diff options
Diffstat (limited to 'vendor/lock_api/src')
| -rw-r--r-- | vendor/lock_api/src/lib.rs | 116 | ||||
| -rw-r--r-- | vendor/lock_api/src/mutex.rs | 960 | ||||
| -rw-r--r-- | vendor/lock_api/src/remutex.rs | 1051 | ||||
| -rw-r--r-- | vendor/lock_api/src/rwlock.rs | 2883 |
4 files changed, 0 insertions, 5010 deletions
diff --git a/vendor/lock_api/src/lib.rs b/vendor/lock_api/src/lib.rs deleted file mode 100644 index 3ea417a..0000000 --- a/vendor/lock_api/src/lib.rs +++ /dev/null @@ -1,116 +0,0 @@ -// Copyright 2018 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. - -//! This library provides type-safe and fully-featured `Mutex` and `RwLock` -//! types which wrap a simple raw mutex or rwlock type. This has several -//! benefits: not only does it eliminate a large portion of the work in -//! implementing custom lock types, it also allows users to write code which is -//! generic with regards to different lock implementations. -//! -//! Basic usage of this crate is very straightforward: -//! -//! 1. Create a raw lock type. This should only contain the lock state, not any -//! data protected by the lock. -//! 2. Implement the `RawMutex` trait for your custom lock type. -//! 3. Export your mutex as a type alias for `lock_api::Mutex`, and -//! your mutex guard as a type alias for `lock_api::MutexGuard`. -//! See the [example](#example) below for details. -//! -//! This process is similar for RwLocks, except that two guards need to be -//! exported instead of one. (Or 3 guards if your type supports upgradable read -//! locks, see [extension traits](#extension-traits) below for details) -//! -//! # Example -//! -//! ``` -//! use lock_api::{RawMutex, Mutex, GuardSend}; -//! use std::sync::atomic::{AtomicBool, Ordering}; -//! -//! // 1. Define our raw lock type -//! pub struct RawSpinlock(AtomicBool); -//! -//! // 2. Implement RawMutex for this type -//! unsafe impl RawMutex for RawSpinlock { -//! const INIT: RawSpinlock = RawSpinlock(AtomicBool::new(false)); -//! -//! // A spinlock guard can be sent to another thread and unlocked there -//! type GuardMarker = GuardSend; -//! -//! fn lock(&self) { -//! // Note: This isn't the best way of implementing a spinlock, but it -//! // suffices for the sake of this example. -//! while !self.try_lock() {} -//! } -//! -//! fn try_lock(&self) -> bool { -//! self.0 -//! .compare_exchange(false, true, Ordering::Acquire, Ordering::Relaxed) -//! .is_ok() -//! } -//! -//! unsafe fn unlock(&self) { -//! self.0.store(false, Ordering::Release); -//! } -//! } -//! -//! // 3. Export the wrappers. This are the types that your users will actually use. -//! pub type Spinlock<T> = lock_api::Mutex<RawSpinlock, T>; -//! pub type SpinlockGuard<'a, T> = lock_api::MutexGuard<'a, RawSpinlock, T>; -//! ``` -//! -//! # Extension traits -//! -//! In addition to basic locking & unlocking functionality, you have the option -//! of exposing additional functionality in your lock types by implementing -//! additional traits for it. Examples of extension features include: -//! -//! - Fair unlocking (`RawMutexFair`, `RawRwLockFair`) -//! - Lock timeouts (`RawMutexTimed`, `RawRwLockTimed`) -//! - Downgradable write locks (`RawRwLockDowngradable`) -//! - Recursive read locks (`RawRwLockRecursive`) -//! - Upgradable read locks (`RawRwLockUpgrade`) -//! -//! The `Mutex` and `RwLock` wrappers will automatically expose this additional -//! functionality if the raw lock type implements these extension traits. -//! -//! # Cargo features -//! -//! This crate supports three cargo features: -//! -//! - `owning_ref`: Allows your lock types to be used with the `owning_ref` crate. -//! - `arc_lock`: Enables locking from an `Arc`. This enables types such as `ArcMutexGuard`. Note that this -//! requires the `alloc` crate to be present. - -#![no_std] -#![cfg_attr(docsrs, feature(doc_auto_cfg))] -#![warn(missing_docs)] -#![warn(rust_2018_idioms)] - -#[macro_use] -extern crate scopeguard; - -#[cfg(feature = "arc_lock")] -extern crate alloc; - -/// Marker type which indicates that the Guard type for a lock is `Send`. -pub struct GuardSend(()); - -/// Marker type which indicates that the Guard type for a lock is not `Send`. -pub struct GuardNoSend(*mut ()); - -unsafe impl Sync for GuardNoSend {} - -mod mutex; -pub use crate::mutex::*; - -#[cfg(feature = "atomic_usize")] -mod remutex; -#[cfg(feature = "atomic_usize")] -pub use crate::remutex::*; - -mod rwlock; -pub use crate::rwlock::*; diff --git a/vendor/lock_api/src/mutex.rs b/vendor/lock_api/src/mutex.rs deleted file mode 100644 index 80eadfa..0000000 --- a/vendor/lock_api/src/mutex.rs +++ /dev/null @@ -1,960 +0,0 @@ -// Copyright 2018 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 core::cell::UnsafeCell; -use core::fmt; -use core::marker::PhantomData; -use core::mem; -use core::ops::{Deref, DerefMut}; - -#[cfg(feature = "arc_lock")] -use alloc::sync::Arc; -#[cfg(feature = "arc_lock")] -use core::mem::ManuallyDrop; -#[cfg(feature = "arc_lock")] -use core::ptr; - -#[cfg(feature = "owning_ref")] -use owning_ref::StableAddress; - -#[cfg(feature = "serde")] -use serde::{Deserialize, Deserializer, Serialize, Serializer}; - -/// Basic operations for a mutex. -/// -/// Types implementing this trait can be used by `Mutex` to form a safe and -/// fully-functioning mutex type. -/// -/// # Safety -/// -/// Implementations of this trait must ensure that the mutex is actually -/// exclusive: a lock can't be acquired while the mutex is already locked. -pub unsafe trait RawMutex { - /// Initial value for an unlocked mutex. - // A “non-constant” const item is a legacy way to supply an initialized value to downstream - // static items. Can hopefully be replaced with `const fn new() -> Self` at some point. - #[allow(clippy::declare_interior_mutable_const)] - const INIT: Self; - - /// Marker type which determines whether a lock guard should be `Send`. Use - /// one of the `GuardSend` or `GuardNoSend` helper types here. - type GuardMarker; - - /// Acquires this mutex, blocking the current thread until it is able to do so. - fn lock(&self); - - /// Attempts to acquire this mutex without blocking. Returns `true` - /// if the lock was successfully acquired and `false` otherwise. - fn try_lock(&self) -> bool; - - /// Unlocks this mutex. - /// - /// # Safety - /// - /// This method may only be called if the mutex is held in the current context, i.e. it must - /// be paired with a successful call to [`lock`], [`try_lock`], [`try_lock_for`] or [`try_lock_until`]. - /// - /// [`lock`]: #tymethod.lock - /// [`try_lock`]: #tymethod.try_lock - /// [`try_lock_for`]: trait.RawMutexTimed.html#tymethod.try_lock_for - /// [`try_lock_until`]: trait.RawMutexTimed.html#tymethod.try_lock_until - unsafe fn unlock(&self); - - /// Checks whether the mutex is currently locked. - #[inline] - fn is_locked(&self) -> bool { - let acquired_lock = self.try_lock(); - if acquired_lock { - // Safety: The lock has been successfully acquired above. - unsafe { - self.unlock(); - } - } - !acquired_lock - } -} - -/// Additional methods for mutexes which support fair unlocking. -/// -/// Fair unlocking means that a lock is handed directly over to the next waiting -/// thread if there is one, without giving other threads the opportunity to -/// "steal" the lock in the meantime. This is typically slower than unfair -/// unlocking, but may be necessary in certain circumstances. -pub unsafe trait RawMutexFair: RawMutex { - /// Unlocks this mutex using a fair unlock protocol. - /// - /// # Safety - /// - /// This method may only be called if the mutex is held in the current context, see - /// the documentation of [`unlock`]. - /// - /// [`unlock`]: trait.RawMutex.html#tymethod.unlock - unsafe fn unlock_fair(&self); - - /// Temporarily yields the mutex to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `unlock_fair` followed - /// by `lock`, however it can be much more efficient in the case where there - /// are no waiting threads. - /// - /// # Safety - /// - /// This method may only be called if the mutex is held in the current context, see - /// the documentation of [`unlock`]. - /// - /// [`unlock`]: trait.RawMutex.html#tymethod.unlock - unsafe fn bump(&self) { - self.unlock_fair(); - self.lock(); - } -} - -/// Additional methods for mutexes which support locking with timeouts. -/// -/// The `Duration` and `Instant` types are specified as associated types so that -/// this trait is usable even in `no_std` environments. -pub unsafe trait RawMutexTimed: RawMutex { - /// Duration type used for `try_lock_for`. - type Duration; - - /// Instant type used for `try_lock_until`. - type Instant; - - /// Attempts to acquire this lock until