hasher for sure. Especially if you need handle fairly large inputs (e.g. file, other binary blobs)

Other notes to consider:

• Most efficient way to hash is using oneshot functions: xxh3_128 and xxh3_64
• If you need streaming variant then prefer to reset rather than creating new hasher every time

Do note that if you need uniquness prefer hashes that has at least 128 bytes output like xxh3

[DoumanAsh]

btw I believe default hasher is SipHasher13 for HashMap