feat(lib): add optional tcp feature, split from runtime

The `HttpConnector` and `AddrListener` types which make use of
`tokio::tcp` have been made their own optional feature. This allows
using them without requiring the *full* tokio runtime.

src/client/connect/dns.rs

@@ -249,15 +249,18 @@ impl Iterator for IpAddrs {
 ///
 /// Unlike the `GaiResolver` this will not spawn dedicated threads, but only works when running on the
 /// multi-threaded Tokio runtime.
+#[cfg(feature = "runtime")]
 #[derive(Clone, Debug)]
 pub struct TokioThreadpoolGaiResolver(());
 
 /// The future returned by `TokioThreadpoolGaiResolver`.
+#[cfg(feature = "runtime")]
 #[derive(Debug)]
 pub struct TokioThreadpoolGaiFuture {
     name: Name,
 }
 
+#[cfg(feature = "runtime")]
 impl TokioThreadpoolGaiResolver {
     /// Creates a new DNS resolver that will use tokio threadpool's blocking
     /// feature.
@@ -268,6 +271,7 @@ impl TokioThreadpoolGaiResolver {
     }
 }
 
+#[cfg(feature = "runtime")]
 impl Resolve for TokioThreadpoolGaiResolver {
     type Addrs = GaiAddrs;
     type Future = TokioThreadpoolGaiFuture;
@@ -277,6 +281,7 @@ impl Resolve for TokioThreadpoolGaiResolver {
     }
 }
 
+#[cfg(feature = "runtime")]
 impl Future for TokioThreadpoolGaiFuture {
     type Output = Result<GaiAddrs, io::Error>;
 

src/client/connect/http.rs

@@ -14,7 +14,8 @@ use tokio_timer::Delay;
 
 use crate::common::{Future, Pin, Poll, task};
 use super::{Connect, Connected, Destination};
-use super::dns::{self, GaiResolver, Resolve, TokioThreadpoolGaiResolver};
+use super::dns::{self, GaiResolver, Resolve};
+#[cfg(feature = "runtime")] use super::dns::TokioThreadpoolGaiResolver;
 
 // TODO: unbox me?
 type ConnectFuture = Pin<Box<dyn Future<Output = io::Result<TcpStream>> + Send>>;
@@ -81,6 +82,7 @@ impl HttpConnector {
     }
 }
 
+#[cfg(feature = "runtime")]
 impl HttpConnector<TokioThreadpoolGaiResolver> {
     /// Construct a new HttpConnector using the `TokioThreadpoolGaiResolver`.
     ///

src/client/connect/mod.rs

@@ -15,9 +15,9 @@ use tokio_io::{AsyncRead, AsyncWrite};
 
 use crate::common::{Future, Unpin};
 
-#[cfg(feature = "runtime")] pub mod dns;
-#[cfg(feature = "runtime")] mod http;
-#[cfg(feature = "runtime")] pub use self::http::{HttpConnector, HttpInfo};
+#[cfg(feature = "tcp")] pub mod dns;
+#[cfg(feature = "tcp")] mod http;
+#[cfg(feature = "tcp")] pub use self::http::{HttpConnector, HttpInfo};
 
 /// Connect to a destination, returning an IO transport.
 ///

src/client/mod.rs

@@ -29,7 +29,7 @@
 //! ```
 //! use hyper::{Client, Uri};
 //!
-//! # #[cfg(feature = "runtime")]
+//! # #[cfg(feature = "tcp")]
 //! # async fn fetch_httpbin() -> hyper::Result<()> {
 //! let client = Client::new();
 //!
@@ -75,7 +75,7 @@ use crate::common::{lazy as hyper_lazy, Lazy, Future, Pin, Poll, task};
 use self::connect::{Alpn, Connect, Connected, Destination};
 use self::pool::{Key as PoolKey, Pool, Poolable, Pooled, Reservation};
 
-#[cfg(feature = "runtime")] pub use self::connect::HttpConnector;
+#[cfg(feature = "tcp")] pub use self::connect::HttpConnector;
 
 pub mod conn;
 pub mod connect;
@@ -110,7 +110,7 @@ pub struct ResponseFuture {
 
 // ===== impl Client =====
 
-#[cfg(feature = "runtime")]
+#[cfg(feature = "tcp")]
 impl Client<HttpConnector, Body> {
     /// Create a new Client with the default [config](Builder).
     ///
@@ -125,7 +125,7 @@ impl Client<HttpConnector, Body> {
     }
 }
 
-#[cfg(feature = "runtime")]
+#[cfg(feature = "tcp")]
 impl Default for Client<HttpConnector, Body> {
     fn default() -> Client<HttpConnector, Body> {
         Client::new()
@@ -1018,7 +1018,7 @@ impl Builder {
     }
 
     /// Builder a client with this configuration and the default `HttpConnector`.
-    #[cfg(feature = "runtime")]
+    #[cfg(feature = "tcp")]
     pub fn build_http<B>(&self) -> Client<HttpConnector, B>
     where
         B: Payload + Send,