feat(server): Make the server code an optional feature (#2334)

cc #2223 

BREAKING CHANGE: The HTTP server code is now an optional feature. To
  enable the server, add `features = ["server"]` to the dependency in
  your `Cargo.toml`.

Cargo.toml

@@ -75,13 +75,15 @@ default = [
     "runtime",
     "stream",
     "client",
+    "server",
     "http1",
     "http2",
 ]
 full = [
     "client",
     "http1",
     "http2",
+    "server",
     "stream",
     "runtime",
 ]
@@ -100,7 +102,9 @@ tcp = [
 http1 = []
 http2 = ["h2"]
 
+# Client/Server
 client = []
+server = []
 
 # `impl Stream` for things
 stream = []

src/body/body.rs

@@ -21,7 +21,7 @@ use crate::common::{task, watch, Pin, Poll};
 #[cfg(any(feature = "http1", feature = "http2"))]
 #[cfg(feature = "client")]
 use crate::common::{Future, Never};
-#[cfg(feature = "http2")]
+#[cfg(all(feature = "http2", any(feature = "client", feature = "server")))]
 use crate::proto::h2::ping;
 use crate::upgrade::OnUpgrade;
 
@@ -46,7 +46,7 @@ enum Kind {
         want_tx: watch::Sender,
         rx: mpsc::Receiver<Result<Bytes, crate::Error>>,
     },
-    #[cfg(feature = "http2")]
+    #[cfg(all(feature = "http2", any(feature = "client", feature = "server")))]
     H2 {
         ping: ping::Recorder,
         content_length: DecodedLength,
@@ -200,7 +200,7 @@ impl Body {
         Body { kind, extra: None }
     }
 
-    #[cfg(feature = "http2")]
+    #[cfg(all(feature = "http2", any(feature = "client", feature = "server")))]
     pub(crate) fn h2(
         recv: h2::RecvStream,
         content_length: DecodedLength,
@@ -301,7 +301,7 @@ impl Body {
                     None => Poll::Ready(None),
                 }
             }
-            #[cfg(feature = "http2")]
+            #[cfg(all(feature = "http2", any(feature = "client", feature = "server")))]
             Kind::H2 {
                 ref ping,
                 recv: ref mut h2,
@@ -359,7 +359,7 @@ impl HttpBody for Body {
         #[cfg_attr(not(feature = "http2"), allow(unused))] cx: &mut task::Context<'_>,
     ) -> Poll<Result<Option<HeaderMap>, Self::Error>> {
         match self.kind {
-            #[cfg(feature = "http2")]
+            #[cfg(all(feature = "http2", any(feature = "client", feature = "server")))]
             Kind::H2 {
                 recv: ref mut h2,
                 ref ping,
@@ -379,7 +379,7 @@ impl HttpBody for Body {
         match self.kind {
             Kind::Once(ref val) => val.is_none(),
             Kind::Chan { content_length, .. } => content_length == DecodedLength::ZERO,
-            #[cfg(feature = "http2")]
+            #[cfg(all(feature = "http2", any(feature = "client", feature = "server")))]
             Kind::H2 { recv: ref h2, .. } => h2.is_end_stream(),
             #[cfg(feature = "stream")]
             Kind::Wrapped(..) => false,
@@ -405,7 +405,7 @@ impl HttpBody for Body {
             #[cfg(feature = "stream")]
             Kind::Wrapped(..) => SizeHint::default(),
             Kind::Chan { content_length, .. } => opt_len!(content_length),
-            #[cfg(feature = "http2")]
+            #[cfg(all(feature = "http2", any(feature = "client", feature = "server")))]
             Kind::H2 { content_length, .. } => opt_len!(content_length),
         }
     }

src/cfg.rs

@@ -11,16 +11,19 @@ macro_rules! cfg_feature {
     }
 }
 
-macro_rules! cfg_any_http {
+macro_rules! cfg_proto {
     ($($item:item)*) => {
         cfg_feature! {
-            #![any(feature = "http1", feature = "http2")]
+            #![all(
+                any(feature = "http1", feature = "http2"),
+                any(feature = "client", feature = "server"),
+            )]
             $($item)*
         }
     }
 }
 
