library/std/src/sync/barrier/tests.rs

   1 use crate::sync::mpsc::{channel, TryRecvError};
   2 use crate::sync::{Arc, Barrier};
   3 use crate::thread;
   4
   5 #[test]
   6 #[cfg_attr(target_os = "emscripten", ignore)]
   7 fn test_barrier() {
   8     const N: usize = 10;
   9
  10     let barrier = Arc::new(Barrier::new(N));
  11     let (tx, rx) = channel();
  12
  13     for _ in 0..N - 1 {
  14         let c = barrier.clone();
  15         let tx = tx.clone();
  16         thread::spawn(move || {
  17             tx.send(c.wait().is_leader()).unwrap();
  18         });
  19     }
  20
  21     // At this point, all spawned threads should be blocked,
  22     // so we shouldn't get anything from the port
  23     assert!(matches!(rx.try_recv(), Err(TryRecvError::Empty)));
  24
  25     let mut leader_found = barrier.wait().is_leader();
  26
  27     // Now, the barrier is cleared and we should get data.
  28     for _ in 0..N - 1 {
  29         if rx.recv().unwrap() {
  30             assert!(!leader_found);
  31             leader_found = true;
  32         }
  33     }
  34     assert!(leader_found);
  35 }