Move normalization routine out of hrw library

HRW library supports weighted sorting. Weights must be normalized before applying. Since there could be different types of normalization for multiple criteria, there is no point to perform simple normalization in this library. Pass a slice of normalized weights to the `SortByWeight` functions. This commit proposes to: - remove normalization routine from `SortByWeight` function; - add `ValidateWeights` function to check if weights are normalized; - rename `weight` -> `distance` to avoid naming confusion between hash distance and actual weights; - use testify lib in the tests;
2019-07-05 09:46:01 +03:00
10 changed files with 211 additions and 406 deletions
--- a/.gitlint
+++ b/.gitlint
@ -1,10 +0,0 @@
-[general]
-fail-without-commits=true
-contrib=CC1
-
-[title-match-regex]
-regex=^\[\#[0-9]+\]\s
-
-[ignore-by-title]
-regex=^Release(.*)
-ignore=title-match-regex
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@ -1,30 +0,0 @@
-ci:
-  autofix_prs: false
-
-repos:
-  - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v4.4.0
-    hooks:
-    - id: check-added-large-files
-    - id: check-case-conflict
-    - id: check-executables-have-shebangs
-    - id: check-shebang-scripts-are-executable
-    - id: check-merge-conflict
-    - id: check-json
-    - id: check-xml
-    - id: check-yaml
-    - id: trailing-whitespace
-      args: [--markdown-linebreak-ext=md]
-    - id: end-of-file-fixer
-      exclude: ".key$"
-
-  - repo: https://github.com/golangci/golangci-lint
-    rev: v1.51.2
-    hooks:
-    - id: golangci-lint
-
-  - repo: https://github.com/jorisroovers/gitlint
-    rev:  v0.18.0
-    hooks:
-      - id: gitlint
-        stages: [commit-msg]
--- a/.travis.yml
+++ b/.travis.yml
@ -0,0 +1,17 @@
+language: go
+go:
+  - 1.11.x
+  - 1.12.x
+env:
+  - GO111MODULE=on
+install:
+  - go get -v golang.org/x/lint/golint
+  - go mod tidy -v
+script:
+  - golint -set_exit_status ./...
+  - go test -race -coverprofile=coverage.txt -covermode=atomic ./...
+after_success:
+  - bash <(curl -s https://codecov.io/bash)
+matrix:
+  allow_failures:
+    - go: tip
--- a/3
+++ b/3
@ -1,7 +1,6 @@
 MIT License

-Copyright (c) 2023-2024 TrueCloudLab
-Copyright (c) 2019-2023 NSPCC
+Copyright (c) 2019 NSPCC

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
--- a/README.md
+++ b/README.md
@ -1,45 +1,38 @@
 # Golang HRW implementation

+[![Build Status](https://travis-ci.org/nspcc-dev/hrw.svg?branch=master)](https://travis-ci.org/nspcc-dev/hrw)
+[![codecov](https://codecov.io/gh/nspcc-dev/hrw/badge.svg)](https://codecov.io/gh/nspcc-dev/hrw)
+[![Report](https://goreportcard.com/badge/github.com/nspcc-dev/hrw)](https://goreportcard.com/report/github.com/nspcc-dev/hrw)
+[![GitHub release](https://img.shields.io/github/release/nspcc-dev/hrw.svg)](https://github.com/nspcc-dev/hrw)
+
 [Rendezvous or highest random weight](https://en.wikipedia.org/wiki/Rendezvous_hashing) (HRW) hashing is an algorithm that allows clients to achieve distributed agreement on a set of k options out of a possible set of n options. A typical application is when clients need to agree on which sites (or proxies) objects are assigned to. When k is 1, it subsumes the goals of consistent hashing, using an entirely different method.

