Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1328 insertions, 0 deletions

diff --git a/third_party/rust/crossbeam-channel/tests/select.rs b/third_party/rust/crossbeam-channel/tests/select.rs
new file mode 100644
index 0000000000..bc5824daba
--- /dev/null
+++ b/third_party/rust/crossbeam-channel/tests/select.rs
@@ -0,0 +1,1328 @@
+//! Tests for channel selection using the `Select` struct.
+
+#![allow(clippy::drop_copy)]
+
+use std::any::Any;
+use std::cell::Cell;
+use std::thread;
+use std::time::{Duration, Instant};
+
+use crossbeam_channel::{after, bounded, tick, unbounded, Receiver, Select, TryRecvError};
+use crossbeam_utils::thread::scope;
+
+fn ms(ms: u64) -> Duration {
+    Duration::from_millis(ms)
+}
+
+#[test]
+fn smoke1() {
+    let (s1, r1) = unbounded::<usize>();
+    let (s2, r2) = unbounded::<usize>();
+
+    s1.send(1).unwrap();
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r1);
+    let oper2 = sel.recv(&r2);
+    let oper = sel.select();
+    match oper.index() {
+        i if i == oper1 => assert_eq!(oper.recv(&r1), Ok(1)),
+        i if i == oper2 => panic!(),
+        _ => unreachable!(),
+    }
+
+    s2.send(2).unwrap();
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r1);
+    let oper2 = sel.recv(&r2);
+    let oper = sel.select();
+    match oper.index() {
+        i if i == oper1 => panic!(),
+        i if i == oper2 => assert_eq!(oper.recv(&r2), Ok(2)),
+        _ => unreachable!(),
+    }
+}
+
+#[test]
+fn smoke2() {
+    let (_s1, r1) = unbounded::<i32>();
+    let (_s2, r2) = unbounded::<i32>();
+    let (_s3, r3) = unbounded::<i32>();
+    let (_s4, r4) = unbounded::<i32>();
+    let (s5, r5) = unbounded::<i32>();
+
+    s5.send(5).unwrap();
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r1);
+    let oper2 = sel.recv(&r2);
+    let oper3 = sel.recv(&r3);
+    let oper4 = sel.recv(&r4);
+    let oper5 = sel.recv(&r5);
+    let oper = sel.select();
+    match oper.index() {
+        i if i == oper1 => panic!(),
+        i if i == oper2 => panic!(),
+        i if i == oper3 => panic!(),
+        i if i == oper4 => panic!(),
+        i if i == oper5 => assert_eq!(oper.recv(&r5), Ok(5)),
+        _ => unreachable!(),
+    }
+}
+
+#[test]
+fn disconnected() {
+    let (s1, r1) = unbounded::<i32>();
+    let (s2, r2) = unbounded::<i32>();
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            drop(s1);
+            thread::sleep(ms(500));
+            s2.send(5).unwrap();
+        });
+
+        let mut sel = Select::new();
+        let oper1 = sel.recv(&r1);
+        let oper2 = sel.recv(&r2);
+        let oper = sel.select_timeout(ms(1000));
+        match oper {
+            Err(_) => panic!(),
+            Ok(oper) => match oper.index() {
+                i if i == oper1 => assert!(oper.recv(&r1).is_err()),
+                i if i == oper2 => panic!(),
+                _ => unreachable!(),
+            },
+        }
+
+        r2.recv().unwrap();
+    })
+    .unwrap();
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r1);
+    let oper2 = sel.recv(&r2);
+    let oper = sel.select_timeout(ms(1000));
+    match oper {
+        Err(_) => panic!(),
+        Ok(oper) => match oper.index() {
+            i if i == oper1 => assert!(oper.recv(&r1).is_err()),
+            i if i == oper2 => panic!(),
+            _ => unreachable!(),
+        },
+    }
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            thread::sleep(ms(500));
+            drop(s2);
+        });
+
+        let mut sel = Select::new();
+        let oper1 = sel.recv(&r2);
+        let oper = sel.select_timeout(ms(1000));
+        match oper {
+            Err(_) => panic!(),
+            Ok(oper) => match oper.index() {
+                i if i == oper1 => assert!(oper.recv(&r2).is_err()),
+                _ => unreachable!(),
+            },
+        }
+    })
+    .unwrap();
+}
+
+#[test]
+fn default() {
+    let (s1, r1) = unbounded::<i32>();
+    let (s2, r2) = unbounded::<i32>();
+
+    let mut sel = Select::new();
+    let _oper1 = sel.recv(&r1);
+    let _oper2 = sel.recv(&r2);
+    let oper = sel.try_select();
+    match oper {
+        Err(_) => {}
+        Ok(_) => panic!(),
+    }
+
+    drop(s1);
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r1);
+    let oper2 = sel.recv(&r2);
+    let oper = sel.try_select();
+    match oper {
+        Err(_) => panic!(),
+        Ok(oper) => match oper.index() {
+            i if i == oper1 => assert!(oper.recv(&r1).is_err()),
+            i if i == oper2 => panic!(),
+            _ => unreachable!(),
+        },
+    }
+
+    s2.send(2).unwrap();
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r2);
