1 files changed, 465 insertions, 0 deletions
diff --git a/vendor/crossbeam-epoch/src/collector.rs b/vendor/crossbeam-epoch/src/collector.rs
new file mode 100644
index 000000000..099a2ffc6
--- /dev/null
+++ b/vendor/crossbeam-epoch/src/collector.rs
@@ -0,0 +1,465 @@
+/// Epoch-based garbage collector.
+///
+/// # Examples
+///
+/// ```
+/// use crossbeam_epoch::Collector;
+///
+/// let collector = Collector::new();
+///
+/// let handle = collector.register();
+/// drop(collector); // `handle` still works after dropping `collector`
+///
+/// handle.pin().flush();
+/// ```
+use core::fmt;
+
+use crate::guard::Guard;
+use crate::internal::{Global, Local};
+use crate::primitive::sync::Arc;
+
+/// An epoch-based garbage collector.
+pub struct Collector {
+    pub(crate) global: Arc<Global>,
+}
+
+unsafe impl Send for Collector {}
+unsafe impl Sync for Collector {}
+
+impl Default for Collector {
+    fn default() -> Self {
+        Self {
+            global: Arc::new(Global::new()),
+        }
+    }
+}
+
+impl Collector {
+    /// Creates a new collector.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Registers a new handle for the collector.
+    pub fn register(&self) -> LocalHandle {
+        Local::register(self)
+    }
+}
+
+impl Clone for Collector {
+    /// Creates another reference to the same garbage collector.
+    fn clone(&self) -> Self {
+        Collector {
+            global: self.global.clone(),
+        }
+    }
+}
+
+impl fmt::Debug for Collector {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.pad("Collector { .. }")
+    }
+}
+
+impl PartialEq for Collector {
+    /// Checks if both handles point to the same collector.
+    fn eq(&self, rhs: &Collector) -> bool {
+        Arc::ptr_eq(&self.global, &rhs.global)
+    }
+}
+impl Eq for Collector {}
+
+/// A handle to a garbage collector.
+pub struct LocalHandle {
+    pub(crate) local: *const Local,
+}
+
+impl LocalHandle {
+    /// Pins the handle.
+    #[inline]
+    pub fn pin(&self) -> Guard {
+        unsafe { (*self.local).pin() }
+    }
+
+    /// Returns `true` if the handle is pinned.
+    #[inline]
+    pub fn is_pinned(&self) -> bool {
+        unsafe { (*self.local).is_pinned() }
+    }
+
+    /// Returns the `Collector` associated with this handle.
+    #[inline]
+    pub fn collector(&self) -> &Collector {
+        unsafe { (*self.local).collector() }
+    }
+}
+
+impl Drop for LocalHandle {
+    #[inline]
+    fn drop(&mut self) {
+        unsafe {
+            Local::release_handle(&*self.local);
+        }
+    }
+}
+
+impl fmt::Debug for LocalHandle {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.pad("LocalHandle { .. }")
+    }
+}
+
+#[cfg(all(test, not(crossbeam_loom)))]
+mod tests {
+    use std::mem;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    use crossbeam_utils::thread;
+
+    use crate::{Collector, Owned};
+
+    const NUM_THREADS: usize = 8;
+
+    #[test]
+    fn pin_reentrant() {
+        let collector = Collector::new();
+        let handle = collector.register();
+        drop(collector);
+
+        assert!(!handle.is_pinned());
+        {
+            let _guard = &handle.pin();
+            assert!(handle.is_pinned());
+            {
+                let _guard = &handle.pin();
+                assert!(handle.is_pinned());
+            }
+            assert!(handle.is_pinned());
+        }
+        assert!(!handle.is_pinned());
+    }
+
+    #[test]
+    fn flush_local_bag() {
+        let collector = Collector::new();
+        let handle = collector.register();
+        drop(collector);
+
+        for _ in 0..100 {
+            let guard = &handle.pin();
+            unsafe {
+                let a = Owned::new(7).into_shared(guard);
+                guard.defer_destroy(a);
+
+                assert!(!(*guard.local).bag.with(|b| (*b).is_empty()));
+
+                while !(*guard.local).bag.with(|b| (*b).is_empty()) {
+                    guard.flush();
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn garbage_buffering() {
+        let collector = Collector::new();
+        let handle = collector.register();
+        drop(collector);
+
+        let guard = &handle.pin();
+        unsafe {
+            for _ in 0..10 {
+                let a = Owned::new(7).into_shared(guard);
