Introduce a Standard enum for connections (#237)

* Enum Conn POC

* Make alias public

* Add docs, Debug impl, format

* Add comment delete dead code

* A couple of missing cargo-formats

* Cleanup, address CR feedback

* Derive clone instead of implementing it manually

aws/rust-runtime/aws-hyper/Cargo.toml

@@ -22,6 +22,7 @@ smithy-types = { path = "../../../rust-runtime/smithy-types" }
 smithy-http-tower = { path = "../../../rust-runtime/smithy-http-tower" }
 fastrand = "1.4.0"
 tokio = { version = "1", features = ["time"]}
+pin-project = "1"
 tracing = "0.1.25"
 
 [dev-dependencies]

aws/rust-runtime/aws-hyper/src/conn.rs

@@ -0,0 +1,154 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0.
+ */
+
+use crate::BoxError;
+use http::Request;
+use hyper::client::{HttpConnector, ResponseFuture};
+use hyper::Response;
+use hyper_tls::HttpsConnector;
+use smithy_http::body::SdkBody;
+use std::future::{Future, Ready};
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use tower::Service;
+
+#[derive(Clone)]
+pub struct Standard(Connector);
+
+impl Standard {
+    /// An https connection
+    pub fn https() -> Self {
+        let https = HttpsConnector::new();
+        Self(Connector::Https(hyper::Client::builder().build::<_, SdkBody>(https)))
+    }
+
+    /// A connection based on the provided `Box<dyn HttpService>`
+    ///
+    /// Generally, `https()` should be used instead. This constructor is intended to support
+    /// using things like [`TestConnection`](crate::test_connection::TestConnection) or alternative
+    /// http implementations.
+    pub fn new(connector: Box<dyn HttpService>) -> Self {
+        Self(Connector::Dyn(connector))
+    }
+}
+
+/// An Http connection type for most use cases
+///
+/// This supports three options:
+/// 1. HTTPS
+/// 2. A `TestConnection`
+/// 3. Any implementation of the `HttpService` trait
+///
+/// This is designed to be used with [`aws_hyper::Client`](crate::Client) as a connector.
+#[derive(Clone)]
+enum Connector {
+    /// An Https Connection
+    ///
+    /// This is the correct connection for use cases talking to real AWS services.
+    Https(hyper::Client<HttpsConnector<HttpConnector>, SdkBody>),
+
+    /// A generic escape hatch
+    ///
+    /// This enables using any implementation of the HttpService trait. This allows using a totally
+    /// separate HTTP stack or your own custom `TestConnection`.
+    Dyn(Box<dyn HttpService>),
+}
+
+impl Clone for Box<dyn HttpService> {
+    fn clone(&self) -> Self {
+        self.clone_box()
+    }
+}
+
+pub trait HttpService: Send {
+    /// Return whether this service is ready to accept a request
+    ///
+    /// See [`Service::poll_ready`](tower::Service::poll_ready)
+    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), BoxError>>;
+
+    /// Call this service and return a response
+    ///
+    /// See [`Service::call`](tower::Service::call)
+    fn call(
+        &mut self,
+        req: http::Request<SdkBody>,
+    ) -> Pin<Box<dyn Future<Output = Result<http::Response<hyper::Body>, BoxError>> + Send>>;
+
+    /// Return a Boxed-clone of this service
+    ///
+    /// `aws_hyper::Client` will clone the inner service for each request so this should be a cheap
+    /// clone operation.
+    fn clone_box(&self) -> Box<dyn HttpService>;
+}
+
+/// Reverse implementation: If you have a correctly shaped tower service, it _is_ an `HttpService`
+///
+/// This is to facilitate ease of use for people using `Standard::Dyn`
+impl<S> HttpService for S
+where
+    S: Service<http::Request<SdkBody>, Response = http::Response<hyper::Body>>
+        + Send
+        + Clone
+        + 'static,
+    S::Error: Into<BoxError> + Send + Sync + 'static,
+    S::Future: Send + 'static,
+{
+    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), BoxError>> {
+        Service::poll_ready(self, cx).map_err(|err| err.into())
+    }
+
+    fn call(
+        &mut self,
+        req: Request<SdkBody>,
+    ) -> Pin<Box<dyn Future<Output = Result<Response<hyper::Body>, BoxError>> + Send>> {
+        let fut = Service::call(self, req);
+        let fut = async move { fut.await.map_err(|err| err.into()) };
+        Box::pin(fut)
+    }
+
+    fn clone_box(&self) -> Box<dyn HttpService> {
+        Box::new(self.clone())
+    }
+}
+
+impl tower::Service<http::Request<SdkBody>> for Standard {
+    type Response = http::Response<hyper::Body>;
+    type Error = BoxError;
+    type Future = StandardFuture;
+
+    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        match &mut self.0 {
+            Connector::Https(https) => Service::poll_ready(https, cx).map_err(|err| err.into()),
+            Connector::Dyn(conn) => conn.poll_ready(cx),
+        }
+    }
+
+    fn call(&mut self, req: http::Request<SdkBody>) -> Self::Future {
+        match &mut self.0 {
+            Connector::Https(https) => StandardFuture::Https(Service::call(https, req)),
+            Connector::Dyn(conn) => StandardFuture::Dyn(conn.call(req)),
+        }
+    }
+}
+
+/// Future returned by `Standard` when used as a tower::Service
+#[pin_project::pin_project(project = FutProj)]
+pub enum StandardFuture {
+    Https(#[pin] ResponseFuture),
+    TestConn(#[pin] Ready<Result<http::Response<hyper::Body>, BoxError>>),
+    Dyn(#[pin] Pin<Box<dyn Future<Output = Result<http::Response<hyper::Body>, BoxError>> + Send>>),
+}
+
+impl Future for StandardFuture {
+    type Output = Result<http::Response<hyper::Body>, BoxError>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.project() {
+            FutProj::TestConn(ready_fut) => ready_fut.poll(cx),
+            FutProj::Https(fut) => fut.poll(cx).map_err(|err| err.into()),
+            FutProj::Dyn(dyn_fut) => dyn_fut.poll(cx),
+        }
+    }
+}

