How can you correctly stop a running goroutine if it needs to terminate based on an external signal or condition, even if the result has not yet been received?

To properly stop a running goroutine in Go based on an external signal or condition, the common approach is to use a context.Context or channels to transmit a cancellation signal.

Example using context:

func worker(ctx context.Context) {
    for {
        select {
        case <-ctx.Done():
            // Cancellation signal received, ending goroutine
            return
        default:
            // Perform work
        }
    }
}

func main() {
    ctx, cancel := context.WithCancel(context.Background())
    go worker(ctx)

    // At some point, call cancel() to stop the goroutine
    cancel()
}

This approach allows the goroutine to regularly check if a stop signal has been sent and terminate gracefully, even if the result has not yet been received. Similarly, a channel can be used to transmit a stop signal, but context is a more idiomatic and convenient method in Go.