peculiar crawler - 1

crawler1.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"sync"
	"time"
)

const (
	noOfWorker    = 10000
	userRequiredd = 350
	minAge        = 10
	maxAge        = 12
	timeLimit     = 3
)

type User struct {
	Name string
	Age  int
}

func worker(id int, wg *sync.WaitGroup, ch chan User) {
	defer wg.Done()
	url := fmt.Sprintf("http://localhost:8080/user/%d", id)
	client := http.Client{
		Timeout: 5 * time.Second,
	}
	res, err := client.Get(url)
	if err != nil {
		return
	}
	data, err := ioutil.ReadAll(res.Body)
	defer res.Body.Close()
	if err != nil {
		return
	}
	var user User
	err = json.Unmarshal(data, &user)
	if err != nil {
		return
	}
	if user.Age >= minAge && user.Age <= maxAge {
		ch <- user
	}
}

func terminator(wg *sync.WaitGroup, termination chan bool) {
	wg.Wait()
	termination <- true
}
func printResult(myusers []User) {
	fmt.Printf("total users found : %d\n", len(myusers))
	for _, user := range myusers {
		fmt.Printf("user name :%s \nage :%d\n\n", user.Name, user.Age)
	}
}
func main() {
	var myusers []User
	ch := make(chan User)
	termination := make(chan bool)
	var wg sync.WaitGroup
	for i := 1; i <= noOfWorker; i++ {
		wg.Add(1)
		go worker(i, &wg, ch)
	}
	go terminator(&wg, termination)
	for true {
		select {
		case res := <-ch:
			myusers = append(myusers, res)
			if len(myusers) == userRequiredd {
				printResult(myusers)
				return
			}
		case <-termination:
			log.Println("All Worker Finished")
			printResult(myusers)
			return
		case <-time.After(timeLimit * time.Second):
			log.Println("Time Up")
			printResult(myusers)
			return
		}
	}
}