+    let oper = sel.try_select();
+    match oper {
+        Err(_) => panic!(),
+        Ok(oper) => match oper.index() {
+            i if i == oper1 => assert_eq!(oper.recv(&r2), Ok(2)),
+            _ => unreachable!(),
+        },
+    }
+
+    let mut sel = Select::new();
+    let _oper1 = sel.recv(&r2);
+    let oper = sel.try_select();
+    match oper {
+        Err(_) => {}
+        Ok(_) => panic!(),
+    }
+
+    let mut sel = Select::new();
+    let oper = sel.try_select();
+    match oper {
+        Err(_) => {}
+        Ok(_) => panic!(),
+    }
+}
+
+#[test]
+fn timeout() {
+    let (_s1, r1) = unbounded::<i32>();
+    let (s2, r2) = unbounded::<i32>();
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            thread::sleep(ms(1500));
+            s2.send(2).unwrap();
+        });
+
+        let mut sel = Select::new();
+        let oper1 = sel.recv(&r1);
+        let oper2 = sel.recv(&r2);
+        let oper = sel.select_timeout(ms(1000));
+        match oper {
+            Err(_) => {}
+            Ok(oper) => match oper.index() {
+                i if i == oper1 => panic!(),
+                i if i == oper2 => panic!(),
+                _ => unreachable!(),
+            },
+        }
+
+        let mut sel = Select::new();
+        let oper1 = sel.recv(&r1);
+        let oper2 = sel.recv(&r2);
+        let oper = sel.select_timeout(ms(1000));
+        match oper {
+            Err(_) => panic!(),
+            Ok(oper) => match oper.index() {
+                i if i == oper1 => panic!(),
+                i if i == oper2 => assert_eq!(oper.recv(&r2), Ok(2)),
+                _ => unreachable!(),
+            },
+        }
+    })
+    .unwrap();
+
+    scope(|scope| {
+        let (s, r) = unbounded::<i32>();
+
+        scope.spawn(move |_| {
+            thread::sleep(ms(500));
+            drop(s);
+        });
+
+        let mut sel = Select::new();
+        let oper = sel.select_timeout(ms(1000));
+        match oper {
+            Err(_) => {
+                let mut sel = Select::new();
+                let oper1 = sel.recv(&r);
+                let oper = sel.try_select();
+                match oper {
+                    Err(_) => panic!(),
+                    Ok(oper) => match oper.index() {
+                        i if i == oper1 => assert!(oper.recv(&r).is_err()),
+                        _ => unreachable!(),
+                    },
+                }
+            }
+            Ok(_) => unreachable!(),
+        }
+    })
+    .unwrap();
+}
+
+#[test]
+fn default_when_disconnected() {
+    let (_, r) = unbounded::<i32>();
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r);
+    let oper = sel.try_select();
+    match oper {
+        Err(_) => panic!(),
+        Ok(oper) => match oper.index() {
+            i if i == oper1 => assert!(oper.recv(&r).is_err()),
+            _ => unreachable!(),
+        },
+    }
+
+    let (_, r) = unbounded::<i32>();
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r);
+    let oper = sel.select_timeout(ms(1000));
+    match oper {
+        Err(_) => panic!(),
+        Ok(oper) => match oper.index() {
+            i if i == oper1 => assert!(oper.recv(&r).is_err()),
+            _ => unreachable!(),
+        },
+    }
+
+    let (s, _) = bounded::<i32>(0);
+
+    let mut sel = Select::new();
+    let oper1 = sel.send(&s);
+    let oper = sel.try_select();
+    match oper {
+        Err(_) => panic!(),
+        Ok(oper) => match oper.index() {
+            i if i == oper1 => assert!(oper.send(&s, 0).is_err()),
+            _ => unreachable!(),
+        },
+    }
+
+    let (s, _) = bounded::<i32>(0);
+
+    let mut sel = Select::new();
+    let oper1 = sel.send(&s);
+    let oper = sel.select_timeout(ms(1000));
+    match oper {
+        Err(_) => panic!(),
+        Ok(oper) => match oper.index() {
+            i if i == oper1 => assert!(oper.send(&s, 0).is_err()),
+            _ => unreachable!(),
+        },
+    }
+}
+
+#[test]
+fn default_only() {
+    let start = Instant::now();
+
+    let mut sel = Select::new();
+    let oper = sel.try_select();
+    assert!(oper.is_err());
+    let now = Instant::now();
+    assert!(now - start <= ms(50));
+
+    let start = Instant::now();
+    let mut sel = Select::new();
+    let oper = sel.select_timeout(ms(500));
+    assert!(oper.is_err());
+    let now = Instant::now();
+    assert!(now - start >= ms(450));
+    assert!(now - start <= ms(550));
+}
+
+#[test]
+fn unblocks() {
+    let (s1, r1) = bounded::<i32>(0);
+    let (s2, r2) = bounded::<i32>(0);
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            thread::sleep(ms(500));
+            s2.send(2).unwrap();
+        });