 ## Install

-`go get git.frostfs.info/TrueCloudLab/hrw`
+`go get github.com/nspcc-dev/hrw`

 ## Benchmark:

 ```
-BenchmarkSort_fnv_10-8                                           4812801               240.9 ns/op           216 B/op          4 allocs/op
-BenchmarkSort_fnv_100-8                                           434767              2600 ns/op            1848 B/op          4 allocs/op
-BenchmarkSort_fnv_1000-8                                           20428             66116 ns/op           16440 B/op          4 allocs/op
-BenchmarkSortByIndex_fnv_10-8                                    2505410               486.5 ns/op           352 B/op          7 allocs/op
-BenchmarkSortByIndex_fnv_100-8                                    254556              4697 ns/op            1984 B/op          7 allocs/op
-BenchmarkSortByIndex_fnv_1000-8                                    13581             88334 ns/op           16576 B/op          7 allocs/op
-BenchmarkSortByValue_fnv_10-8                                    1761030               682.1 ns/op           592 B/op         18 allocs/op
-BenchmarkSortByValue_fnv_100-8                                    258838              4675 ns/op            4480 B/op        108 allocs/op
-BenchmarkSortByValue_fnv_1000-8                                    27027             44649 ns/op           40768 B/op       1008 allocs/op
-BenchmarkSortHashersByValue_Reflection_fnv_10-8                  1013560              1249 ns/op             768 B/op         29 allocs/op
-BenchmarkSortHashersByValue_Reflection_fnv_100-8                  106029             11414 ns/op            6096 B/op        209 allocs/op
-BenchmarkSortHashersByValue_Reflection_fnv_1000-8                  10000            108977 ns/op           56784 B/op       2009 allocs/op
-BenchmarkSortHashersByValue_Typed_fnv_10-8                       1577814               700.3 ns/op           584 B/op         17 allocs/op
-BenchmarkSortHashersByValue_Typed_fnv_100-8                       215938              5024 ns/op            4472 B/op        107 allocs/op
-BenchmarkSortHashersByValue_Typed_fnv_1000-8                       24447             46889 ns/op           40760 B/op       1007 allocs/op
+BenchmarkSort_fnv_10-8                           5000000               365 ns/op             224 B/op          3 allocs/op
+BenchmarkSort_fnv_100-8                           300000              5261 ns/op            1856 B/op          3 allocs/op
+BenchmarkSort_fnv_1000-8                           10000            119462 ns/op           16448 B/op          3 allocs/op
+BenchmarkSortByIndex_fnv_10-8                    3000000               546 ns/op             384 B/op          7 allocs/op
+BenchmarkSortByIndex_fnv_100-8                    200000              5965 ns/op            2928 B/op          7 allocs/op
+BenchmarkSortByIndex_fnv_1000-8                    10000            127732 ns/op           25728 B/op          7 allocs/op
+BenchmarkSortByValue_fnv_10-8                    2000000               962 ns/op             544 B/op         17 allocs/op
+BenchmarkSortByValue_fnv_100-8                    200000              9604 ns/op            4528 B/op        107 allocs/op
+BenchmarkSortByValue_fnv_1000-8                    10000            111741 ns/op           41728 B/op       1007 allocs/op

-BenchmarkSortByWeight_fnv_10-8                                   2924833               370.6 ns/op           448 B/op          8 allocs/op
-BenchmarkSortByWeight_fnv_100-8                                   816069              1516 ns/op            2896 B/op          8 allocs/op
-BenchmarkSortByWeight_fnv_1000-8                                   80391             17478 ns/op           24784 B/op          8 allocs/op
-BenchmarkSortByWeightIndex_fnv_10-8                              1945612               550.3 ns/op           368 B/op          7 allocs/op
-BenchmarkSortByWeightIndex_fnv_100-8                              140473              8084 ns/op            2000 B/op          7 allocs/op
-BenchmarkSortByWeightIndex_fnv_1000-8                               5518            200949 ns/op           16592 B/op          7 allocs/op
-BenchmarkSortByWeightValue_fnv_10-8                              1305580               909.8 ns/op           608 B/op         18 allocs/op
-BenchmarkSortByWeightValue_fnv_100-8                              165410              6796 ns/op            4496 B/op        108 allocs/op
-BenchmarkSortByWeightValue_fnv_1000-8                              17922             78555 ns/op           40784 B/op       1008 allocs/op
-BenchmarkSortHashersByWeightValueReflection_fnv_10-8              454976              2229 ns/op             784 B/op         29 allocs/op
-BenchmarkSortHashersByWeightValueReflection_fnv_100-8              76264             15332 ns/op            6112 B/op        209 allocs/op
-BenchmarkSortHashersByWeightValueReflection_fnv_1000-8             80288             13192 ns/op            6112 B/op        209 allocs/op
-BenchmarkSortHashersByWeightValueTyped_fnv_10-8                  1433113               901.4 ns/op           600 B/op         17 allocs/op
-BenchmarkSortHashersByWeightValueTyped_fnv_100-8                  188626              5896 ns/op            4488 B/op        107 allocs/op
-BenchmarkSortHashersByWeightValueTyped_fnv_1000-8                 178131              6518 ns/op            4488 B/op        107 allocs/op
+BenchmarkSortByWeight_fnv_10-8                   3000000               501 ns/op             320 B/op          4 allocs/op
+BenchmarkSortByWeight_fnv_100-8                   200000              8495 ns/op            2768 B/op          4 allocs/op
+BenchmarkSortByWeight_fnv_1000-8                   10000            197880 ns/op           24656 B/op          4 allocs/op
+BenchmarkSortByWeightIndex_fnv_10-8              2000000               702 ns/op             480 B/op          8 allocs/op
+BenchmarkSortByWeightIndex_fnv_100-8              200000              9338 ns/op            3840 B/op          8 allocs/op
+BenchmarkSortByWeightIndex_fnv_1000-8              10000            204669 ns/op           33936 B/op          8 allocs/op
+BenchmarkSortByWeightValue_fnv_10-8              1000000              1083 ns/op             640 B/op         18 allocs/op
+BenchmarkSortByWeightValue_fnv_100-8              200000             11444 ns/op            5440 B/op        108 allocs/op
+BenchmarkSortByWeightValue_fnv_1000-8              10000            148471 ns/op           49936 B/op       1008 allocs/op
 ```