-cfg_any_http! {
+cfg_proto! {
     macro_rules! cfg_http1 {
         ($($item:item)*) => {
             cfg_feature! {
@@ -47,4 +50,13 @@ cfg_any_http! {
             }
         }
     }
+
+    macro_rules! cfg_server {
+        ($($item:item)*) => {
+            cfg_feature! {
+                #![feature = "server"]
+                $($item)*
+            }
+        }
+    }
 }

src/common/exec.rs

@@ -3,17 +3,23 @@ use std::future::Future;
 use std::pin::Pin;
 use std::sync::Arc;
 
+#[cfg(feature = "server")]
 use crate::body::{Body, HttpBody};
 #[cfg(feature = "http2")]
+#[cfg(feature = "server")]
 use crate::proto::h2::server::H2Stream;
 use crate::rt::Executor;
+#[cfg(feature = "server")]
 use crate::server::conn::spawn_all::{NewSvcTask, Watcher};
+#[cfg(feature = "server")]
 use crate::service::HttpService;
 
+#[cfg(feature = "server")]
 pub trait ConnStreamExec<F, B: HttpBody>: Clone {
     fn execute_h2stream(&mut self, fut: H2Stream<F, B>);
 }
 
+#[cfg(feature = "server")]
 pub trait NewSvcExec<I, N, S: HttpService<Body>, E, W: Watcher<I, S, E>>: Clone {
     fn execute_new_svc(&mut self, fut: NewSvcTask<I, N, S, E, W>);
 }
@@ -60,6 +66,7 @@ impl fmt::Debug for Exec {
     }
 }
 
+#[cfg(feature = "server")]
 impl<F, B> ConnStreamExec<F, B> for Exec
 where
     H2Stream<F, B>: Future<Output = ()> + Send + 'static,
@@ -70,6 +77,7 @@ where
     }
 }
 
+#[cfg(feature = "server")]
 impl<I, N, S, E, W> NewSvcExec<I, N, S, E, W> for Exec
 where
     NewSvcTask<I, N, S, E, W>: Future<Output = ()> + Send + 'static,
@@ -83,6 +91,7 @@ where
 
 // ==== impl Executor =====
 
+#[cfg(feature = "server")]
 impl<E, F, B> ConnStreamExec<F, B> for E
 where
     E: Executor<H2Stream<F, B>> + Clone,
@@ -94,6 +103,7 @@ where
     }
 }
 
+#[cfg(feature = "server")]
 impl<I, N, S, E, W> NewSvcExec<I, N, S, E, W> for E
 where
     E: Executor<NewSvcTask<I, N, S, E, W>> + Clone,
@@ -119,7 +129,7 @@ pub struct H2Stream<F, B>(std::marker::PhantomData<(F, B)>);
 impl<F, B, E> Future for H2Stream<F, B>
 where
     F: Future<Output = Result<http::Response<B>, E>>,
-    B: HttpBody,
+    B: crate::body::HttpBody,
     B::Error: Into<Box<dyn std::error::Error + Send + Sync>>,
     E: Into<Box<dyn std::error::Error + Send + Sync>>,
 {

src/common/io/rewind.rs

@@ -15,6 +15,7 @@ pub(crate) struct Rewind<T> {
 
 impl<T> Rewind<T> {
     #[cfg(any(feature = "http2", test))]
+    #[cfg(feature = "server")]
     pub(crate) fn new(io: T) -> Self {
         Rewind {
             pre: None,
@@ -29,7 +30,7 @@ impl<T> Rewind<T> {
         }
     }
 
