Retry Stability Pattern

• like the Circuit, the effector will have a function signature as follows

type Effector func(context.Context) (string, error)

• the Retry can take in paramters like the number of retries and delay durations, returning a closure of the same signature as the Effector

  func Retry(effector Effector, retries int, delay time.Duration) Effector{
          return func(ctx context.Context) (string, error) {
                  for r := 0; ; r++ {
                          response, err := effector(ctx)
                          if err == nil || r >= retries {
                                  return response, err
                          }
                          log.Printf("Attempt %d failed; retrying in %v", r + 1, delay)
  
                          select {
                          case <- time.After(delay):
                          case <- ctx.Done():
                                  return "", ctx.Err()
                          }
                  }
          }
  }
  

  • emulating an erroneous function to try out retry

    #+begin_src go

var count int

func EmulateTransientError(ctx context.Context) (string, error) { count++

if count <= 3 { return "intentional fail", errors.New("error") } else { return "success", nil } }

func main() { r := Retry(EmulateTransientError, 5, 2*time.Second)

res, err := r(context.Background())

fmt.Println(res,err) } #+