 ## Example
@ -50,7 +43,7 @@ package main
 import (
 	"fmt"
 	
-	"git.frostfs.info/TrueCloudLab/hrw"
+	"github.com/nspcc-dev/hrw"
 )

 func main() {
--- a/go.mod
+++ b/go.mod
@ -1,13 +1,6 @@
-module git.frostfs.info/TrueCloudLab/hrw
-
-go 1.18
+module github.com/nspcc-dev/hrw

 require (
+	github.com/spaolacci/murmur3 v1.1.0
 	github.com/stretchr/testify v1.3.0
-	github.com/twmb/murmur3 v1.1.8
-)
-
-require (
-	github.com/davecgh/go-spew v1.1.0 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
 )
--- a/go.sum
+++ b/go.sum
@ -2,8 +2,8 @@ github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/spaolacci/murmur3 v1.1.0 h1:7c1g84S4BPRrfL5Xrdp6fOJ206sU9y293DDHaoy0bLI=
+github.com/spaolacci/murmur3 v1.1.0/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2Kzu9HwQUA=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
-github.com/twmb/murmur3 v1.1.8 h1:8Yt9taO/WN3l08xErzjeschgZU2QSrwm1kclYq+0aRg=
-github.com/twmb/murmur3 v1.1.8/go.mod h1:Qq/R7NUyOfr65zD+6Q5IHKsJLwP7exErjN6lyyq3OSQ=
--- a/hrw.go
+++ b/hrw.go
@ -5,27 +5,27 @@ package hrw
 import (
 	"encoding/binary"
 	"errors"
-	"math"
 	"reflect"
 	"sort"

-	"github.com/twmb/murmur3"
+	"github.com/spaolacci/murmur3"
 )

 type (
+	swapper func(i, j int)
+
 	// Hasher interface used by SortSliceByValue
 	Hasher interface{ Hash() uint64 }

-	sorter struct {
-		l    int
-		less func(i, j int) bool
-		swap func(i, j int)
+	hashed struct {
+		length   int
+		sorted   []uint64
+		distance []uint64
 	}

-	hasherSorter[T Hasher, N interface{ ~uint64 | ~float64 }] struct {
-		slice []T
-		dist  []N
-		asc   bool
+	weighted struct {
+		h      hashed
+		normal []float64 // normalized input weights
 	}
 )

@ -35,22 +35,6 @@ const (
 	NormalizedMinWeight = 0.0
 )

-func (s *sorter) Len() int           { return s.l }
-func (s *sorter) Less(i, j int) bool { return s.less(i, j) }
-func (s *sorter) Swap(i, j int)      { s.swap(i, j) }
-
-func (s *hasherSorter[T, N]) Len() int { return len(s.slice) }
-func (s *hasherSorter[T, N]) Less(i, j int) bool {
-	if s.asc {
-		return s.dist[i] < s.dist[j]
-	}
-	return s.dist[i] > s.dist[j]
-}
-func (s *hasherSorter[T, N]) Swap(i, j int) {
-	s.slice[i], s.slice[j] = s.slice[j], s.slice[i]
-	s.dist[i], s.dist[j] = s.dist[j], s.dist[i]
-}
-
 func distance(x uint64, y uint64) uint64 {
 	acc := x ^ y
 	// here used mmh3 64 bit finalizer
@ -63,38 +47,83 @@ func distance(x uint64, y uint64) uint64 {
 	return acc
 }

