mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
synced 2024-12-29 15:20:04 +01:00
66 lines
1.9 KiB
Go
66 lines
1.9 KiB
Go
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package netstorage
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import (
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"math"
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"math/rand"
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"testing"
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)
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func TestConsistentHash(t *testing.T) {
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r := rand.New(rand.NewSource(1))
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nodes := []string{
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"node1",
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"node2",
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"node3",
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"node4",
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}
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rh := newConsistentHash(nodes, 0)
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keys := make([]uint64, 100000)
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for i := 0; i < len(keys); i++ {
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keys[i] = r.Uint64()
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}
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perIdxCounts := make([]int, len(nodes))
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keyIndexes := make([]int, len(keys))
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for i, k := range keys {
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idx := rh.getNodeIdx(k, nil)
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perIdxCounts[idx]++
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keyIndexes[i] = idx
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}
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// verify that the number of selected node indexes per each node is roughly the same
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expectedPerIdxCount := float64(len(keys)) / float64(len(nodes))
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for _, perIdxCount := range perIdxCounts {
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if p := math.Abs(float64(perIdxCount)-expectedPerIdxCount) / expectedPerIdxCount; p > 0.005 {
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t.Fatalf("uneven number of per-index items %f: %d", p, perIdxCounts)
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}
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}
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// Ignore a single node and verify that the selection for the remaining nodes is even
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perIdxCounts = make([]int, len(nodes))
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idxsExclude := []int{1}
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indexMismatches := 0
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for i, k := range keys {
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idx := rh.getNodeIdx(k, idxsExclude)
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perIdxCounts[idx]++
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if keyIndexes[i] != idx {
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indexMismatches++
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}
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}
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maxIndexMismatches := float64(len(keys)) / float64(len(nodes))
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if float64(indexMismatches) > maxIndexMismatches {
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t.Fatalf("too many index mismtaches after excluding a node; got %d; want no more than %f", indexMismatches, maxIndexMismatches)
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}
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expectedPerIdxCount = float64(len(keys)) / float64(len(nodes)-1)
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for i, perIdxCount := range perIdxCounts {
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if i == idxsExclude[0] {
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if perIdxCount != 0 {
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t.Fatalf("unexpected non-zero items for excluded index %d: %d items", idxsExclude[0], perIdxCount)
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}
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continue
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}
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if p := math.Abs(float64(perIdxCount)-expectedPerIdxCount) / expectedPerIdxCount; p > 0.005 {
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t.Fatalf("uneven number of per-index items %f: %d", p, perIdxCounts)
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}
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}
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}
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