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std::rt: Fix a race in the UvRemoteCallback dtor

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This commit is contained in:
Brian Anderson 2013-06-06 17:46:45 -07:00
parent d6ccc6bc99
commit d4de99aa6c
1 changed files with 15 additions and 11 deletions
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26
src/libstd/rt/uv/uvio.rs
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@ -24,7 +24,7 @@ use rt::sched::Scheduler;
use rt::io::{standard_error, OtherIoError};
use rt::tube::Tube;
use rt::local::Local;
use unstable::sync::{UnsafeAtomicRcBox, AtomicInt};
use unstable::sync::{Exclusive, exclusive};
#[cfg(test)] use container::Container;
#[cfg(test)] use uint;
@ -105,21 +105,20 @@ fn test_callback_run_once() {
pub struct UvRemoteCallback {
// The uv async handle for triggering the callback
async: AsyncWatcher,
// An atomic flag to tell the callback to exit,
// set from the dtor.
exit_flag: UnsafeAtomicRcBox<AtomicInt>
// A flag to tell the callback to exit, set from the dtor. This is
// almost never contested - only in rare races with the dtor.
exit_flag: Exclusive<bool>
}
impl UvRemoteCallback {
pub fn new(loop_: &mut Loop, f: ~fn()) -> UvRemoteCallback {
let exit_flag = UnsafeAtomicRcBox::new(AtomicInt::new(0));
let exit_flag = exclusive(false);
let exit_flag_clone = exit_flag.clone();
let async = do AsyncWatcher::new(loop_) |watcher, status| {
assert!(status.is_none());
f();
let exit_flag_ptr = exit_flag_clone.get();
unsafe {
if (*exit_flag_ptr).load() == 1 {
do exit_flag_clone.with_imm |&should_exit| {
if should_exit {
watcher.close(||());
}
}
@ -139,9 +138,14 @@ impl Drop for UvRemoteCallback {
fn finalize(&self) {
unsafe {
let this: &mut UvRemoteCallback = cast::transmute_mut(self);
let exit_flag_ptr = this.exit_flag.get();
(*exit_flag_ptr).store(1);
this.async.send();
do this.exit_flag.with |should_exit| {
// NB: These two things need to happen atomically. Otherwise
// the event handler could wake up due to a *previous*
// signal and see the exit flag, destroying the handle
// before the final send.
*should_exit = true;
this.async.send();
}
}
}
}