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#![allow(unused)]
use super::sync::{Condvar, Mutex};
#[derive(Default)]
pub(crate) struct Signal {
value: Mutex<usize>,
cond_var: Condvar,
}
impl Signal {
pub(crate) fn signal(&self, stage: usize) {
// When running with shuttle we want to explore as many possible
// executions, so we avoid signals entirely.
#[cfg(not(feature = "shuttle"))]
{
// This check avoids acquiring the lock for things that will
// clearly be a no-op. Not *necessary* but helps to ensure we
// are more likely to encounter weird race conditions;
// otherwise calls to `sum` will tend to be unnecessarily
// synchronous.
if stage > 0 {
let mut v = self.value.lock().unwrap();
if stage > *v {
*v = stage;
self.cond_var.notify_all();
}
}
}
}
/// Waits until the given condition is true; the fn is invoked
/// with the current stage.
pub(crate) fn wait_for(&self, stage: usize) {
#[cfg(not(feature = "shuttle"))]
{
// As above, avoid lock if clearly a no-op.
if stage > 0 {
let mut v = self.value.lock().unwrap();
while *v < stage {
v = self.cond_var.wait(v).unwrap();
}
}
}
}
}