+                guard.defer_destroy(a);
+            }
+            assert!(!(*guard.local).bag.with(|b| (*b).is_empty()));
+        }
+    }
+
+    #[test]
+    fn pin_holds_advance() {
+        #[cfg(miri)]
+        const N: usize = 500;
+        #[cfg(not(miri))]
+        const N: usize = 500_000;
+
+        let collector = Collector::new();
+
+        thread::scope(|scope| {
+            for _ in 0..NUM_THREADS {
+                scope.spawn(|_| {
+                    let handle = collector.register();
+                    for _ in 0..N {
+                        let guard = &handle.pin();
+
+                        let before = collector.global.epoch.load(Ordering::Relaxed);
+                        collector.global.collect(guard);
+                        let after = collector.global.epoch.load(Ordering::Relaxed);
+
+                        assert!(after.wrapping_sub(before) <= 2);
+                    }
+                });
+            }
+        })
+        .unwrap();
+    }
+
+    #[cfg(not(crossbeam_sanitize))] // TODO: assertions failed due to `cfg(crossbeam_sanitize)` reduce `internal::MAX_OBJECTS`
+    #[test]
+    fn incremental() {
+        #[cfg(miri)]
+        const COUNT: usize = 500;
+        #[cfg(not(miri))]
+        const COUNT: usize = 100_000;
+        static DESTROYS: AtomicUsize = AtomicUsize::new(0);
+
+        let collector = Collector::new();
+        let handle = collector.register();
+
+        unsafe {
+            let guard = &handle.pin();
+            for _ in 0..COUNT {
+                let a = Owned::new(7i32).into_shared(guard);
+                guard.defer_unchecked(move || {
+                    drop(a.into_owned());
+                    DESTROYS.fetch_add(1, Ordering::Relaxed);
+                });
+            }
+            guard.flush();
+        }
+
+        let mut last = 0;
+
+        while last < COUNT {
+            let curr = DESTROYS.load(Ordering::Relaxed);
+            assert!(curr - last <= 1024);
+            last = curr;
+
+            let guard = &handle.pin();
+            collector.global.collect(guard);
+        }
+        assert!(DESTROYS.load(Ordering::Relaxed) == COUNT);
+    }
+
+    #[test]
+    fn buffering() {
+        const COUNT: usize = 10;
+        #[cfg(miri)]
+        const N: usize = 500;
+        #[cfg(not(miri))]
+        const N: usize = 100_000;
+        static DESTROYS: AtomicUsize = AtomicUsize::new(0);
+
+        let collector = Collector::new();
+        let handle = collector.register();
+
+        unsafe {
+            let guard = &handle.pin();
+            for _ in 0..COUNT {
+                let a = Owned::new(7i32).into_shared(guard);
+                guard.defer_unchecked(move || {
+                    drop(a.into_owned());
+                    DESTROYS.fetch_add(1, Ordering::Relaxed);
+                });
+            }
+        }
+
+        for _ in 0..N {
+            collector.global.collect(&handle.pin());
+        }
+        assert!(DESTROYS.load(Ordering::Relaxed) < COUNT);
+
+        handle.pin().flush();
+
+        while DESTROYS.load(Ordering::Relaxed) < COUNT {
+            let guard = &handle.pin();
+            collector.global.collect(guard);
+        }
+        assert_eq!(DESTROYS.load(Ordering::Relaxed), COUNT);
+    }
+
+    #[test]
+    fn count_drops() {
+        #[cfg(miri)]
+        const COUNT: usize = 500;
+        #[cfg(not(miri))]
+        const COUNT: usize = 100_000;
+        static DROPS: AtomicUsize = AtomicUsize::new(0);
+
+        struct Elem(i32);
+
+        impl Drop for Elem {
+            fn drop(&mut self) {
+                DROPS.fetch_add(1, Ordering::Relaxed);
+            }
+        }
+
+        let collector = Collector::new();
+        let handle = collector.register();
+
+        unsafe {
+            let guard = &handle.pin();
+
+            for _ in 0..COUNT {
+                let a = Owned::new(Elem(7i32)).into_shared(guard);
+                guard.defer_destroy(a);
+            }
+            guard.flush();
+        }
+
+        while DROPS.load(Ordering::Relaxed) < COUNT {
+            let guard = &handle.pin();
+            collector.global.collect(guard);
+        }
+        assert_eq!(DROPS.load(Ordering::Relaxed), COUNT);
+    }
+