+func (h hashed) Len() int           { return h.length }
+func (h hashed) Less(i, j int) bool { return h.distance[i] < h.distance[j] }
+func (h hashed) Swap(i, j int) {
+	h.sorted[i], h.sorted[j] = h.sorted[j], h.sorted[i]
+	h.distance[i], h.distance[j] = h.distance[j], h.distance[i]
+}
+
+func (w weighted) Len() int { return w.h.length }
+func (w weighted) Less(i, j int) bool {
+	// `maxUint64 - distance` makes the shorter distance more valuable
+	// it is necessary for operation with normalized values
+	wi := float64(^uint64(0)-w.h.distance[i]) * w.normal[i]
+	wj := float64(^uint64(0)-w.h.distance[j]) * w.normal[j]
+	return wi > wj // higher distance must be placed lower to be first
+}
+func (w weighted) Swap(i, j int) { w.normal[i], w.normal[j] = w.normal[j], w.normal[i]; w.h.Swap(i, j) }
+
 // Hash uses murmur3 hash to return uint64
 func Hash(key []byte) uint64 {
 	return murmur3.Sum64(key)
 }

-// StringHash uses murmur3 hash to return uint64
-func StringHash(key string) uint64 {
-	return murmur3.StringSum64(key)
-}
-
 // Sort receive nodes and hash, and sort it by distance
 func Sort(nodes []uint64, hash uint64) []uint64 {
-	l := len(nodes)
-	sorted := make([]uint64, l)
-	dist := make([]uint64, l)
+	var (
+		l = len(nodes)
+		h = hashed{
+			length:   l,
+			sorted:   make([]uint64, 0, l),
+			distance: make([]uint64, 0, l),
+		}
+	)
+
 	for i := range nodes {
-		sorted[i] = uint64(i)
-		dist[i] = distance(nodes[i], hash)
+		h.sorted = append(h.sorted, uint64(i))
+		h.distance = append(h.distance, distance(nodes[i], hash))
 	}

-	sort.Slice(sorted, func(i, j int) bool {
-		return dist[sorted[i]] < dist[sorted[j]]
-	})
-	return sorted
+	sort.Sort(h)
+	return h.sorted
 }

 // SortByWeight receive nodes, weights and hash, and sort it by distance * weight
 func SortByWeight(nodes []uint64, weights []float64, hash uint64) []uint64 {
-	result := make([]uint64, len(nodes))
-	copy(nodes, result)
-	sortByWeight(len(nodes), false, nodes, weights, hash, reflect.Swapper(result))
-	return result
+	// check if numbers of weights and nodes are equal
+	uniform := true
+	for i := range weights {
+		// check if all nodes have the same distance
+		if weights[i] != weights[0] {
+			uniform = false
+			break
+		}
+	}
+
+	l := len(nodes)
+	w := weighted{
+		h: hashed{
+			length:   l,
+			sorted:   make([]uint64, 0, l),
+			distance: make([]uint64, 0, l),
+		},
+		normal: make([]float64, l),
+	}
+
+	// if all nodes have the same distance then sort uniformly
+	if uniform || len(weights) != l {
+		return Sort(nodes, hash)
+	}
+
+	for i := range nodes {
+		w.h.sorted = append(w.h.sorted, uint64(i))
+		w.h.distance = append(w.h.distance, distance(nodes[i], hash))
+	}
+	copy(w.normal, weights)
+
+	sort.Sort(w)
+	return w.h.sorted
 }

 // SortSliceByValue received []T and hash to sort by value-distance
@ -102,89 +131,76 @@ func SortSliceByValue(slice interface{}, hash uint64) {
 	rule := prepareRule(slice)
 	if rule != nil {
 		swap := reflect.Swapper(slice)
-		sortByDistance(len(rule), false, rule, hash, swap)
+		rule = Sort(rule, hash)
+		sortByRuleInverse(swap, uint64(len(rule)), rule)
 	}
 }

