"""Create cache if it doesn't exist.
    Raises:
        SdkException: Momento service or network error
        Exception: Unexpected response
    """
    from momento.responses import CreateCache
    create_cache_response = cache_client.create_cache(cache_name)
    if isinstance(create_cache_response, CreateCache.Success) or isinstance(
        create_cache_response, CreateCache.CacheAlreadyExists
    ):
        return None
    elif isinstance(create_cache_response, CreateCache.Error):
        raise create_cache_response.inner_exception
    else:
        raise Exception(f"Unexpected response cache creation: {create_cache_response}")
def _validate_ttl(ttl: Optional[timedelta]) -> None:
    if ttl is not None and ttl <= timedelta(seconds=0):
        raise ValueError(f"ttl must be positive but was {ttl}.")
[docs]class MomentoCache(BaseCache):
    """Cache that uses Momento as a backend. See https://gomomento.com/"""
[docs]    def __init__(
        self,
        cache_client: momento.CacheClient,
        cache_name: str,
        *,
        ttl: Optional[timedelta] = None,
        ensure_cache_exists: bool = True,
    ):
        """Instantiate a prompt cache using Momento as a backend.
        Note: to instantiate the cache client passed to MomentoCache,
        you must have a Momento account. See https://gomomento.com/.
        Args:
            cache_client (CacheClient): The Momento cache client.
            cache_name (str): The name of the cache to use to store the data.
            ttl (Optional[timedelta], optional): The time to live for the cache items.
                Defaults to None, ie use the client default TTL.
            ensure_cache_exists (bool, optional): Create the cache if it doesn't