+
+        let mut sel = Select::new();
+        let oper1 = sel.recv(&r1);
+        let oper2 = sel.recv(&r2);
+        let oper = sel.select_timeout(ms(1000));
+        match oper {
+            Err(_) => panic!(),
+            Ok(oper) => match oper.index() {
+                i if i == oper1 => panic!(),
+                i if i == oper2 => assert_eq!(oper.recv(&r2), Ok(2)),
+                _ => unreachable!(),
+            },
+        }
+    })
+    .unwrap();
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            thread::sleep(ms(500));
+            assert_eq!(r1.recv().unwrap(), 1);
+        });
+
+        let mut sel = Select::new();
+        let oper1 = sel.send(&s1);
+        let oper2 = sel.send(&s2);
+        let oper = sel.select_timeout(ms(1000));
+        match oper {
+            Err(_) => panic!(),
+            Ok(oper) => match oper.index() {
+                i if i == oper1 => oper.send(&s1, 1).unwrap(),
+                i if i == oper2 => panic!(),
+                _ => unreachable!(),
+            },
+        }
+    })
+    .unwrap();
+}
+
+#[test]
+fn both_ready() {
+    let (s1, r1) = bounded(0);
+    let (s2, r2) = bounded(0);
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            thread::sleep(ms(500));
+            s1.send(1).unwrap();
+            assert_eq!(r2.recv().unwrap(), 2);
+        });
+
+        for _ in 0..2 {
+            let mut sel = Select::new();
+            let oper1 = sel.recv(&r1);
+            let oper2 = sel.send(&s2);
+            let oper = sel.select();
+            match oper.index() {
+                i if i == oper1 => assert_eq!(oper.recv(&r1), Ok(1)),
+                i if i == oper2 => oper.send(&s2, 2).unwrap(),
+                _ => unreachable!(),
+            }
+        }
+    })
+    .unwrap();
+}
+
+#[test]
+fn loop_try() {
+    const RUNS: usize = 20;
+
+    for _ in 0..RUNS {
+        let (s1, r1) = bounded::<i32>(0);
+        let (s2, r2) = bounded::<i32>(0);
+        let (s_end, r_end) = bounded::<()>(0);
+
+        scope(|scope| {
+            scope.spawn(|_| loop {
+                let mut done = false;
+
+                let mut sel = Select::new();
+                let oper1 = sel.send(&s1);
+                let oper = sel.try_select();
+                match oper {
+                    Err(_) => {}
+                    Ok(oper) => match oper.index() {
+                        i if i == oper1 => {
+                            let _ = oper.send(&s1, 1);
+                            done = true;
+                        }
+                        _ => unreachable!(),
+                    },
+                }
+                if done {
+                    break;
+                }
+
+                let mut sel = Select::new();
+                let oper1 = sel.recv(&r_end);
+                let oper = sel.try_select();
+                match oper {
+                    Err(_) => {}
+                    Ok(oper) => match oper.index() {
+                        i if i == oper1 => {
+                            let _ = oper.recv(&r_end);
+                            done = true;
+                        }
+                        _ => unreachable!(),
+                    },
+                }
+                if done {
+                    break;
+                }
+            });
+
+            scope.spawn(|_| loop {
+                if let Ok(x) = r2.try_recv() {
+                    assert_eq!(x, 2);
+                    break;
+                }
+
+                let mut done = false;
+                let mut sel = Select::new();
+                let oper1 = sel.recv(&r_end);
+                let oper = sel.try_select();
+                match oper {
+                    Err(_) => {}
+                    Ok(oper) => match oper.index() {
+                        i if i == oper1 => {
+                            let _ = oper.recv(&r_end);
+                            done = true;
+                        }
+                        _ => unreachable!(),
+                    },
+                }
+                if done {
+                    break;
+                }
+            });
+
+            scope.spawn(|_| {
+                thread::sleep(ms(500));
+
+                let mut sel = Select::new();
+                let oper1 = sel.recv(&r1);
+                let oper2 = sel.send(&s2);
+                let oper = sel.select_timeout(ms(1000));
+                match oper {
+                    Err(_) => {}
+                    Ok(oper) => match oper.index() {
+                        i if i == oper1 => assert_eq!(oper.recv(&r1), Ok(1)),
+                        i if i == oper2 => assert!(oper.send(&s2, 2).is_ok()),