-// SortHasherSliceByValue receives []Hasher and hash to sort by value-distance.
-func SortHasherSliceByValue[T Hasher](slice []T, hash uint64) {
-	if len(slice) == 0 {
-		return
-	}
-
-	dist := make([]uint64, len(slice))
-	for i := range dist {
-		dist[i] = distance(slice[i].Hash(), hash)
-	}
-	sortHasherByDistance(slice, false, dist)
-}
-
 // SortSliceByWeightValue received []T, weights and hash to sort by value-distance * weights
 func SortSliceByWeightValue(slice interface{}, weights []float64, hash uint64) {
 	rule := prepareRule(slice)
 	if rule != nil {
 		swap := reflect.Swapper(slice)
-		sortByWeight(reflect.ValueOf(slice).Len(), false, rule, weights, hash, swap)
+		rule = SortByWeight(rule, weights, hash)
+		sortByRuleInverse(swap, uint64(len(rule)), rule)
 	}
 }

-// SortHasherSliceByWeightValue receives []Hasher, weights and hash to sort by value-distance * weights.
-func SortHasherSliceByWeightValue[T Hasher](slice []T, weights []float64, hash uint64) {
-	if len(slice) == 0 {
-		return
-	}
-
-	if allSameF64(weights) {
-		dist := make([]uint64, len(slice))
-		for i := range dist {
-			dist[i] = distance(slice[i].Hash(), hash)
-		}
-		sortHasherByDistance(slice, false, dist)
-		return
-	}
-
-	dist := make([]float64, len(slice))
-	for i := range dist {
-		d := distance(slice[i].Hash(), hash)
-		// `maxUint64 - distance` makes the shorter distance more valuable
-		// it is necessary for operation with normalized values
-		dist[i] = float64(^uint64(0)-d) * weights[i]
-	}
-
-	sort.Sort(&hasherSorter[T, float64]{
-		slice: slice,
-		dist:  dist,
-		asc:   false,
-	})
-}
-
-// sortHasherByDistance is similar to sortByDistance but accepts slice directly.
-func sortHasherByDistance[T Hasher](slice []T, byIndex bool, dist []uint64) {
-	sort.Sort(&hasherSorter[T, uint64]{
-		slice: slice,
-		dist:  dist,
-		asc:   true,
-	})
-}
-
 // SortSliceByIndex received []T and hash to sort by index-distance
 func SortSliceByIndex(slice interface{}, hash uint64) {
-	length := reflect.ValueOf(slice).Len()
+	length := uint64(reflect.ValueOf(slice).Len())
 	swap := reflect.Swapper(slice)
-	sortByDistance(length, true, nil, hash, swap)
+	rule := make([]uint64, 0, length)
+	for i := uint64(0); i < length; i++ {
+		rule = append(rule, i)
+	}
+	rule = Sort(rule, hash)
+	sortByRuleInverse(swap, length, rule)
 }

 // SortSliceByWeightIndex received []T, weights and hash to sort by index-distance * weights
 func SortSliceByWeightIndex(slice interface{}, weights []float64, hash uint64) {
-	length := reflect.ValueOf(slice).Len()
+	length := uint64(reflect.ValueOf(slice).Len())
 	swap := reflect.Swapper(slice)
-	sortByWeight(length, true, nil, weights, hash, swap)
+	rule := make([]uint64, 0, length)
+	for i := uint64(0); i < length; i++ {
+		rule = append(rule, i)
+	}
+	rule = SortByWeight(rule, weights, hash)
+	sortByRuleInverse(swap, length, rule)
+}
+
+func sortByRuleDirect(swap swapper, length uint64, rule []uint64) {
+	done := make([]bool, length)
+	for i := uint64(0); i < length; i++ {
+		if done[i] {
+			continue
+		}
+		for j := rule[i]; !done[rule[j]]; j = rule[j] {
+			swap(int(i), int(j))
+			done[j] = true
+		}
+	}
+}
+
+func sortByRuleInverse(swap swapper, length uint64, rule []uint64) {
+	done := make([]bool, length)
+	for i := uint64(0); i < length; i++ {
+		if done[i] {
+			continue
+		}
+
+		for j := i; !done[rule[j]]; j = rule[j] {
+			swap(int(j), int(rule[j]))
+			done[j] = true
+		}
+	}
 }

 func prepareRule(slice interface{}) []uint64 {
 	t := reflect.TypeOf(slice)
 	if t.Kind() != reflect.Slice {
-		panic("HRW sort expects slice, got " + t.Kind().String())
+		return nil
 	}

 	var (
@ -263,7 +279,7 @@ func prepareRule(slice interface{}) []uint64 {

 	default:
 		if _, ok := val.Index(0).Interface().(Hasher); !ok {
-			panic("slice elements must implement hrw.Hasher")
+			return nil
 		}

