mirror of
https://github.com/tokio-rs/tokio.git
synced 2026-08-20 00:00:08 +02:00
Michael P. Jung
9211adbe01
Provide an asynchronous Semaphore implementation. This is useful for synchronizing concurrent access to a shared resource.
82 lines
1.9 KiB
Rust
82 lines
1.9 KiB
Rust
#![cfg(feature = "full")]
|
|
|
|
use std::sync::Arc;
|
|
use tokio::sync::Semaphore;
|
|
|
|
#[test]
|
|
fn no_permits() {
|
|
// this should not panic
|
|
Semaphore::new(0);
|
|
}
|
|
|
|
#[test]
|
|
fn try_acquire() {
|
|
let sem = Semaphore::new(1);
|
|
{
|
|
let p1 = sem.try_acquire();
|
|
assert!(p1.is_ok());
|
|
let p2 = sem.try_acquire();
|
|
assert!(p2.is_err());
|
|
}
|
|
let p3 = sem.try_acquire();
|
|
assert!(p3.is_ok());
|
|
}
|
|
|
|
#[tokio::test]
|
|
async fn acquire() {
|
|
let sem = Arc::new(Semaphore::new(1));
|
|
let p1 = sem.try_acquire().unwrap();
|
|
let sem_clone = sem.clone();
|
|
let j = tokio::spawn(async move {
|
|
let _p2 = sem_clone.acquire().await;
|
|
});
|
|
drop(p1);
|
|
j.await.unwrap();
|
|
}
|
|
|
|
#[tokio::test]
|
|
async fn add_permits() {
|
|
let sem = Arc::new(Semaphore::new(0));
|
|
let sem_clone = sem.clone();
|
|
let j = tokio::spawn(async move {
|
|
let _p2 = sem_clone.acquire().await;
|
|
});
|
|
sem.add_permits(1);
|
|
j.await.unwrap();
|
|
}
|
|
|
|
#[test]
|
|
fn forget() {
|
|
let sem = Arc::new(Semaphore::new(1));
|
|
{
|
|
let p = sem.try_acquire().unwrap();
|
|
assert_eq!(sem.available_permits(), 0);
|
|
p.forget();
|
|
assert_eq!(sem.available_permits(), 0);
|
|
}
|
|
assert_eq!(sem.available_permits(), 0);
|
|
assert!(sem.try_acquire().is_err());
|
|
}
|
|
|
|
#[tokio::test]
|
|
async fn stresstest() {
|
|
let sem = Arc::new(Semaphore::new(5));
|
|
let mut join_handles = Vec::new();
|
|
for _ in 0..1000 {
|
|
let sem_clone = sem.clone();
|
|
join_handles.push(tokio::spawn(async move {
|
|
let _p = sem_clone.acquire().await;
|
|
}));
|
|
}
|
|
for j in join_handles {
|
|
j.await.unwrap();
|
|
}
|
|
// there should be exactly 5 semaphores available now
|
|
let _p1 = sem.try_acquire().unwrap();
|
|
let _p2 = sem.try_acquire().unwrap();
|
|
let _p3 = sem.try_acquire().unwrap();
|
|
let _p4 = sem.try_acquire().unwrap();
|
|
let _p5 = sem.try_acquire().unwrap();
|
|
assert!(sem.try_acquire().is_err());
|
|
}
|