+                        _ => unreachable!(),
+                    },
+                }
+
+                drop(s_end);
+            });
+        })
+        .unwrap();
+    }
+}
+
+#[test]
+fn cloning1() {
+    scope(|scope| {
+        let (s1, r1) = unbounded::<i32>();
+        let (_s2, r2) = unbounded::<i32>();
+        let (s3, r3) = unbounded::<()>();
+
+        scope.spawn(move |_| {
+            r3.recv().unwrap();
+            drop(s1.clone());
+            assert!(r3.try_recv().is_err());
+            s1.send(1).unwrap();
+            r3.recv().unwrap();
+        });
+
+        s3.send(()).unwrap();
+
+        let mut sel = Select::new();
+        let oper1 = sel.recv(&r1);
+        let oper2 = sel.recv(&r2);
+        let oper = sel.select();
+        match oper.index() {
+            i if i == oper1 => drop(oper.recv(&r1)),
+            i if i == oper2 => drop(oper.recv(&r2)),
+            _ => unreachable!(),
+        }
+
+        s3.send(()).unwrap();
+    })
+    .unwrap();
+}
+
+#[test]
+fn cloning2() {
+    let (s1, r1) = unbounded::<()>();
+    let (s2, r2) = unbounded::<()>();
+    let (_s3, _r3) = unbounded::<()>();
+
+    scope(|scope| {
+        scope.spawn(move |_| {
+            let mut sel = Select::new();
+            let oper1 = sel.recv(&r1);
+            let oper2 = sel.recv(&r2);
+            let oper = sel.select();
+            match oper.index() {
+                i if i == oper1 => panic!(),
+                i if i == oper2 => drop(oper.recv(&r2)),
+                _ => unreachable!(),
+            }
+        });
+
+        thread::sleep(ms(500));
+        drop(s1.clone());
+        s2.send(()).unwrap();
+    })
+    .unwrap();
+}
+
+#[test]
+fn preflight1() {
+    let (s, r) = unbounded();
+    s.send(()).unwrap();
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r);
+    let oper = sel.select();
+    match oper.index() {
+        i if i == oper1 => drop(oper.recv(&r)),
+        _ => unreachable!(),
+    }
+}
+
+#[test]
+fn preflight2() {
+    let (s, r) = unbounded();
+    drop(s.clone());
+    s.send(()).unwrap();
+    drop(s);
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r);
+    let oper = sel.select();
+    match oper.index() {
+        i if i == oper1 => assert_eq!(oper.recv(&r), Ok(())),
+        _ => unreachable!(),
+    }
+
+    assert_eq!(r.try_recv(), Err(TryRecvError::Disconnected));
+}
+
+#[test]
+fn preflight3() {
+    let (s, r) = unbounded();
+    drop(s.clone());
+    s.send(()).unwrap();
+    drop(s);
+    r.recv().unwrap();
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(&r);
+    let oper = sel.select();
+    match oper.index() {
+        i if i == oper1 => assert!(oper.recv(&r).is_err()),
+        _ => unreachable!(),
+    }
+}
+
+#[test]
+fn duplicate_operations() {
+    let (s, r) = unbounded::<i32>();
+    let hit = vec![Cell::new(false); 4];
+
+    while hit.iter().map(|h| h.get()).any(|hit| !hit) {
+        let mut sel = Select::new();
+        let oper0 = sel.recv(&r);
+        let oper1 = sel.recv(&r);
+        let oper2 = sel.send(&s);
+        let oper3 = sel.send(&s);
+        let oper = sel.select();
+        match oper.index() {
+            i if i == oper0 => {
+                assert!(oper.recv(&r).is_ok());
+                hit[0].set(true);
+            }
+            i if i == oper1 => {
+                assert!(oper.recv(&r).is_ok());
+                hit[1].set(true);
+            }
+            i if i == oper2 => {
+                assert!(oper.send(&s, 0).is_ok());
+                hit[2].set(true);
+            }
+            i if i == oper3 => {
+                assert!(oper.send(&s, 0).is_ok());
+                hit[3].set(true);
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+
+#[test]
+fn nesting() {
+    let (s, r) = unbounded::<i32>();
+
+    let mut sel = Select::new();
+    let oper1 = sel.send(&s);
+    let oper = sel.select();
+    match oper.index() {
+        i if i == oper1 => {
+            assert!(oper.send(&s, 0).is_ok());
+
+            let mut sel = Select::new();
+            let oper1 = sel.recv(&r);
+            let oper = sel.select();
+            match oper.index() {
+                i if i == oper1 => {
+                    assert_eq!(oper.recv(&r), Ok(0));
+
+                    let mut sel = Select::new();
+                    let oper1 = sel.send(&s);
+                    let oper = sel.select();
+                    match oper.index() {
+                        i if i == oper1 => {
+                            assert!(oper.send(&s, 1).is_ok());
+
+                            let mut sel = Select::new();
+                            let oper1 = sel.recv(&r);
