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auto merge of #8327 : sstewartgallus/rust/factor_out_waitqueue, r=bblum

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I'm a bit disappointed that I couldn't figure out how to factor out more of the code implementing `extra::sync` but I feel this is an okay start. Also I added some documentation explaining that `WaitQueue` isn't thread safe, and needs an exclusive lock.
 
@bblum
This commit is contained in:
bors 2013-08-10 07:47:14 -07:00
commit 2ba36ec629
1 changed files with 13 additions and 13 deletions
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26
src/libextra/sync.rs
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@ -72,6 +72,12 @@ impl WaitQueue {
}
count
}
fn wait_end(&self) -> WaitEnd {
let (wait_end, signal_end) = comm::oneshot();
self.tail.send_deferred(signal_end);
wait_end
}
}
// The building-block used to make semaphores, mutexes, and rwlocks.
@ -100,12 +106,9 @@ impl<Q:Send> Sem<Q> {
do (**self).with |state| {
state.count -= 1;
if state.count < 0 {
// Create waiter nobe.
let (WaitEnd, SignalEnd) = comm::oneshot();
// Tell outer scope we need to block.
waiter_nobe = Some(WaitEnd);
// Enqueue ourself.
state.waiters.tail.send_deferred(SignalEnd);
// Create waiter nobe, enqueue ourself, and tell
// outer scope we need to block.
waiter_nobe = Some(state.waiters.wait_end());
}
}
// Uncomment if you wish to test for sem races. Not valgrind-friendly.
@ -201,10 +204,7 @@ impl<'self> Condvar<'self> {
* wait() is equivalent to wait_on(0).
*/
pub fn wait_on(&self, condvar_id: uint) {
// Create waiter nobe.
let (WaitEnd, SignalEnd) = comm::oneshot();
let mut WaitEnd = Some(WaitEnd);
let mut SignalEnd = Some(SignalEnd);
let mut WaitEnd = None;
let mut out_of_bounds = None;
do task::unkillable {
// Release lock, 'atomically' enqueuing ourselves in so doing.
@ -216,9 +216,9 @@ impl<'self> Condvar<'self> {
if state.count <= 0 {
state.waiters.signal();
}
// Enqueue ourself to be woken up by a signaller.
let SignalEnd = SignalEnd.take_unwrap();
state.blocked[condvar_id].tail.send_deferred(SignalEnd);
// Create waiter nobe, and enqueue ourself to
// be woken up by a signaller.
WaitEnd = Some(state.blocked[condvar_id].wait_end());
} else {
out_of_bounds = Some(state.blocked.len());
}