Function grpcio_sys::grpc_channel_register_call

pub unsafe extern "C" fn grpc_channel_register_call(
    channel: *mut grpc_channel, 
    method: *const c_char, 
    host: *const c_char, 
    reserved: *mut c_void
) -> *mut c_void

Pre-register a method/host pair on a channel. method and host are not owned and must remain alive while the channel is alive.