+                            let oper = sel.select();
+                            match oper.index() {
+                                i if i == oper1 => {
+                                    assert_eq!(oper.recv(&r), Ok(1));
+                                }
+                                _ => unreachable!(),
+                            }
+                        }
+                        _ => unreachable!(),
+                    }
+                }
+                _ => unreachable!(),
+            }
+        }
+        _ => unreachable!(),
+    }
+}
+
+#[test]
+fn stress_recv() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 10_000;
+
+    let (s1, r1) = unbounded();
+    let (s2, r2) = bounded(5);
+    let (s3, r3) = bounded(100);
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            for i in 0..COUNT {
+                s1.send(i).unwrap();
+                r3.recv().unwrap();
+
+                s2.send(i).unwrap();
+                r3.recv().unwrap();
+            }
+        });
+
+        for i in 0..COUNT {
+            for _ in 0..2 {
+                let mut sel = Select::new();
+                let oper1 = sel.recv(&r1);
+                let oper2 = sel.recv(&r2);
+                let oper = sel.select();
+                match oper.index() {
+                    ix if ix == oper1 => assert_eq!(oper.recv(&r1), Ok(i)),
+                    ix if ix == oper2 => assert_eq!(oper.recv(&r2), Ok(i)),
+                    _ => unreachable!(),
+                }
+
+                s3.send(()).unwrap();
+            }
+        }
+    })
+    .unwrap();
+}
+
+#[test]
+fn stress_send() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 10_000;
+
+    let (s1, r1) = bounded(0);
+    let (s2, r2) = bounded(0);
+    let (s3, r3) = bounded(100);
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            for i in 0..COUNT {
+                assert_eq!(r1.recv().unwrap(), i);
+                assert_eq!(r2.recv().unwrap(), i);
+                r3.recv().unwrap();
+            }
+        });
+
+        for i in 0..COUNT {
+            for _ in 0..2 {
+                let mut sel = Select::new();
+                let oper1 = sel.send(&s1);
+                let oper2 = sel.send(&s2);
+                let oper = sel.select();
+                match oper.index() {
+                    ix if ix == oper1 => assert!(oper.send(&s1, i).is_ok()),
+                    ix if ix == oper2 => assert!(oper.send(&s2, i).is_ok()),
+                    _ => unreachable!(),
+                }
+            }
+            s3.send(()).unwrap();
+        }
+    })
+    .unwrap();
+}
+
+#[test]
+fn stress_mixed() {
+    #[cfg(miri)]
+    const COUNT: usize = 100;
+    #[cfg(not(miri))]
+    const COUNT: usize = 10_000;
+
+    let (s1, r1) = bounded(0);
+    let (s2, r2) = bounded(0);
+    let (s3, r3) = bounded(100);
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            for i in 0..COUNT {
+                s1.send(i).unwrap();
+                assert_eq!(r2.recv().unwrap(), i);
+                r3.recv().unwrap();
+            }
+        });
+
+        for i in 0..COUNT {
+            for _ in 0..2 {
+                let mut sel = Select::new();
+                let oper1 = sel.recv(&r1);
+                let oper2 = sel.send(&s2);
+                let oper = sel.select();
+                match oper.index() {
+                    ix if ix == oper1 => assert_eq!(oper.recv(&r1), Ok(i)),
+                    ix if ix == oper2 => assert!(oper.send(&s2, i).is_ok()),
+                    _ => unreachable!(),
+                }
+            }
+            s3.send(()).unwrap();
+        }
+    })
+    .unwrap();
+}
+
+#[test]
+fn stress_timeout_two_threads() {
+    const COUNT: usize = 20;
+
+    let (s, r) = bounded(2);
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            for i in 0..COUNT {
+                if i % 2 == 0 {
+                    thread::sleep(ms(500));
+                }
+
+                loop {
+                    let mut sel = Select::new();
+                    let oper1 = sel.send(&s);
+                    let oper = sel.select_timeout(ms(100));
+                    match oper {
+                        Err(_) => {}
+                        Ok(oper) => match oper.index() {
+                            ix if ix == oper1 => {
+                                assert!(oper.send(&s, i).is_ok());
+                                break;
+                            }
+                            _ => unreachable!(),
+                        },
+                    }
+                }
+            }
+        });
+
+        scope.spawn(|_| {
+            for i in 0..COUNT {
