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| package main | |
| import ( | |
| "context" | |
| "errors" | |
| "fmt" | |
| "math/rand" | |
| "sync" | |
| "time" | |
| ) | |
| // Более оптимальное решение задачи из этого видео: | |
| // https://youtu.be/wZCLVt_5-4c | |
| // Из сигнатуры функции processData убран кастомный тип + убран один селект | |
| // (он не был прям сильно лишним, но от него можно избавиться +- безболезненно) | |
| // условие задачи: | |
| // реализовать функцию processParallel | |
| // прокинуть контекст | |
| var errTimeout = errors.New("timed out") | |
| func processData(ctx context.Context, v int) (int, error) { | |
| ch := make(chan struct{}) | |
| go func() { | |
| time.Sleep(time.Duration(rand.Intn(10)) * time.Second) | |
| close(ch) | |
| }() | |
| select { | |
| case <-ch: | |
| case <-ctx.Done(): | |
| return 0, errTimeout | |
| } | |
| return v * 2, nil | |
| } | |
| func main() { | |
| in := make(chan int) | |
| out := make(chan int) | |
| ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second) | |
| defer cancel() | |
| go func() { | |
| defer close(in) | |
| for i := range 10 { | |
| select { | |
| case in <- i + 1: | |
| case <-ctx.Done(): | |
| return | |
| } | |
| } | |
| }() | |
| start := time.Now() | |
| processParallel(ctx, in, out, 5) | |
| for v := range out { | |
| fmt.Println("v =", v) | |
| } | |
| fmt.Println("main duration:", time.Since(start)) | |
| } | |
| func processParallel(ctx context.Context, in <-chan int, out chan<- int, numWorkers int) { | |
| wg := &sync.WaitGroup{} | |
| for range numWorkers { | |
| wg.Add(1) | |
| go worker(ctx, in, out, wg) | |
| } | |
| go func() { | |
| wg.Wait() | |
| close(out) | |
| }() | |
| } | |
| func worker(ctx context.Context, in <-chan int, out chan<- int, wg *sync.WaitGroup) { | |
| defer wg.Done() | |
| for { | |
| select { | |
| case v, ok := <-in: | |
| if !ok { | |
| return | |
| } | |
| val, err := processData(ctx, v) | |
| if errors.Is(err, errTimeout) { | |
| return | |
| } | |
| //...handle other error types | |
| select { | |
| case <-ctx.Done(): | |
| return | |
| case out <- val: | |
| } | |
| case <-ctx.Done(): | |
| return | |
| } | |
| } | |
| } |
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