diff options
Diffstat (limited to 'vendor/crossbeam-utils/src/sync')
| -rw-r--r-- | vendor/crossbeam-utils/src/sync/mod.rs | 17 | ||||
| -rw-r--r-- | vendor/crossbeam-utils/src/sync/once_lock.rs | 88 | ||||
| -rw-r--r-- | vendor/crossbeam-utils/src/sync/parker.rs | 415 | ||||
| -rw-r--r-- | vendor/crossbeam-utils/src/sync/sharded_lock.rs | 636 | ||||
| -rw-r--r-- | vendor/crossbeam-utils/src/sync/wait_group.rs | 145 |
5 files changed, 0 insertions, 1301 deletions
diff --git a/vendor/crossbeam-utils/src/sync/mod.rs b/vendor/crossbeam-utils/src/sync/mod.rs deleted file mode 100644 index f9eec71..0000000 --- a/vendor/crossbeam-utils/src/sync/mod.rs +++ /dev/null @@ -1,17 +0,0 @@ -//! Thread synchronization primitives. -//! -//! * [`Parker`], a thread parking primitive. -//! * [`ShardedLock`], a sharded reader-writer lock with fast concurrent reads. -//! * [`WaitGroup`], for synchronizing the beginning or end of some computation. - -#[cfg(not(crossbeam_loom))] -mod once_lock; -mod parker; -#[cfg(not(crossbeam_loom))] -mod sharded_lock; -mod wait_group; - -pub use self::parker::{Parker, Unparker}; -#[cfg(not(crossbeam_loom))] -pub use self::sharded_lock::{ShardedLock, ShardedLockReadGuard, ShardedLockWriteGuard}; -pub use self::wait_group::WaitGroup; diff --git a/vendor/crossbeam-utils/src/sync/once_lock.rs b/vendor/crossbeam-utils/src/sync/once_lock.rs deleted file mode 100644 index e057aca..0000000 --- a/vendor/crossbeam-utils/src/sync/once_lock.rs +++ /dev/null @@ -1,88 +0,0 @@ -// Based on unstable std::sync::OnceLock. -// -// Source: https://github.com/rust-lang/rust/blob/8e9c93df464b7ada3fc7a1c8ccddd9dcb24ee0a0/library/std/src/sync/once_lock.rs - -use core::cell::UnsafeCell; -use core::mem::MaybeUninit; -use std::sync::Once; - -pub(crate) struct OnceLock<T> { - once: Once, - value: UnsafeCell<MaybeUninit<T>>, - // Unlike std::sync::OnceLock, we don't need PhantomData here because - // we don't use #[may_dangle]. -} - -unsafe impl<T: Sync + Send> Sync for OnceLock<T> {} -unsafe impl<T: Send> Send for OnceLock<T> {} - -impl<T> OnceLock<T> { - /// Creates a new empty cell. - #[must_use] - pub(crate) const fn new() -> Self { - Self { - once: Once::new(), - value: UnsafeCell::new(MaybeUninit::uninit()), - } - } - - /// Gets the contents of the cell, initializing it with `f` if the cell - /// was empty. - /// - /// Many threads may call `get_or_init` concurrently with different - /// initializing functions, but it is guaranteed that only one function - /// will be executed. - /// - /// # Panics - /// - /// If `f` panics, the panic is propagated to the caller, and the cell - /// remains uninitialized. - /// - /// It is an error to reentrantly initialize the cell from `f`. The - /// exact outcome is unspecified. Current implementation deadlocks, but - /// this may be changed to a panic in the future. - pub(crate) fn get_or_init<F>(&self, f: F) -> &T - where - F: FnOnce() -> T, - { - // Fast path check - if self.once.is_completed() { - // SAFETY: The inner value has been initialized - return unsafe { self.get_unchecked() }; - } - self.initialize(f); - - // SAFETY: The inner value has been initialized - unsafe { self.get_unchecked() } - } - - #[cold] - fn initialize<F>(&self, f: F) - where - F: FnOnce() -> T, - { - let slot = self.value.get(); - - self.once.call_once(|| { - let value = f(); - unsafe { slot.write(MaybeUninit::new(value)) } - }); - } - - /// # Safety - /// - /// The value must be initialized - unsafe fn get_unchecked(&self) -> &T { - debug_assert!(self.once.is_completed()); - &*self.value.get().cast::<T>() - } -} - -impl<T> Drop for OnceLock<T> { - fn drop(&mut self) { - if self.once.is_completed() { - // SAFETY: The inner value has been initialized - unsafe { (*self.value.get()).assume_init_drop() }; - } - } -} diff --git a/vendor/crossbeam-utils/src/sync/parker.rs b/vendor/crossbeam-utils/src/sync/parker.rs deleted file mode 100644 index 971981d..0000000 --- a/vendor/crossbeam-utils/src/sync/parker.rs +++ /dev/null @@ -1,415 +0,0 @@ -use crate::primitive::sync::atomic::{AtomicUsize, Ordering::SeqCst}; -use crate::primitive::sync::{Arc, Condvar, Mutex}; -use std::fmt; -use std::marker::PhantomData; -use std::time::{Duration, Instant}; - -/// A thread parking primitive. -/// -/// Conceptually, each `Parker` has an associated token which is initially not present: -/// -/// * The [`park`] method blocks the current thread unless or until the token is available, at -/// which point it automatically consumes the token. -/// -/// * The [`park_timeout`] and [`park_deadline`] methods work the same as [`park`], but