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Don't use unkillable in UnsafeArc dtor when there's no unwrapper. Close #8382.

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This commit is contained in:
Ben Blum 2013-08-07 20:26:15 -04:00
parent ecfc9a8223
commit ee5cfb0c2d
1 changed files with 21 additions and 19 deletions
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40
src/libstd/unstable/sync.rs
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@ -229,20 +229,22 @@ impl<T> Drop for UnsafeAtomicRcBox<T>{
if self.data.is_null() {
return; // Happens when destructing an unwrapper's handle.
}
do task::unkillable {
let mut data: ~AtomicRcBoxData<T> = cast::transmute(self.data);
// Must be acquire+release, not just release, to make sure this
// doesn't get reordered to after the unwrapper pointer load.
let old_count = data.count.fetch_sub(1, SeqCst);
assert!(old_count >= 1);
if old_count == 1 {
// Were we really last, or should we hand off to an
// unwrapper? It's safe to not xchg because the unwrapper
// will set the unwrap lock *before* dropping his/her
// reference. In effect, being here means we're the only
// *awake* task with the data.
match data.unwrapper.take(Acquire) {
Some(~(message,response)) => {
let mut data: ~AtomicRcBoxData<T> = cast::transmute(self.data);
// Must be acquire+release, not just release, to make sure this
// doesn't get reordered to after the unwrapper pointer load.
let old_count = data.count.fetch_sub(1, SeqCst);
assert!(old_count >= 1);
if old_count == 1 {
// Were we really last, or should we hand off to an
// unwrapper? It's safe to not xchg because the unwrapper
// will set the unwrap lock *before* dropping his/her
// reference. In effect, being here means we're the only
// *awake* task with the data.
match data.unwrapper.take(Acquire) {
Some(~(message,response)) => {
let cell = Cell::new((message, response, data));
do task::unkillable {
let (message, response, data) = cell.take();
// Send 'ready' and wait for a response.
message.send(());
// Unkillable wait. Message guaranteed to come.
@ -253,13 +255,13 @@ impl<T> Drop for UnsafeAtomicRcBox<T>{
// Other task was killed. drop glue takes over.
}
}
None => {
// drop glue takes over.
}
}
} else {
cast::forget(data);
None => {
// drop glue takes over.
}
}
} else {
cast::forget(data);
}
}
}