fix(client): never call connect if idle connection is available

The HttpConnector's connect future was lazy, but if any custom connector
did not use a lazy future, then a connect would always be started, even
if an idle connection was available.

Author: seanmonstar

src/client/mod.rs

@@ -182,22 +182,25 @@ where C: Connect,
             let pool = self.pool.clone();
             let pool_key = Rc::new(domain.to_string());
             let h1_writev = self.h1_writev;
-            self.connector.connect(url)
-                .and_then(move |io| {
-                    let (tx, rx) = dispatch::channel();
-                    let tx = HyperClient {
-                        tx: tx,
-                        should_close: Cell::new(true),
-                    };
-                    let pooled = pool.pooled(pool_key, tx);
-                    let mut conn = proto::Conn::<_, _, proto::ClientTransaction, _>::new(io, pooled.clone());
-                    if !h1_writev {
-                        conn.set_write_strategy_flatten();
-                    }
-                    let dispatch = proto::dispatch::Dispatcher::new(proto::dispatch::Client::new(rx), conn);
-                    executor.execute(dispatch.map_err(|e| debug!("client connection error: {}", e)))?;
-                    Ok(pooled)
-                })
+            let connector = self.connector.clone();
+            future::lazy(move || {
+                connector.connect(url)
+                    .and_then(move |io| {
+                        let (tx, rx) = dispatch::channel();
+                        let tx = HyperClient {
+                            tx: tx,
+                            should_close: Cell::new(true),
+                        };
+                        let pooled = pool.pooled(pool_key, tx);
+                        let mut conn = proto::Conn::<_, _, proto::ClientTransaction, _>::new(io, pooled.clone());
+                        if !h1_writev {
+                            conn.set_write_strategy_flatten();
+                        }
+                        let dispatch = proto::dispatch::Dispatcher::new(proto::dispatch::Client::new(rx), conn);
+                        executor.execute(dispatch.map_err(|e| debug!("client connection error: {}", e)))?;
+                        Ok(pooled)
+                    })
+            })
         };
 
         let race = checkout.select(connect)

tests/client.rs

@@ -725,7 +725,7 @@ mod dispatch_impl {
         let handle = core.handle();
         let closes = Arc::new(AtomicUsize::new(0));
         let client = Client::configure()
-            .connector(DebugConnector(HttpConnector::new(1, &core.handle()), closes.clone()))
+            .connector(DebugConnector::with_http_and_closes(HttpConnector::new(1, &core.handle()), closes.clone()))
             .build(&handle);
 
         let (tx1, rx1) = oneshot::channel();
@@ -784,7 +784,7 @@ mod dispatch_impl {
 
         let res = {
             let client = Client::configure()
-                .connector(DebugConnector(HttpConnector::new(1, &handle), closes.clone()))
+                .connector(DebugConnector::with_http_and_closes(HttpConnector::new(1, &handle), closes.clone()))
                 .build(&handle);
             client.get(uri).and_then(move |res| {
                 assert_eq!(res.status(), hyper::StatusCode::Ok);
@@ -834,7 +834,7 @@ mod dispatch_impl {
         let uri = format!("http://{}/a", addr).parse().unwrap();
 
         let client = Client::configure()
-            .connector(DebugConnector(HttpConnector::new(1, &handle), closes.clone()))
+            .connector(DebugConnector::with_http_and_closes(HttpConnector::new(1, &handle), closes.clone()))
             .build(&handle);
         let res = client.get(uri).and_then(move |res| {
             assert_eq!(res.status(), hyper::StatusCode::Ok);
@@ -883,7 +883,7 @@ mod dispatch_impl {
 
         let res = {
             let client = Client::configure()
-                .connector(DebugConnector(HttpConnector::new(1, &handle), closes.clone()))
+                .connector(DebugConnector::with_http_and_closes(HttpConnector::new(1, &handle), closes.clone()))
                 .build(&handle);
             client.get(uri)
         };
@@ -927,7 +927,7 @@ mod dispatch_impl {
 
         let res = {
             let client = Client::configure()
-                .connector(DebugConnector(HttpConnector::new(1, &handle), closes.clone()))
+                .connector(DebugConnector::with_http_and_closes(HttpConnector::new(1, &handle), closes.clone()))
                 .build(&handle);
             // notably, havent read body yet
             client.get(uri)
@@ -966,7 +966,7 @@ mod dispatch_impl {
         let uri = format!("http://{}/a", addr).parse().unwrap();
 
         let client = Client::configure()
-            .connector(DebugConnector(HttpConnector::new(1, &handle), closes.clone()))
+            .connector(DebugConnector::with_http_and_closes(HttpConnector::new(1, &handle), closes.clone()))
             .keep_alive(false)
             .build(&handle);
         let res = client.get(uri).and_then(move |res| {
@@ -1005,7 +1005,7 @@ mod dispatch_impl {
         let uri = format!("http://{}/a", addr).parse().unwrap();
 