a timeout is reached. - fn try_lock_for(&self, timeout: Self::Duration) -> bool; - - /// Attempts to acquire this lock until a timeout is reached. - fn try_lock_until(&self, timeout: Self::Instant) -> bool; -} - -/// A mutual exclusion primitive useful for protecting shared data -/// -/// This mutex will block threads waiting for the lock to become available. The -/// mutex can also be statically initialized or created via a `new` -/// constructor. Each mutex has a type parameter which represents the data that -/// it is protecting. The data can only be accessed through the RAII guards -/// returned from `lock` and `try_lock`, which guarantees that the data is only -/// ever accessed when the mutex is locked. -pub struct Mutex<R, T: ?Sized> { - raw: R, - data: UnsafeCell<T>, -} - -unsafe impl<R: RawMutex + Send, T: ?Sized + Send> Send for Mutex<R, T> {} -unsafe impl<R: RawMutex + Sync, T: ?Sized + Send> Sync for Mutex<R, T> {} - -impl<R: RawMutex, T> Mutex<R, T> { - /// Creates a new mutex in an unlocked state ready for use. - #[cfg(has_const_fn_trait_bound)] - #[inline] - pub const fn new(val: T) -> Mutex<R, T> { - Mutex { - raw: R::INIT, - data: UnsafeCell::new(val), - } - } - - /// Creates a new mutex in an unlocked state ready for use. - #[cfg(not(has_const_fn_trait_bound))] - #[inline] - pub fn new(val: T) -> Mutex<R, T> { - Mutex { - raw: R::INIT, - data: UnsafeCell::new(val), - } - } - - /// Consumes this mutex, returning the underlying data. - #[inline] - pub fn into_inner(self) -> T { - self.data.into_inner() - } -} - -impl<R, T> Mutex<R, T> { - /// Creates a new mutex based on a pre-existing raw mutex. - /// - /// This allows creating a mutex in a constant context on stable Rust. - #[inline] - pub const fn const_new(raw_mutex: R, val: T) -> Mutex<R, T> { - Mutex { - raw: raw_mutex, - data: UnsafeCell::new(val), - } - } -} - -impl<R: RawMutex, T: ?Sized> Mutex<R, T> { - /// Creates a new `MutexGuard` without checking if the mutex is locked. - /// - /// # Safety - /// - /// This method must only be called if the thread logically holds the lock. - /// - /// Calling this function when a guard has already been produced is undefined behaviour unless - /// the guard was forgotten with `mem::forget`. - #[inline] - pub unsafe fn make_guard_unchecked(&self) -> MutexGuard<'_, R, T> { - MutexGuard { - mutex: self, - marker: PhantomData, - } - } - - /// Acquires a mutex, blocking the current thread until it is able to do so. - /// - /// This function will block the local thread until it is available to acquire - /// the mutex. Upon returning, the thread is the only thread with the mutex - /// held. An RAII guard is returned to allow scoped unlock of the lock. When - /// the guard goes out of scope, the mutex will be unlocked. - /// - /// Attempts to lock a mutex in the thread which already holds the lock will - /// result in a deadlock. - #[inline] - pub fn lock(&self) -> MutexGuard<'_, R, T> { - self.raw.lock(); - // SAFETY: The lock is held, as required. - unsafe { self.make_guard_unchecked() } - } - - /// Attempts to acquire this lock. - /// - /// If the lock could not be acquired at this time, then `None` is returned. - /// Otherwise, an RAII guard is returned. The lock will be unlocked when the - /// guard is dropped. - /// - /// This function does not block. - #[inline] - pub fn try_lock(&self) -> Option<MutexGuard<'_, R, T>> { - if self.raw.try_lock() { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_guard_unchecked() }) - } else { - None - } - } - - /// Returns a mutable reference to the underlying data. - /// - /// Since this call borrows the `Mutex` mutably, no actual locking needs to - /// take place---the mutable borrow statically guarantees no locks exist. - #[inline] - pub fn get_mut(&mut self) -> &mut T { - unsafe { &mut *self.data.get() } - } - - /// Checks whether the mutex is currently locked. - #[inline] - pub fn is_locked(&self) -> bool { - self.raw.is_locked() - } - - /// Forcibly unlocks the mutex. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `MutexGuard` object alive, for example when - /// dealing with FFI. - /// - /// # Safety - /// - /// This method must only be called if the current thread logically owns a - /// `MutexGuard` but that guard has been discarded using `mem::forget`. - /// Behavior is undefined if a mutex is unlocked when not locked. - #[inline] - pub unsafe fn force_unlock(&self) { - self.raw.unlock(); - } - - /// Returns the underlying raw mutex object. - /// - /// Note that you will most likely need to import the `RawMutex` trait from - /// `lock_api` to be able to call functions on the raw mutex. - /// - /// # Safety - /// - /// This method is unsafe because it allows unlocking a mutex while - /// still holding a reference to a `MutexGuard`. - #[inline] - pub unsafe fn raw(&self) -> &R { - &self.raw - } - - /// Returns a raw pointer to the underlying data. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `MutexGuard` object alive, for example when - /// dealing with FFI. - /// - /// # Safety - /// - /// You must ensure that there are no data races when dereferencing the - /// returned pointer, for example if the current thread logically owns - /// a `MutexGuard` but that guard has been discarded using `mem::forget`. - #[inline] - pub fn data_ptr(&self) -> *mut T { - self.data.get() - } - - /// Creates a new `ArcMutexGuard` without checking if the mutex is locked. - /// - /// # Safety - /// - /// This method must only be called if the thread logically holds the lock. - /// - /// Calling this function when a guard has already been produced is undefined behaviour unless - /// the guard was forgotten with `mem::forget`. - #[cfg(feature = "arc_lock")] - #[inline] - unsafe fn make_arc_guard_unchecked(self: &Arc<Self>) -> ArcMutexGuard<R, T> { - ArcMutexGuard { - mutex: self.clone(), - marker: PhantomData, - } - } - - /// Acquires a lock through an `Arc`. - /// - /// This method is similar to the `lock` method; however, it requires the `Mutex` to be inside of an `Arc` - /// and the resulting mutex guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn lock_arc(self: &Arc<Self>) -> ArcMutexGuard<R, T> { - self.raw.lock(); - // SAFETY: the locking guarantee is upheld - unsafe { self.make_arc_guard_unchecked() } - } - - /// Attempts to acquire a lock through an `Arc`. - /// - /// This method is similar to the `try_lock` method; however, it requires the `Mutex` to be inside of an - /// `Arc` and the resulting mutex guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_lock_arc(self: &Arc<Self>) -> Option<ArcMutexGuard<R, T>> { - if self.raw.try_lock() { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_guard_unchecked() }) - } else { - None - } - } -} - -impl<R: RawMutexFair, T: ?Sized> Mutex<R, T> { - /// Forcibly unlocks the mutex using a fair unlock procotol. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `MutexGuard` object alive, for example when - /// dealing with FFI. - /// - /// # Safety - /// - /// This method must only be called if the current thread logically owns a - /// `MutexGuard` but that guard has been discarded using `mem::forget`. - /// Behavior is undefined if a mutex is unlocked when not locked. - #[inline] - pub unsafe fn force_unlock_fair(&self) { - self.raw.unlock_fair(); - } -} - -impl<R: RawMutexTimed, T: ?Sized> Mutex<R, T> { - /// Attempts to acquire this lock until a timeout is reached. - /// - /// If the lock could not be acquired before the timeout expired, then - /// `None` is returned. Otherwise, an RAII guard is returned. The lock will - /// be unlocked when the guard is dropped. - #[inline] - pub fn try_lock_for(&self, timeout: R::Duration) -> Option<MutexGuard<'_, R, T>> { - if self.raw.try_lock_for(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this lock until a timeout is reached. - /// - /// If the lock could not be acquired before the timeout expired, then - /// `None` is returned. Otherwise, an RAII guard is returned. The lock will - /// be unlocked when the guard is dropped. - #[inline] - pub fn try_lock_until(&self, timeout: R::Instant) -> Option<MutexGuard<'_, R, T>> { - if self.raw.try_lock_until(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this lock through an `Arc` until a timeout is reached. - /// - /// This method is similar to the `try_lock_for` method; however, it requires the `Mutex` to be inside of an - /// `Arc` and the resulting mutex guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_lock_arc_for(self: &Arc<Self>, timeout: R::Duration) -> Option<ArcMutexGuard<R, T>> { - if self.raw.try_lock_for(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this lock through an `Arc` until a timeout is