Created
July 16, 2022 09:26
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waitgroup full impl
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| use std::{thread, time::Duration}; | |
| mod sync_primitives { | |
| use std::sync::atomic::{AtomicUsize, Ordering}; | |
| use std::sync::{Arc, Condvar, Mutex}; | |
| struct Wg { | |
| counter: AtomicUsize, | |
| mu: Mutex<bool>, | |
| condvar: Condvar, | |
| } | |
| impl Wg { | |
| fn new() -> Self { | |
| Wg { | |
| counter: AtomicUsize::new(0), | |
| mu: Mutex::new(false), | |
| condvar: Condvar::new(), | |
| } | |
| } | |
| } | |
| pub struct WaitGroup(Arc<Wg>); | |
| impl WaitGroup { | |
| pub fn new() -> Self { | |
| WaitGroup(Arc::new(Wg::new())) | |
| } | |
| pub fn wait(&self) { | |
| let mut started = self.0.mu.lock().unwrap(); | |
| while !*started { | |
| started = self.0.condvar.wait(started).unwrap(); | |
| if self.0.counter.load(Ordering::Relaxed) == 0 { | |
| *started = true; | |
| } | |
| } | |
| } | |
| } | |
| impl Clone for WaitGroup { | |
| fn clone(&self) -> Self { | |
| self.0.counter.fetch_add(1, Ordering::Relaxed); | |
| Self(self.0.clone()) | |
| } | |
| } | |
| impl Drop for WaitGroup { | |
| fn drop(&mut self) { | |
| self.0.counter.fetch_sub(1, Ordering::Relaxed); | |
| self.0.condvar.notify_one(); | |
| } | |
| } | |
| } | |
| fn main() { | |
| use sync_primitives::WaitGroup; | |
| let wg = WaitGroup::new(); | |
| for i in 1..5 { | |
| let wg = wg.clone(); | |
| thread::spawn(move || { | |
| println!("t{} going to sleep for {} secs", i, i); | |
| thread::sleep(Duration::from_secs(i)); | |
| println!("t{} woke up", i); | |
| drop(wg); | |
| }); | |
| } | |
| wg.wait(); | |
| println!("exiting.."); | |
| } |
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