You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: main.rs
    path of file: ./repos/rust-bible/part7/grpc/grpc-hello/src
    
    the code of the file until where you have to start completion: use grpc::{ServerHandlerContext, 
    
fn main() {
    let port = 8081;
    let mut server = grpc::ServerBuilder::new_plain();
    // let _ = server.http.set_addr("0.0.0.0:8081");
    let _ = server.http.set_port(port);

    // 注入grpc server服务
    server.add_service(GreeterServiceServer::new_service_def(GreeterServiceImpl));
    let _ = server.build().expect("build service failed");
    println!("greeter server started on port {} without tls", port,);

    // 防止主线程退出
    // 这里好像启动不起来，估计是grpc rust bug.
    // 推荐使用tonic
    loop {
        thread::park();
    }
}