-    #[cfg(any(all(feature = "http1", feature = "http2"), test))]
+    #[cfg(any(all(feature = "http1", feature = "http2", feature = "server"), test))]
     pub(crate) fn rewind(&mut self, bs: Bytes) {
         debug_assert!(self.pre.is_none());
         self.pre = Some(bs);

src/common/mod.rs

@@ -9,8 +9,10 @@ macro_rules! ready {
 
 pub(crate) mod buf;
 #[cfg(any(feature = "http1", feature = "http2"))]
+#[cfg(feature = "server")]
 pub(crate) mod date;
 #[cfg(any(feature = "http1", feature = "http2"))]
+#[cfg(feature = "server")]
 pub(crate) mod drain;
 #[cfg(any(feature = "http1", feature = "http2"))]
 pub(crate) mod exec;
@@ -24,15 +26,14 @@ pub(crate) mod sync_wrapper;
 pub(crate) mod task;
 pub(crate) mod watch;
 
-//#[cfg(any(feature = "http1", feature = "http2"))]
-//pub(crate) use self::exec::{BoxSendFuture, Exec};
 #[cfg(any(feature = "http1", feature = "http2"))]
 #[cfg(feature = "client")]
 pub(crate) use self::lazy::{lazy, Started as Lazy};
 pub use self::never::Never;
 pub(crate) use self::task::Poll;
 
 // group up types normally needed for `Future`
-#[cfg(any(feature = "http1", feature = "http2"))]
-pub(crate) use std::marker::Unpin;
+cfg_proto! {
+    pub(crate) use std::marker::Unpin;
+}
 pub(crate) use std::{future::Future, pin::Pin};

src/error.rs

@@ -36,10 +36,15 @@ pub(crate) enum Kind {
     /// Error occurred while connecting.
     Connect,
     /// Error creating a TcpListener.
-    #[cfg(all(any(feature = "http1", feature = "http2"), feature = "tcp"))]
+    #[cfg(all(
+        any(feature = "http1", feature = "http2"),
+        feature = "tcp",
+        feature = "server"
+    ))]
     Listen,
     /// Error accepting on an Incoming stream.
     #[cfg(any(feature = "http1", feature = "http2"))]
+    #[cfg(feature = "server")]
     Accept,
     /// Error while reading a body from connection.
     #[cfg(any(feature = "http1", feature = "http2", feature = "stream"))]
@@ -77,6 +82,7 @@ pub(crate) enum User {
     Body,
     /// Error calling user's MakeService.
     #[cfg(any(feature = "http1", feature = "http2"))]
+    #[cfg(feature = "server")]
     MakeService,
     /// Error from future of user's Service.
     #[cfg(any(feature = "http1", feature = "http2"))]
@@ -85,6 +91,7 @@ pub(crate) enum User {
     ///
     /// For example, sending both `content-length` and `transfer-encoding`.
     #[cfg(feature = "http1")]
+    #[cfg(feature = "server")]
     UnexpectedHeader,
     /// User tried to create a Request with bad version.
     #[cfg(any(feature = "http1", feature = "http2"))]
@@ -96,6 +103,7 @@ pub(crate) enum User {
     UnsupportedRequestMethod,
     /// User tried to respond with a 1xx (not 101) response code.
     #[cfg(feature = "http1")]
+    #[cfg(feature = "server")]
     UnsupportedStatusCode,
     /// User tried to send a Request with Client with non-absolute URI.
     #[cfg(any(feature = "http1", feature = "http2"))]
@@ -178,6 +186,7 @@ impl Error {
     }
 
     #[cfg(feature = "http1")]
+    #[cfg(feature = "server")]
     pub(crate) fn kind(&self) -> &Kind {
         &self.inner.kind
     }
@@ -234,11 +243,13 @@ impl Error {
     }
 
     #[cfg(all(any(feature = "http1", feature = "http2"), feature = "tcp"))]
+    #[cfg(feature = "server")]
     pub(crate) fn new_listen<E: Into<Cause>>(cause: E) -> Error {
         Error::new(Kind::Listen).with(cause)
     }
 