reached. - /// - /// This method is similar to the `try_lock_until` method; however, it requires the `Mutex` to be inside of - /// an `Arc` and the resulting mutex guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_lock_arc_until( - self: &Arc<Self>, - timeout: R::Instant, - ) -> Option<ArcMutexGuard<R, T>> { - if self.raw.try_lock_until(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_guard_unchecked() }) - } else { - None - } - } -} - -impl<R: RawMutex, T: ?Sized + Default> Default for Mutex<R, T> { - #[inline] - fn default() -> Mutex<R, T> { - Mutex::new(Default::default()) - } -} - -impl<R: RawMutex, T> From<T> for Mutex<R, T> { - #[inline] - fn from(t: T) -> Mutex<R, T> { - Mutex::new(t) - } -} - -impl<R: RawMutex, T: ?Sized + fmt::Debug> fmt::Debug for Mutex<R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match self.try_lock() { - Some(guard) => f.debug_struct("Mutex").field("data", &&*guard).finish(), - None => { - struct LockedPlaceholder; - impl fmt::Debug for LockedPlaceholder { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.write_str("<locked>") - } - } - - f.debug_struct("Mutex") - .field("data", &LockedPlaceholder) - .finish() - } - } - } -} - -// Copied and modified from serde -#[cfg(feature = "serde")] -impl<R, T> Serialize for Mutex<R, T> -where - R: RawMutex, - T: Serialize + ?Sized, -{ - fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> - where - S: Serializer, - { - self.lock().serialize(serializer) - } -} - -#[cfg(feature = "serde")] -impl<'de, R, T> Deserialize<'de> for Mutex<R, T> -where - R: RawMutex, - T: Deserialize<'de> + ?Sized, -{ - fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> - where - D: Deserializer<'de>, - { - Deserialize::deserialize(deserializer).map(Mutex::new) - } -} - -/// An RAII implementation of a "scoped lock" of a mutex. When this structure is -/// dropped (falls out of scope), the lock will be unlocked. -/// -/// The data protected by the mutex can be accessed through this guard via its -/// `Deref` and `DerefMut` implementations. -#[clippy::has_significant_drop] -#[must_use = "if unused the Mutex will immediately unlock"] -pub struct MutexGuard<'a, R: RawMutex, T: ?Sized> { - mutex: &'a Mutex<R, T>, - marker: PhantomData<(&'a mut T, R::GuardMarker)>, -} - -unsafe impl<'a, R: RawMutex + Sync + 'a, T: ?Sized + Sync + 'a> Sync for MutexGuard<'a, R, T> {} - -impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> MutexGuard<'a, R, T> { - /// Returns a reference to the original `Mutex` object. - pub fn mutex(s: &Self) -> &'a Mutex<R, T> { - s.mutex - } - - /// Makes a new `MappedMutexGuard` for a component of the locked data. - /// - /// This operation cannot fail as the `MutexGuard` passed - /// in already locked the mutex. - /// - /// This is an associated function that needs to be - /// used as `MutexGuard::map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedMutexGuard<'a, R, U> - where - F: FnOnce(&mut T) -> &mut U, - { - let raw = &s.mutex.raw; - let data = f(unsafe { &mut *s.mutex.data.get() }); - mem::forget(s); - MappedMutexGuard { - raw, - data, - marker: PhantomData, - } - } - - /// Attempts to make a new `MappedMutexGuard` for a component of the - /// locked data. The original guard is returned if the closure returns `None`. - /// - /// This operation cannot fail as the `MutexGuard` passed - /// in already locked the mutex. - /// - /// This is an associated function that needs to be - /// used as `MutexGuard::try_map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn try_map<U: ?Sized, F>(s: Self, f: F) -> Result<MappedMutexGuard<'a, R, U>, Self> - where - F: FnOnce(&mut T) -> Option<&mut U>, - { - let raw = &s.mutex.raw; - let data = match f(unsafe { &mut *s.mutex.data.get() }) { - Some(data) => data, - None => return Err(s), - }; - mem::forget(s); - Ok(MappedMutexGuard { - raw, - data, - marker: PhantomData, - }) - } - - /// Temporarily unlocks the mutex to execute the given function. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the mutex. - #[inline] - pub fn unlocked<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: A MutexGuard always holds the lock. - unsafe { - s.mutex.raw.unlock(); - } - defer!(s.mutex.raw.lock()); - f() - } - - /// Leaks the mutex guard and returns a mutable reference to the data - /// protected by the mutex. - /// - /// This will leave the `Mutex` in a locked state. - #[inline] - pub fn leak(s: Self) -> &'a mut T { - let r = unsafe { &mut *s.mutex.data.get() }; - mem::forget(s); - r - } -} - -impl<'a, R: RawMutexFair + 'a, T: ?Sized + 'a> MutexGuard<'a, R, T> { - /// Unlocks the mutex using a fair unlock protocol. - /// - /// By default, mutexes are unfair and allow the current thread to re-lock - /// the mutex before another has the chance to acquire the lock, even if - /// that thread has been blocked on the mutex for a long time. This is the - /// default because it allows much higher throughput as it avoids forcing a - /// context switch on every mutex unlock. This can result in one thread - /// acquiring a mutex many more times than other threads. - /// - /// However in some cases it can be beneficial to ensure fairness by forcing - /// the lock to pass on to a waiting thread if there is one. This is done by - /// using this method instead of dropping the `MutexGuard` normally. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: A MutexGuard always holds the lock. - unsafe { - s.mutex.raw.unlock_fair(); - } - mem::forget(s); - } - - /// Temporarily unlocks the mutex to execute the given function. - /// - /// The mutex is unlocked using a fair unlock protocol. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the mutex. - #[inline] - pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: A MutexGuard always holds the lock. - unsafe { - s.mutex.raw.unlock_fair(); - } - defer!(s.mutex.raw.lock()); - f() - } - - /// Temporarily yields the mutex to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `unlock_fair` followed - /// by `lock`, however it can be much more efficient in the case where there - /// are no waiting threads. - #[inline] - pub fn bump(s: &mut Self) { - // Safety: A MutexGuard always holds the lock. - unsafe { - s.mutex.raw.bump(); - } - } -} - -impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> Deref for MutexGuard<'a, R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.mutex.data.get() } - } -} - -impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> DerefMut for MutexGuard<'a, R, T> { - #[inline] - fn deref_mut(&mut self) -> &mut T { - unsafe { &mut *self.mutex.data.get() } - } -} - -impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> Drop for MutexGuard<'a, R, T> { - #[inline] - fn drop(&mut self) { - // Safety: A MutexGuard always holds the lock. - unsafe { - self.mutex.raw.unlock(); - } - } -} - -impl<'a, R: RawMutex + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug for MutexGuard<'a, R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -impl<'a, R: RawMutex + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display for MutexGuard<'a, R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -#[cfg(feature = "owning_ref")] -unsafe impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> StableAddress for MutexGuard<'a, R, T> {} - -/// An RAII mutex guard returned by the `Arc` locking operations on `Mutex`. -/// -/// This is similar to the `MutexGuard` struct, except instead of using a reference to unlock the `Mutex` it -/// uses an `Arc<Mutex>`. This has several advantages, most notably that it has an `'static` lifetime. -#[cfg(feature = "arc_lock")] -#[clippy::has_significant_drop] -#[must_use = "if unused the Mutex will immediately unlock"] -pub struct ArcMutexGuard<R: RawMutex, T: ?Sized> { - mutex: Arc<Mutex<R, T>>, - marker: PhantomData<*const ()>, -} - -#[cfg(feature = "arc_lock")] -unsafe impl<R: RawMutex + Send + Sync, T: Send + ?Sized> Send for ArcMutexGuard<R, T> where - R::GuardMarker: Send -{ -} -#[cfg(feature = "arc_lock")] -unsafe impl<R: RawMutex + Sync, T: Sync + ?Sized> Sync for ArcMutexGuard<R, T> where - R::GuardMarker: Sync -{ -} - -#[cfg(feature = "arc_lock")] -impl<R: RawMutex, T: ?Sized> ArcMutexGuard<R, T> { - /// Returns a reference to the `Mutex` this is guarding, contained in its `Arc`. - #[inline] - pub fn mutex(s: &Self) -> &Arc<Mutex<R, T>> { - &s.mutex - } - - /// Unlocks the mutex and returns the `Arc` that was held by the [`ArcMutexGuard`]. - #[inline] - pub fn into_arc(s: Self) -> Arc<Mutex<R, T>> { - // Safety: Skip our Drop impl and manually unlock the mutex. - let arc = unsafe { ptr::read(&s.mutex) }; - mem::forget(s); - unsafe { - arc.raw.unlock(); - } - arc - } - - /// Temporarily unlocks the mutex to execute the given function. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the mutex. - #[inline] - pub fn unlocked<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: A MutexGuard always holds the lock. - unsafe { - s.mutex.raw.unlock(); - } - defer!(s.mutex.raw.lock()); - f() - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawMutexFair, T: ?Sized> ArcMutexGuard<R, T> { - /// Unlocks the mutex using a fair unlock protocol. - /// - /// This is functionally identical to the `unlock_fair` method on [`MutexGuard`]. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: A MutexGuard always holds the lock. - unsafe { - s.mutex.raw.unlock_fair(); - } - - // SAFETY: make sure the Arc gets it reference decremented - let mut s = ManuallyDrop::new(s); - unsafe { ptr::drop_in_place(&mut s.mutex) }; - } - - /// Temporarily unlocks the mutex to execute the given function. - /// - /// This is functionally identical to the `unlocked_fair` method on [`MutexGuard`]. - #[inline] - pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: A MutexGuard always holds the lock. - unsafe { - s.mutex.raw.unlock_fair(); - } - defer!(s.mutex.raw.lock()); - f() - } - - /// Temporarily yields the mutex to a waiting thread if there is one. - /// - /// This is functionally identical to the `bump` method on [`MutexGuard`]. - #[inline] - pub fn bump(s: &mut Self) { - // Safety: A MutexGuard always holds the lock. - unsafe { - s.mutex.raw.bump(); - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawMutex, T: ?Sized> Deref for ArcMutexGuard<R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.mutex.data.get() } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawMutex, T: ?Sized> DerefMut for ArcMutexGuard<R, T> { - #[inline] - fn deref_mut(&mut self) -> &mut T { - unsafe { &mut *self.mutex.data.get() } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawMutex, T: ?Sized> Drop for ArcMutexGuard<R, T> { - #[inline] - fn drop(&mut self) { - // Safety: A MutexGuard always holds the lock. - unsafe { - self.mutex.raw.unlock(); - } - } -} - -/// An RAII mutex guard returned by `MutexGuard::map`, which can point to a -/// subfield of the protected data. -/// -/// The main difference between `MappedMutexGuard` and `MutexGuard` 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. -#[clippy::has_significant_drop] -#[must_use = "if unused the Mutex will immediately unlock"] -pub struct MappedMutexGuard<'a, R: RawMutex, T: ?Sized> { - raw: &'a R, - data: *mut T, - marker: PhantomData<&'a mut T>, -} - -unsafe impl<'a, R: RawMutex + Sync + 'a, T: ?Sized + Sync + 'a> Sync - for MappedMutexGuard<'a, R, T> -{ -} -unsafe impl<'a, R: RawMutex + 'a, T: ?Sized + Send + 'a> Send for MappedMutexGuard<'a, R, T> where - R::GuardMarker: Send -{ -} - -impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> MappedMutexGuard<'a, R, T> { - /// Makes a new `MappedMutexGuard` for a component of the locked data. - /// - /// This operation cannot fail as the `MappedMutexGuard` passed - /// in already locked the mutex. - /// - /// This is an associated function that needs to be - /// used as `MappedMutexGuard::map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedMutexGuard<'a, R, U> - where - F: FnOnce(&mut T) -> &mut U, - { - let raw = s.raw; - let data = f(unsafe { &mut *s.data }); - mem::forget(s); - MappedMutexGuard { - raw, - data, - marker: PhantomData, - } - } - - /// Attempts to make a new `MappedMutexGuard` for a component of the - /// locked data. The original guard is returned if the closure returns `None`. - /// - /// This operation cannot fail as the `MappedMutexGuard` passed - /// in already locked the mutex. - /// - /// This is an associated function that needs to be - /// used as `MappedMutexGuard::try_map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn try_map<U: ?Sized, F>(s: Self, f: F) -> Result<MappedMutexGuard<'a, R, U>, Self> - where - F: FnOnce(&mut T) -> Option<&mut U>, - { - let raw = s.raw; - let data = match f(unsafe { &mut *s.data }) { - Some(data) => data, - None => return Err(s), - }; - mem::forget(s); - Ok(MappedMutexGuard { - raw, - data, - marker: PhantomData, - }) - } -} - -impl<'a, R: RawMutexFair + 'a, T: ?Sized + 'a> MappedMutexGuard<'a, R, T> { - /// Unlocks the mutex using a fair unlock protocol. - /// - /// By default, mutexes are unfair and allow the current thread to re-lock - /// the mutex before another has the chance to acquire the lock, even if - /// that thread has been blocked on the mutex for a long time. This is the - /// default because it allows much higher throughput as it avoids forcing a - /// context switch on every mutex unlock. This can result in one thread - /// acquiring a mutex many more times than other threads. - /// - /// However in some cases it can be beneficial to ensure fairness by forcing - /// the lock to pass on to a waiting thread if there is one. This is done by - /// using this method instead of dropping the `MutexGuard` normally. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: A MutexGuard always holds the lock. - unsafe { - s.raw.unlock_fair(); - } - mem::forget(s); - } -} - -impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> Deref for MappedMutexGuard<'a, R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.data } - } -} - -impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> DerefMut for MappedMutexGuard<'a, R, T> { - #[inline] - fn deref_mut(&mut self) -> &mut T { - unsafe { &mut *self.data } - } -} - -impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> Drop for MappedMutexGuard<'a, R, T> { - #[inline] - fn drop(&mut self) { - // Safety: A MappedMutexGuard always holds the lock. - unsafe { - self.raw.unlock(); - } - } -} - -impl<'a, R: RawMutex + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug for MappedMutexGuard<'a, R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -impl<'a, R: RawMutex + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display - for MappedMutexGuard<'a, R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -#[cfg(feature = "owning_ref")] -unsafe impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> StableAddress for MappedMutexGuard<'a, R, T> {} diff --git a/vendor/lock_api/src/remutex.rs b/vendor/lock_api/src/remutex.rs deleted file mode 100644 index 74f2da3..0000000 --- a/vendor/lock_api/src/remutex.rs +++ /dev/null @@ -1,1051 +0,0 @@ -// Copyright 2018 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::{ - mutex::{RawMutex, RawMutexFair, RawMutexTimed}, - GuardNoSend, -}; -use core::{ - cell::{Cell, UnsafeCell}, - fmt, - marker::PhantomData, - mem, - num::NonZeroUsize, - ops::Deref, - sync::atomic::{AtomicUsize, Ordering}, -}; - -#[cfg(feature = "arc_lock")] -use alloc::sync::Arc; -#[cfg(feature = "arc_lock")] -use core::mem::ManuallyDrop; -#[cfg(feature = "arc_lock")] -use core::ptr; - -#[cfg(feature = "owning_ref")] -use owning_ref::StableAddress; - -#[cfg(feature = "serde")] -use serde::{Deserialize, Deserializer, Serialize, Serializer}; - -/// Helper trait which returns a non-zero thread ID. -/// -/// The simplest way to implement this trait is to return the address of a -/// thread-local variable. -/// -/// # Safety -/// -/// Implementations of this trait must ensure that no two active threads share -/// the same thread ID. However the ID of a thread that has exited can be -/// re-used since that thread is no longer active. -pub unsafe trait GetThreadId { - /// Initial value. - // A “non-constant” const item is a legacy way to supply an initialized value to downstream - // static items. Can hopefully be replaced with `const fn new() -> Self` at some point. - #[allow(clippy::declare_interior_mutable_const)] - const INIT: Self; - - /// Returns a non-zero thread ID which identifies the current thread of - /// execution. - fn nonzero_thread_id(&self) -> NonZeroUsize; -} - -/// A raw mutex type that wraps another raw mutex to provide reentrancy. -/// -/// Although this has the same methods as the [`RawMutex`] trait, it does -/// not implement it, and should not be used in the same way, since this -/// mutex can successfully acquire a lock multiple times in the same thread. -/// Only use this when you know you want a raw mutex that can be locked -/// reentrantly; you probably want [`ReentrantMutex`] instead. -/// -/// [`RawMutex`]: trait.RawMutex.html -/// [`ReentrantMutex`]: struct.ReentrantMutex.html -pub struct RawReentrantMutex<R, G> { - owner: AtomicUsize, - lock_count: Cell<usize>, - mutex: R, - get_thread_id: G, -} - -unsafe impl<R: RawMutex + Send, G: GetThreadId + Send> Send for RawReentrantMutex<R, G> {} -unsafe impl<R: RawMutex + Sync, G: GetThreadId + Sync> Sync for RawReentrantMutex<R, G> {} - -impl<R: RawMutex, G: GetThreadId> RawReentrantMutex<R, G> { - /// Initial value for an unlocked mutex. - #[allow(clippy::declare_interior_mutable_const)] - pub const INIT: Self = RawReentrantMutex { - owner: AtomicUsize::new(0), - lock_count: Cell::new(0), - mutex: R::INIT, - get_thread_id: G::INIT, - }; - - #[inline] - fn lock_internal<F: FnOnce() -> bool>(&self, try_lock: F) -> bool { - let id = self.get_thread_id.nonzero_thread_id().get(); - if self.owner.load(Ordering::Relaxed) == id { - self.lock_count.set( - self.lock_count - .get() - .checked_add(1) - .expect("ReentrantMutex lock count overflow"), - ); - } else { - if !try_lock() { - return false; - } - self.owner.store(id, Ordering::Relaxed); - debug_assert_eq!