main.go

package main

import (
	"context"
	"errors"
	"fmt"
	log "github.com/sirupsen/logrus"
	"io/ioutil"
	"net/http"
	"sync"
)

const (
	url = "https://api.binance.com/api/v3/avgPrice?symbol=ETHBTC"
)

func createOrder(orderID int, ch chan<- string, ce chan<- error, wg *sync.WaitGroup){
	defer wg.Done()

	if orderID == 4{
		log.Println("invalid order")
		ce <- errors.New("invalid order number")
		return
	}

	resp, err := http.Get("https://api.binance.com/api/v3/avgPrice?symbol=ETHBTC")
	if err != nil {
		log.Println("err handle it", orderID)
		ce <- err
		return
	}
	defer resp.Body.Close()
	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Println("err handle it")
		ce <- err
		return
	}
	ch <- string(b)
}

func main() {
	ctx := context.Background()
	ctx, cancel := context.WithCancel(ctx)
	
	orders := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
	log.WithFields(log.Fields{
		"orders": orders,
	}).Info("creating orders")

	var wg sync.WaitGroup
	ch := make(chan string)
	errors := make(chan error)
	var responses []string

	for _, orderID := range orders {
		wg.Add(1)
		go createOrder(orderID, ch, errors, &wg)
	}

	// close the channel in the background
	go func() {
		wg.Wait()
		close(ch)
		close(errors)
	}()

	for range orders {
		select {
		case response := <-ch:
			fmt.Println("received", response)
			responses = append(responses, response)
		case err := <-errors:
			fmt.Println("received", err)
			cancel()
			break
		}
	}

	//// read from channel as they come in until its closed
	//for res := range ch {
	//	responses = append(responses, res)
	//}

	for _, r := range responses{
		log.WithFields(log.Fields{
			"response": r,
		}).Info("received response")
	}


}