     #[cfg(any(feature = "http1", feature = "http2"))]
+    #[cfg(feature = "server")]
     pub(crate) fn new_accept<E: Into<Cause>>(cause: E) -> Error {
         Error::new(Kind::Accept).with(cause)
     }
@@ -272,6 +283,7 @@ impl Error {
     }
 
     #[cfg(feature = "http1")]
+    #[cfg(feature = "server")]
     pub(crate) fn new_user_header() -> Error {
         Error::new_user(User::UnexpectedHeader)
     }
@@ -289,6 +301,7 @@ impl Error {
     }
 
     #[cfg(feature = "http1")]
+    #[cfg(feature = "server")]
     pub(crate) fn new_user_unsupported_status_code() -> Error {
         Error::new_user(User::UnsupportedStatusCode)
     }
@@ -309,6 +322,7 @@ impl Error {
     }
 
     #[cfg(any(feature = "http1", feature = "http2"))]
+    #[cfg(feature = "server")]
     pub(crate) fn new_user_make_service<E: Into<Cause>>(cause: E) -> Error {
         Error::new_user(User::MakeService).with(cause)
     }
@@ -354,8 +368,10 @@ impl Error {
             Kind::Connect => "error trying to connect",
             Kind::Canceled => "operation was canceled",
             #[cfg(all(any(feature = "http1", feature = "http2"), feature = "tcp"))]
+            #[cfg(feature = "server")]
             Kind::Listen => "error creating server listener",
             #[cfg(any(feature = "http1", feature = "http2"))]
+            #[cfg(feature = "server")]
             Kind::Accept => "error accepting connection",
             #[cfg(any(feature = "http1", feature = "http2", feature = "stream"))]
             Kind::Body => "error reading a body from connection",
@@ -372,10 +388,12 @@ impl Error {
             #[cfg(any(feature = "http1", feature = "http2"))]
             Kind::User(User::Body) => "error from user's HttpBody stream",
             #[cfg(any(feature = "http1", feature = "http2"))]
+            #[cfg(feature = "server")]
             Kind::User(User::MakeService) => "error from user's MakeService",
             #[cfg(any(feature = "http1", feature = "http2"))]
             Kind::User(User::Service) => "error from user's Service",
             #[cfg(feature = "http1")]
+            #[cfg(feature = "server")]
             Kind::User(User::UnexpectedHeader) => "user sent unexpected header",
             #[cfg(any(feature = "http1", feature = "http2"))]
             #[cfg(feature = "client")]
@@ -384,6 +402,7 @@ impl Error {
             #[cfg(feature = "client")]
             Kind::User(User::UnsupportedRequestMethod) => "request has unsupported HTTP method",
             #[cfg(feature = "http1")]
+            #[cfg(feature = "server")]
             Kind::User(User::UnsupportedStatusCode) => {
                 "response has 1xx status code, not supported by server"
             }

src/headers.rs

@@ -30,6 +30,7 @@ fn connection_has(value: &HeaderValue, needle: &str) -> bool {
 }
 
 #[cfg(feature = "http1")]
+#[cfg(feature = "server")]
 pub fn content_length_parse(value: &HeaderValue) -> Option<u64> {
     value.to_str().ok().and_then(|s| s.parse().ok())
 }

src/lib.rs

@@ -68,12 +68,9 @@ pub mod rt;
 pub mod service;
 pub mod upgrade;
 
-cfg_any_http! {
+cfg_proto! {
     mod headers;
     mod proto;
-    pub mod server;
-
-    pub use crate::server::Server;
 }
 
 cfg_feature! {
@@ -82,3 +79,10 @@ cfg_feature! {
     pub mod client;
     pub use crate::client::Client;
 }
+
+cfg_feature! {
+    #![all(feature = "server", any(feature = "http1", feature = "http2"))]
+
+    pub mod server;
+    pub use crate::server::Server;
+}