core::rt: Add MessageQueue type

This is the queue used to send messages to Schedulers

src/libcore/rt/message_queue.rs

@@ -0,0 +1,44 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use container::Container;
+use kinds::Owned;
+use vec::OwnedVector;
+use cell::Cell;
+use option::*;
+use unstable::sync::{Exclusive, exclusive};
+
+pub struct MessageQueue<T> {
+    // XXX: Another mystery bug fixed by boxing this lock
+    priv queue: ~Exclusive<~[T]>
+}
+
+impl<T: Owned> MessageQueue<T> {
+    pub fn new() -> MessageQueue<T> {
+        MessageQueue {
+            queue: ~exclusive(~[])
+        }
+    }
+
+    pub fn push(&mut self, value: T) {
+        let value = Cell(value);
+        self.queue.with(|q| q.push(value.take()) );
+    }
+
+    pub fn pop(&mut self) -> Option<T> {
+        do self.queue.with |q| {
+            if !q.is_empty() {
+                Some(q.shift())
+            } else {
+                None
+            }
+        }
+    }
+}

src/libcore/rt/mod.rs

@@ -91,9 +91,12 @@ pub mod uv;
 /// Bindings to pthread/windows thread-local storage.
 pub mod thread_local_storage;
 
-/// A parallel work-stealing dequeue.
+/// A parallel work-stealing deque.
 mod work_queue;
 
+/// A parallel queue.
+mod message_queue;
+
 /// Stack segments and caching.
 mod stack;