 		for i := 0; i < length; i++ {
@ -277,85 +293,9 @@ func prepareRule(slice interface{}) []uint64 {
 // ValidateWeights checks if weights are normalized between 0.0 and 1.0
 func ValidateWeights(weights []float64) error {
 	for i := range weights {
-		if math.IsNaN(weights[i]) || weights[i] > NormalizedMaxWeight || weights[i] < NormalizedMinWeight {
+		if weights[i] > NormalizedMaxWeight || weights[i] < NormalizedMinWeight {
 			return errors.New("weights are not normalized")
 		}
 	}
 	return nil
 }
-
-// sortByWeight sorts nodes by weight using provided swapper.
-// nodes contains hrw hashes. If it is nil, indices are used.
-func sortByWeight(l int, byIndex bool, nodes []uint64, weights []float64, hash uint64, swap func(i, j int)) {
-	// if all nodes have the same distance then sort uniformly
-	if allSameF64(weights) {
-		sortByDistance(l, byIndex, nodes, hash, swap)
-		return
-	}
-
-	dist := make([]float64, l)
-	for i := 0; i < l; i++ {
-		d := getDistance(byIndex, i, nodes, hash)
-		// `maxUint64 - distance` makes the shorter distance more valuable
-		// it is necessary for operation with normalized values
-		dist[i] = float64(^uint64(0)-d) * weights[i]
-	}
-
-	s := &sorter{
-		l: l,
-		swap: func(i, j int) {
-			swap(i, j)
-			dist[i], dist[j] = dist[j], dist[i]
-		},
-		less: func(i, j int) bool {
-			return dist[i] > dist[j] // higher distance must be placed lower to be first
-		},
-	}
-	sort.Sort(s)
-}
-
-// sortByDistance sorts nodes by hrw distance using provided swapper.
-// nodes contains hrw hashes. If it is nil, indices are used.
-func sortByDistance(l int, byIndex bool, nodes []uint64, hash uint64, swap func(i, j int)) {
-	dist := make([]uint64, l)
-	for i := 0; i < l; i++ {
-		dist[i] = getDistance(byIndex, i, nodes, hash)
-	}
-
-	s := &sorter{
-		l: l,
-		swap: func(i, j int) {
-			swap(i, j)
-			dist[i], dist[j] = dist[j], dist[i]
-		},
-		less: func(i, j int) bool {
-			return dist[i] < dist[j]
-		},
-	}
-	sort.Sort(s)
-}
-
-// getDistance return distance from nodes[i] to h.
-// If byIndex is true, nodes index is used.
-// Else if nodes[i] != nil, distance is calculated from this value.
-// Otherwise, and hash from node index is taken.
-func getDistance(byIndex bool, i int, nodes []uint64, h uint64) uint64 {
-	if nodes != nil {
-		return distance(nodes[i], h)
-	} else if byIndex {
-		return distance(uint64(i), h)
-	} else {
-		buf := make([]byte, 8)
-		binary.LittleEndian.PutUint64(buf, uint64(i))
-		return distance(Hash(buf), h)
-	}
-}
-
-func allSameF64(fs []float64) bool {
-	for i := range fs {
-		if fs[i] != fs[0] {
-			return false
-		}
-	}
-	return true
-}
--- a/hrw_test.go
+++ b/hrw_test.go
@ -61,7 +61,7 @@ func Example() {
 }

 func (h hashString) Hash() uint64 {
-	return StringHash(string(h))
+	return Hash([]byte(h))
 }

 func TestSortSliceByIndex(t *testing.T) {
@ -76,9 +76,6 @@ func TestValidateWeights(t *testing.T) {
 	weights := []float64{10, 10, 10, 2, 2, 2}
 	err := ValidateWeights(weights)
 	require.Error(t, err)
-	weights = []float64{math.NaN(), 1, 1, 0.2, 0.2, 0.2}
-	err = ValidateWeights(weights)
-	require.Error(t, err)
 	weights = []float64{1, 1, 1, 0.2, 0.2, 0.2}
 	err = ValidateWeights(weights)
 	require.NoError(t, err)
@ -101,6 +98,36 @@ func TestSortSliceByValue(t *testing.T) {
 	require.Equal(t, expect, actual)
 }

