45 lines
880 B
Go
45 lines
880 B
Go
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package hasher
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import "hash/maphash"
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var instance = NewHasher()
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func Reseed(id string) {
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instance.Reseed(id)
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}
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func HashFunc() func(id, str string) uint64 {
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return instance.HashFunc()
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}
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type hasher struct {
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seeds map[string]maphash.Seed
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}
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func NewHasher() *hasher {
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h := new(hasher)
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h.seeds = make(map[string]maphash.Seed)
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return h
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}
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// Reseed generates a new seed for the given id
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func (h *hasher) Reseed(id string) {
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h.seeds[id] = maphash.MakeSeed()
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}
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// HashFunc returns a function that hashes a string using the seed for the given id
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func (h *hasher) HashFunc() func(id, str string) uint64 {
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return func(id, str string) uint64 {
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var hash maphash.Hash
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var seed maphash.Seed
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var ok bool
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if seed, ok = h.seeds[id]; !ok {
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seed = maphash.MakeSeed()
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h.seeds[id] = seed
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}
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hash.SetSeed(seed)
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_, _ = hash.WriteString(str)
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return hash.Sum64()
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}
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}
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