+                if i % 2 == 0 {
+                    thread::sleep(ms(500));
+                }
+
+                loop {
+                    let mut sel = Select::new();
+                    let oper1 = sel.recv(&r);
+                    let oper = sel.select_timeout(ms(100));
+                    match oper {
+                        Err(_) => {}
+                        Ok(oper) => match oper.index() {
+                            ix if ix == oper1 => {
+                                assert_eq!(oper.recv(&r), Ok(i));
+                                break;
+                            }
+                            _ => unreachable!(),
+                        },
+                    }
+                }
+            }
+        });
+    })
+    .unwrap();
+}
+
+#[test]
+fn send_recv_same_channel() {
+    let (s, r) = bounded::<i32>(0);
+    let mut sel = Select::new();
+    let oper1 = sel.send(&s);
+    let oper2 = sel.recv(&r);
+    let oper = sel.select_timeout(ms(100));
+    match oper {
+        Err(_) => {}
+        Ok(oper) => match oper.index() {
+            ix if ix == oper1 => panic!(),
+            ix if ix == oper2 => panic!(),
+            _ => unreachable!(),
+        },
+    }
+
+    let (s, r) = unbounded::<i32>();
+    let mut sel = Select::new();
+    let oper1 = sel.send(&s);
+    let oper2 = sel.recv(&r);
+    let oper = sel.select_timeout(ms(100));
+    match oper {
+        Err(_) => panic!(),
+        Ok(oper) => match oper.index() {
+            ix if ix == oper1 => assert!(oper.send(&s, 0).is_ok()),
+            ix if ix == oper2 => panic!(),
+            _ => unreachable!(),
+        },
+    }
+}
+
+#[test]
+fn matching() {
+    const THREADS: usize = 44;
+
+    let (s, r) = &bounded::<usize>(0);
+
+    scope(|scope| {
+        for i in 0..THREADS {
+            scope.spawn(move |_| {
+                let mut sel = Select::new();
+                let oper1 = sel.recv(r);
+                let oper2 = sel.send(s);
+                let oper = sel.select();
+                match oper.index() {
+                    ix if ix == oper1 => assert_ne!(oper.recv(r), Ok(i)),
+                    ix if ix == oper2 => assert!(oper.send(s, i).is_ok()),
+                    _ => unreachable!(),
+                }
+            });
+        }
+    })
+    .unwrap();
+
+    assert_eq!(r.try_recv(), Err(TryRecvError::Empty));
+}
+
+#[test]
+fn matching_with_leftover() {
+    const THREADS: usize = 55;
+
+    let (s, r) = &bounded::<usize>(0);
+
+    scope(|scope| {
+        for i in 0..THREADS {
+            scope.spawn(move |_| {
+                let mut sel = Select::new();
+                let oper1 = sel.recv(r);
+                let oper2 = sel.send(s);
+                let oper = sel.select();
+                match oper.index() {
+                    ix if ix == oper1 => assert_ne!(oper.recv(r), Ok(i)),
+                    ix if ix == oper2 => assert!(oper.send(s, i).is_ok()),
+                    _ => unreachable!(),
+                }
+            });
+        }
+        s.send(!0).unwrap();
+    })
+    .unwrap();
+
+    assert_eq!(r.try_recv(), Err(TryRecvError::Empty));
+}
+
+#[test]
+fn channel_through_channel() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 1000;
+
+    type T = Box<dyn Any + Send>;
+
+    for cap in 0..3 {
+        let (s, r) = bounded::<T>(cap);
+
+        scope(|scope| {
+            scope.spawn(move |_| {
+                let mut s = s;
+
+                for _ in 0..COUNT {
+                    let (new_s, new_r) = bounded(cap);
+                    let new_r: T = Box::new(Some(new_r));
+
+                    {
+                        let mut sel = Select::new();
+                        let oper1 = sel.send(&s);
+                        let oper = sel.select();
+                        match oper.index() {
+                            ix if ix == oper1 => assert!(oper.send(&s, new_r).is_ok()),
+                            _ => unreachable!(),
+                        }
+                    }
+
+                    s = new_s;
+                }
+            });
+
+            scope.spawn(move |_| {
+                let mut r = r;
+
+                for _ in 0..COUNT {
+                    let new = {
+                        let mut sel = Select::new();
+                        let oper1 = sel.recv(&r);
+                        let oper = sel.select();
+                        match oper.index() {
+                            ix if ix == oper1 => oper
+                                .recv(&r)
+                                .unwrap()
+                                .downcast_mut::<Option<Receiver<T>>>()
+                                .unwrap()
