ydb/contrib/libs/wyhash/README.md

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.

salted: We use dynamic secret to avoid intended attack.

wyhash is the default hashing algorithm of the great Zig, V, Nim and Go (since 1.17) language. One milestone is that wyhash has deployed by Microsoft on Windows Terminal.

Simple Example:

#include  "wyhash.h"
uint64_t _wyp[4];
make_secret(time(NULL),_wyp);
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

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C# https://github.com/cocowalla/wyhash-dotnet

C++ https://github.com/tommyettinger/waterhash

C++ https://github.com/alainesp/wy

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 && 3)

Java https://github.com/OpenHFT/Zero-Allocation-Hashing

Java https://github.com/dynatrace-oss/hash4j (final version 3)

Kotlin Multiplatform https://github.com/appmattus/crypto/tree/main/cryptohash

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