1 files changed, 26 insertions, 5 deletions
diff --git a/src/libstd/sys/common/helper_thread.rs b/src/libstd/sys/common/helper_thread.rs
index 9ef1c33312f..7093c417b11 100644
--- a/src/libstd/sys/common/helper_thread.rs
+++ b/src/libstd/sys/common/helper_thread.rs
@@ -20,6 +20,8 @@
 //! can be created in the future and there must be no active timers at that
 //! time.
 
+#![macro_escape]
+
 use prelude::*;
 
 use cell::UnsafeCell;
@@ -68,6 +70,17 @@ struct RaceBox(helper_signal::signal);
 unsafe impl Send for RaceBox {}
 unsafe impl Sync for RaceBox {}
 
+macro_rules! helper_init { (static $name:ident: Helper<$m:ty>) => (
+    static $name: Helper<$m> = Helper {
+        lock: ::sync::MUTEX_INIT,
+        cond: ::sync::CONDVAR_INIT,
+        chan: ::cell::UnsafeCell { value: 0 as *mut Sender<$m> },
+        signal: ::cell::UnsafeCell { value: 0 },
+        initialized: ::cell::UnsafeCell { value: false },
+        shutdown: ::cell::UnsafeCell { value: false },
+    };
+) }
+
 impl<M: Send> Helper<M> {
     /// Lazily boots a helper thread, becoming a no-op if the helper has already
     /// been spawned.
@@ -84,7 +97,7 @@ impl<M: Send> Helper<M> {
     {
         unsafe {
             let _guard = self.lock.lock().unwrap();
-            if !*self.initialized.get() {
+            if *self.chan.get() as uint == 0 {
                 let (tx, rx) = channel();
                 *self.chan.get() = mem::transmute(box tx);
                 let (receive, send) = helper_signal::new();
@@ -93,15 +106,17 @@ impl<M: Send> Helper<M> {
                 let receive = RaceBox(receive);
 
                 let t = f();
-                Thread::spawn(move |:| {
+                Thread::spawn(move || {
                     helper(receive.0, rx, t);
                     let _g = self.lock.lock().unwrap();
                     *self.shutdown.get() = true;
                     self.cond.notify_one()
                 }).detach();
 
-                rt::at_exit(move|:| { self.shutdown() });
+                rt::at_exit(move || { self.shutdown() });
                 *self.initialized.get() = true;
+            } else if *self.chan.get() as uint == 1 {
+                panic!("cannot continue usage after shutdown");
             }
         }
     }
@@ -116,7 +131,9 @@ impl<M: Send> Helper<M> {
             // Must send and *then* signal to ensure that the child receives the
             // message. Otherwise it could wake up and go to sleep before we
             // send the message.
-            assert!(!self.chan.get().is_null());
+            assert!(*self.chan.get() as uint != 0);
+            assert!(*self.chan.get() as uint != 1,
+                    "cannot continue usage after shutdown");
             (**self.chan.get()).send(msg);
             helper_signal::signal(*self.signal.get() as helper_signal::signal);
         }
@@ -129,9 +146,13 @@ impl<M: Send> Helper<M> {
             // returns.
             let mut guard = self.lock.lock().unwrap();
 
+            let ptr = *self.chan.get();
+            if ptr as uint == 1 {
+                panic!("cannot continue usage after shutdown");
+            }
             // Close the channel by destroying it
             let chan: Box<Sender<M>> = mem::transmute(*self.chan.get());
-            *self.chan.get() = 0 as *mut Sender<M>;
+            *self.chan.get() = 1 as *mut Sender<M>;
             drop(chan);
             helper_signal::signal(*self.signal.get() as helper_signal::signal);