Go provider-consumer as funcs

main.go

package main

import (
	"context"
	"log"
	"runtime"
	"sync"
	"time"
)

func main() {
	log.Println("Setting up...")

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	ticker := time.NewTicker(2 * time.Second)
	defer ticker.Stop()
	q := producer(ctx, ticker.C)

	var N int = runtime.GOMAXPROCS(0)
	wg := &sync.WaitGroup{}

	wg.Add(N)
	for i := 1; i <= N; i++ {
		go consumer(i, wg, q)
	}

	log.Println("Waiting...")
	wg.Wait()
	log.Println("... All done")
}

func producer[T any](ctx context.Context, supplier <-chan T) <-chan T {
	log.Printf(" P  -> initializing")

	q := make(chan T)

	go func() {
		defer close(q)
		defer log.Printf(" P  -> done")

		log.Printf(" P  -> started")

		for {
			select {
			case t, ok := <-supplier:
				if !ok {
					log.Printf(" P  <- reports supplier closed")
					return
				}

				log.Printf(" P  -> %v", t)
				q <- t
			case <-ctx.Done():
				log.Printf(" P  -> %v", ctx.Err())
				return
			}
		}
	}()

	return q
}

func consumer[T any](id int, wg *sync.WaitGroup, q <-chan T) {
	defer wg.Done()

	log.Printf(" W%d -- started", id)

	for t := range q {
		log.Printf(" W%d <- %v", id, t)
	}

	log.Printf(" W%d <- reports q closed", id)
	log.Printf(" W%d -- done", id)
}