73 lines
1.6 KiB
Go
73 lines
1.6 KiB
Go
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package randutil
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import (
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mrand "math/rand" // used for non-crypto unique ID and random port selection
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"sync"
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"time"
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)
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// MathRandomGenerator is a random generator for non-crypto usage.
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type MathRandomGenerator interface {
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// Intn returns random integer within [0:n).
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Intn(n int) int
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// Uint32 returns random 32-bit unsigned integer.
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Uint32() uint32
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// Uint64 returns random 64-bit unsigned integer.
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Uint64() uint64
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// GenerateString returns ranom string using given set of runes.
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// It can be used for generating unique ID to avoid name collision.
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//
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// Caution: DO NOT use this for cryptographic usage.
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GenerateString(n int, runes string) string
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}
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type mathRandomGenerator struct {
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r *mrand.Rand
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mu sync.Mutex
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}
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// NewMathRandomGenerator creates new mathmatical random generator.
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// Random generator is seeded by crypto random.
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func NewMathRandomGenerator() MathRandomGenerator {
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seed, err := CryptoUint64()
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if err != nil {
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// crypto/rand is unavailable. Fallback to seed by time.
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seed = uint64(time.Now().UnixNano())
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}
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return &mathRandomGenerator{r: mrand.New(mrand.NewSource(int64(seed)))}
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}
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func (g *mathRandomGenerator) Intn(n int) int {
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g.mu.Lock()
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v := g.r.Intn(n)
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g.mu.Unlock()
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return v
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}
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func (g *mathRandomGenerator) Uint32() uint32 {
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g.mu.Lock()
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v := g.r.Uint32()
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g.mu.Unlock()
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return v
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}
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func (g *mathRandomGenerator) Uint64() uint64 {
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g.mu.Lock()
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v := g.r.Uint64()
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g.mu.Unlock()
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return v
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}
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func (g *mathRandomGenerator) GenerateString(n int, runes string) string {
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letters := []rune(runes)
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b := make([]rune, n)
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for i := range b {
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b[i] = letters[g.Intn(len(letters))]
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}
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return string(b)
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}
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