Constant grpcio_sys::grpc_status_code::GRPC_STATUS_UNAVAILABLE

pub const GRPC_STATUS_UNAVAILABLE: Type = 14;

The service is currently unavailable. This is a most likely a transient condition and may be corrected by retrying with a backoff. Note that it is not always safe to retry non-idempotent operations.

WARNING: Although data MIGHT not have been transmitted when this status occurs, there is NOT A GUARANTEE that the server has not seen anything. So in general it is unsafe to retry on this status code if the call is non-idempotent.

See litmus test above for deciding between FAILED_PRECONDITION, ABORTED, and UNAVAILABLE.