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add counting latch low level waiters #110

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Merged
qwp0905 merged 1 commit into from
May 6, 2026
Merged

add counting latch low level waiters #110

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12 changes: 9 additions & 3 deletions src/cache/latch.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ use crate::utils::ShortenedMutex;
struct State {
locked: bool,
high_waiters: usize,
low_waiters: usize,
}

pub struct Latch {
Expand All @@ -18,6 +19,7 @@ impl Latch {
state: Mutex::new(State {
locked: false,
high_waiters: 0,
low_waiters: 0,
}),
high_cv: Condvar::new(),
low_cv: Condvar::new(),
Expand Down Expand Up @@ -45,7 +47,9 @@ impl Latch {
{
let mut state = self.state.l();
while state.locked || state.high_waiters > 0 {
state.low_waiters += 1;
state = self.low_cv.wait(state).unwrap();
state.low_waiters -= 1;
}
state.locked = true;

Expand All @@ -56,10 +60,12 @@ impl Latch {
let mut state = self.state.l();
state.locked = false;
if state.high_waiters > 0 {
self.high_cv.notify_one();
} else {
self.low_cv.notify_one();
return self.high_cv.notify_one();
}
if state.low_waiters == 0 {
return;
}
self.low_cv.notify_one();
}
}

Expand Down
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