examples: Add tower-client example (#466)

2020-09-29 11:16:07 -04:00
parent d4899df832
commit 9ea4a64a6c
2 changed files with 74 additions and 1 deletions
@@ -70,6 +70,10 @@ path = "src/tls_client_auth/client.rs"
 name = "tower-server"
 path = "src/tower/server.rs"

+[[bin]]
+name = "tower-client"
+path = "src/tower/client.rs"
+
 [[bin]]
 name = "multiplex-server"
 path = "src/multiplex/server.rs"
@@ -163,4 +167,4 @@ tonic-health = { path = "../tonic-health" }
 listenfd = "0.3"

 [build-dependencies]
-tonic-build = { path = "../tonic-build", features = ["prost"] }
+tonic-build = { path = "../tonic-build", features = ["prost"] }
@@ -0,0 +1,69 @@
+use hello_world::greeter_client::GreeterClient;
+use hello_world::HelloRequest;
+use service::AuthSvc;
+
+use tonic::transport::Channel;
+
+pub mod hello_world {
+    tonic::include_proto!("helloworld");
+}
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let channel = Channel::from_static("http://[::1]:50051").connect().await?;
+    let auth = AuthSvc::new(channel);
+
+    let mut client = GreeterClient::new(auth);
+
+    let request = tonic::Request::new(HelloRequest {
+        name: "Tonic".into(),
+    });
+
+    let response = client.say_hello(request).await?;
+
+    println!("RESPONSE={:?}", response);
+
+    Ok(())
+}
+
+mod service {
+    use http::{Request, Response};
+    use std::future::Future;
+    use std::pin::Pin;
+    use std::task::{Context, Poll};
+    use tonic::body::BoxBody;
+    use tonic::client::GrpcService;
+    use tonic::transport::Body;
+    use tonic::transport::Channel;
+    use tower::Service;
+
+    pub struct AuthSvc {
+        inner: Channel,
+    }
+
+    impl AuthSvc {
+        pub fn new(inner: Channel) -> Self {
+            AuthSvc { inner }
+        }
+    }
+
+    impl Service<Request<BoxBody>> for AuthSvc {
+        type Response = Response<Body>;
+        type Error = Box<dyn std::error::Error + Send + Sync>;
+        type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send>>;
+
+        fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+            self.inner.poll_ready(cx).map_err(Into::into)
+        }
+
+        fn call(&mut self, req: Request<BoxBody>) -> Self::Future {
+            let mut channel = self.inner.clone();
+
+            Box::pin(async move {
+                // Do extra async work here...
+
+                channel.call(req).await.map_err(Into::into)
+            })
+        }
+    }
+}