aws/rust-runtime/aws-hyper/src/lib.rs

@@ -1,15 +1,15 @@
+pub mod conn;
 mod retry;
 pub mod test_connection;
+
 pub use retry::RetryConfig;
 
+use crate::conn::Standard;
 use crate::retry::RetryHandlerFactory;
 use aws_endpoint::AwsEndpointStage;
 use aws_http::user_agent::UserAgentStage;
 use aws_sig_auth::middleware::SigV4SigningStage;
 use aws_sig_auth::signer::SigV4Signer;
-use hyper::client::HttpConnector;
-use hyper::Client as HyperClient;
-use hyper_tls::HttpsConnector;
 use smithy_http::body::SdkBody;
 use smithy_http::operation::Operation;
 use smithy_http::response::ParseHttpResponse;
@@ -19,9 +19,12 @@ use smithy_http_tower::map_request::MapRequestLayer;
 use smithy_http_tower::parse_response::ParseResponseLayer;
 use smithy_types::retry::ProvideErrorKind;
 use std::error::Error;
+use std::fmt;
+use std::fmt::{Debug, Formatter};
 use tower::{Service, ServiceBuilder, ServiceExt};
 
 type BoxError = Box<dyn Error + Send + Sync>;
+pub type StandardClient = Client<conn::Standard>;
 
 pub type SdkError<E> = smithy_http::result::SdkError<E, hyper::Body>;
 pub type SdkSuccess<T> = smithy_http::result::SdkSuccess<T, hyper::Body>;
@@ -41,35 +44,40 @@ pub type SdkSuccess<T> = smithy_http::result::SdkSuccess<T, hyper::Body>;
 ///    S::Error: Into<BoxError> + Send + Sync + 'static,
 ///    S::Future: Send + 'static,
 /// ```
-
 pub struct Client<S> {
     inner: S,
-    retry_strategy: RetryHandlerFactory,
+    retry_handler: RetryHandlerFactory,
+}
+
+impl<S> Debug for Client<S> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        let mut formatter = f.debug_struct("Client");
+        formatter.field("retry_handler", &self.retry_handler);
+        formatter.finish()
+    }
 }
 
 impl<S> Client<S> {
     /// Construct a new `Client` with a custom connector
     pub fn new(connector: S) -> Self {
         Client {
             inner: connector,
-            retry_strategy: RetryHandlerFactory::new(RetryConfig::default()),
+            retry_handler: RetryHandlerFactory::new(RetryConfig::default()),
         }
     }
 
     pub fn with_retry_config(mut self, retry_config: RetryConfig) -> Self {
-        self.retry_strategy.with_config(retry_config);
+        self.retry_handler.with_config(retry_config);
         self
     }
 }
 
