---

yaml
---
r: 125423
b: refs/heads/master
c: 355c798
h: refs/heads/master
i:
  125421: c4ad202
  125419: 5d7792e
  125415: fb2e629
  125407: 53505e3
v: v3

Author: alexcrichton

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: e156d001c6577593295f6eee417ea8758fbc4a84
+refs/heads/master: 355c798ac3eba15bb2d53a6c553c6149391f9615
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: 9fc8394d3bce22ab483f98842434c84c396212ae
 refs/heads/try: e5e0db5bc45aa2de6887fbf51dec013ca5c025c6

trunk/src/libnative/task.rs

@@ -71,7 +71,7 @@ pub fn spawn_opts(opts: TaskOpts, f: proc():Send) {
     // Note that this increment must happen *before* the spawn in order to
     // guarantee that if this task exits it will always end up waiting for the
     // spawned task to exit.
-    bookkeeping::increment();
+    let token = bookkeeping::increment();
 
     // Spawning a new OS thread guarantees that __morestack will never get
     // triggered, but we must manually set up the actual stack bounds once this
@@ -93,7 +93,7 @@ pub fn spawn_opts(opts: TaskOpts, f: proc():Send) {
         let mut task = task;
         task.put_runtime(ops);
         drop(task.run(|| { f.take_unwrap()() }).destroy());
-        bookkeeping::decrement();
+        drop(token);
     })
 }
 

trunk/src/librustrt/bookkeeping.rs

@@ -19,14 +19,24 @@
 //! decrement() manually.
 
 use core::atomics;
+use core::ops::Drop;
 
 use mutex::{StaticNativeMutex, NATIVE_MUTEX_INIT};
 
 static mut TASK_COUNT: atomics::AtomicUint = atomics::INIT_ATOMIC_UINT;
 static mut TASK_LOCK: StaticNativeMutex = NATIVE_MUTEX_INIT;
 
-pub fn increment() {
+pub struct Token(());
+
+impl Drop for Token {
+    fn drop(&mut self) { decrement() }
+}
+
+/// Increment the number of live tasks, returning a token which will decrement
+/// the count when dropped.
+pub fn increment() -> Token {
     let _ = unsafe { TASK_COUNT.fetch_add(1, atomics::SeqCst) };
+    Token(())
 }
 
 pub fn decrement() {