mirror of
https://github.com/etcd-io/etcd.git
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65 lines
1.4 KiB
Go
65 lines
1.4 KiB
Go
// Copyright 2018 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package tester
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import (
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"math/rand"
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"time"
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"go.uber.org/zap"
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)
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func (clus *Cluster) shuffleCases() {
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rand.Seed(time.Now().UnixNano())
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offset := rand.Intn(1000)
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n := len(clus.cases)
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cp := coprime(n)
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css := make([]Case, n)
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for i := 0; i < n; i++ {
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css[i] = clus.cases[(cp*i+offset)%n]
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}
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clus.cases = css
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clus.lg.Info("shuffled test failure cases", zap.Int("total", n))
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}
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/*
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x and y of GCD 1 are coprime to each other
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x1 = ( coprime of n * idx1 + offset ) % n
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x2 = ( coprime of n * idx2 + offset ) % n
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(x2 - x1) = coprime of n * (idx2 - idx1) % n
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= (idx2 - idx1) = 1
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Consecutive x's are guaranteed to be distinct
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*/
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func coprime(n int) int {
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coprime := 1
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for i := n / 2; i < n; i++ {
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if gcd(i, n) == 1 {
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coprime = i
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break
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}
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}
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return coprime
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}
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func gcd(x, y int) int {
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if y == 0 {
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return x
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}
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return gcd(y, x%y)
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}
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