Exponential backoff with jitter for retries

                  package retry

import (
  "context"
  "math/rand"
  "time"
)

func Retry(ctx context.Context, attempts int, base time.Duration, fn func() error, shouldRetry func(error) bool) error {
  var err error
  for i := 0; i < attempts; i++ {
    if err = fn(); err == nil {
      return nil
    }
    if !shouldRetry(err) {
      return err
    }

    d := base * (1 << i)
    if d > 2*time.Second {
      d = 2 * time.Second
    }
    jitter := time.Duration(rand.Int63n(int64(d / 2)))
    sleep := d/2 + jitter

    select {
    case <-ctx.Done():
      return ctx.Err()
    case <-time.After(sleep):
    }
  }
  return err
}