test(http): addn a benchmark for encoding a response head

src/http/conn.rs

@@ -236,7 +236,7 @@ where I: AsyncRead + AsyncWrite,
         let wants_keep_alive = head.should_keep_alive();
         self.state.keep_alive &= wants_keep_alive;
         let mut buf = Vec::new();
-        let encoder = T::encode(&mut head, &mut buf);
+        let encoder = T::encode(head, &mut buf);
         //TODO: handle when there isn't enough room to buffer the head
         assert!(self.io.buffer(buf) > 0);
         self.state.writing = if body {

src/http/h1/parse.rs

@@ -86,7 +86,7 @@ impl Http1Transaction for ServerTransaction {
     }
 
 
-    fn encode(head: &mut MessageHead<Self::Outgoing>, dst: &mut Vec<u8>) -> Encoder {
+    fn encode(mut head: MessageHead<Self::Outgoing>, dst: &mut Vec<u8>) -> Encoder {
         use ::header;
         trace!("writing head: {:?}", head);
 
@@ -213,7 +213,7 @@ impl Http1Transaction for ClientTransaction {
         }
     }
 
-    fn encode(head: &mut MessageHead<Self::Outgoing>, dst: &mut Vec<u8>) -> Encoder {
+    fn encode(mut head: MessageHead<Self::Outgoing>, dst: &mut Vec<u8>) -> Encoder {
         trace!("writing head: {:?}", head);
 
 
@@ -421,4 +421,27 @@ mod tests {
             }
         }
     }
+
+    #[cfg(feature = "nightly")]
+    #[bench]
+    fn bench_server_transaction_encode(b: &mut Bencher) {
+        use ::http::MessageHead;
+        use ::header::{Headers, ContentLength};
+        use ::{StatusCode, HttpVersion};
+        b.bytes = 75;
+
+        let mut head = MessageHead {
+            subject: StatusCode::Ok,
+            headers: Headers::new(),
+            version: HttpVersion::Http11,
+        };
+        head.headers.set(ContentLength(0));
+
+        b.iter(|| {
+            let mut vec = Vec::new();
+            ServerTransaction::encode(head.clone(), &mut vec);
+            assert_eq!(vec.len(), 75);
+            ::test::black_box(vec);
+        })
+    }
 }

src/http/mod.rs

@@ -42,7 +42,7 @@ macro_rules! nonblocking {
 */
 
 /// An Incoming Message head. Includes request/status line, and headers.
-#[derive(Debug, Default, PartialEq)]
+#[derive(Clone, Debug, Default, PartialEq)]
 pub struct MessageHead<S> {
     /// HTTP version of the message.
     pub version: HttpVersion,
@@ -145,7 +145,7 @@ pub trait Http1Transaction {
     type Outgoing: Default;
     fn parse(bytes: &mut BytesMut) -> ParseResult<Self::Incoming>;
     fn decoder(head: &MessageHead<Self::Incoming>) -> ::Result<h1::Decoder>;
-    fn encode(head: &mut MessageHead<Self::Outgoing>, dst: &mut Vec<u8>) -> h1::Encoder;
+    fn encode(head: MessageHead<Self::Outgoing>, dst: &mut Vec<u8>) -> h1::Encoder;
     fn should_set_length(head: &MessageHead<Self::Outgoing>) -> bool;
 }