Where and how to run the cleanup function? How to pass the context to the rate limiter?

The cleanup function is usually run at the end of an application's or goroutine's lifecycle to free resources, such as closing connections or stopping timers. In Go, defer is often used to call cleanup immediately after resource initialization:

func main() {
    resource := acquireResource()
    defer resource.cleanup()
    // main logic
}

To pass context to a rate limiter, you can use the context package. For example, if you have a rate limiter that should consider the context (such as cancellation or deadline), you pass a context.Context to the limiter's methods:

func (rl *RateLimiter) Allow(ctx context.Context) bool {
    select {
    case <-ctx.Done():
        return false
    case <-rl.tokenBucket:
        return true
    }
}

Thus, the context allows controlling the behavior of the rate limiter, for example, interrupting waiting when the operation is canceled.