forked from extern/smegmesh
49 lines
862 B
Go
49 lines
862 B
Go
package lib
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import (
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"hash/fnv"
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"sort"
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)
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type consistentHashRecord[V any] struct {
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record V
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value int
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}
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func HashString(value string) int {
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f := fnv.New32a()
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f.Write([]byte(value))
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return int(f.Sum32())
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}
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// ConsistentHash implementation. Traverse the values until we find a key
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// greater than ours.
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func ConsistentHash[V any, K any](values []V, client K, bucketFunc func(V) int, keyFunc func(K) int) V {
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if len(values) == 0 {
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panic("values is empty")
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}
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vs := Map(values, func(v V) consistentHashRecord[V] {
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return consistentHashRecord[V]{
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v,
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bucketFunc(v),
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}
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})
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sort.SliceStable(vs, func(i, j int) bool {
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return vs[i].value < vs[j].value
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})
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ourKey := keyFunc(client)
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idx := sort.Search(len(vs), func(i int) bool {
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return vs[i].value >= ourKey
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})
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if idx == len(vs) {
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return vs[0].record
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}
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return vs[idx].record
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}
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