From dec9db10da062b1c528d46426d9f62e201d39bc6 Mon Sep 17 00:00:00 2001
From: Brian Anderson <banderson@mozilla.com>
Date: Tue, 28 May 2013 18:39:52 -0700
Subject: [PATCH] core::rt: Add SleeperList

Just a simple place to stuff handles to sleeping schedulers.
---
 src/libcore/rt/mod.rs          |  3 +++
 src/libcore/rt/sleeper_list.rs | 46 ++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 src/libcore/rt/sleeper_list.rs

diff --git a/src/libcore/rt/mod.rs b/src/libcore/rt/mod.rs
index f136732c00b9..82496ec55894 100644
--- a/src/libcore/rt/mod.rs
+++ b/src/libcore/rt/mod.rs
@@ -88,6 +88,9 @@ mod work_queue;
 /// A parallel queue.
 mod message_queue;
 
+/// A parallel data structure for tracking sleeping schedulers.
+mod sleeper_list;
+
 /// Stack segments and caching.
 mod stack;
 
diff --git a/src/libcore/rt/sleeper_list.rs b/src/libcore/rt/sleeper_list.rs
new file mode 100644
index 000000000000..9507dec001d5
--- /dev/null
+++ b/src/libcore/rt/sleeper_list.rs
@@ -0,0 +1,46 @@
+// 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.
+
+//! Maintains a shared list of sleeping schedulers. Schedulers
+//! use this to wake each other up.
+
+use container::Container;
+use vec::OwnedVector;
+use option::{Option, Some, None};
+use cell::Cell;
+use unstable::sync::{Exclusive, exclusive};
+use rt::sched::{Scheduler, SchedHandle};
+
+pub struct SleeperList {
+    priv stack: ~Exclusive<~[SchedHandle]>
+}
+
+impl SleeperList {
+    pub fn new() -> SleeperList {
+        SleeperList {
+            stack: ~exclusive(~[])
+        }
+    }
+
+    pub fn push(&mut self, handle: SchedHandle) {
+        let handle = Cell(handle);
+        self.stack.with(|s| s.push(handle.take()));
+    }
+
+    pub fn pop(&mut self) -> Option<SchedHandle> {
+        do self.stack.with |s| {
+            if !s.is_empty() {
+                Some(s.pop())
+            } else {
+                None
+            }
+        }
+    }
+}