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https://github.com/mjl-/mox.git
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de435fceba
this allows removing some ugly instantiations of an rng based on the current time. Intn is now IntN for our concurrency-safe prng wrapper to match the randv2 api. v2 exists since go1.22, which we already require.
46 lines
919 B
Go
46 lines
919 B
Go
package mox
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import (
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cryptorand "crypto/rand"
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"encoding/binary"
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"fmt"
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mathrand2 "math/rand/v2"
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"sync"
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)
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type rand struct {
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rand *mathrand2.Rand
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sync.Mutex
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}
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// NewPseudoRand returns a new PRNG seeded with random bytes from crypto/rand. Its
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// functions can be called concurrently.
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func NewPseudoRand() *rand {
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var seed [32]byte
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if _, err := cryptorand.Read(seed[:]); err != nil {
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panic(err)
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}
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return &rand{rand: mathrand2.New(mathrand2.NewChaCha8(seed))}
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}
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func (r *rand) Float64() float64 {
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r.Lock()
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defer r.Unlock()
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return r.rand.Float64()
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}
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func (r *rand) IntN(n int) int {
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r.Lock()
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defer r.Unlock()
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return r.rand.IntN(n)
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}
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// CryptoRandInt returns a cryptographically random number.
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func CryptoRandInt() int64 {
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buf := make([]byte, 8)
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_, err := cryptorand.Read(buf)
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if err != nil {
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panic(fmt.Errorf("reading random bytes: %v", err))
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}
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return int64(binary.LittleEndian.Uint64(buf))
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}
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