build docs for apln and tls features

.travis.yml

@@ -72,7 +72,7 @@ script:
 after_success:
   - |
     if [[ "$TRAVIS_OS_NAME" == "linux" && "$TRAVIS_PULL_REQUEST" = "false" && "$TRAVIS_BRANCH" == "master" && "$TRAVIS_RUST_VERSION" == "1.21.0" ]]; then
-      cargo doc --features alpn --no-deps &&
+      cargo doc --features "alpn, tls" --no-deps &&
       echo "<meta http-equiv=refresh content=0;url=os_balloon/index.html>" > target/doc/index.html &&
       cargo install mdbook &&
       cd guide && mdbook build -d ../target/doc/guide && cd .. &&

src/server/worker.rs

@@ -6,15 +6,14 @@ use tokio_core::net::TcpStream;
 use tokio_core::reactor::Handle;
 use net2::TcpStreamExt;
 
-#[cfg(feature="tls")]
+#[cfg(any(feature="tls", feature="alpn"))]
 use futures::future;
+
 #[cfg(feature="tls")]
 use native_tls::TlsAcceptor;
 #[cfg(feature="tls")]
 use tokio_tls::TlsAcceptorExt;
 
-#[cfg(feature="alpn")]
-use futures::future;
 #[cfg(feature="alpn")]
 use openssl::ssl::SslAcceptor;
 #[cfg(feature="alpn")]