-impl Client<hyper::Client<HttpsConnector<HttpConnector>, SdkBody>> {
+impl Client<Standard> {
     /// Construct an `https` based client
-    pub fn https() -> Self {
-        let https = HttpsConnector::new();
-        let client = HyperClient::builder().build::<_, SdkBody>(https);
+    pub fn https() -> StandardClient {
         Client {
-            inner: client,
-            retry_strategy: RetryHandlerFactory::new(RetryConfig::default()),
+            inner: Standard::https(),
+            retry_handler: RetryHandlerFactory::new(RetryConfig::default()),
         }
     }
 }
@@ -115,7 +123,7 @@ where
         let inner = self.inner.clone();
         let mut svc = ServiceBuilder::new()
             // Create a new request-scoped policy
-            .retry(self.retry_strategy.new_handler())
+            .retry(self.retry_handler.new_handler())
             .layer(ParseResponseLayer::<O, Retry>::new())
             .layer(endpoint_resolver)
             .layer(signer)
@@ -135,4 +143,12 @@ mod tests {
     fn construct_default_client() {
         let _ = Client::https();
     }
+
+    #[test]
+    fn client_debug_includes_retry_info() {
+        let client = Client::https();
+        let s = format!("{:?}", client);
+        assert!(s.contains("RetryConfig"));
+        assert!(s.contains("quota_available"));
+    }
 }

aws/rust-runtime/aws-hyper/src/retry.rs

@@ -33,7 +33,7 @@ use tracing::Instrument;
 /// Without specific use cases, users should generally rely on the default values set by `[RetryConfig::default]`(RetryConfig::default).`
 ///
 /// Currently these fields are private and no setters provided. As needed, this configuration will become user-modifiable in the future..
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct RetryConfig {
     initial_retry_tokens: usize,
     retry_cost: usize,
@@ -87,6 +87,7 @@ const RETRY_COST: usize = 5;
 /// `CrossRequestRetryState`
 /// Its main functionality is via `new_handler` which creates a `RetryHandler` to manage the retry for
 /// an individual request.
+#[derive(Debug)]
 pub struct RetryHandlerFactory {
     config: RetryConfig,
     shared_state: CrossRequestRetryState,
@@ -132,7 +133,7 @@ impl RequestLocalRetryState {
 struct RetryPartition(Cow<'static, str>); */
 
 /// Shared state between multiple requests to the same client.
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 struct CrossRequestRetryState {
     quota_available: Arc<Mutex<usize>>,
 }

aws/rust-runtime/aws-hyper/src/test_connection.rs

@@ -47,6 +47,7 @@ impl ValidateRequest {
 /// - Response to requests with a preloaded series of responses
 /// - Record requests for future examination
 ///
+/// The generic parameter `B` is the type of the response body.
 /// For more complex use cases, see [Tower Test](https://docs.rs/tower-test/0.4.0/tower_test/)
 /// Usage example:
 /// ```rust
@@ -62,12 +63,21 @@ impl ValidateRequest {
 /// let conn = TestConnection::new(events);
 /// let client = aws_hyper::Client::new(conn);
 /// ```
-#[derive(Clone)]
 pub struct TestConnection<B> {
     data: Arc<Mutex<ConnectVec<B>>>,
     requests: Arc<Mutex<Vec<ValidateRequest>>>,
 }
 
+// Need a clone impl that ignores `B`
+impl<B> Clone for TestConnection<B> {
+    fn clone(&self) -> Self {
+        TestConnection {
+            data: self.data.clone(),
+            requests: self.requests.clone(),
+        }
+    }
+}
+
 impl<B> TestConnection<B> {
     pub fn new(mut data: ConnectVec<B>) -> Self {
         data.reverse();

aws/sdk/examples/kms-helloworld/src/main.rs

@@ -2,6 +2,7 @@ use kms::operation::GenerateRandom;
 use kms::Region;
 use tracing_subscriber::fmt::SubscriberBuilder;
 use tracing_subscriber::fmt::format::FmtSpan;
+use aws_hyper::StandardClient;
 
 #[tokio::main]
 async fn main() {
@@ -12,7 +13,7 @@ async fn main() {
         // creds loaded from environment variables, or they can be hard coded.
         // Other credential providers not currently supported
         .build();
-    let client = aws_hyper::Client::https();
+    let client: StandardClient = aws_hyper::Client::https();
     let data = client
         .call(GenerateRandom::builder().number_of_bytes(64).build(&config))
         .await

rust-runtime/inlineable/src/lib.rs

@@ -53,14 +53,22 @@ mod test {
     fn default_token_generator_smoke_test() {
         // smoke test to make sure the default token generator produces a token-like object
         use crate::idempotency_token::MakeIdempotencyToken;
-        assert_eq!(idempotency_token::default_provider().make_idempotency_token().len(), 36);
+        assert_eq!(
+            idempotency_token::default_provider()
+                .make_idempotency_token()
+                .len(),
+            36
+        );
     }
 
     #[test]
     fn token_generator() {
         let provider = Mutex::new(fastrand::Rng::with_seed(123));
         use crate::idempotency_token::MakeIdempotencyToken;
-        assert_eq!(provider.make_idempotency_token(), "b4021a03-ae07-4db5-fc1b-38bf919691f8");
+        assert_eq!(
+            provider.make_idempotency_token(),
+            "b4021a03-ae07-4db5-fc1b-38bf919691f8"
+        );
     }
 
     fn assert_valid(uuid: String) {