from django.core.cache import cache


def cached_or_set(key, timeout, func):
    value = cache.get(key)
    if value is None:
        value = func()
        cache.set(key, value, timeout)
    return value


def cached_or_set_locked(key, timeout, func):
    value = cache.get(key)
    if value is None:
        if cache.add(f"{key}:lock", True, 30):  # 30s lukko
            value = func()
            cache.set(key, value, timeout)
            cache.delete(f"{key}:lock")
        else:
            import time
            for _ in range(10):  # max 1s odotus
                value = cache.get(key)
                if value is not None:
                    break
                time.sleep(0.1)
    return value