         let client = Client::configure()
-            .connector(DebugConnector(HttpConnector::new(1, &handle), closes.clone()))
+            .connector(DebugConnector::with_http_and_closes(HttpConnector::new(1, &handle), closes.clone()))
             .build(&handle);
         let res = client.get(uri).and_then(move |res| {
             assert_eq!(res.status(), hyper::StatusCode::Ok);
@@ -1095,7 +1095,7 @@ mod dispatch_impl {
         let uri = format!("http://{}/a", addr).parse().unwrap();
 
         let client = Client::configure()
-            .connector(DebugConnector(HttpConnector::new(1, &handle), closes.clone()))
+            .connector(DebugConnector::with_http_and_closes(HttpConnector::new(1, &handle), closes.clone()))
             .executor(handle.clone());
         let res = client.get(uri).and_then(move |res| {
             assert_eq!(res.status(), hyper::StatusCode::Ok);
@@ -1110,7 +1110,79 @@ mod dispatch_impl {
         assert_eq!(closes.load(Ordering::Relaxed), 1);
     }
 
-    struct DebugConnector(HttpConnector, Arc<AtomicUsize>);
+    #[test]
+    fn idle_conn_prevents_connect_call() {
+        let _ = pretty_env_logger::try_init();
+
+        let server = TcpListener::bind("127.0.0.1:0").unwrap();
+        let addr = server.local_addr().unwrap();
+        let mut core = Core::new().unwrap();
+        let handle = core.handle();
+        let connector = DebugConnector::new(&handle);
+        let connects = connector.connects.clone();
+
+        let (tx1, rx1) = oneshot::channel();
+        let (tx2, rx2) = oneshot::channel();
+
+        thread::spawn(move || {
+            let mut sock = server.accept().unwrap().0;
+            sock.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
+            sock.set_write_timeout(Some(Duration::from_secs(5))).unwrap();
+            let mut buf = [0; 4096];
+            sock.read(&mut buf).expect("read 1");
+            sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n").unwrap();
+            let _ = tx1.send(());
+
+            sock.read(&mut buf).expect("read 2");
+            sock.write_all(b"HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n").unwrap();
+            let _ = tx2.send(());
+        });
+
+        let uri: hyper::Uri = format!("http://{}/a", addr).parse().unwrap();
+
+        let client = Client::configure()
+            .connector(connector)
+            .build(&handle);
+
+        let res = client.get(uri.clone()).and_then(move |res| {
+            assert_eq!(res.status(), hyper::StatusCode::Ok);
+            res.body().concat2()
+        });
+        let rx = rx1.map_err(|_| hyper::Error::Io(io::Error::new(io::ErrorKind::Other, "thread panicked")));
+        core.run(res.join(rx).map(|r| r.0)).unwrap();
+        assert_eq!(connects.load(Ordering::Relaxed), 1);
+
+        let res2 = client.get(uri).and_then(move |res| {
+            assert_eq!(res.status(), hyper::StatusCode::Ok);
+            res.body().concat2()
+        });
+        let rx = rx2.map_err(|_| hyper::Error::Io(io::Error::new(io::ErrorKind::Other, "thread panicked")));
+        core.run(res2.join(rx).map(|r| r.0)).unwrap();
+
+        assert_eq!(connects.load(Ordering::Relaxed), 1);
+    }
+
+
+    struct DebugConnector {
+        http: HttpConnector,
+        closes: Arc<AtomicUsize>,
+        connects: Arc<AtomicUsize>,
+    }
+
+    impl DebugConnector {
+        fn new(handle: &Handle) -> DebugConnector {
+            let http = HttpConnector::new(1, handle);
+            DebugConnector::with_http_and_closes(http, Arc::new(AtomicUsize::new(0)))
+        }
+
+        fn with_http_and_closes(http: HttpConnector, closes: Arc<AtomicUsize>) -> DebugConnector {
+            DebugConnector {
+                http: http,
+                closes: closes,
+                connects: Arc::new(AtomicUsize::new(0)),
+            }
+        }
+    }
 
     impl Service for DebugConnector {
         type Request = Uri;
@@ -1119,8 +1191,11 @@ mod dispatch_impl {
         type Future = Box<Future<Item = DebugStream, Error = io::Error>>;
 
         fn call(&self, uri: Uri) -> Self::Future {
-            let counter = self.1.clone();
-            Box::new(self.0.call(uri).map(move |s| DebugStream(s, counter)))
+            self.connects.fetch_add(1, Ordering::SeqCst);
+            let closes = self.closes.clone();
+            Box::new(self.http.call(uri).map(move |s| {
+                DebugStream(s, closes)
+            }))
         }
     }