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Remove the per-Bus unparking thread #42

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Remove the per-Bus unparking thread #42

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20 changes: 1 addition & 19 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -294,9 +294,6 @@ pub struct Bus<T> {
mpsc::Receiver<(thread::Thread, usize)>,
),

// channel used to communicate to unparker that a given thread should be woken up
unpark: mpsc::Sender<thread::Thread>,

// cache used to keep track of threads waiting for next write.
// this is only here to avoid allocating one on every broadcast()
cache: Vec<(thread::Thread, usize)>,
Expand All @@ -310,7 +307,6 @@ impl<T> fmt::Debug for Bus<T> {
.field("rleft", &self.rleft)
.field("leaving", &self.leaving)
.field("waiting", &self.waiting)
.field("unpark", &self.unpark)
.field("cache", &self.cache)
.finish()
}
Expand Down Expand Up @@ -340,26 +336,12 @@ impl<T> Bus<T> {
let _ = time::Instant::now().elapsed();
}

// we run a separate thread responsible for unparking
// so we don't have to wait for unpark() to return in broadcast_inner
// sending on a channel without contention is cheap, unparking is not
let (unpark_tx, unpark_rx) = mpsc::unbounded::<thread::Thread>();
let _ = thread::Builder::new()
.name("bus_unparking".to_owned())
.spawn(move || {
for t in unpark_rx.iter() {
t.unpark();
}
});

Bus {
state: inner,
readers: 0,
rleft: iter::repeat(0).take(len).collect(),
leaving: mpsc::unbounded(),
waiting: mpsc::unbounded(),
unpark: unpark_tx,

cache: Vec::new(),
}
}
Expand Down Expand Up @@ -479,7 +461,7 @@ impl<T> Bus<T> {
if at == tail {
self.cache.push((t, at))
} else {
self.unpark.send(t).unwrap();
t.unpark();
}
}
for w in self.cache.drain(..) {
Expand Down