test(h1): add benchmarks for server date checking and rendering

src/proto/h1/date.rs

@@ -59,11 +59,15 @@ impl CachedDate {
     }
 
     fn update(&mut self, now: time::Timespec) {
+        self.render(now);
+        self.next_update = now + Duration::seconds(1);
+        self.next_update.nsec = 0;
+    }
+
+    fn render(&mut self, now: time::Timespec) {
         self.pos = 0;
         let _ = write!(self, "{}", time::at_utc(now).rfc822());
         debug_assert!(self.pos == DATE_VALUE_LENGTH);
-        self.next_update = now + Duration::seconds(1);
-        self.next_update.nsec = 0;
     }
 }
 
@@ -76,7 +80,41 @@ impl fmt::Write for CachedDate {
     }
 }
 
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[cfg(feature = "nightly")]
+    use test::Bencher;
+
     #[test]
     fn test_date_len() {
         assert_eq!(DATE_VALUE_LENGTH, "Sun, 06 Nov 1994 08:49:37 GMT".len());
     }
+
+    #[cfg(feature = "nightly")]
+    #[bench]
+    fn bench_date_check(b: &mut Bencher) {
+        let mut date = CachedDate::new();
+        // cache the first update
+        date.check();
+
+        b.iter(|| {
+            date.check();
+        });
+    }
+
+    #[cfg(feature = "nightly")]
+    #[bench]
+    fn bench_date_render(b: &mut Bencher) {
+        let mut date = CachedDate::new();
+        let now = time::get_time();
+        date.render(now);
+        b.bytes = date.buffer().len() as u64;
+
+        b.iter(|| {
+            date.render(now);
+            test::black_box(&date);
+        });
+    }
+}