(self.lock_count.get(), 0); - self.lock_count.set(1); - } - true - } - - /// Acquires this mutex, blocking if it's held by another thread. - #[inline] - pub fn lock(&self) { - self.lock_internal(|| { - self.mutex.lock(); - true - }); - } - - /// Attempts to acquire this mutex without blocking. Returns `true` - /// if the lock was successfully acquired and `false` otherwise. - #[inline] - pub fn try_lock(&self) -> bool { - self.lock_internal(|| self.mutex.try_lock()) - } - - /// Unlocks this mutex. The inner mutex may not be unlocked if - /// this mutex was acquired previously in the current thread. - /// - /// # Safety - /// - /// This method may only be called if the mutex is held by the current thread. - #[inline] - pub unsafe fn unlock(&self) { - let lock_count = self.lock_count.get() - 1; - self.lock_count.set(lock_count); - if lock_count == 0 { - self.owner.store(0, Ordering::Relaxed); - self.mutex.unlock(); - } - } - - /// Checks whether the mutex is currently locked. - #[inline] - pub fn is_locked(&self) -> bool { - self.mutex.is_locked() - } - - /// Checks whether the mutex is currently held by the current thread. - #[inline] - pub fn is_owned_by_current_thread(&self) -> bool { - let id = self.get_thread_id.nonzero_thread_id().get(); - self.owner.load(Ordering::Relaxed) == id - } -} - -impl<R: RawMutexFair, G: GetThreadId> RawReentrantMutex<R, G> { - /// Unlocks this mutex using a fair unlock protocol. The inner mutex - /// may not be unlocked if this mutex was acquired previously in the - /// current thread. - /// - /// # Safety - /// - /// This method may only be called if the mutex is held by the current thread. - #[inline] - pub unsafe fn unlock_fair(&self) { - let lock_count = self.lock_count.get() - 1; - self.lock_count.set(lock_count); - if lock_count == 0 { - self.owner.store(0, Ordering::Relaxed); - self.mutex.unlock_fair(); - } - } - - /// Temporarily yields the mutex to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `unlock_fair` followed - /// by `lock`, however it can be much more efficient in the case where there - /// are no waiting threads. - /// - /// # Safety - /// - /// This method may only be called if the mutex is held by the current thread. - #[inline] - pub unsafe fn bump(&self) { - if self.lock_count.get() == 1 { - let id = self.owner.load(Ordering::Relaxed); - self.owner.store(0, Ordering::Relaxed); - self.lock_count.set(0); - self.mutex.bump(); - self.owner.store(id, Ordering::Relaxed); - self.lock_count.set(1); - } - } -} - -impl<R: RawMutexTimed, G: GetThreadId> RawReentrantMutex<R, G> { - /// Attempts to acquire this lock until a timeout is reached. - #[inline] - pub fn try_lock_until(&self, timeout: R::Instant) -> bool { - self.lock_internal(|| self.mutex.try_lock_until(timeout)) - } - - /// Attempts to acquire this lock until a timeout is reached. - #[inline] - pub fn try_lock_for(&self, timeout: R::Duration) -> bool { - self.lock_internal(|| self.mutex.try_lock_for(timeout)) - } -} - -/// A mutex which can be recursively locked by a single thread. -/// -/// This type is identical to `Mutex` except for the following points: -/// -/// - Locking multiple times from the same thread will work correctly instead of -/// deadlocking. -/// - `ReentrantMutexGuard` does not give mutable references to the locked data. -/// Use a `RefCell` if you need this. -/// -/// See [`Mutex`](struct.Mutex.html) for more details about the underlying mutex -/// primitive. -pub struct ReentrantMutex<R, G, T: ?Sized> { - raw: RawReentrantMutex<R, G>, - data: UnsafeCell<T>, -} - -unsafe impl<R: RawMutex + Send, G: GetThreadId + Send, T: ?Sized + Send> Send - for ReentrantMutex<R, G, T> -{ -} -unsafe impl<R: RawMutex + Sync, G: GetThreadId + Sync, T: ?Sized + Send> Sync - for ReentrantMutex<R, G, T> -{ -} - -impl<R: RawMutex, G: GetThreadId, T> ReentrantMutex<R, G, T> { - /// Creates a new reentrant mutex in an unlocked state ready for use. - #[cfg(has_const_fn_trait_bound)] - #[inline] - pub const fn new(val: T) -> ReentrantMutex<R, G, T> { - ReentrantMutex { - data: UnsafeCell::new(val), - raw: RawReentrantMutex { - owner: AtomicUsize::new(0), - lock_count: Cell::new(0), - mutex: R::INIT, - get_thread_id: G::INIT, - }, - } - } - - /// Creates a new reentrant mutex in an unlocked state ready for use. - #[cfg(not(has_const_fn_trait_bound))] - #[inline] - pub fn new(val: T) -> ReentrantMutex<R, G, T> { - ReentrantMutex { - data: UnsafeCell::new(val), - raw: RawReentrantMutex { - owner: AtomicUsize::new(0), - lock_count: Cell::new(0), - mutex: R::INIT, - get_thread_id: G::INIT, - }, - } - } - - /// Consumes this mutex, returning the underlying data. - #[inline] - pub fn into_inner(self) -> T { - self.data.into_inner() - } -} - -impl<R, G, T> ReentrantMutex<R, G, T> { - /// Creates a new reentrant mutex based on a pre-existing raw mutex and a - /// helper to get the thread ID. - /// - /// This allows creating a reentrant mutex in a constant context on stable - /// Rust. - #[inline] - pub const fn const_new(raw_mutex: R, get_thread_id: G, val: T) -> ReentrantMutex<R, G, T> { - ReentrantMutex { - data: UnsafeCell::new(val), - raw: RawReentrantMutex { - owner: AtomicUsize::new(0), - lock_count: Cell::new(0), - mutex: raw_mutex, - get_thread_id, - }, - } - } -} - -impl<R: RawMutex, G: GetThreadId, T: ?Sized> ReentrantMutex<R, G, T> { - /// Creates a new `ReentrantMutexGuard` without checking if the lock is held. - /// - /// # Safety - /// - /// This method must only be called if the thread logically holds the lock. - /// - /// Calling this function when a guard has already been produced is undefined behaviour unless - /// the guard was forgotten with `mem::forget`. - #[inline] - pub unsafe fn make_guard_unchecked(&self) -> ReentrantMutexGuard<'_, R, G, T> { - ReentrantMutexGuard { - remutex: &self, - marker: PhantomData, - } - } - - /// Acquires a reentrant mutex, blocking the current thread until it is able - /// to do so. - /// - /// If the mutex is held by another thread then this function will block the - /// local thread until it is available to acquire the mutex. If the mutex is - /// already held by the current thread then this function will increment the - /// lock reference count and return immediately. Upon returning, - /// the thread is the only thread with the mutex held. An RAII guard is - /// returned to allow scoped unlock of the lock. When the guard goes out of - /// scope, the mutex will be unlocked. - #[inline] - pub fn lock(&self) -> ReentrantMutexGuard<'_, R, G, T> { - self.raw.lock(); - // SAFETY: The lock is held, as required. - unsafe { self.make_guard_unchecked() } - } - - /// Attempts to acquire this lock. - /// - /// If the lock could not be acquired at this time, then `None` is returned. - /// Otherwise, an RAII guard is returned. The lock will be unlocked when the - /// guard is dropped. - /// - /// This function does not block. - #[inline] - pub fn try_lock(&self) -> Option<ReentrantMutexGuard<'_, R, G, T>> { - if self.raw.try_lock() { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_guard_unchecked() }) - } else { - None - } - } - - /// Returns a mutable reference to the underlying data. - /// - /// Since this call borrows the `ReentrantMutex` mutably, no actual locking needs to - /// take place---the mutable borrow statically guarantees no locks exist. - #[inline] - pub fn get_mut(&mut self) -> &mut T { - unsafe { &mut *self.data.get() } - } - - /// Checks whether the mutex is currently locked. - #[inline] - pub fn is_locked(&self) -> bool { - self.raw.is_locked() - } - - /// Checks whether the mutex is currently held by the current thread. - #[inline] - pub fn is_owned_by_current_thread(&self) -> bool { - self.raw.is_owned_by_current_thread() - } - - /// Forcibly unlocks the mutex. