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// ================================================================
// Thinly wraps Go's rand library, with seed-function support
// ================================================================
package lib
import (
"math/rand"
"os"
"time"
)
// By default, Miller random numbers are different on every run.
var defaultSeed = time.Now().UnixNano() ^ int64(os.Getpid())
var source = rand.NewSource(defaultSeed)
var generator = rand.New(source)
// Users can request specific seeds if they want the same random-number
// sequence on each run.
func SeedRandom(seed int64) {
source = rand.NewSource(seed)
generator = rand.New(source)
}
func RandFloat64() float64 {
return generator.Float64()
}
func RandUint32() uint32 {
return generator.Uint32()
}
func RandInt63() int64 {
return generator.Int63()
}
func RandRange(lowInclusive, highExclusive int64) int64 {
if lowInclusive == highExclusive {
return lowInclusive
} else {
u := generator.Int63()
// TODO: test divide-by-zero cases in UT
return lowInclusive + (u % (highExclusive - lowInclusive))
}
}
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