1 files changed, 124 insertions, 0 deletions
diff --git a/third_party/rust/hyper/src/common/date.rs b/third_party/rust/hyper/src/common/date.rs
new file mode 100644
index 0000000000..a436fc07c0
--- /dev/null
+++ b/third_party/rust/hyper/src/common/date.rs
@@ -0,0 +1,124 @@
+use std::cell::RefCell;
+use std::fmt::{self, Write};
+use std::str;
+use std::time::{Duration, SystemTime};
+
+#[cfg(feature = "http2")]
+use http::header::HeaderValue;
+use httpdate::HttpDate;
+
+// "Sun, 06 Nov 1994 08:49:37 GMT".len()
+pub(crate) const DATE_VALUE_LENGTH: usize = 29;
+
+#[cfg(feature = "http1")]
+pub(crate) fn extend(dst: &mut Vec<u8>) {
+    CACHED.with(|cache| {
+        dst.extend_from_slice(cache.borrow().buffer());
+    })
+}
+
+#[cfg(feature = "http1")]
+pub(crate) fn update() {
+    CACHED.with(|cache| {
+        cache.borrow_mut().check();
+    })
+}
+
+#[cfg(feature = "http2")]
+pub(crate) fn update_and_header_value() -> HeaderValue {
+    CACHED.with(|cache| {
+        let mut cache = cache.borrow_mut();
+        cache.check();
+        HeaderValue::from_bytes(cache.buffer()).expect("Date format should be valid HeaderValue")
+    })
+}
+
+struct CachedDate {
+    bytes: [u8; DATE_VALUE_LENGTH],
+    pos: usize,
+    next_update: SystemTime,
+}
+
+thread_local!(static CACHED: RefCell<CachedDate> = RefCell::new(CachedDate::new()));
+
+impl CachedDate {
+    fn new() -> Self {
+        let mut cache = CachedDate {
+            bytes: [0; DATE_VALUE_LENGTH],
+            pos: 0,
+            next_update: SystemTime::now(),
+        };
+        cache.update(cache.next_update);
+        cache
+    }
+
+    fn buffer(&self) -> &[u8] {
+        &self.bytes[..]
+    }
+
+    fn check(&mut self) {
+        let now = SystemTime::now();
+        if now > self.next_update {
+            self.update(now);
+        }
+    }
+
+    fn update(&mut self, now: SystemTime) {
+        self.render(now);
+        self.next_update = now + Duration::new(1, 0);
+    }
+
+    fn render(&mut self, now: SystemTime) {
+        self.pos = 0;
+        let _ = write!(self, "{}", HttpDate::from(now));
+        debug_assert!(self.pos == DATE_VALUE_LENGTH);
+    }
+}
+
+impl fmt::Write for CachedDate {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        let len = s.len();
+        self.bytes[self.pos..self.pos + len].copy_from_slice(s.as_bytes());
+        self.pos += len;
+        Ok(())
+    }
+}
+
+#[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 = SystemTime::now();
+        date.render(now);
+        b.bytes = date.buffer().len() as u64;
+
+        b.iter(|| {
+            date.render(now);
+            test::black_box(&date);
+        });
+    }
+}