block for -/// a specified maximum time. -/// -/// * The [`unpark`] method atomically makes the token available if it wasn't already. Because the -/// token is initially absent, [`unpark`] followed by [`park`] will result in the second call -/// returning immediately. -/// -/// In other words, each `Parker` acts a bit like a spinlock that can be locked and unlocked using -/// [`park`] and [`unpark`]. -/// -/// # Examples -/// -/// ``` -/// use std::thread; -/// use std::time::Duration; -/// use crossbeam_utils::sync::Parker; -/// -/// let p = Parker::new(); -/// let u = p.unparker().clone(); -/// -/// // Make the token available. -/// u.unpark(); -/// // Wakes up immediately and consumes the token. -/// p.park(); -/// -/// thread::spawn(move || { -/// thread::sleep(Duration::from_millis(500)); -/// u.unpark(); -/// }); -/// -/// // Wakes up when `u.unpark()` provides the token. -/// p.park(); -/// # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371 -/// ``` -/// -/// [`park`]: Parker::park -/// [`park_timeout`]: Parker::park_timeout -/// [`park_deadline`]: Parker::park_deadline -/// [`unpark`]: Unparker::unpark -pub struct Parker { - unparker: Unparker, - _marker: PhantomData<*const ()>, -} - -unsafe impl Send for Parker {} - -impl Default for Parker { - fn default() -> Self { - Self { - unparker: Unparker { - inner: Arc::new(Inner { - state: AtomicUsize::new(EMPTY), - lock: Mutex::new(()), - cvar: Condvar::new(), - }), - }, - _marker: PhantomData, - } - } -} - -impl Parker { - /// Creates a new `Parker`. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::Parker; - /// - /// let p = Parker::new(); - /// ``` - /// - pub fn new() -> Parker { - Self::default() - } - - /// Blocks the current thread until the token is made available. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::Parker; - /// - /// let p = Parker::new(); - /// let u = p.unparker().clone(); - /// - /// // Make the token available. - /// u.unpark(); - /// - /// // Wakes up immediately and consumes the token. - /// p.park(); - /// ``` - pub fn park(&self) { - self.unparker.inner.park(None); - } - - /// Blocks the current thread until the token is made available, but only for a limited time. - /// - /// # Examples - /// - /// ``` - /// use std::time::Duration; - /// use crossbeam_utils::sync::Parker; - /// - /// let p = Parker::new(); - /// - /// // Waits for the token to become available, but will not wait longer than 500 ms. - /// p.park_timeout(Duration::from_millis(500)); - /// ``` - pub fn park_timeout(&self, timeout: Duration) { - match Instant::now().checked_add(timeout) { - Some(deadline) => self.park_deadline(deadline), - None => self.park(), - } - } - - /// Blocks the current thread until the token is made available, or until a certain deadline. - /// - /// # Examples - /// - /// ``` - /// use std::time::{Duration, Instant}; - /// use crossbeam_utils::sync::Parker; - /// - /// let p = Parker::new(); - /// let deadline = Instant::now() + Duration::from_millis(500); - /// - /// // Waits for the token to become available, but will not wait longer than 500 ms. - /// p.park_deadline(deadline); - /// ``` - pub fn park_deadline(&self, deadline: Instant) { - self.unparker.inner.park(Some(deadline)) - } - - /// Returns a reference to an associated [`Unparker`]. - /// - /// The returned [`Unparker`] doesn't have to be used by reference - it can also be cloned. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::Parker; - /// - /// let p = Parker::new(); - /// let u = p.unparker().clone(); - /// - /// // Make the token available. - /// u.unpark(); - /// // Wakes up immediately and consumes the token. - /// p.park(); - /// ``` - /// - /// [`park`]: Parker::park - /// [`park_timeout`]: Parker::park_timeout - pub fn unparker(&self) -> &Unparker { - &self.unparker - } - - /// Converts a `Parker` into a raw pointer. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::Parker; - /// - /// let p = Parker::new(); - /// let raw = Parker::into_raw(p); - /// # let _ = unsafe { Parker::from_raw(raw) }; - /// ``` - pub fn into_raw(this: Parker) -> *const () { - Unparker::into_raw(this.unparker) - } - - /// Converts a raw pointer into a `Parker`. - /// - /// # Safety - /// - /// This method is safe to use only with pointers returned by [`Parker::into_raw`]. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::Parker; - /// - /// let p = Parker::new(); - /// let raw = Parker::into_raw(p); - /// let p = unsafe { Parker::from_raw(raw) }; - /// ``` - pub unsafe fn from_raw(ptr: *const ()) -> Parker { - Parker { - unparker: Unparker::from_raw(ptr), - _marker: PhantomData, - } - } -} - -impl fmt::Debug for Parker { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.pad("Parker { .. }") - } -} - -/// Unparks a thread parked by the associated [`Parker`]. -pub struct Unparker { - inner: Arc<Inner>, -} - -unsafe impl Send for Unparker {} -unsafe impl Sync for Unparker {} - -impl Unparker { - /// Atomically makes the token available if it is not already. - /// - /// This method will wake up the thread blocked on [`park`] or [`park_timeout`], if there is - /// any. - /// - /// # Examples - /// - /// ``` - /// use std::thread; - /// use std::time::Duration; - /// use crossbeam_utils::sync::Parker; - /// - /// let p = Parker::new(); - /// let u = p.unparker().clone(); - /// - /// thread::spawn(move || { - /// thread::sleep(Duration::from_millis(500)); - /// u.unpark(); - /// }); - /// - /// // Wakes up when `u.unpark()` provides the token. - /// p.park(); - /// # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371 - /// ``` - /// - /// [`park`]: Parker::park - /// [`park_timeout`]: Parker::park_timeout - pub fn unpark(&self) { - self.inner.unpark() - } - - /// Converts an `Unparker` into a raw pointer. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::{Parker, Unparker}; - /// - /// let p = Parker::new(); - /// let u = p.unparker().clone(); - /// let raw = Unparker::into_raw(u); - /// # let _ = unsafe { Unparker::from_raw(raw) }; - /// ``` - pub fn into_raw(this: Unparker) -> *const () { - Arc::into_raw(this.inner).cast::<()>() - } - - /// Converts a raw pointer into an `Unparker`. - /// - /// # Safety - /// - /// This method is safe to use only with pointers returned by [`Unparker::into_raw`]. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::{Parker, Unparker}; - /// - /// let p = Parker::new(); - /// let u = p.unparker().clone(); - /// - /// let raw = Unparker::into_raw(u); - /// let u = unsafe { Unparker::from_raw(raw) }; - /// ``` - pub unsafe fn from_raw(ptr: *const ()) -> Unparker { - Unparker { - inner: Arc::from_raw(ptr.cast::<Inner>()), - } - } -} - -impl fmt::Debug for Unparker { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.pad("Unparker { .. }") - } -} - -impl Clone for Unparker { - fn clone(&self) -> Unparker { - Unparker { - inner: self.inner.clone(), - } - } -} - -const EMPTY: usize = 0; -const PARKED: usize = 1; -const NOTIFIED: usize = 2; - -struct Inner { - state: AtomicUsize, - lock: Mutex<()>, - cvar: Condvar, -} - -impl Inner { - fn park(&self, deadline: Option<Instant>) { - // If we were previously notified then we consume this notification and return quickly. - if self - .state - .compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst) - .is_ok() - { - return; - } - - // If the timeout is zero, then there is no need to actually block. - if let Some(deadline) = deadline { - if deadline <= Instant::now() { - return; - } - } - - // Otherwise we need to coordinate going to sleep. - let mut m = self.lock.lock().unwrap(); - - match self.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) { - Ok(_) => {} - // Consume this notification to avoid spurious wakeups in the next park. - Err(NOTIFIED) => { - // We must read `state` here, even though we know it will be `NOTIFIED`. This is - // because `unpark` may have been called again since we read `NOTIFIED` in the - // `compare_exchange` above. We must perform an acquire operation that synchronizes - // with that `unpark` to observe any writes it made before the call to `unpark`. To - // do that we must read from the write it made to `state`. - let old = self.state.swap(EMPTY, SeqCst); - assert_eq!(old, NOTIFIED, "park state changed unexpectedly"); - return; - } - Err(n) => panic!("inconsistent park_timeout state: {}", n), - } - - loop { - // Block the current thread on the conditional variable. - m = match deadline { - None => self.cvar.wait(m).unwrap(), - Some(deadline) => { - let now = Instant::now(); - if now < deadline { - // We could check for a timeout here, in the return value of wait_timeout, - // but in the case that a timeout and an unpark arrive simultaneously, we - // prefer to report the former. - self.cvar.wait_timeout(m, deadline - now).unwrap().0 - } else { - // We've timed out; swap out the state back to empty on our way out - match self.state.swap(EMPTY, SeqCst) { - NOTIFIED | PARKED => return, - n => panic!("inconsistent park_timeout state: {}", n), - }; - } - } - }; - - if self - .state - .compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst) - .is_ok() - { - // got a notification - return; - } - - // Spurious wakeup, go back to sleep. Alternatively, if we timed out, it will be caught - // in the branch above, when we discover the deadline is in the past - } - } - - pub(crate) fn unpark(&self) { - // To ensure the unparked thread will observe any writes we made before this call, we must - // perform a release operation that `park` can synchronize with. To do that we must write - // `NOTIFIED` even if `state` is already `NOTIFIED`. That is why this must be a swap rather - // than a compare-and-swap that returns if it reads `NOTIFIED` on failure. - match self.state.swap(NOTIFIED, SeqCst) { - EMPTY => return, // no one was waiting - NOTIFIED => return, // already unparked - PARKED => {} // gotta go wake someone up - _ => panic!("inconsistent state in unpark"), - } - - // There is a period between when the parked thread sets `state` to `PARKED` (or last - // checked `state` in the case of a spurious wakeup) and when it actually waits on `cvar`. - // If we were to notify during this period it would be ignored and then when the parked - // thread went to sleep it would never wake up. Fortunately, it has `lock` locked at this - // stage so we can acquire `lock` to wait until it is ready to receive the notification. - // - // Releasing `lock` before the call to `notify_one` means that when the parked thread wakes - // it doesn't get woken only to have to wait for us to release `lock`. - drop(self.lock.lock().unwrap()); - self.cvar.notify_one(); - } -} diff --git a/vendor/crossbeam-utils/src/sync/sharded_lock.rs b/vendor/crossbeam-utils/src/sync/sharded_lock.rs deleted file mode 100644 index 5aee56f..0000000 --- a/vendor/crossbeam-utils/src/sync/sharded_lock.rs +++ /dev/null @@ -1,636 +0,0 @@ -use std::cell::UnsafeCell; -use std::collections::HashMap; -use std::fmt; -use std::marker::PhantomData; -use std::mem; -use std::ops::{Deref, DerefMut}; -use std::panic::{RefUnwindSafe, UnwindSafe}; -use std::sync::{LockResult, PoisonError, TryLockError, TryLockResult}; -use std::sync::{Mutex, RwLock, RwLockReadGuard, RwLockWriteGuard}; -use std::thread::{self, ThreadId}; - -use crate::sync::once_lock::OnceLock; -use crate::CachePadded; - -/// The number of shards per sharded lock. Must be a power of two. -const NUM_SHARDS: usize = 8; - -/// A shard containing a single reader-writer lock. -struct Shard { - /// The inner reader-writer lock. - lock: RwLock<()>, - - /// The write-guard keeping this shard locked. - /// - /// Write operations will lock each shard and store the guard here. These guards get dropped at - /// the same time the big guard is dropped. - write_guard: UnsafeCell<Option<RwLockWriteGuard<'static, ()>>>, -} - -/// A sharded reader-writer lock. -/// -/// This lock is equivalent to [`RwLock`], except read operations are faster and write operations -/// are slower. -/// -/// A `ShardedLock` is internally made of a list of *shards*, each being a [`RwLock`] occupying a -/// single cache line. Read operations will pick one of the shards depending on the current thread -/// and lock it. Write operations need to lock all shards in succession. -/// -/// By splitting the lock into shards, concurrent read operations will in most cases choose -/// different shards and thus update different cache lines, which is good for scalability. However, -/// write operations need to do more work and are therefore slower than usual. -/// -/// The priority policy of the lock is dependent on the underlying operating system's -/// implementation, and this type does not guarantee that any particular policy will be used. -/// -/// # Poisoning -/// -/// A `ShardedLock`, like [`RwLock`], will become poisoned on a panic. Note that it may only be -/// poisoned if a panic occurs while a write operation is in progress. If a panic occurs in any -/// read operation, the lock will not be poisoned. -/// -/// # Examples -/// -/// ``` -/// use crossbeam_utils::sync::ShardedLock; -/// -/// let lock = ShardedLock::new(5); -/// -/// // Any number of read locks can be held at once. -/// { -/// let r1 = lock.read().unwrap(); -/// let r2 = lock.read().unwrap(); -/// assert_eq!(*r1, 5); -/// assert_eq!(*r2, 5); -/// } // Read locks are dropped at this point. -/// -/// // However, only one write lock may be held. -/// { -/// let mut w = lock.write().unwrap(); -/// *w += 1; -/// assert_eq!(*w, 6); -/// } // Write lock is dropped here. -/// ``` -/// -/// [`RwLock`]: std::sync::RwLock -pub struct ShardedLock<T: ?Sized> { - /// A list of locks protecting the internal data. - shards: Box<[CachePadded<Shard>]>, - - /// The internal data. - value: UnsafeCell<T>, -} - -unsafe impl<T: ?Sized + Send> Send for ShardedLock<T> {} -unsafe impl<T: ?Sized + Send + Sync> Sync for ShardedLock<T> {} - -impl<T: ?Sized> UnwindSafe for ShardedLock<T> {} -impl<T: ?Sized> RefUnwindSafe for ShardedLock<T> {} - -impl<T> ShardedLock<T> { - /// Creates a new sharded reader-writer lock. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::ShardedLock; - /// - /// let lock = ShardedLock::new(5); - /// ``` - pub fn new(value: T) -> ShardedLock<T> { - ShardedLock { - shards: (0..NUM_SHARDS) - .map(|_| { - CachePadded::new(Shard { - lock: RwLock::new(()), - write_guard: UnsafeCell::new(None), - }) - }) - .collect::<Box<[_]>>(), - value: UnsafeCell::new(value), - } - } - - /// Consumes this lock, returning the underlying data. - /// - /// # Errors - /// - /// This method will return an error if the lock is poisoned. A lock gets poisoned when a write - /// operation panics. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::ShardedLock; - /// - /// let lock = ShardedLock::new(String::new()); - /// { - /// let mut s = lock.write().unwrap(); - /// *s = "modified".to_owned(); - /// } - /// assert_eq!(lock.into_inner().unwrap(), "modified"); - /// ``` - pub fn into_inner(self) -> LockResult<T> { - let is_poisoned = self.is_poisoned(); - let inner = self.value.into_inner(); - - if is_poisoned { - Err(PoisonError::new(inner)) - } else { - Ok(inner) - } - } -} - -impl<T: ?Sized> ShardedLock<T> { - /// Returns `true` if the lock is poisoned. - /// - /// If another thread can still access the lock, it may become poisoned at any time. A `false` - /// result should not be trusted without additional synchronization. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::ShardedLock; - /// use std::sync::Arc; - /// use std::thread; - /// - /// let lock = Arc::new(ShardedLock::new(0)); - /// let c_lock = lock.clone(); - /// - /// let _ = thread::spawn(move || { - /// let _lock = c_lock.write().unwrap(); - /// panic!(); // the lock gets poisoned - /// }).join(); - /// assert_eq!(lock.is_poisoned(), true); - /// ``` - pub fn is_poisoned(&self) -> bool { - self.shards[0].lock.is_poisoned() - } - - /// Returns a mutable reference to the underlying data. - /// - /// Since this call borrows the lock mutably, no actual locking needs to take place. - /// - /// # Errors - /// - /// This method will return an error if the lock is poisoned. A lock gets poisoned when a write - /// operation panics. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::ShardedLock; - /// - /// let mut lock = ShardedLock::new(0); - /// *lock.get_mut().unwrap() = 10; - /// assert_eq!(*lock.read().unwrap(), 10); - /// ``` - pub fn get_mut(&mut self) -> LockResult<&mut T> { - let is_poisoned = self.is_poisoned(); - let inner = unsafe { &mut *self.value.get() }; - - if is_poisoned { - Err(PoisonError::new(inner)) - } else { - Ok(inner) - } - } - - /// Attempts to acquire this lock with shared read access. - /// - /// If the access could not be granted at this time, an error is returned. Otherwise, a guard - /// is returned which will release the shared access when it is dropped. This method does not - /// provide any guarantees with respect to the ordering of whether contentious readers or - /// writers will acquire the lock first. - /// - /// # Errors - /// - /// This method will return an error if the lock is poisoned. A lock gets poisoned when a write - /// operation panics. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::ShardedLock; - /// - /// let lock = ShardedLock::new(1); - /// - /// match lock.try_read() { - /// Ok(n) => assert_eq!(*n, 1), - /// Err(_) => unreachable!(), - /// }; - /// ``` - pub fn try_read(&self) -> TryLockResult<ShardedLockReadGuard<'_, T>> { - // Take the current thread index and map it to a shard index. Thread indices will tend to - // distribute shards among threads equally, thus reducing contention due to read-locking. - let current_index = current_index().unwrap_or(0); - let shard_index = current_index & (self.shards.len() - 1); - - match self.shards[shard_index].lock.try_read() { - Ok(guard) => Ok(ShardedLockReadGuard { - lock: self, - _guard: guard, - _marker: PhantomData, - }), - Err(TryLockError::Poisoned(err)) => { - let guard = ShardedLockReadGuard { - lock: self, - _guard: err.into_inner(), - _marker: PhantomData, - }; - Err(TryLockError::Poisoned(PoisonError::new(guard))) - } - Err(TryLockError::WouldBlock) => Err(TryLockError::WouldBlock), - } - } - - /// Locks with shared read access, blocking the current thread until it can be acquired. - /// - /// The calling thread will be blocked until there are no more writers which hold the lock. - /// There may be other readers currently inside the lock when this method returns. This method - /// does not provide any guarantees with respect to the ordering of whether contentious readers - /// or writers will acquire the lock first. - /// - /// Returns a guard which will release the shared access when dropped. - /// - /// # Errors - /// - /// This method will return an error if the lock is poisoned. A lock gets poisoned when a write - /// operation panics. - /// - /// # Panics - /// - /// This method might panic when called if the lock is already held by the current thread. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::ShardedLock; - /// use std::sync::Arc; - /// use std::thread; - /// - /// let lock = Arc::new(ShardedLock::new(1)); - /// let c_lock = lock.clone(); - /// - /// let n = lock.read().unwrap(); - /// assert_eq!(*n, 1); - /// - /// thread::spawn(move || { - /// let r = c_lock.read(); - /// assert!(r.is_ok()); - /// }).join().unwrap(); - /// ``` - pub fn read(&self) -> LockResult<ShardedLockReadGuard<'_, T>> { - // Take the current thread index and map it to a shard index. Thread indices will tend to - // distribute shards among threads equally, thus reducing contention due to read-locking. - let current_index = current_index().unwrap_or(0); - let shard_index = current_index & (self.shards.len() - 1); - - match self.shards[shard_index].lock.read() { - Ok(guard) => Ok(ShardedLockReadGuard { - lock: self, - _guard: guard, - _marker: PhantomData, - }), - Err(err) => Err(PoisonError::new(ShardedLockReadGuard { - lock: self, - _guard: err.into_inner(), - _marker: PhantomData, - })), - } - } - - /// Attempts to acquire this lock with exclusive write access. - /// - /// If the access could not be granted at this time, an error is returned. Otherwise, a guard - /// is returned which will release the exclusive access when it is dropped. This method does - /// not provide any guarantees with respect to the ordering of whether contentious readers or - /// writers will acquire the lock first. - /// - /// # Errors - /// - /// This method will return an error if the lock is poisoned. A lock gets poisoned when a write - /// operation panics. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::ShardedLock; - /// - /// let lock = ShardedLock::new(1); - /// - /// let n = lock.read().unwrap(); - /// assert_eq!(*n, 1); - /// - /// assert!(lock.try_write().is_err()); - /// ``` - pub fn try_write(&self) -> TryLockResult<ShardedLockWriteGuard<'_, T>> { - let mut poisoned = false; - let mut blocked = None; - - // Write-lock each shard in succession. - for (i, shard) in self.shards.iter().enumerate() { - let guard = match shard.lock.try_write() { - Ok(guard) => guard, - Err(TryLockError::Poisoned(err)) => { - poisoned = true; - err.into_inner() - } - Err(TryLockError::WouldBlock) => { - blocked = Some(i); - break; - } - }; - - // Store the guard into the shard. - unsafe { - let guard: RwLockWriteGuard<'static, ()> = mem::transmute(guard); - let dest: *mut _ = shard.write_guard.get(); - *dest = Some(guard); - } - } - - if let Some(i) = blocked { - // Unlock the shards in reverse order of locking. - for shard in self.shards[0..i].iter().rev() { - unsafe { - let dest: *mut _ = shard.write_guard.get(); - let guard = (*dest).take(); - drop(guard); - } - } - Err(TryLockError::WouldBlock) - } else if poisoned { - let guard = ShardedLockWriteGuard { - lock: self, - _marker: PhantomData, - }; - Err(TryLockError::Poisoned(PoisonError::new(guard))) - } else { - Ok(ShardedLockWriteGuard { - lock: self, - _marker: PhantomData, - }) - } - } - - /// Locks with exclusive write access, blocking the current thread until it can be acquired. - /// - /// The calling thread will be blocked until there are no more writers which hold the lock. - /// There may be other readers currently inside the lock when this method returns. This method - /// does not provide any guarantees with respect to the ordering of whether contentious readers - /// or writers will acquire the lock first. - /// - /// Returns a guard which will release the exclusive access when dropped. - /// - /// # Errors - /// - /// This method will return an error if the lock is poisoned. A lock gets poisoned when a write - /// operation panics. - /// - /// # Panics - /// - /// This method might panic when called if the lock is already held by the current thread. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::ShardedLock; - /// - /// let lock = ShardedLock::new(1); - /// - /// let mut n = lock.write().unwrap(); - /// *n = 2; - /// - /// assert!(lock.try_read().is_err()); - /// ``` - pub fn write(&self) -> LockResult<ShardedLockWriteGuard<'_, T>> { - let mut poisoned = false; - - // Write-lock each shard in succession. - for shard in self.shards.iter() { - let guard = match shard.lock.write() { - Ok(guard) => guard, - Err(err) => { - poisoned = true; - err.into_inner() - } - }; - - // Store the guard into the shard. - unsafe { - let guard: RwLockWriteGuard<'_, ()> = guard; - let guard: RwLockWriteGuard<'static, ()> = mem::transmute(guard); - let dest: *mut _ = shard.write_guard.get(); - *dest = Some(guard); - } - } - - if poisoned { - Err(PoisonError::new(ShardedLockWriteGuard { - lock: self, - _marker: PhantomData, - })) - } else { - Ok(ShardedLockWriteGuard { - lock: self, - _marker: PhantomData, - }) - } - } -} - -impl<T: ?Sized + fmt::Debug> fmt::Debug for ShardedLock<T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match self.try_read() { - Ok(guard) => f - .debug_struct("ShardedLock") - .field("data", &&*guard) - .finish(), - Err(TryLockError::Poisoned(err)) => f - .debug_struct("ShardedLock") - .field("data", &&**err.get_ref()) - .finish(), - Err(TryLockError::WouldBlock) => { - struct LockedPlaceholder; - impl fmt::Debug for LockedPlaceholder { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.write_str("<locked>") - } - } - f.debug_struct("ShardedLock") - .field("data", &LockedPlaceholder) - .finish() - } - } - } -} - -impl<T: Default> Default for ShardedLock<T> { - fn default() -> ShardedLock<T> { - ShardedLock::new(Default::default()) - } -} - -impl<T> From<T> for ShardedLock<T> { - fn from(t: T) -> Self { - ShardedLock::new(t) - } -} - -/// A guard used to release the shared read access of a [`ShardedLock`] when dropped. -#[clippy::has_significant_drop] -pub struct ShardedLockReadGuard<'a, T: ?Sized> { - lock: &'a ShardedLock<T>, - _guard: RwLockReadGuard<'a, ()>, - _marker: PhantomData<RwLockReadGuard<'a, T>>, -} - -unsafe impl<T: ?Sized + Sync> Sync for ShardedLockReadGuard<'_, T> {} - -impl<T: ?Sized> Deref for ShardedLockReadGuard<'_, T> { - type Target = T; - - fn deref(&self) -> &T { - unsafe { &*self.lock.value.get() } - } -} - -impl<T: fmt::Debug> fmt::Debug for ShardedLockReadGuard<'_, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_struct("ShardedLockReadGuard") - .field("lock", &self.lock) - .finish() - } -} - -impl<T: ?Sized + fmt::Display> fmt::Display for ShardedLockReadGuard<'_, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -/// A guard used to release the exclusive write access of a [`ShardedLock`] when dropped. -#[clippy::has_significant_drop] -pub struct ShardedLockWriteGuard<'a, T: ?Sized> { - lock: &'a ShardedLock<T>, - _marker: PhantomData<RwLockWriteGuard<'a, T>>, -} - -unsafe impl<T: ?Sized + Sync> Sync for ShardedLockWriteGuard<'_, T> {} - -impl<T: ?Sized> Drop for ShardedLockWriteGuard<'_, T> { - fn drop(&mut self) { - // Unlock the shards in reverse order of locking. - for shard in self.lock.shards.iter().rev() { - unsafe { - let dest: *mut _ = shard.write_guard.get(); - let guard = (*dest).take(); - drop(guard); - } - } - } -} - -impl<T: fmt::Debug> fmt::Debug for ShardedLockWriteGuard<'_, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_struct("ShardedLockWriteGuard") - .field("lock", &self.lock) - .finish() - } -} - -impl<T: ?Sized + fmt::Display> fmt::Display for ShardedLockWriteGuard<'_, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -impl<T: ?Sized> Deref for ShardedLockWriteGuard<'_, T> { - type Target = T; - - fn deref(&self) -> &T { - unsafe { &*self.lock.value.get() } - } -} - -impl<T: ?Sized> DerefMut for ShardedLockWriteGuard<'_, T> { - fn deref_mut(&mut self) -> &mut T { - unsafe { &mut *self.lock.value.get() } - } -} - -/// Returns a `usize` that identifies the current thread. -/// -/// Each thread is associated with an 'index'. While there are no particular guarantees, indices -/// usually tend to be consecutive numbers between 0 and the number of running threads. -/// -/// Since this function accesses TLS, `None` might be returned if the current thread's TLS is -/// tearing down. -#[inline] -fn current_index() -> Option<usize> { - REGISTRATION.try_with(|reg| reg.index).ok() -} - -/// The global registry keeping track of registered threads and indices. -struct ThreadIndices { - /// Mapping from `ThreadId` to thread index. - mapping: HashMap<ThreadId, usize>, - - /// A list of free indices. - free_list: Vec<usize>, - - /// The next index to allocate if the free list is empty. - next_index: usize, -} - -fn thread_indices() -> &'static Mutex<ThreadIndices> { - static THREAD_INDICES: OnceLock<Mutex<ThreadIndices>> = OnceLock::new(); - fn init() -> Mutex<ThreadIndices> { - Mutex::new(ThreadIndices { - mapping: HashMap::new(), - free_list: Vec::new(), - next_index: 0, - }) - } - THREAD_INDICES.get_or_init(init) -} - -/// A registration of a thread with an index. -/// -/// When dropped, unregisters the thread and frees the reserved index. -struct Registration { - index: usize, - thread_id: ThreadId, -} - -impl Drop for Registration { - fn drop(&mut self) { - let mut indices = thread_indices().lock().unwrap(); - indices.mapping.remove(&self.thread_id); - indices.free_list.push(self.index); - } -} - -thread_local! { - static REGISTRATION: Registration = { - let thread_id = thread::current().id(); - let mut indices = thread_indices().lock().unwrap(); - - let index = match indices.free_list.pop() { - Some(i) => i, - None => { - let i = indices.next_index; - indices.next_index += 1; - i - } - }; - indices.mapping.insert(thread_id, index); - - Registration { - index, - thread_id, - } - }; -} diff --git a/vendor/crossbeam-utils/src/sync/wait_group.rs b/vendor/crossbeam-utils/src/sync/wait_group.rs deleted file mode 100644 index 19d6074..0000000 --- a/vendor/crossbeam-utils/src/sync/wait_group.rs +++ /dev/null @@ -1,145 +0,0 @@ -use crate::primitive::sync::{Arc, Condvar, Mutex}; -use std::fmt; - -/// Enables threads to synchronize the beginning or end of some computation. -/// -/// # Wait groups vs barriers -/// -/// `WaitGroup` is very similar to [`Barrier`], but there are a few differences: -/// -/// * [`Barrier`] needs to know the number of threads at construction, while `WaitGroup` is cloned to -/// register more threads. -/// -/// * A [`Barrier`] can be reused even after all threads have synchronized, while a `WaitGroup` -/// synchronizes threads only once. -/// -/// * All threads wait for others to reach the [`Barrier`]. With `WaitGroup`, each thread can choose -/// to either wait for other threads or to continue without blocking. -/// -/// # Examples -/// -/// ``` -/// use crossbeam_utils::sync::WaitGroup; -/// use std::thread; -/// -/// // Create a new wait group. -/// let wg = WaitGroup::new(); -/// -/// for _ in 0..4 { -/// // Create another reference to the wait group. -/// let wg = wg.clone(); -/// -/// thread::spawn(move || { -/// // Do some work. -/// -/// // Drop the reference to the wait group. -/// drop(wg); -/// }); -/// } -/// -/// // Block until all threads have finished their work. -/// wg.wait(); -/// # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371 -/// ``` -/// -/// [`Barrier`]: std::sync::Barrier -pub struct WaitGroup { - inner: Arc<Inner>, -} - -/// Inner state of a `WaitGroup`. -struct Inner { - cvar: Condvar, - count: Mutex<usize>, -} - -impl Default for WaitGroup { - fn default() -> Self { - Self { - inner: Arc::new(Inner { - cvar: Condvar::new(), - count: Mutex::new(1), - }), - } - } -} - -impl WaitGroup { - /// Creates a new wait group and returns the single reference to it. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::WaitGroup; - /// - /// let wg = WaitGroup::new(); - /// ``` - pub fn new() -> Self { - Self::default() - } - - /// Drops this reference and waits until all other references are dropped. - /// - /// # Examples - /// - /// ``` - /// use crossbeam_utils::sync::WaitGroup; - /// use std::thread; - /// - /// let wg = WaitGroup::new(); - /// - /// thread::spawn({ - /// let wg = wg.clone(); - /// move || { - /// // Block until both threads have reached `wait()`. - /// wg.wait(); - /// } - /// }); - /// - /// // Block until both threads have reached `wait()`. - /// wg.wait(); - /// # std::thread::sleep(std::time::Duration::from_millis(500)); // wait for background threads closed: https://github.com/rust-lang/miri/issues/1371 - /// ``` - pub fn wait(self) { - if *self.inner.count.lock().unwrap() == 1 { - return; - } - - let inner = self.inner.clone(); - drop(self); - - let mut count = inner.count.lock().unwrap(); - while *count > 0 { - count = inner.cvar.wait(count).unwrap(); - } - } -} - -impl Drop for WaitGroup { - fn drop(&mut self) { - let mut count = self.inner.count.lock().unwrap(); - *count -= 1; - - if *count == 0 { - self.inner.cvar.notify_all(); - } - } -} - -impl Clone for WaitGroup { - fn clone(&self) -> WaitGroup { - let mut count = self.inner.count.lock().unwrap(); - *count += 1; - - WaitGroup { - inner: self.inner.clone(), - } - } -} - -impl fmt::Debug for WaitGroup { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - let count: &usize = &*self.inner.count.lock().unwrap(); - f.debug_struct("WaitGroup").field("count", count).finish() - } -} |