Praktische taak: implementeer de functie FastestSearcher, die het testen van meerdere zoekmachines parallel uitvoert en de naam van de snelste, de responstijd en een fout (als ten minste één een fout retourneert) teruggeeft.

go package main

import ( "errors" "fmt" "sync" "time" )

type SearchResult struct { Name string Duration time.Duration Err error }

// FastestSearcher запускает параллельно несколько функций поиска и возвращает имя самого быстрого, время и ошибку. func FastestSearcher(searchers map[string]func() error) (string, time.Duration, error) { results := make(chan SearchResult, len(searchers)) var wg sync.WaitGroup

for name, searchFunc := range searchers {
	wg.Add(1)
	go func(n string, f func() error) {
		defer wg.Done()
		start := time.Now()
		err := f()
		dur := time.Since(start)
		results <- SearchResult{Name: n, Duration: dur, Err: err}
	}(name, searchFunc)
}

wg.Wait()
close(results)

var fastest SearchResult
var hasError bool
first := true

for res := range results {
	if res.Err != nil {
		hasError = true
	}
	if first || res.Duration < fastest.Duration {
		fastest = res
		first = false
	}
}

if hasError {
	return fastest.Name, fastest.Duration, errors.New("at least one searcher returned an error")
}
return fastest.Name, fastest.Duration, nil

}

func main() { searchers := map[string]func() error{ "Google": func() error { time.Sleep(100 * time.Millisecond) return nil }, "Bing": func() error { time.Sleep(80 * time.Millisecond) return nil }, "Yahoo": func() error { time.Sleep(120 * time.Millisecond) return errors.New("timeout") }, }

name, duration, err := FastestSearcher(searchers)
fmt.Printf("Fastest: %s, Duration: %v, Error: %v\n", name, duration, err)

}