+func TestSortByRule(t *testing.T) {
+	t.Run("direct", func(t *testing.T) {
+		//                  0    1    2    3    4    5
+		actual := []string{"a", "b", "c", "d", "e", "f"}
+		//                  4    2    0    5    3    1
+		expect := []string{"c", "f", "b", "e", "a", "d"}
+		rule := []uint64{4, 2, 0, 5, 3, 1}
+
+		sortByRuleDirect(
+			func(i, j int) { actual[i], actual[j] = actual[j], actual[i] },
+			6, rule)
+
+		require.Equal(t, expect, actual)
+	})
+
+	t.Run("inverse", func(t *testing.T) {
+		//                  0    1    2    3    4    5
+		actual := []string{"a", "b", "c", "d", "e", "f"}
+		//                  4    2    0    5    3    1
+		expect := []string{"e", "c", "a", "f", "d", "b"}
+		rule := []uint64{4, 2, 0, 5, 3, 1}
+
+		sortByRuleInverse(
+			func(i, j int) { actual[i], actual[j] = actual[j], actual[i] },
+			6, rule)
+
+		require.Equal(t, expect, actual)
+	})
+}
+
 func TestSortSliceByValueFail(t *testing.T) {
 	t.Run("empty slice", func(t *testing.T) {
 		var (
@ -113,13 +140,15 @@ func TestSortSliceByValueFail(t *testing.T) {
 	t.Run("must be slice", func(t *testing.T) {
 		actual := 10
 		hash := Hash(testKey)
-		require.Panics(t, func() { SortSliceByValue(actual, hash) })
+		require.NotPanics(t, func() { SortSliceByValue(actual, hash) })
 	})

 	t.Run("must 'fail' for unknown type", func(t *testing.T) {
 		actual := []unknown{1, 2, 3, 4, 5}
+		expect := []unknown{1, 2, 3, 4, 5}
 		hash := Hash(testKey)
-		require.Panics(t, func() { SortSliceByValue(actual, hash) })
+		SortSliceByValue(actual, hash)
+		require.Equal(t, expect, actual)
 	})
 }

@ -131,23 +160,6 @@ func TestSortSliceByValueHasher(t *testing.T) {
 	require.Equal(t, expect, actual)
 }

-func TestSortHasherSliceByValue(t *testing.T) {
-	actual := []hashString{"a", "b", "c", "d", "e", "f"}
-	expect := []hashString{"d", "f", "c", "b", "a", "e"}
-	hash := Hash(testKey)
-	SortHasherSliceByValue(actual, hash)
-	require.EqualValues(t, expect, actual)
-}
-
-func TestSortHasherSliceByWeightValue(t *testing.T) {
-	actual := []hashString{"a", "b", "c", "d", "e", "f"}
-	weights := []float64{1.0, 1.0, 1.0, 1.0, 1.0, 1.0}
-	expect := []hashString{"d", "f", "c", "b", "a", "e"}
-	hash := Hash(testKey)
-	SortHasherSliceByWeightValue(actual, weights, hash)
-	require.EqualValues(t, expect, actual)
-}
-
 func TestSortSliceByValueIntSlice(t *testing.T) {
 	cases := []slices{
 		{
@ -190,6 +202,11 @@ func TestSortSliceByValueIntSlice(t *testing.T) {
 			expect: []uint32{5, 1, 2, 0, 3, 4},
 		},

+		{
+			actual: Uint32Slice{0, 1, 2, 3, 4, 5},
+			expect: Uint32Slice{0, 1, 2, 3, 4, 5},
+		},
+
 		{
 			actual: []int64{0, 1, 2, 3, 4, 5},
 			expect: []int64{5, 3, 0, 1, 4, 2},
@ -653,36 +670,6 @@ func BenchmarkSortByValue_fnv_1000(b *testing.B) {
 	benchmarkSortByValue(b, 1000, hash)
 }

-func BenchmarkSortHashersByValue_Reflection_fnv_10(b *testing.B) {
-	hash := Hash(testKey)
-	benchmarkSortHashersByValueReflection(b, 10, hash)
-}
-
-func BenchmarkSortHashersByValue_Reflection_fnv_100(b *testing.B) {
-	hash := Hash(testKey)
-	benchmarkSortHashersByValueReflection(b, 100, hash)
-}
-
-func BenchmarkSortHashersByValue_Reflection_fnv_1000(b *testing.B) {
-	hash := Hash(testKey)
-	benchmarkSortHashersByValueReflection(b, 1000, hash)
-}
-
-func BenchmarkSortHashersByValue_Typed_fnv_10(b *testing.B) {
-	hash := Hash(testKey)
-	benchmarkSortHashersByValueTyped(b, 10, hash)
-}
-
-func BenchmarkSortHashersByValue_Typed_fnv_100(b *testing.B) {
-	hash := Hash(testKey)
-	benchmarkSortHashersByValueTyped(b, 100, hash)
-}
-
-func BenchmarkSortHashersByValue_Typed_fnv_1000(b *testing.B) {
-	hash := Hash(testKey)
-	benchmarkSortHashersByValueTyped(b, 1000, hash)
-}
-
 func BenchmarkSortByWeight_fnv_10(b *testing.B) {
 	hash := Hash(testKey)
 	_ = benchmarkSortByWeight(b, 10, hash)
@ -728,30 +715,6 @@ func BenchmarkSortByWeightValue_fnv_1000(b *testing.B) {
 	benchmarkSortByWeightValue(b, 1000, hash)
 }

