在Golang中生成固定长度的随机十六进制字符串的有效方法?
我需要生成很多固定长度的随机十六进制字符串.
我找到了这个解决方案 How to generate a random string of a fixed length in golang? 我正在做这样的事情: const letterBytes = "abcdef0123456789" const ( letterIdxBits = 6 // 6 bits to represent a letter index letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits,as many as letterIdxBits letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits ) var src = rand.NewSource(time.Now().UnixNano()) // RandStringBytesMaskImprSrc ... // Src: https://stackoverflow.com/a/31832326/710955 func RandStringBytesMaskImprSrc(n int) string { b := make([]byte,n) // A src.Int63() generates 63 random bits,enough for letterIdxMax characters! for i,cache,remain := n-1,src.Int63(),letterIdxMax; i >= 0; { if remain == 0 { cache,remain = src.Int63(),letterIdxMax } if idx := int(cache & letterIdxMask); idx < len(letterBytes) { b[i] = letterBytes[idx] i-- } cache >>= letterIdxBits remain-- } return string(b) } var tryArr = make([]string,10000) for i := 0; i < 10000; i++ { tryArr[i] = RandStringBytesMaskImprSrc(8) } 但我得到了这个恐慌错误 panic: runtime error: index out of range goroutine 36 [running]: math/rand.(*rngSource).Int63(0x11bb1300,0x8,0x8) D:/Applications/Go/src/math/rand/rng.go:231 +0xa0 main.RandStringBytesMaskImprSrc(0x8,0x11f81be8,0x8) main.go:60 +0x5f 错误似乎是为了i,缓存,保留:= n-1,letterIdxMax;我> = 0;,但我不知道为什么会出现这个错误. 在Go中生成大量固定长度的随机十六进制字符串的最快最简单的方法是什么? 基准 package bench import ( "encoding/hex" "math/rand" "testing" "time" ) const letterBytes = "abcdef0123456789" const ( letterIdxBits = 4 // 4 bits to represent a letter index letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits,as many as letterIdxBits letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits ) var src1 = rand.NewSource(time.Now().UnixNano()) var src2 = rand.New(rand.NewSource(time.Now().UnixNano())) // RandStringBytesMaskImprSrc returns a random hexadecimal string of length n. func RandStringBytesMaskImprSrc1(n int) string { b := make([]byte,n) for i,src1.Int63(),remain = src1.Int63(),letterIdxMax } if idx := int(cache & letterIdxMask); idx < len(letterBytes) { b[i] = letterBytes[idx] i-- } cache >>= letterIdxBits remain-- } return string(b) } func RandStringBytesMaskImprSrc2(n int) string { b := make([]byte,(n+1)/2) // can be simplified to n/2 if n is always even if _,err := src2.Read(b); err != nil { panic(err) } return hex.EncodeToString(b)[:n] } func BenchmarkRandStringBytesMaskImprSrc1(b *testing.B) { for n := 0; n < b.N; n++ { _ = RandStringBytesMaskImprSrc1(8) } } func BenchmarkRandStringBytesMaskImprSrc2(b *testing.B) { for n := 0; n < b.N; n++ { _ = RandStringBytesMaskImprSrc2(8) } } goos: windows goarch: 386 BenchmarkRandStringBytesMaskImprSrc1-4 20000000 116 ns/op 16 B/op 2 allocs/op BenchmarkRandStringBytesMaskImprSrc2-4 10000000 231 ns/op 24 B/op 3 allocs/op PASS ok command-line-arguments 5.139s => icza RandStringBytesMaskImprSrcsolution更高效 解决方法
实际上你发布的代码运行,即使它有一个错误(见下文),它仍然不会引起恐慌(只会使性能变差).
您发布的堆栈跟踪指示math / rand包中的错误,我没有遇到它.请发布完整代码和Go版本env(转到版本并进入环境). 恐慌原因/解决方案: 事实证明,提问者同时从多个goroutine调用RandStringBytesMaskImprSrc(). RandStringBytesMaskImprSrc()使用共享的rand.Source实例,这对于并发使用是不安全的,因此来自math / rand包的恐慌.修复是为每个goroutine创建一个单独的rand.Source(),并将其传递给RandStringBytesMaskImprSrc(). 开头的“配置”常量有一个错误: const letterBytes = "abcdef0123456789" const ( letterIdxBits = 6 // 6 bits to represent a letter index letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits,as many as letterIdxBits letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits ) 常量letterIdxBits应包含表示符号索引所需的位数.由于您使用的是16个元素的字母表(letterBytes的长度),因此16种组合仅需要4位: letterIdxBits = 4 // 4 bits to represent a letter index 测试示例: var tryArr = make([]string,10) for i := range tryArr { tryArr[i] = RandStringBytesMaskImprSrc(8) } fmt.Println(tryArr) 输出(在Go Playground上试试): [d3e7caa6 a69c9b7d c37a613b 92d5a43b 64059c4a 4f08141b 70130c65 1546daaf fe140fcd 0d714e4d] (注意:由于Go操场上的开始时间是固定的并且输出被缓存,因此您将始终看到这些随机生成的字符串.在您的机器上运行它以查看随机结果.) (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |