Adding upstream version 110.0.1.upstream/110.0.1upstream

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

1 files changed, 618 insertions, 0 deletions

diff --git a/third_party/rust/parking_lot/src/rwlock.rs b/third_party/rust/parking_lot/src/rwlock.rs
new file mode 100644
index 0000000000..70e1b1a7c6
--- /dev/null
+++ b/third_party/rust/parking_lot/src/rwlock.rs
@@ -0,0 +1,618 @@
+// Copyright 2016 Amanieu d'Antras
+//
+// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
+// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+// http://opensource.org/licenses/MIT>, at your option. This file may not be
+// copied, modified, or distributed except according to those terms.
+
+use crate::raw_rwlock::RawRwLock;
+use lock_api;
+
+/// A reader-writer lock
+///
+/// This type of lock allows a number of readers or at most one writer at any
+/// point in time. The write portion of this lock typically allows modification
+/// of the underlying data (exclusive access) and the read portion of this lock
+/// typically allows for read-only access (shared access).
+///
+/// This lock uses a task-fair locking policy which avoids both reader and
+/// writer starvation. This means that readers trying to acquire the lock will
+/// block even if the lock is unlocked when there are writers waiting to acquire
+/// the lock. Because of this, attempts to recursively acquire a read lock
+/// within a single thread may result in a deadlock.
+///
+/// The type parameter `T` represents the data that this lock protects. It is
+/// required that `T` satisfies `Send` to be shared across threads and `Sync` to
+/// allow concurrent access through readers. The RAII guards returned from the
+/// locking methods implement `Deref` (and `DerefMut` for the `write` methods)
+/// to allow access to the contained of the lock.
+///
+/// # Fairness
+///
+/// A typical unfair lock can often end up in a situation where a single thread
+/// quickly acquires and releases the same lock in succession, which can starve
+/// other threads waiting to acquire the rwlock. While this improves throughput
+/// because it doesn't force a context switch when a thread tries to re-acquire
+/// a rwlock it has just released, this can starve other threads.
+///
+/// This rwlock uses [eventual fairness](https://trac.webkit.org/changeset/203350)
+/// to ensure that the lock will be fair on average without sacrificing
+/// throughput. This is done by forcing a fair unlock on average every 0.5ms,
+/// which will force the lock to go to the next thread waiting for the rwlock.
+///
+/// Additionally, any critical section longer than 1ms will always use a fair
+/// unlock, which has a negligible impact on throughput considering the length
+/// of the critical section.
+///
+/// You can also force a fair unlock by calling `RwLockReadGuard::unlock_fair`
+/// or `RwLockWriteGuard::unlock_fair` when unlocking a mutex instead of simply
+/// dropping the guard.
+///
+/// # Differences from the standard library `RwLock`
+///
+/// - Supports atomically downgrading a write lock into a read lock.
+/// - Task-fair locking policy instead of an unspecified platform default.
+/// - No poisoning, the lock is released normally on panic.
+/// - Only requires 1 word of space, whereas the standard library boxes the
+///   `RwLock` due to platform limitations.
+/// - Can be statically constructed (requires the `const_fn` nightly feature).
+/// - Does not require any drop glue when dropped.
+/// - Inline fast path for the uncontended case.
+/// - Efficient handling of micro-contention using adaptive spinning.
+/// - Allows raw locking & unlocking without a guard.
+/// - Supports eventual fairness so that the rwlock is fair on average.
+/// - Optionally allows making the rwlock fair by calling
+///   `RwLockReadGuard::unlock_fair` and `RwLockWriteGuard::unlock_fair`.
+///
+/// # Examples
+///
+/// ```
+/// use parking_lot::RwLock;
+///
+/// let lock = RwLock::new(5);
+///
+/// // many reader locks can be held at once
+/// {
+///     let r1 = lock.read();
+///     let r2 = lock.read();
+///     assert_eq!(*r1, 5);
+///     assert_eq!(*r2, 5);
+/// } // read locks are dropped at this point
+///
+/// // only one write lock may be held, however
+/// {
+///     let mut w = lock.write();
+///     *w += 1;
+///     assert_eq!(*w, 6);
+/// } // write lock is dropped here
+/// ```
+pub type RwLock<T> = lock_api::RwLock<RawRwLock, T>;
+
+/// Creates a new instance of an `RwLock<T>` which is unlocked.
+///
+/// This allows creating a `RwLock<T>` in a constant context on stable Rust.
+pub const fn const_rwlock<T>(val: T) -> RwLock<T> {
+    RwLock::const_new(<RawRwLock as lock_api::RawRwLock>::INIT, val)
+}
+
+/// RAII structure used to release the shared read access of a lock when
+/// dropped.
+pub type RwLockReadGuard<'a, T> = lock_api::RwLockReadGuard<'a, RawRwLock, T>;
+
+/// RAII structure used to release the exclusive write access of a lock when
+/// dropped.
+pub type RwLockWriteGuard<'a, T> = lock_api::RwLockWriteGuard<'a, RawRwLock, T>;
+
+/// An RAII read lock guard returned by `RwLockReadGuard::map`, which can point to a
+/// subfield of the protected data.
+///
+/// The main difference between `MappedRwLockReadGuard` and `RwLockReadGuard` is that the
+/// former doesn't support temporarily unlocking and re-locking, since that
+/// could introduce soundness issues if the locked object is modified by another
+/// thread.
+pub type MappedRwLockReadGuard<'a, T> = lock_api::MappedRwLockReadGuard<'a, RawRwLock, T>;
+
+/// An RAII write lock guard returned by `RwLockWriteGuard::map`, which can point to a
+/// subfield of the protected data.
+///
+/// The main difference between `MappedRwLockWriteGuard` and `RwLockWriteGuard` is that the
+/// former doesn't support temporarily unlocking and re-locking, since that
+/// could introduce soundness issues if the locked object is modified by another
+/// thread.
+pub type MappedRwLockWriteGuard<'a, T> = lock_api::MappedRwLockWriteGuard<'a, RawRwLock, T>;
+
+/// RAII structure used to release the upgradable read access of a lock when
+/// dropped.
+pub type RwLockUpgradableReadGuard<'a, T> = lock_api::RwLockUpgradableReadGuard<'a, RawRwLock, T>;
+
+#[cfg(test)]
+mod tests {
+    use crate::{RwLock, RwLockUpgradableReadGuard, RwLockWriteGuard};
+    use rand::Rng;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+    use std::sync::mpsc::channel;
+    use std::sync::Arc;
+    use std::thread;
+    use std::time::Duration;
+
+    #[cfg(feature = "serde")]
+    use bincode::{deserialize, serialize};
+
+    #[derive(Eq, PartialEq, Debug)]
+    struct NonCopy(i32);
+
+    #[test]
+    fn smoke() {
+        let l = RwLock::new(());
+        drop(l.read());
+        drop(l.write());
+        drop(l.upgradable_read());
+        drop((l.read(), l.read()));
+        drop((l.read(), l.upgradable_read()));
+        drop(l.write());
+    }
+
+    #[test]
+    fn frob() {
+        const N: u32 = 10;
+        const M: u32 = 1000;
+
+        let r = Arc::new(RwLock::new(()));
+
+        let (tx, rx) = channel::<()>();
+        for _ in 0..N {
+            let tx = tx.clone();
+            let r = r.clone();
+            thread::spawn(move || {
+                let mut rng = rand::thread_rng();
+                for _ in 0..M {
+                    if rng.gen_bool(1.0 / N as f64) {
+                        drop(r.write());
+                    } else {
+                        drop(r.read());
+                    }
+                }
+                drop(tx);
+            });
+        }
+        drop(tx);
+        let _ = rx.recv();
+    }
+
+    #[test]
+    fn test_rw_arc_no_poison_wr() {
+        let arc = Arc::new(RwLock::new(1));
+        let arc2 = arc.clone();
+        let _: Result<(), _> = thread::spawn(move || {
+            let _lock = arc2.write();
+            panic!();
+        })
+        .join();
+        let lock = arc.read();
+        assert_eq!(*lock, 1);
+    }
+
+    #[test]
+    fn test_rw_arc_no_poison_ww() {
+        let arc = Arc::new(RwLock::new(1));
+        let arc2 = arc.clone();
+        let _: Result<(), _> = thread::spawn(move || {
+            let _lock = arc2.write();
+            panic!();
+        })
+        .join();
+        let lock = arc.write();
+        assert_eq!(*lock, 1);
+    }
+
+    #[test]
+    fn test_rw_arc_no_poison_rr() {
+        let arc = Arc::new(RwLock::new(1));
+        let arc2 = arc.clone();
+        let _: Result<(), _> = thread::spawn(move || {
+            let _lock = arc2.read();
+            panic!();
+        })
+        .join();
+        let lock = arc.read();
+        assert_eq!(*lock, 1);
+    }
+
+    #[test]
+    fn test_rw_arc_no_poison_rw() {
+        let arc = Arc::new(RwLock::new(1));
+        let arc2 = arc.clone();
+        let _: Result<(), _> = thread::spawn(move || {
+            let _lock = arc2.read();
+            panic!()
+        })
+        .join();
+        let lock = arc.write();
+        assert_eq!(*lock, 1);
+    }
+
+    #[test]
+    fn test_ruw_arc() {
+        let arc = Arc::new(RwLock::new(0));
+        let arc2 = arc.clone();
+        let (tx, rx) = channel();
+
+        thread::spawn(move || {
+            for _ in 0..10 {
+                let mut lock = arc2.write();
+                let tmp = *lock;
+                *lock = -1;
+                thread::yield_now();
+                *lock = tmp + 1;
+            }
+            tx.send(()).unwrap();
+        });
+
+        let mut children = Vec::new();
+
+        // Upgradable readers try to catch the writer in the act and also
+        // try to touch the value
+        for _ in 0..5 {
+            let arc3 = arc.clone();
+            children.push(thread::spawn(move || {
+                let lock = arc3.upgradable_read();
+                let tmp = *lock;
+                assert!(tmp >= 0);
+                thread::yield_now();
+                let mut lock = RwLockUpgradableReadGuard::upgrade(lock);
+                assert_eq!(tmp, *lock);
+                *lock = -1;
+                thread::yield_now();
+                *lock = tmp + 1;
+            }));
+        }
+
+        // Readers try to catch the writers in the act
+        for _ in 0..5 {
+            let arc4 = arc.clone();
+            children.push(thread::spawn(move || {
+                let lock = arc4.read();
+                assert!(*lock >= 0);
+            }));
+        }
+
+        // Wait for children to pass their asserts
+        for r in children {
+            assert!(r.join().is_ok());
+        }
+
+        // Wait for writer to finish
+        rx.recv().unwrap();
+        let lock = arc.read();
+        assert_eq!(*lock, 15);
+    }
+
+    #[test]
+    fn test_rw_arc() {
+        let arc = Arc::new(RwLock::new(0));
+        let arc2 = arc.clone();
+        let (tx, rx) = channel();
+
+        thread::spawn(move || {
+            let mut lock = arc2.write();
+            for _ in 0..10 {
+                let tmp = *lock;
+                *lock = -1;
+                thread::yield_now();
+                *lock = tmp + 1;
+            }
+            tx.send(()).unwrap();
+        });
+
+        // Readers try to catch the writer in the act
+        let mut children = Vec::new();
+        for _ in 0..5 {
+            let arc3 = arc.clone();
+            children.push(thread::spawn(move || {
+                let lock = arc3.read();
+                assert!(*lock >= 0);
+            }));
+        }
+
+        // Wait for children to pass their asserts
+        for r in children {
+            assert!(r.join().is_ok());
+        }
+
+        // Wait for writer to finish
+        rx.recv().unwrap();
+        let lock = arc.read();
+        assert_eq!(*lock, 10);
+    }
+
+    #[test]
+    fn test_rw_arc_access_in_unwind() {
+        let arc = Arc::new(RwLock::new(1));
+        let arc2 = arc.clone();
+        let _ = thread::spawn(move || {
+            struct Unwinder {
+                i: Arc<RwLock<isize>>,
+            }
+            impl Drop for Unwinder {
+                fn drop(&mut self) {
+                    let mut lock = self.i.write();
+                    *lock += 1;
+                }
+            }
+            let _u = Unwinder { i: arc2 };
+            panic!();
+        })
+        .join();
+        let lock = arc.read();
+        assert_eq!(*lock, 2);
+    }
+
+    #[test]
+    fn test_rwlock_unsized() {
+        let rw: &RwLock<[i32]> = &RwLock::new([1, 2, 3]);
+        {
+            let b = &mut *rw.write();
+            b[0] = 4;
+            b[2] = 5;
+        }
+        let comp: &[i32] = &[4, 2, 5];
+        assert_eq!(&*rw.read(), comp);
+    }
+
+    #[test]
+    fn test_rwlock_try_read() {
+        let lock = RwLock::new(0isize);
+        {
+            let read_guard = lock.read();
+
+            let read_result = lock.try_read();
+            assert!(
+                read_result.is_some(),
+                "try_read should succeed while read_guard is in scope"
+            );
+
+            drop(read_guard);
+        }
+        {
+            let upgrade_guard = lock.upgradable_read();
+
+            let read_result = lock.try_read();
+            assert!(
+                read_result.is_some(),
+                "try_read should succeed while upgrade_guard is in scope"
+            );
+
+            drop(upgrade_guard);
+        }
+        {
+            let write_guard = lock.write();
+
+            let read_result = lock.try_read();
+            assert!(
+                read_result.is_none(),
+                "try_read should fail while write_guard is in scope"
+            );
+
+            drop(write_guard);
+        }
+    }
+
+    #[test]
+    fn test_rwlock_try_write() {
+        let lock = RwLock::new(0isize);
+        {
+            let read_guard = lock.read();
+
+            let write_result = lock.try_write();
+            assert!(
+                write_result.is_none(),
+                "try_write should fail while read_guard is in scope"
+            );
+
+            drop(read_guard);
+        }
+        {
+            let upgrade_guard = lock.upgradable_read();
+
+            let write_result = lock.try_write();
+            assert!(
+                write_result.is_none(),
+                "try_write should fail while upgrade_guard is in scope"
+            );
+
+            drop(upgrade_guard);
+        }
+        {
+            let write_guard = lock.write();
+
+            let write_result = lock.try_write();
+            assert!(
+                write_result.is_none(),
+                "try_write should fail while write_guard is in scope"
+            );
+
+            drop(write_guard);
+        }
+    }
+
+    #[test]
+    fn test_rwlock_try_upgrade() {
+        let lock = RwLock::new(0isize);
+        {
+            let read_guard = lock.read();
+
+            let upgrade_result = lock.try_upgradable_read();
+            assert!(
+                upgrade_result.is_some(),
+                "try_upgradable_read should succeed while read_guard is in scope"
+            );
+
+            drop(read_guard);
+        }
+        {
+            let upgrade_guard = lock.upgradable_read();
+
+            let upgrade_result = lock.try_upgradable_read();
+            assert!(
+                upgrade_result.is_none(),
+                "try_upgradable_read should fail while upgrade_guard is in scope"
+            );
+
+            drop(upgrade_guard);
+        }
+        {
+            let write_guard = lock.write();
+
+            let upgrade_result = lock.try_upgradable_read();
+            assert!(
+                upgrade_result.is_none(),
+                "try_upgradable should fail while write_guard is in scope"
+            );
+
+            drop(write_guard);
+        }
+    }
+
+    #[test]
+    fn test_into_inner() {
+        let m = RwLock::new(NonCopy(10));
+        assert_eq!(m.into_inner(), NonCopy(10));
+    }
+
+    #[test]
+    fn test_into_inner_drop() {
+        struct Foo(Arc<AtomicUsize>);
+        impl Drop for Foo {
+            fn drop(&mut self) {
+                self.0.fetch_add(1, Ordering::SeqCst);
+            }
+        }
+        let num_drops = Arc::new(AtomicUsize::new(0));
+        let m = RwLock::new(Foo(num_drops.clone()));
+        assert_eq!(num_drops.load(Ordering::SeqCst), 0);
+        {
+            let _inner = m.into_inner();
+            assert_eq!(num_drops.load(Ordering::SeqCst), 0);
+        }
+        assert_eq!(num_drops.load(Ordering::SeqCst), 1);
+    }
+
+    #[test]
+    fn test_get_mut() {
+        let mut m = RwLock::new(NonCopy(10));
+        *m.get_mut() = NonCopy(20);
+        assert_eq!(m.into_inner(), NonCopy(20));
+    }
+
+    #[test]
+    fn test_rwlockguard_sync() {
+        fn sync<T: Sync>(_: T) {}
+
+        let rwlock = RwLock::new(());
+        sync(rwlock.read());
+        sync(rwlock.write());
+    }
+
+    #[test]
+    fn test_rwlock_downgrade() {
+        let x = Arc::new(RwLock::new(0));
+        let mut handles = Vec::new();
+        for _ in 0..8 {
+            let x = x.clone();
+            handles.push(thread::spawn(move || {
+                for _ in 0..100 {
+                    let mut writer = x.write();
+                    *writer += 1;
+                    let cur_val = *writer;
+                    let reader = RwLockWriteGuard::downgrade(writer);
+                    assert_eq!(cur_val, *reader);
+                }
+            }));
+        }
+        for handle in handles {
+            handle.join().unwrap()
+        }
+        assert_eq!(*x.read(), 800);
+    }
+
+    #[test]
+    fn test_rwlock_recursive() {
+        let arc = Arc::new(RwLock::new(1));
+        let arc2 = arc.clone();
+        let lock1 = arc.read();
+        let t = thread::spawn(move || {
+            let _lock = arc2.write();
+        });
+
+        if cfg!(not(all(target_env = "sgx", target_vendor = "fortanix"))) {
+            thread::sleep(Duration::from_millis(100));
+        } else {
+            // FIXME: https://github.com/fortanix/rust-sgx/issues/31
+            for _ in 0..100 {
+                thread::yield_now();
+            }
+        }
+
+        // A normal read would block here since there is a pending writer
+        let lock2 = arc.read_recursive();
+
+        // Unblock the thread and join it.
+        drop(lock1);
+        drop(lock2);
+        t.join().unwrap();
+    }
+
+    #[test]
+    fn test_rwlock_debug() {
+        let x = RwLock::new(vec![0u8, 10]);
+
+        assert_eq!(format!("{:?}", x), "RwLock { data: [0, 10] }");
+        let _lock = x.write();
+        assert_eq!(format!("{:?}", x), "RwLock { data: <locked> }");
+    }
+
+    #[test]
+    fn test_clone() {
+        let rwlock = RwLock::new(Arc::new(1));
+        let a = rwlock.read_recursive();
+        let b = a.clone();
+        assert_eq!(Arc::strong_count(&b), 2);
+    }
+
+    #[cfg(feature = "serde")]
+    #[test]
+    fn test_serde() {
+        let contents: Vec<u8> = vec![0, 1, 2];
+        let mutex = RwLock::new(contents.clone());
+
+        let serialized = serialize(&mutex).unwrap();
+        let deserialized: RwLock<Vec<u8>> = deserialize(&serialized).unwrap();
+
+        assert_eq!(*(mutex.read()), *(deserialized.read()));
+        assert_eq!(contents, *(deserialized.read()));
+    }
+
+    #[test]
+    fn test_issue_203() {
+        struct Bar(RwLock<()>);
+
+        impl Drop for Bar {
+            fn drop(&mut self) {
+                let _n = self.0.write();
+            }
+        }
+
+        thread_local! {
+            static B: Bar = Bar(RwLock::new(()));
+        }
+
+        thread::spawn(|| {
+            B.with(|_| ());
+
+            let a = RwLock::new(());
+            let _a = a.read();
+        })
+        .join()
+        .unwrap();
+    }
+}