---

yaml
---
r: 22241
b: refs/heads/snap-stage3
c: c7354e6
h: refs/heads/master
i:
  22239: 6e4f26e
v: v3

Author: Daniel Patterson

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: e430a699f2c60890d9b86069fd0c68a70ece7120
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
-refs/heads/snap-stage3: 4d30b346733f345711a55504ef8abc81152c97a2
+refs/heads/snap-stage3: c7354e6c104ce88ef862501e6b65d0620314f849
 refs/heads/try: ffbe0e0e00374358b789b0037bcb3a577cd218be
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b

branches/snap-stage3/src/libcore/rand.rs

@@ -308,6 +308,33 @@ pub fn seeded_xorshift(x: u32, y: u32, z: u32, w: u32) -> Rng {
     {mut x: x, mut y: y, mut z: z, mut w: w} as Rng
 }
 
+
+// used to make space in TLS for a random number generator
+fn tls_rng_state(+_v: @RandRes) {}
+
+/**
+ * Gives back a lazily initialized task-local random number generator,
+ * seeded by the system. Intended to be used in method chaining style, ie
+ * task_rng().gen_int().
+ */
+pub fn task_rng() -> Rng {
+    let r : Option<@RandRes>;
+    unsafe {
+        r = task::local_data::local_data_get(tls_rng_state);
+    }
+    match r {
+        None => {
+            let rng = @RandRes(rustrt::rand_new());
+            unsafe {
+                task::local_data::local_data_set(tls_rng_state, rng);
+            }
+            rng as Rng
+        }
+        Some(rng) => rng as Rng
+    }
+}
+
+
 #[cfg(test)]
 pub mod tests {
     #[test]