Use 'AtomicIsize', not 'Cell', in URI.

lib/src/http/uri.rs

@@ -1,25 +1,29 @@
 //! Borrowed and owned string types for absolute URIs.
 
-use std::cell::Cell;
 use std::convert::From;
 use std::fmt;
 use std::borrow::Cow;
 use std::str::Utf8Error;
+use std::sync::atomic::{AtomicIsize, Ordering};
 
 use url;
 
 /// Index (start, end) into a string, to prevent borrowing.
 type Index = (usize, usize);
 
+/// Representation of an empty segment count.
+const EMPTY: isize = -1;
+
 // TODO: Reconsider deriving PartialEq and Eq to make "//a/b" == "/a/b".
 /// Borrowed string type for absolute URIs.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug)]
 pub struct URI<'a> {
     uri: Cow<'a, str>,
     path: Index,
     query: Option<Index>,
     fragment: Option<Index>,
-    segment_count: Cell<Option<usize>>,
+    // The cached segment count. `EMPTY` is used to represent no segment count.
+    segment_count: AtomicIsize,
 }
 
 impl<'a> URI<'a> {
@@ -43,7 +47,7 @@ impl<'a> URI<'a> {
             path: path,
             query: query,
             fragment: fragment,
-            segment_count: Cell::new(None),
+            segment_count: AtomicIsize::new(EMPTY),
         }
     }
 
@@ -74,11 +78,17 @@ impl<'a> URI<'a> {
     /// ```
     #[inline(always)]
     pub fn segment_count(&self) -> usize {
-        self.segment_count.get().unwrap_or_else(|| {
-            let count = self.segments().count();
-            self.segment_count.set(Some(count));
-            count
-        })
+        let count = self.segment_count.load(Ordering::Relaxed);
+        if count == EMPTY {
+            let real_count = self.segments().count();
+            if real_count <= isize::max_value() as usize {
+                self.segment_count.store(real_count as isize, Ordering::Relaxed);
+            }
+
+            real_count
+        } else {
+            count as usize
+        }
     }
 
     /// Returns an iterator over the segments of the path in this URI. Skips
@@ -275,6 +285,30 @@ impl<'a> URI<'a> {
     }
 }
 
+impl<'a> Clone for URI<'a> {
+    #[inline(always)]
+    fn clone(&self) -> URI<'a> {
+        URI {
+            uri: self.uri.clone(),
+            path: self.path,
+            query: self.query,
+            fragment: self.fragment,
+            segment_count: AtomicIsize::new(EMPTY),
+        }
+    }
+}
+
+impl<'a, 'b> PartialEq<URI<'b>> for URI<'a> {
+    #[inline]
+    fn eq(&self, other: &URI<'b>) -> bool {
+        self.path() == other.path() &&
+            self.query() == other.query() &&
+            self.fragment() == other.fragment()
+    }
+}
+
+impl<'a> Eq for URI<'a> {}
+
 impl<'a> From<&'a str> for URI<'a> {
     #[inline(always)]
     fn from(uri: &'a str) -> URI<'a> {
@@ -312,8 +346,6 @@ impl<'a> fmt::Display for URI<'a> {
     }
 }
 
-unsafe impl<'a> Sync for URI<'a> { /* It's safe! */ }
-
 /// Iterator over the segments of an absolute URI path. Skips empty segments.
 ///
 /// ### Examples
@@ -405,6 +437,12 @@ mod tests {
         actual == expected
     }
 
+    #[test]
+    fn send_and_sync() {
+        fn assert<T: Send + Sync>() {};
+        assert::<URI>();
+    }
+
     #[test]
     fn simple_segment_count() {
         assert!(seg_count("", 0));

lib/src/rocket.rs

@@ -72,7 +72,6 @@ impl hyper::Handler for Rocket {
         };
 
         // Dispatch the request to get a response, then write that response out.
-        // let req = UnsafeCell::new(req);
         let response = self.dispatch(&mut req, data);
         self.issue_response(response, res)
     }