+                                .take()
+                                .unwrap(),
+                            _ => unreachable!(),
+                        }
+                    };
+                    r = new;
+                }
+            });
+        })
+        .unwrap();
+    }
+}
+
+#[test]
+fn linearizable_try() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 100_000;
+
+    for step in 0..2 {
+        let (start_s, start_r) = bounded::<()>(0);
+        let (end_s, end_r) = bounded::<()>(0);
+
+        let ((s1, r1), (s2, r2)) = if step == 0 {
+            (bounded::<i32>(1), bounded::<i32>(1))
+        } else {
+            (unbounded::<i32>(), unbounded::<i32>())
+        };
+
+        scope(|scope| {
+            scope.spawn(|_| {
+                for _ in 0..COUNT {
+                    start_s.send(()).unwrap();
+
+                    s1.send(1).unwrap();
+
+                    let mut sel = Select::new();
+                    let oper1 = sel.recv(&r1);
+                    let oper2 = sel.recv(&r2);
+                    let oper = sel.try_select();
+                    match oper {
+                        Err(_) => unreachable!(),
+                        Ok(oper) => match oper.index() {
+                            ix if ix == oper1 => assert!(oper.recv(&r1).is_ok()),
+                            ix if ix == oper2 => assert!(oper.recv(&r2).is_ok()),
+                            _ => unreachable!(),
+                        },
+                    }
+
+                    end_s.send(()).unwrap();
+                    let _ = r2.try_recv();
+                }
+            });
+
+            for _ in 0..COUNT {
+                start_r.recv().unwrap();
+
+                s2.send(1).unwrap();
+                let _ = r1.try_recv();
+
+                end_r.recv().unwrap();
+            }
+        })
+        .unwrap();
+    }
+}
+
+#[test]
+fn linearizable_timeout() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 100_000;
+
+    for step in 0..2 {
+        let (start_s, start_r) = bounded::<()>(0);
+        let (end_s, end_r) = bounded::<()>(0);
+
+        let ((s1, r1), (s2, r2)) = if step == 0 {
+            (bounded::<i32>(1), bounded::<i32>(1))
+        } else {
+            (unbounded::<i32>(), unbounded::<i32>())
+        };
+
+        scope(|scope| {
+            scope.spawn(|_| {
+                for _ in 0..COUNT {
+                    start_s.send(()).unwrap();
+
+                    s1.send(1).unwrap();
+
+                    let mut sel = Select::new();
+                    let oper1 = sel.recv(&r1);
+                    let oper2 = sel.recv(&r2);
+                    let oper = sel.select_timeout(ms(0));
+                    match oper {
+                        Err(_) => unreachable!(),
+                        Ok(oper) => match oper.index() {
+                            ix if ix == oper1 => assert!(oper.recv(&r1).is_ok()),
+                            ix if ix == oper2 => assert!(oper.recv(&r2).is_ok()),
+                            _ => unreachable!(),
+                        },
+                    }
+
+                    end_s.send(()).unwrap();
+                    let _ = r2.try_recv();
+                }
+            });
+
+            for _ in 0..COUNT {
+                start_r.recv().unwrap();
+
+                s2.send(1).unwrap();
+                let _ = r1.try_recv();
+
+                end_r.recv().unwrap();
+            }
+        })
+        .unwrap();
+    }
+}
+
+#[test]
+fn fairness1() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 10_000;
+
+    let (s1, r1) = bounded::<()>(COUNT);
+    let (s2, r2) = unbounded::<()>();
+
+    for _ in 0..COUNT {
+        s1.send(()).unwrap();
+        s2.send(()).unwrap();
+    }
+
+    let hits = vec![Cell::new(0usize); 4];
+    for _ in 0..COUNT {
+        let after = after(ms(0));
+        let tick = tick(ms(0));
+
+        let mut sel = Select::new();
+        let oper1 = sel.recv(&r1);
+        let oper2 = sel.recv(&r2);
+        let oper3 = sel.recv(&after);
+        let oper4 = sel.recv(&tick);
+        let oper = sel.select();
+        match oper.index() {
+            i if i == oper1 => {
+                oper.recv(&r1).unwrap();
+                hits[0].set(hits[0].get() + 1);
+            }
+            i if i == oper2 => {
+                oper.recv(&r2).unwrap();
+                hits[1].set(hits[1].get() + 1);
+            }
+            i if i == oper3 => {
+                oper.recv(&after).unwrap();
+                hits[2].set(hits[2].get() + 1);
+            }
+            i if i == oper4 => {
+                oper.recv(&tick).unwrap();
+                hits[3].set(hits[3].get() + 1);
