41 lines
1.1 KiB
Rust
41 lines
1.1 KiB
Rust
use parking_lot::{Condvar, Mutex};
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#[derive(Default)]
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pub(crate) struct Signal {
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value: Mutex<usize>,
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cond_var: Condvar,
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}
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impl Signal {
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pub(crate) fn signal(&self, stage: usize) {
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tracing::debug!("signal({})", stage);
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// This check avoids acquiring the lock for things that will
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// clearly be a no-op. Not *necessary* but helps to ensure we
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// are more likely to encounter weird race conditions;
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// otherwise calls to `sum` will tend to be unnecessarily
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// synchronous.
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if stage > 0 {
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let mut v = self.value.lock();
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if stage > *v {
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*v = stage;
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self.cond_var.notify_all();
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}
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}
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}
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/// Waits until the given condition is true; the fn is invoked
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/// with the current stage.
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pub(crate) fn wait_for(&self, stage: usize) {
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tracing::debug!("wait_for({})", stage);
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// As above, avoid lock if clearly a no-op.
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if stage > 0 {
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let mut v = self.value.lock();
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while *v < stage {
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self.cond_var.wait(&mut v);
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}
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}
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}
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}
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