No hash function is perfect, but some are useful.
wyhash and wyrand are the ideal 64-bit hash function and PRNG respectively:
solid: wyhash passed SMHasher, wyrand passed BigCrush, practrand.
portable: 64-bit/32-bit system, big/little endian.
fastest: Efficient on 64-bit machines, especially for short keys.
simplest: In the sense of code size.
wyhash is the default hasher for a hash table of the great Zig, V and Nim language.
Simple Example:
#include "wyhash.h"
string s="fcdskhfjs";
uint64_t h=wyhash(s.c_str(),s.size(),0,_wyp);
g++-9 benchmark.cpp t1ha/src/t1ha2.c -o benchmark -Ofast -s -Wall -march=native
/usr/share/dict/words
| hash function | short hash/us | bulk_256B GB/s | bulk_64KB GB/s |
|---|---|---|---|
| wyhash_final3 | 419.63 | 20.97 | 25.10 |
| wyhash_final2 | 204.08 | 21.12 | 25.10 |
| wyhash_final1 | 196.33 | 15.56 | 17.92 |
| wyhash_gamma (dangerous) | 399.92 | 19.16 | 25.80 |
| wyhash_beta | 180.51 | 18.20 | 17.37 |
| wyhash_alpha | 204.50 | 20.54 | 25.92 |
| wyhash_v6 (avx2) | 164.08 | 12.08 | 41.35 |
| wyhash_v5 | 221.59 | 15.40 | 16.78 |
| wyhash_v4 | 153.03 | 13.89 | 16.81 |
| wyhash_v3 | 191.32 | 13.55 | 15.72 |
| wyhash_v2 | 94.28 | 11.91 | 11.22 |
| wyhash_v1 | 91.66 | 16.03 | 18.95 |
| wyhash32 (32 bit) | 149.78 | 5.45 | 4.89 |
| xxh3_scalar | 152.47 | 8.39 | 13.05 |
| xxh3_avx2 | 144.62 | 9.85 | 44.82 |
C# https://github.com/cocowalla/wyhash-dotnet
C++ https://github.com/tommyettinger/waterhash
GO https://github.com/dgryski/go-wyhash
GO https://github.com/orisano/wyhash
GO https://github.com/littleli/go-wyhash16
GO https://github.com/zeebo/wyhash
GO https://github.com/lonewolf3739/wyhash-go
GO https://github.com/zhangyunhao116/wyhash (final version 1)
Java https://github.com/OpenHFT/Zero-Allocation-Hashing
Nim https://github.com/nim-lang/Nim/blob/devel/lib/pure/hashes.nim
Nim https://github.com/jackhftang/wyhash.nim
Nim https://github.com/littleli/nim-wyhash16
Rust https://github.com/eldruin/wyhash-rs
Swift https://github.com/lemire/SwiftWyhash
Swift https://github.com/lemire/SwiftWyhashBenchmark
Swift https://github.com/jeudesprits/PSWyhash
V https://github.com/vlang/v/tree/master/vlib/hash/wyhash (v4)
Zig https://github.com/ManDeJan/zig-wyhash
absl hashmap https://github.com/abseil/abseil-cpp/blob/master/absl/hash/internal/wyhash.cc
I thank these names:
Reini Urban
Dietrich Epp
Joshua Haberman
Tommy Ettinger
Daniel Lemire
Otmar Ertl
cocowalla
leo-yuriev
Diego Barrios Romero
paulie-g
dumblob
Yann Collet
ivte-ms
hyb
James Z.M. Gao
easyaspi314 (Devin)
TheOneric