+    #[test]
+    fn count_destroy() {
+        #[cfg(miri)]
+        const COUNT: usize = 500;
+        #[cfg(not(miri))]
+        const COUNT: usize = 100_000;
+        static DESTROYS: AtomicUsize = AtomicUsize::new(0);
+
+        let collector = Collector::new();
+        let handle = collector.register();
+
+        unsafe {
+            let guard = &handle.pin();
+
+            for _ in 0..COUNT {
+                let a = Owned::new(7i32).into_shared(guard);
+                guard.defer_unchecked(move || {
+                    drop(a.into_owned());
+                    DESTROYS.fetch_add(1, Ordering::Relaxed);
+                });
+            }
+            guard.flush();
+        }
+
+        while DESTROYS.load(Ordering::Relaxed) < COUNT {
+            let guard = &handle.pin();
+            collector.global.collect(guard);
+        }
+        assert_eq!(DESTROYS.load(Ordering::Relaxed), COUNT);
+    }
+
+    #[test]
+    fn drop_array() {
+        const COUNT: usize = 700;
+        static DROPS: AtomicUsize = AtomicUsize::new(0);
+
+        struct Elem(i32);
+
+        impl Drop for Elem {
+            fn drop(&mut self) {
+                DROPS.fetch_add(1, Ordering::Relaxed);
+            }
+        }
+
+        let collector = Collector::new();
+        let handle = collector.register();
+
+        let mut guard = handle.pin();
+
+        let mut v = Vec::with_capacity(COUNT);
+        for i in 0..COUNT {
+            v.push(Elem(i as i32));
+        }
+
+        {
+            let a = Owned::new(v).into_shared(&guard);
+            unsafe {
+                guard.defer_destroy(a);
+            }
+            guard.flush();
+        }
+
+        while DROPS.load(Ordering::Relaxed) < COUNT {
+            guard.repin();
+            collector.global.collect(&guard);
+        }
+        assert_eq!(DROPS.load(Ordering::Relaxed), COUNT);
+    }
+
+    #[test]
+    fn destroy_array() {
+        #[cfg(miri)]
+        const COUNT: usize = 500;
+        #[cfg(not(miri))]
+        const COUNT: usize = 100_000;
+        static DESTROYS: AtomicUsize = AtomicUsize::new(0);
+
+        let collector = Collector::new();
+        let handle = collector.register();
+
+        unsafe {
+            let guard = &handle.pin();
+
+            let mut v = Vec::with_capacity(COUNT);
+            for i in 0..COUNT {
+                v.push(i as i32);
+            }
+
+            let ptr = v.as_mut_ptr() as usize;
+            let len = v.len();
+            guard.defer_unchecked(move || {
+                drop(Vec::from_raw_parts(ptr as *const i32 as *mut i32, len, len));
+                DESTROYS.fetch_add(len, Ordering::Relaxed);
+            });
+            guard.flush();
+
+            mem::forget(v);
+        }
+
+        while DESTROYS.load(Ordering::Relaxed) < COUNT {
+            let guard = &handle.pin();
+            collector.global.collect(guard);
+        }
+        assert_eq!(DESTROYS.load(Ordering::Relaxed), COUNT);
+    }
+
+    #[test]
+    fn stress() {
+        const THREADS: usize = 8;
+        #[cfg(miri)]
+        const COUNT: usize = 500;
+        #[cfg(not(miri))]
+        const COUNT: usize = 100_000;
+        static DROPS: AtomicUsize = AtomicUsize::new(0);
+
+        struct Elem(i32);
+
+        impl Drop for Elem {
+            fn drop(&mut self) {
+                DROPS.fetch_add(1, Ordering::Relaxed);
+            }
+        }
+
+        let collector = Collector::new();
+
+        thread::scope(|scope| {
+            for _ in 0..THREADS {
+                scope.spawn(|_| {
+                    let handle = collector.register();
+                    for _ in 0..COUNT {
+                        let guard = &handle.pin();
+                        unsafe {
+                            let a = Owned::new(Elem(7i32)).into_shared(guard);
+                            guard.defer_destroy(a);
+                        }
+                    }
+                });
+            }
+        })
+        .unwrap();
+
+        let handle = collector.register();
+        while DROPS.load(Ordering::Relaxed) < COUNT * THREADS {
+            let guard = &handle.pin();
+            collector.global.collect(guard);
+        }
+        assert_eq!(DROPS.load(Ordering::Relaxed), COUNT * THREADS);
+    }
+}