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fix async Philosopher execise livelock error (#2372)

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xiaohu-zhang 2024-09-20 20:13:16 +08:00 committed by GitHub
parent 7a6abee0da
commit db0b161424
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1 changed files with 8 additions and 22 deletions
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30
src/concurrency/async-exercises/dining-philosophers.rs
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@ -43,26 +43,9 @@ impl Philosopher {
async fn eat(&self) {
// Keep trying until we have both forks
// ANCHOR_END: Philosopher-eat
let (_left_fork, _right_fork) = loop {
// Pick up forks...
let left_fork = self.left_fork.try_lock();
let right_fork = self.right_fork.try_lock();
let Ok(left_fork) = left_fork else {
// If we didn't get the left fork, drop the right fork if we
// have it and let other tasks make progress.
drop(right_fork);
time::sleep(time::Duration::from_millis(1)).await;
continue;
};
let Ok(right_fork) = right_fork else {
// If we didn't get the right fork, drop the left fork and let
// other tasks make progress.
drop(left_fork);
time::sleep(time::Duration::from_millis(1)).await;
continue;
};
break (left_fork, right_fork);
};
// Pick up forks...
let _left_fork = self.left_fork.lock().await;
let _right_fork = self.right_fork.lock().await;
// ANCHOR: Philosopher-eat-body
println!("{} is eating...", &self.name);
@ -89,8 +72,11 @@ async fn main() {
let mut philosophers = vec![];
let (tx, rx) = mpsc::channel(10);
for (i, name) in PHILOSOPHERS.iter().enumerate() {
let left_fork = Arc::clone(&forks[i]);
let right_fork = Arc::clone(&forks[(i + 1) % PHILOSOPHERS.len()]);
let mut left_fork = Arc::clone(&forks[i]);
let mut right_fork = Arc::clone(&forks[(i + 1) % PHILOSOPHERS.len()]);
if i == PHILOSOPHERS.len() - 1 {
std::mem::swap(&mut left_fork, &mut right_fork);
}
philosophers.push(Philosopher {
name: name.to_string(),
left_fork,