producer-consumer-enhanced.go

package main

import (
	crypto "crypto/rand"
	"fmt"
	"math/big"
	"runtime"
	"time"
)

// ProducedData represents some data the producer function will output.
//
// Data: actual data produced
// ProducerID: id of the producer goroutine
type ProducedData struct {
	Data       int64
	ProducerID int
}

func main() {
	producer := make(chan ProducedData)

	// spawn N producers, where N is the number of cpu cores
	cpuCoresNumber := runtime.NumCPU()
	fmt.Println("*** SPAWNING ", cpuCoresNumber, " GOROUTINES ***")
	for i := 0; i < cpuCoresNumber; i++ {
		go func(id int) {
			for {
				var bigN *big.Int
				val := *big.NewInt(4)

				bigN, _ = crypto.Int(crypto.Reader, &val)
				time.Sleep(time.Duration(bigN.Int64()) * time.Second)
				newN, _ := crypto.Int(crypto.Reader, &val)

				kek := ProducedData{newN.Int64(), id}

				producer <- kek
			}
		}(i)
	}

	// the consumer is the main itself
	for {
		select {
		case got := <-producer:
			fmt.Println("Producer ", got.ProducerID, " sent in something: ", got.Data)

		case <-time.After(3 * time.Second):
			fmt.Println("you're too slow, feed me faster!")
			return

		}
	}
}