M.V. Hutz
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## Description Currently, the name of `bucket` is a bit confusing, because it is considered a 'table' in literature (as well as the whole hash table). A `bucket` is better described as a 'subtable', which is used by the total hash table to perform cuckoo hashing. In addition, the constructors `NewTable`, `NewTableBy`, and `NewCustomTable` were given shorter names, because the package name `cuckoo` already implies that `New*` would create a hash table with cuckoo hashing. This package has one use-case, and so it unambiguous what constructors produce. ## Changes - `NewTable` -> `New` - `NewTableBy` -> `NewBy` - `NewCustomTable` -> `NewCustom` - `bucket` -> `subtable` ### Design Decisions - I would have renamed `Table` and `subtable` to map equivalents, but 'submap' implies that a certain subsection of the map is contained within it, which isn't quite right. - I chose not to go with `Map` and `table`, because of the split naming convention. ## Checklist - [x] Tests pass - [x] Docs updated Reviewed-on: #22 Co-authored-by: M.V. Hutz <git@maximhutz.me> Co-committed-by: M.V. Hutz <git@maximhutz.me>
93 lines
2.0 KiB
Go
93 lines
2.0 KiB
Go
package cuckoo_test
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import (
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"fmt"
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"maps"
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"os"
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"testing"
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"github.com/stretchr/testify/assert"
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go_fuzz_utils "github.com/trailofbits/go-fuzz-utils"
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"git.maximhutz.com/tools/go-cuckoo"
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)
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func offsetHash(seed uint32) cuckoo.Hash[uint32] {
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return func(x uint32) uint64 {
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v := uint64(x) ^ uint64(seed)
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v = (v ^ (v >> 30)) * 0xbf58476d1ce4e5b9
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v = (v ^ (v >> 27)) * 0x94d049bb133111eb
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return v ^ (v >> 31)
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}
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}
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type fuzzStep struct {
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drop bool
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key, value uint32
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}
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type fuzzScenario struct {
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seedA, seedB uint32
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capacity, growthFactor uint8
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steps []fuzzStep
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}
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func FuzzInsertLookup(f *testing.F) {
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f.Fuzz(func(t *testing.T, data []byte) {
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var scenario fuzzScenario
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assert := assert.New(t)
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if tp, err := go_fuzz_utils.NewTypeProvider(data); err != nil {
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return
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} else if err := tp.Fill(&scenario); err != nil {
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return
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}
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seedA, seedB := scenario.seedA, scenario.seedB
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growthFactor := max(2, int(scenario.growthFactor))
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capacity := int(scenario.capacity)
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// If they are the same number, the hashes will clash, always causing an
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// error.
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if seedA == seedB {
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t.Skip()
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}
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fmt.Fprintf(os.Stderr, "seedA=%d seedB=%d capacity=%d growthFactor=%d\n",
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seedA, seedB, capacity, growthFactor)
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actual := cuckoo.NewCustom[uint32, uint32](
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offsetHash(seedA),
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offsetHash(seedB),
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func(a, b uint32) bool { return a == b },
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cuckoo.Capacity(capacity),
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cuckoo.GrowthFactor(growthFactor),
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)
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expected := map[uint32]uint32{}
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for _, step := range scenario.steps {
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if step.drop {
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err := actual.Drop(step.key)
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assert.NoError(err)
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delete(expected, step.key)
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_, ok := actual.Get(step.key)
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assert.False(ok)
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} else {
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err := actual.Put(step.key, step.value)
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assert.NoError(err)
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expected[step.key] = step.value
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found, ok := actual.Get(step.key)
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assert.True(ok)
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assert.Equal(step.value, found)
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}
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assert.Equal(expected, maps.Collect(actual.Entries()))
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}
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})
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}
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