miller/pkg/lib/rand.go
John Kerl 5eb40c9e7b
Multiple style updates (#1974)
* Comment style

* IRecordTransformer -> RecordTransfomer

* make fmt

* else-return style mod

* snake-case -> camel-case

* Remove redundant err = nil and similar zero-value initializations.

* redundant break;

* bugfix

* neaten

* typofix

* simplify/standardize init of zero-length slices

* Standardize fmt.Fprintf w/ errors

* fix double print of "mlr:"

* neatening

* Uniformize error messages

* make docs

* avoid shadowing package names

* shorten some receiver names
2026-02-16 15:49:21 -05:00

39 lines
922 B
Go

// 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
}
u := generator.Int63()
// TODO: test divide-by-zero cases in UT
return lowInclusive + (u % (highExclusive - lowInclusive))
}