update hello-world rpc example to use tokio 0.3.0

Author: dwrensha

capnp-rpc/examples/hello-world/Cargo.toml

@@ -17,8 +17,8 @@ capnpc = { path = "../../../capnpc" }
 [dependencies]
 capnp = { path = "../../../capnp" }
 futures = "0.3.0"
-tokio = { version = "0.2.0", features = ["net", "rt-util", "tcp", "macros"]}
-tokio-util = { version = "0.3.0", features = ["compat"] }
+tokio = { version = "0.3.0", features = ["net", "rt", "macros"]}
+tokio-util = { version = "0.4.0", features = ["compat"] }
 
 [dependencies.capnp-rpc]
 path = "../.."

capnp-rpc/examples/hello-world/main.rs

@@ -28,7 +28,7 @@ pub mod hello_world_capnp {
 pub mod client;
 pub mod server;
 
-#[tokio::main]
+#[tokio::main(flavor = "current_thread")]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let args: Vec<String> = ::std::env::args().collect();
     if args.len() >= 2 {

capnp-rpc/examples/hello-world/server.rs

@@ -60,7 +60,7 @@ pub async fn main() -> Result<(), Box<dyn std::error::Error>> {
         .expect("could not parse address");
 
     tokio::task::LocalSet::new().run_until(async move {
-        let mut listener = tokio::net::TcpListener::bind(&addr).await?;
+        let listener = tokio::net::TcpListener::bind(&addr).await?;
         let hello_world_client: hello_world::Client = capnp_rpc::new_client(HelloWorldImpl);
 
         loop {