randomstd

Abstract

GoLang has first class concurrency, which is AWESOME!

A big problem that catches many beginners and new users is the use of random. The philosophy of the core language team is to NOT make things safe. The reason for this is to allow application developers to make choices about how to implement the safety for their given use-case.

If you want to use Random, you have to create a concurrent safe Source which is not difficult to do, but there is an on-going discussion on whether to make this part of the core library: golang/go#21393 (I've included this in the safe package for simplicity but this is not what this library is for).

This is an implementation that takes advantage of first class function pointers and concurrency and creates a safe pool that allows end-developers to use random concurrently without having to think about concurrency

Usage

You can use it however you want. All you have to do is pass in a function pointer that matches the following signature, consuming a random pointer and returning void:

type RandomPoolJob func(r randomstd.Random)

A potentially time-expensive example is the need to generate UUIDs randomly in a time efficient manor like this example demonstrates:

package main

import (
	"github.com/paul-nelson-baker/randomstd"
	"github.com/paul-nelson-baker/randomstd/pool"
	"log"
	"strconv"
	"strings"
)

func main() {
	count := 100_000
	uuidChannel := make(chan string)

	// The magic happens here, we kick off our `n` goroutines
	// and not worry about managing the random itself. We just
	// call random's methods like normal and let the concurrency
	// magic happen on its own!
	var r randomstd.Random = pool.New(150, pool.AtomicOffsetRandomConstructor)
	for i := 0; i < count; i++ {
		go func() {
			uuidChannel <- naiveUUID(r)
		}()
	}

	for i := 0; i < count; i++ {
		log.Println(<-uuidChannel)
	}
	close(uuidChannel)
}

func naiveUUID(r randomstd.Random) string {
	b := strings.Builder{}
	for i := 0; i < 8; i++ {
		b.WriteString(value(r))
	}
	b.WriteString("-")
	for i := 0; i < 4; i++ {
		b.WriteString(value(r))
	}
	b.WriteString("-")
	for i := 0; i < 4; i++ {
		b.WriteString(value(r))
	}
	b.WriteString("-")
	for i := 0; i < 4; i++ {
		b.WriteString(value(r))
	}
	b.WriteString("-")
	for i := 0; i < 12; i++ {
		b.WriteString(value(r))
	}
	return b.String()
}

func value(r randomstd.Random) string {
	i := r.Int63n(16)
	return strconv.FormatInt(i, 16)
}