mirror of https://github.com/bastion-rs/bastion
58 lines
1.6 KiB
Rust
58 lines
1.6 KiB
Rust
//!
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//! Where workers went to parking while no workload is in their worker queue.
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//!
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//! If a workload received pool will wake them up.
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use std::sync::atomic::{AtomicBool, Ordering};
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use std::sync::{Condvar, Mutex};
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/// The place where worker threads go to sleep.
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///
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/// Similar to how thread parking works, if a notification comes up while no threads are sleeping,
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/// the next thread that attempts to go to sleep will pick up the notification immediately.
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#[derive(Debug)]
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pub struct Sleepers {
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/// How many threads are currently a sleep.
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sleep: Mutex<usize>,
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/// A condvar for notifying sleeping threads.
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wake: Condvar,
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/// Set to `true` if a notification came up while nobody was sleeping.
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notified: AtomicBool,
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}
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impl Sleepers {
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/// Creates a new `Sleepers`.
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pub fn new() -> Sleepers {
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Sleepers {
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sleep: Mutex::new(0),
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wake: Condvar::new(),
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notified: AtomicBool::new(false),
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}
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}
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/// Puts the current thread to sleep.
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pub fn wait(&self) {
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let mut sleep = self.sleep.lock().unwrap();
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if !self.notified.swap(false, Ordering::SeqCst) {
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*sleep += 1;
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let _ = self.wake.wait(sleep).unwrap();
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}
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}
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/// Notifies one thread.
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pub fn notify_one(&self) {
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if !self.notified.load(Ordering::SeqCst) {
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let mut sleep = self.sleep.lock().unwrap();
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if *sleep > 0 {
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*sleep -= 1;
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self.wake.notify_one();
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} else {
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self.notified.store(true, Ordering::SeqCst);
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}
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}
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}
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}
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