+            }
+            _ => unreachable!(),
+        }
+    }
+    assert!(hits.iter().all(|x| x.get() >= COUNT / hits.len() / 2));
+}
+
+#[test]
+fn fairness2() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 10_000;
+
+    let (s1, r1) = unbounded::<()>();
+    let (s2, r2) = bounded::<()>(1);
+    let (s3, r3) = bounded::<()>(0);
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            for _ in 0..COUNT {
+                let mut sel = Select::new();
+                let mut oper1 = None;
+                let mut oper2 = None;
+                if s1.is_empty() {
+                    oper1 = Some(sel.send(&s1));
+                }
+                if s2.is_empty() {
+                    oper2 = Some(sel.send(&s2));
+                }
+                let oper3 = sel.send(&s3);
+                let oper = sel.select();
+                match oper.index() {
+                    i if Some(i) == oper1 => assert!(oper.send(&s1, ()).is_ok()),
+                    i if Some(i) == oper2 => assert!(oper.send(&s2, ()).is_ok()),
+                    i if i == oper3 => assert!(oper.send(&s3, ()).is_ok()),
+                    _ => unreachable!(),
+                }
+            }
+        });
+
+        let hits = vec![Cell::new(0usize); 3];
+        for _ in 0..COUNT {
+            let mut sel = Select::new();
+            let oper1 = sel.recv(&r1);
+            let oper2 = sel.recv(&r2);
+            let oper3 = sel.recv(&r3);
+            let oper = sel.select();
+            match oper.index() {
+                i if i == oper1 => {
+                    oper.recv(&r1).unwrap();
+                    hits[0].set(hits[0].get() + 1);
+                }
+                i if i == oper2 => {
+                    oper.recv(&r2).unwrap();
+                    hits[1].set(hits[1].get() + 1);
+                }
+                i if i == oper3 => {
+                    oper.recv(&r3).unwrap();
+                    hits[2].set(hits[2].get() + 1);
+                }
+                _ => unreachable!(),
+            }
+        }
+        assert!(hits.iter().all(|x| x.get() >= COUNT / hits.len() / 50));
+    })
+    .unwrap();
+}
+
+#[test]
+fn sync_and_clone() {
+    const THREADS: usize = 20;
+
+    let (s, r) = &bounded::<usize>(0);
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(r);
+    let oper2 = sel.send(s);
+    let sel = &sel;
+
+    scope(|scope| {
+        for i in 0..THREADS {
+            scope.spawn(move |_| {
+                let mut sel = sel.clone();
+                let oper = sel.select();
+                match oper.index() {
+                    ix if ix == oper1 => assert_ne!(oper.recv(r), Ok(i)),
+                    ix if ix == oper2 => assert!(oper.send(s, i).is_ok()),
+                    _ => unreachable!(),
+                }
+            });
+        }
+    })
+    .unwrap();
+
+    assert_eq!(r.try_recv(), Err(TryRecvError::Empty));
+}
+
+#[test]
+fn send_and_clone() {
+    const THREADS: usize = 20;
+
+    let (s, r) = &bounded::<usize>(0);
+
+    let mut sel = Select::new();
+    let oper1 = sel.recv(r);
+    let oper2 = sel.send(s);
+
+    scope(|scope| {
+        for i in 0..THREADS {
+            let mut sel = sel.clone();
+            scope.spawn(move |_| {
+                let oper = sel.select();
+                match oper.index() {
+                    ix if ix == oper1 => assert_ne!(oper.recv(r), Ok(i)),
+                    ix if ix == oper2 => assert!(oper.send(s, i).is_ok()),
+                    _ => unreachable!(),
+                }
+            });
+        }
+    })
+    .unwrap();
+
+    assert_eq!(r.try_recv(), Err(TryRecvError::Empty));
+}
+
+#[test]
+fn reuse() {
+    #[cfg(miri)]
+    const COUNT: usize = 50;
+    #[cfg(not(miri))]
+    const COUNT: usize = 10_000;
+
+    let (s1, r1) = bounded(0);
+    let (s2, r2) = bounded(0);
+    let (s3, r3) = bounded(100);
+
+    scope(|scope| {
+        scope.spawn(|_| {
+            for i in 0..COUNT {
+                s1.send(i).unwrap();
+                assert_eq!(r2.recv().unwrap(), i);
+                r3.recv().unwrap();
+            }
+        });
+
+        let mut sel = Select::new();
+        let oper1 = sel.recv(&r1);
+        let oper2 = sel.send(&s2);
+
+        for i in 0..COUNT {
+            for _ in 0..2 {
+                let oper = sel.select();
+                match oper.index() {
+                    ix if ix == oper1 => assert_eq!(oper.recv(&r1), Ok(i)),
+                    ix if ix == oper2 => assert!(oper.send(&s2, i).is_ok()),
+                    _ => unreachable!(),
+                }
+            }
+            s3.send(()).unwrap();
+        }
+    })
+    .unwrap();
+}