mirror of
https://github.com/nabbar/golib.git
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100 lines
2.2 KiB
Go
100 lines
2.2 KiB
Go
/*
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* MIT License
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*
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* Copyright (c) 2022 Nicolas JUHEL
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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*
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*/
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package prometheus
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import (
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"sync"
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"github.com/bits-and-blooms/bitset"
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)
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const defaultSize = 2 << 24
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var seeds = []uint{7, 11, 13, 31, 37, 61}
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type bloomFilter struct {
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m sync.Mutex
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Set *bitset.BitSet
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Funcs [6]simpleHash
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}
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type BloomFilter interface {
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Add(value string)
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Contains(value string) bool
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}
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func NewBloomFilter() BloomFilter {
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bf := new(bloomFilter)
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for i := 0; i < len(bf.Funcs); i++ {
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bf.Funcs[i] = simpleHash{defaultSize, seeds[i]}
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}
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bf.Set = bitset.New(defaultSize)
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return bf
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}
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func (bf *bloomFilter) Add(value string) {
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bf.m.Lock()
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defer bf.m.Unlock()
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for _, f := range bf.Funcs {
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bf.Set.Set(f.hash(value))
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}
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}
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func (bf *bloomFilter) Contains(value string) bool {
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if value == "" {
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return false
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}
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ret := true
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bf.m.Lock()
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defer bf.m.Unlock()
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for _, f := range bf.Funcs {
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ret = ret && bf.Set.Test(f.hash(value))
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}
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return ret
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}
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type simpleHash struct {
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Cap uint
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Seed uint
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}
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func (s *simpleHash) hash(value string) uint {
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var result uint = 0
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for i := 0; i < len(value); i++ {
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result = result*s.Seed + uint(value[i])
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}
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return (s.Cap - 1) & result
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}
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