-func BenchmarkSortHashersByWeightValueReflection_fnv_10(b *testing.B) {
-	benchmarkSortHashersByWeightValueRelection(b, 10, Hash(testKey))
-}
-
-func BenchmarkSortHashersByWeightValueReflection_fnv_100(b *testing.B) {
-	benchmarkSortHashersByWeightValueRelection(b, 100, Hash(testKey))
-}
-
-func BenchmarkSortHashersByWeightValueReflection_fnv_1000(b *testing.B) {
-	benchmarkSortHashersByWeightValueRelection(b, 1000, Hash(testKey))
-}
-
-func BenchmarkSortHashersByWeightValueTyped_fnv_10(b *testing.B) {
-	benchmarkSortHashersByWeightValueTyped(b, 10, Hash(testKey))
-}
-
-func BenchmarkSortHashersByWeightValueTyped_fnv_100(b *testing.B) {
-	benchmarkSortHashersByWeightValueTyped(b, 100, Hash(testKey))
-}
-
-func BenchmarkSortHashersByWeightValueTyped_fnv_1000(b *testing.B) {
-	benchmarkSortHashersByWeightValueTyped(b, 1000, Hash(testKey))
-}
-
 func benchmarkSort(b *testing.B, n int, hash uint64) uint64 {
 	servers := make([]uint64, n)
 	for i := uint64(0); i < uint64(len(servers)); i++ {
@ -845,63 +808,3 @@ func benchmarkSortByWeightValue(b *testing.B, n int, hash uint64) {
 		SortSliceByWeightValue(servers, weights, hash)
 	}
 }
-
-func benchmarkSortHashersByWeightValueRelection(b *testing.B, n int, hash uint64) {
-	servers := make([]hashString, n)
-	weights := make([]float64, n)
-	for i := uint64(0); i < uint64(len(servers)); i++ {
-		weights[i] = float64(uint64(n)-i) / float64(n)
-		servers[i] = hashString("localhost:" + strconv.FormatUint(60000-i, 10))
-	}
-
-	b.ResetTimer()
-	b.ReportAllocs()
-
-	for i := 0; i < b.N; i++ {
-		SortSliceByWeightValue(servers, weights, hash)
-	}
-}
-
-func benchmarkSortHashersByWeightValueTyped(b *testing.B, n int, hash uint64) {
-	servers := make([]hashString, n)
-	weights := make([]float64, n)
-	for i := uint64(0); i < uint64(len(servers)); i++ {
-		weights[i] = float64(uint64(n)-i) / float64(n)
-		servers[i] = hashString("localhost:" + strconv.FormatUint(60000-i, 10))
-	}
-
-	b.ResetTimer()
-	b.ReportAllocs()
-
-	for i := 0; i < b.N; i++ {
-		SortHasherSliceByWeightValue(servers, weights, hash)
-	}
-}
-
-func benchmarkSortHashersByValueReflection(b *testing.B, n int, hash uint64) {
-	servers := make([]hashString, n)
-	for i := uint64(0); i < uint64(len(servers)); i++ {
-		servers[i] = hashString("localhost:" + strconv.FormatUint(60000-i, 10))
-	}
-
-	b.ResetTimer()
-	b.ReportAllocs()
-
-	for i := 0; i < b.N; i++ {
-		SortSliceByValue(servers, hash)
-	}
-}
-
-func benchmarkSortHashersByValueTyped(b *testing.B, n int, hash uint64) {
-	servers := make([]hashString, n)
-	for i := uint64(0); i < uint64(len(servers)); i++ {
-		servers[i] = hashString("localhost:" + strconv.FormatUint(60000-i, 10))
-	}
-
-	b.ResetTimer()
-	b.ReportAllocs()
-
-	for i := 0; i < b.N; i++ {
-		SortHasherSliceByValue(servers, hash)
-	}
-}