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `ReentrantMutexGuard` object alive, for example when - /// dealing with FFI. - /// - /// # Safety - /// - /// This method must only be called if the current thread logically owns a - /// `ReentrantMutexGuard` but that guard has be discarded using `mem::forget`. - /// Behavior is undefined if a mutex is unlocked when not locked. - #[inline] - pub unsafe fn force_unlock(&self) { - self.raw.unlock(); - } - - /// Returns the underlying raw mutex object. - /// - /// Note that you will most likely need to import the `RawMutex` trait from - /// `lock_api` to be able to call functions on the raw mutex. - /// - /// # Safety - /// - /// This method is unsafe because it allows unlocking a mutex while - /// still holding a reference to a `ReentrantMutexGuard`. - #[inline] - pub unsafe fn raw(&self) -> &R { - &self.raw.mutex - } - - /// Returns a raw pointer to the underlying data. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `ReentrantMutexGuard` object alive, for example - /// when dealing with FFI. - /// - /// # Safety - /// - /// You must ensure that there are no data races when dereferencing the - /// returned pointer, for example if the current thread logically owns a - /// `ReentrantMutexGuard` but that guard has been discarded using - /// `mem::forget`. - #[inline] - pub fn data_ptr(&self) -> *mut T { - self.data.get() - } - - /// Creates a new `ArcReentrantMutexGuard` without checking if the lock is held. - /// - /// # Safety - /// - /// This method must only be called if the thread logically holds the lock. - /// - /// Calling this function when a guard has already been produced is undefined behaviour unless - /// the guard was forgotten with `mem::forget`. - #[cfg(feature = "arc_lock")] - #[inline] - pub unsafe fn make_arc_guard_unchecked(self: &Arc<Self>) -> ArcReentrantMutexGuard<R, G, T> { - ArcReentrantMutexGuard { - remutex: self.clone(), - marker: PhantomData, - } - } - - /// Acquires a reentrant mutex through an `Arc`. - /// - /// This method is similar to the `lock` method; however, it requires the `ReentrantMutex` to be inside of an - /// `Arc` and the resulting mutex guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn lock_arc(self: &Arc<Self>) -> ArcReentrantMutexGuard<R, G, T> { - self.raw.lock(); - // SAFETY: locking guarantee is upheld - unsafe { self.make_arc_guard_unchecked() } - } - - /// Attempts to acquire a reentrant mutex through an `Arc`. - /// - /// This method is similar to the `try_lock` method; however, it requires the `ReentrantMutex` to be inside - /// of an `Arc` and the resulting mutex guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_lock_arc(self: &Arc<Self>) -> Option<ArcReentrantMutexGuard<R, G, T>> { - if self.raw.try_lock() { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_guard_unchecked() }) - } else { - None - } - } -} - -impl<R: RawMutexFair, G: GetThreadId, T: ?Sized> ReentrantMutex<R, G, T> { - /// Forcibly unlocks the mutex using a fair unlock protocol. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `ReentrantMutexGuard` object alive, for example when - /// dealing with FFI. - /// - /// # Safety - /// - /// This method must only be called if the current thread logically owns a - /// `ReentrantMutexGuard` but that guard has be discarded using `mem::forget`. - /// Behavior is undefined if a mutex is unlocked when not locked. - #[inline] - pub unsafe fn force_unlock_fair(&self) { - self.raw.unlock_fair(); - } -} - -impl<R: RawMutexTimed, G: GetThreadId, T: ?Sized> ReentrantMutex<R, G, T> { - /// Attempts to acquire this lock until a timeout is reached. - /// - /// If the lock could not be acquired before the timeout expired, then - /// `None` is returned. Otherwise, an RAII guard is returned. The lock will - /// be unlocked when the guard is dropped. - #[inline] - pub fn try_lock_for(&self, timeout: R::Duration) -> Option<ReentrantMutexGuard<'_, R, G, T>> { - if self.raw.try_lock_for(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this lock until a timeout is reached. - /// - /// If the lock could not be acquired before the timeout expired, then - /// `None` is returned. Otherwise, an RAII guard is returned. The lock will - /// be unlocked when the guard is dropped. - #[inline] - pub fn try_lock_until(&self, timeout: R::Instant) -> Option<ReentrantMutexGuard<'_, R, G, T>> { - if self.raw.try_lock_until(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this lock until a timeout is reached, through an `Arc`. - /// - /// This method is similar to the `try_lock_for` method; however, it requires the `ReentrantMutex` to be - /// inside of an `Arc` and the resulting mutex guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_lock_arc_for( - self: &Arc<Self>, - timeout: R::Duration, - ) -> Option<ArcReentrantMutexGuard<R, G, T>> { - if self.raw.try_lock_for(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this lock until a timeout is reached, through an `Arc`. - /// - /// This method is similar to the `try_lock_until` method; however, it requires the `ReentrantMutex` to be - /// inside of an `Arc` and the resulting mutex guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_lock_arc_until( - self: &Arc<Self>, - timeout: R::Instant, - ) -> Option<ArcReentrantMutexGuard<R, G, T>> { - if self.raw.try_lock_until(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_guard_unchecked() }) - } else { - None - } - } -} - -impl<R: RawMutex, G: GetThreadId, T: ?Sized + Default> Default for ReentrantMutex<R, G, T> { - #[inline] - fn default() -> ReentrantMutex<R, G, T> { - ReentrantMutex::new(Default::default()) - } -} - -impl<R: RawMutex, G: GetThreadId, T> From<T> for ReentrantMutex<R, G, T> { - #[inline] - fn from(t: T) -> ReentrantMutex<R, G, T> { - ReentrantMutex::new(t) - } -} - -impl<R: RawMutex, G: GetThreadId, T: ?Sized + fmt::Debug> fmt::Debug for ReentrantMutex<R, G, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match self.try_lock() { - Some(guard) => f - .debug_struct("ReentrantMutex") - .field("data", &&*guard) - .finish(), - None => { - struct LockedPlaceholder; - impl fmt::Debug for LockedPlaceholder { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.write_str("<locked>") - } - } - - f.debug_struct("ReentrantMutex") - .field("data", &LockedPlaceholder) - .finish() - } - } - } -} - -// Copied and modified from serde -#[cfg(feature = "serde")] -impl<R, G, T> Serialize for ReentrantMutex<R, G, T> -where - R: RawMutex, - G: GetThreadId, - T: Serialize + ?Sized, -{ - fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> - where - S: Serializer, - { - self.lock().serialize(serializer) - } -} - -#[cfg(feature = "serde")] -impl<'de, R, G, T> Deserialize<'de> for ReentrantMutex<R, G, T> -where - R: RawMutex, - G: GetThreadId, - T: Deserialize<'de> + ?Sized, -{ - fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> - where - D: Deserializer<'de>, - { - Deserialize::deserialize(deserializer).map(ReentrantMutex::new) - } -} - -/// An RAII implementation of a "scoped lock" of a reentrant mutex. When this structure -/// is dropped (falls out of scope), the lock will be unlocked. -/// -/// The data protected by the mutex can be accessed through this guard via its -/// `Deref` implementation. -#[clippy::has_significant_drop] -#[must_use = "if unused the ReentrantMutex will immediately unlock"] -pub struct ReentrantMutexGuard<'a, R: RawMutex, G: GetThreadId, T: ?Sized> { - remutex: &'a ReentrantMutex<R, G, T>, - marker: PhantomData<(&'a T, GuardNoSend)>, -} - -unsafe impl<'a, R: RawMutex + Sync + 'a, G: GetThreadId + Sync + 'a, T: ?Sized + Sync + 'a> Sync - for ReentrantMutexGuard<'a, R, G, T> -{ -} - -impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> ReentrantMutexGuard<'a, R, G, T> { - /// Returns a reference to the original `ReentrantMutex` object. - pub fn remutex(s: &Self) -> &'a ReentrantMutex<R, G, T> { - s.remutex - } - - /// Makes a new `MappedReentrantMutexGuard` for a component of the locked data. - /// - /// This operation cannot fail as the `ReentrantMutexGuard` passed - /// in already locked the mutex. - /// - /// This is an associated function that needs to be - /// used as `ReentrantMutexGuard::map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedReentrantMutexGuard<'a, R, G, U> - where - F: FnOnce(&T) -> &U, - { - let raw = &s.remutex.raw; - let data = f(unsafe { &*s.remutex.data.get() }); - mem::forget(s); - MappedReentrantMutexGuard { - raw, - data, - marker: PhantomData, - } - } - - /// Attempts to make a new `MappedReentrantMutexGuard` for a component of the - /// locked data. The original guard is return if the closure returns `None`. - /// - /// This operation cannot fail as the `ReentrantMutexGuard` passed - /// in already locked the mutex. - /// - /// This is an associated function that needs to be - /// used as `ReentrantMutexGuard::try_map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn try_map<U: ?Sized, F>( - s: Self, - f: F, - ) -> Result<MappedReentrantMutexGuard<'a, R, G, U>, Self> - where - F: FnOnce(&T) -> Option<&U>, - { - let raw = &s.remutex.raw; - let data = match f(unsafe { &*s.remutex.data.get() }) { - Some(data) => data, - None => return Err(s), - }; - mem::forget(s); - Ok(MappedReentrantMutexGuard { - raw, - data, - marker: PhantomData, - }) - } - - /// Temporarily unlocks the mutex to execute the given function. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the mutex. - #[inline] - pub fn unlocked<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: A ReentrantMutexGuard always holds the lock. - unsafe { - s.remutex.raw.unlock(); - } - defer!(s.remutex.raw.lock()); - f() - } -} - -impl<'a, R: RawMutexFair + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> - ReentrantMutexGuard<'a, R, G, T> -{ - /// Unlocks the mutex using a fair unlock protocol. - /// - /// By default, mutexes are unfair and allow the current thread to re-lock - /// the mutex before another has the chance to acquire the lock, even if - /// that thread has been blocked on the mutex for a long time. This is the - /// default because it allows much higher throughput as it avoids forcing a - /// context switch on every mutex unlock. This can result in one thread - /// acquiring a mutex many more times than other threads. - /// - /// However in some cases it can be beneficial to ensure fairness by forcing - /// the lock to pass on to a waiting thread if there is one. This is done by - /// using this method instead of dropping the `ReentrantMutexGuard` normally. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: A ReentrantMutexGuard always holds the lock - unsafe { - s.remutex.raw.unlock_fair(); - } - mem::forget(s); - } - - /// Temporarily unlocks the mutex to execute the given function. - /// - /// The mutex is unlocked a fair unlock protocol. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the mutex. - #[inline] - pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: A ReentrantMutexGuard always holds the lock - unsafe { - s.remutex.raw.unlock_fair(); - } - defer!(s.remutex.raw.lock()); - f() - } - - /// Temporarily yields the mutex to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `unlock_fair` followed - /// by `lock`, however it can be much more efficient in the case where there - /// are no waiting threads. - #[inline] - pub fn bump(s: &mut Self) { - // Safety: A ReentrantMutexGuard always holds the lock - unsafe { - s.remutex.raw.bump(); - } - } -} - -impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Deref - for ReentrantMutexGuard<'a, R, G, T> -{ - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.remutex.data.get() } - } -} - -impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Drop - for ReentrantMutexGuard<'a, R, G, T> -{ - #[inline] - fn drop(&mut self) { - // Safety: A ReentrantMutexGuard always holds the lock. - unsafe { - self.remutex.raw.unlock(); - } - } -} - -impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug - for ReentrantMutexGuard<'a, R, G, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display - for ReentrantMutexGuard<'a, R, G, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -#[cfg(feature = "owning_ref")] -unsafe impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> StableAddress - for ReentrantMutexGuard<'a, R, G, T> -{ -} - -/// An RAII mutex guard returned by the `Arc` locking operations on `ReentrantMutex`. -/// -/// This is similar to the `ReentrantMutexGuard` struct, except instead of using a reference to unlock the -/// `Mutex` it uses an `Arc<ReentrantMutex>`. This has several advantages, most notably that it has an `'static` -/// lifetime. -#[cfg(feature = "arc_lock")] -#[clippy::has_significant_drop] -#[must_use = "if unused the ReentrantMutex will immediately unlock"] -pub struct ArcReentrantMutexGuard<R: RawMutex, G: GetThreadId, T: ?Sized> { - remutex: Arc<ReentrantMutex<R, G, T>>, - marker: PhantomData<GuardNoSend>, -} - -#[cfg(feature = "arc_lock")] -impl<R: RawMutex, G: GetThreadId, T: ?Sized> ArcReentrantMutexGuard<R, G, T> { - /// Returns a reference to the `ReentrantMutex` this object is guarding, contained in its `Arc`. - pub fn remutex(s: &Self) -> &Arc<ReentrantMutex<R, G, T>> { - &s.remutex - } - - /// Temporarily unlocks the mutex to execute the given function. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the mutex. - #[inline] - pub fn unlocked<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: A ReentrantMutexGuard always holds the lock. - unsafe { - s.remutex.raw.unlock(); - } - defer!(s.remutex.raw.lock()); - f() - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawMutexFair, G: GetThreadId, T: ?Sized> ArcReentrantMutexGuard<R, G, T> { - /// Unlocks the mutex using a fair unlock protocol. - /// - /// This is functionally identical to the `unlock_fair` method on [`ReentrantMutexGuard`]. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: A ReentrantMutexGuard always holds the lock - unsafe { - s.remutex.raw.unlock_fair(); - } - - // SAFETY: ensure that the Arc's refcount is decremented - let mut s = ManuallyDrop::new(s); - unsafe { ptr::drop_in_place(&mut s.remutex) }; - } - - /// Temporarily unlocks the mutex to execute the given function. - /// - /// This is functionally identical to the `unlocked_fair` method on [`ReentrantMutexGuard`]. - #[inline] - pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: A ReentrantMutexGuard always holds the lock - unsafe { - s.remutex.raw.unlock_fair(); - } - defer!(s.remutex.raw.lock()); - f() - } - - /// Temporarily yields the mutex to a waiting thread if there is one. - /// - /// This is functionally equivalent to the `bump` method on [`ReentrantMutexGuard`]. - #[inline] - pub fn bump(s: &mut Self) { - // Safety: A ReentrantMutexGuard always holds the lock - unsafe { - s.remutex.raw.bump(); - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawMutex, G: GetThreadId, T: ?Sized> Deref for ArcReentrantMutexGuard<R, G, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.remutex.data.get() } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawMutex, G: GetThreadId, T: ?Sized> Drop for ArcReentrantMutexGuard<R, G, T> { - #[inline] - fn drop(&mut self) { - // Safety: A ReentrantMutexGuard always holds the lock. - unsafe { - self.remutex.raw.unlock(); - } - } -} - -/// An RAII mutex guard returned by `ReentrantMutexGuard::map`, which can point to a -/// subfield of the protected data. -/// -/// The main difference between `MappedReentrantMutexGuard` and `ReentrantMutexGuard` 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. -#[clippy::has_significant_drop] -#[must_use = "if unused the ReentrantMutex will immediately unlock"] -pub struct MappedReentrantMutexGuard<'a, R: RawMutex, G: GetThreadId, T: ?Sized> { - raw: &'a RawReentrantMutex<R, G>, - data: *const T, - marker: PhantomData<&'a T>, -} - -unsafe impl<'a, R: RawMutex + Sync + 'a, G: GetThreadId + Sync + 'a, T: ?Sized + Sync + 'a> Sync - for MappedReentrantMutexGuard<'a, R, G, T> -{ -} - -impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> - MappedReentrantMutexGuard<'a, R, G, T> -{ - /// Makes a new `MappedReentrantMutexGuard` for a component of the locked data. - /// - /// This operation cannot fail as the `MappedReentrantMutexGuard` passed - /// in already locked the mutex. - /// - /// This is an associated function that needs to be - /// used as `MappedReentrantMutexGuard::map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedReentrantMutexGuard<'a, R, G, U> - where - F: FnOnce(&T) -> &U, - { - let raw = s.raw; - let data = f(unsafe { &*s.data }); - mem::forget(s); - MappedReentrantMutexGuard { - raw, - data, - marker: PhantomData, - } - } - - /// Attempts to make a new `MappedReentrantMutexGuard` for a component of the - /// locked data. The original guard is return if the closure returns `None`. - /// - /// This operation cannot fail as the `MappedReentrantMutexGuard` passed - /// in already locked the mutex. - /// - /// This is an associated function that needs to be - /// used as `MappedReentrantMutexGuard::try_map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn try_map<U: ?Sized, F>( - s: Self, - f: F, - ) -> Result<MappedReentrantMutexGuard<'a, R, G, U>, Self> - where - F: FnOnce(&T) -> Option<&U>, - { - let raw = s.raw; - let data = match f(unsafe { &*s.data }) { - Some(data) => data, - None => return Err(s), - }; - mem::forget(s); - Ok(MappedReentrantMutexGuard { - raw, - data, - marker: PhantomData, - }) - } -} - -impl<'a, R: RawMutexFair + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> - MappedReentrantMutexGuard<'a, R, G, T> -{ - /// Unlocks the mutex using a fair unlock protocol. - /// - /// By default, mutexes are unfair and allow the current thread to re-lock - /// the mutex before another has the chance to acquire the lock, even if - /// that thread has been blocked on the mutex for a long time. This is the - /// default because it allows much higher throughput as it avoids forcing a - /// context switch on every mutex unlock. This can result in one thread - /// acquiring a mutex many more times than other threads. - /// - /// However in some cases it can be beneficial to ensure fairness by forcing - /// the lock to pass on to a waiting thread if there is one. This is done by - /// using this method instead of dropping the `ReentrantMutexGuard` normally. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: A MappedReentrantMutexGuard always holds the lock - unsafe { - s.raw.unlock_fair(); - } - mem::forget(s); - } -} - -impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Deref - for MappedReentrantMutexGuard<'a, R, G, T> -{ - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.data } - } -} - -impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> Drop - for MappedReentrantMutexGuard<'a, R, G, T> -{ - #[inline] - fn drop(&mut self) { - // Safety: A MappedReentrantMutexGuard always holds the lock. - unsafe { - self.raw.unlock(); - } - } -} - -impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug - for MappedReentrantMutexGuard<'a, R, G, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display - for MappedReentrantMutexGuard<'a, R, G, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -#[cfg(feature = "owning_ref")] -unsafe impl<'a, R: RawMutex + 'a, G: GetThreadId + 'a, T: ?Sized + 'a> StableAddress - for MappedReentrantMutexGuard<'a, R, G, T> -{ -} diff --git a/vendor/lock_api/src/rwlock.rs b/vendor/lock_api/src/rwlock.rs deleted file mode 100644 index cf9e8aa..0000000 --- a/vendor/lock_api/src/rwlock.rs +++ /dev/null @@ -1,2883 +0,0 @@ -// 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 core::cell::UnsafeCell; -use core::fmt; -use core::marker::PhantomData; -use core::mem; -use core::ops::{Deref, DerefMut}; - -#[cfg(feature = "arc_lock")] -use alloc::sync::Arc; -#[cfg(feature = "arc_lock")] -use core::mem::ManuallyDrop; -#[cfg(feature = "arc_lock")] -use core::ptr; - -#[cfg(feature = "owning_ref")] -use owning_ref::StableAddress; - -#[cfg(feature = "serde")] -use serde::{Deserialize, Deserializer, Serialize, Serializer}; - -/// Basic operations for a reader-writer lock. -/// -/// Types implementing this trait can be used by `RwLock` to form a safe and -/// fully-functioning `RwLock` type. -/// -/// # Safety -/// -/// Implementations of this trait must ensure that the `RwLock` is actually -/// exclusive: an exclusive lock can't be acquired while an exclusive or shared -/// lock exists, and a shared lock can't be acquire while an exclusive lock -/// exists. -pub unsafe trait RawRwLock { - /// Initial value for an unlocked `RwLock`. - // A “non-constant” const item is a legacy way to supply an initialized value to downstream - // static items. Can hopefully be replaced with `const fn new() -> Self` at some point. - #[allow(clippy::declare_interior_mutable_const)] - const INIT: Self; - - /// Marker type which determines whether a lock guard should be `Send`. Use - /// one of the `GuardSend` or `GuardNoSend` helper types here. - type GuardMarker; - - /// Acquires a shared lock, blocking the current thread until it is able to do so. - fn lock_shared(&self); - - /// Attempts to acquire a shared lock without blocking. - fn try_lock_shared(&self) -> bool; - - /// Releases a shared lock. - /// - /// # Safety - /// - /// This method may only be called if a shared lock is held in the current context. - unsafe fn unlock_shared(&self); - - /// Acquires an exclusive lock, blocking the current thread until it is able to do so. - fn lock_exclusive(&self); - - /// Attempts to acquire an exclusive lock without blocking. - fn try_lock_exclusive(&self) -> bool; - - /// Releases an exclusive lock. - /// - /// # Safety - /// - /// This method may only be called if an exclusive lock is held in the current context. - unsafe fn unlock_exclusive(&self); - - /// Checks if this `RwLock` is currently locked in any way. - #[inline] - fn is_locked(&self) -> bool { - let acquired_lock = self.try_lock_exclusive(); - if acquired_lock { - // Safety: A lock was successfully acquired above. - unsafe { - self.unlock_exclusive(); - } - } - !acquired_lock - } - - /// Check if this `RwLock` is currently exclusively locked. - fn is_locked_exclusive(&self) -> bool { - let acquired_lock = self.try_lock_shared(); - if acquired_lock { - // Safety: A shared lock was successfully acquired above. - unsafe { - self.unlock_shared(); - } - } - !acquired_lock - } -} - -/// Additional methods for RwLocks which support fair unlocking. -/// -/// Fair unlocking means that a lock is handed directly over to the next waiting -/// thread if there is one, without giving other threads the opportunity to -/// "steal" the lock in the meantime. This is typically slower than unfair -/// unlocking, but may be necessary in certain circumstances. -pub unsafe trait RawRwLockFair: RawRwLock { - /// Releases a shared lock using a fair unlock protocol. - /// - /// # Safety - /// - /// This method may only be called if a shared lock is held in the current context. - unsafe fn unlock_shared_fair(&self); - - /// Releases an exclusive lock using a fair unlock protocol. - /// - /// # Safety - /// - /// This method may only be called if an exclusive lock is held in the current context. - unsafe fn unlock_exclusive_fair(&self); - - /// Temporarily yields a shared lock to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `unlock_shared_fair` followed - /// by `lock_shared`, however it can be much more efficient in the case where there - /// are no waiting threads. - /// - /// # Safety - /// - /// This method may only be called if a shared lock is held in the current context. - unsafe fn bump_shared(&self) { - self.unlock_shared_fair(); - self.lock_shared(); - } - - /// Temporarily yields an exclusive lock to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `unlock_exclusive_fair` followed - /// by `lock_exclusive`, however it can be much more efficient in the case where there - /// are no waiting threads. - /// - /// # Safety - /// - /// This method may only be called if an exclusive lock is held in the current context. - unsafe fn bump_exclusive(&self) { - self.unlock_exclusive_fair(); - self.lock_exclusive(); - } -} - -/// Additional methods for RwLocks which support atomically downgrading an -/// exclusive lock to a shared lock. -pub unsafe trait RawRwLockDowngrade: RawRwLock { - /// Atomically downgrades an exclusive lock into a shared lock without - /// allowing any thread to take an exclusive lock in the meantime. - /// - /// # Safety - /// - /// This method may only be called if an exclusive lock is held in the current context. - unsafe fn downgrade(&self); -} - -/// Additional methods for RwLocks which support locking with timeouts. -/// -/// The `Duration` and `Instant` types are specified as associated types so that -/// this trait is usable even in `no_std` environments. -pub unsafe trait RawRwLockTimed: RawRwLock { - /// Duration type used for `try_lock_for`. - type Duration; - - /// Instant type used for `try_lock_until`. - type Instant; - - /// Attempts to acquire a shared lock until a timeout is reached. - fn try_lock_shared_for(&self, timeout: Self::Duration) -> bool; - - /// Attempts to acquire a shared lock until a timeout is reached. - fn try_lock_shared_until(&self, timeout: Self::Instant) -> bool; - - /// Attempts to acquire an exclusive lock until a timeout is reached. - fn try_lock_exclusive_for(&self, timeout: Self::Duration) -> bool; - - /// Attempts to acquire an exclusive lock until a timeout is reached. - fn try_lock_exclusive_until(&self, timeout: Self::Instant) -> bool; -} - -/// Additional methods for RwLocks which support recursive read locks. -/// -/// These are guaranteed to succeed without blocking if -/// another read lock is held at the time of the call. This allows a thread -/// to recursively lock a `RwLock`. However using this method can cause -/// writers to starve since readers no longer block if a writer is waiting -/// for the lock. -pub unsafe trait RawRwLockRecursive: RawRwLock { - /// Acquires a shared lock without deadlocking in case of a recursive lock. - fn lock_shared_recursive(&self); - - /// Attempts to acquire a shared lock without deadlocking in case of a recursive lock. - fn try_lock_shared_recursive(&self) -> bool; -} - -/// Additional methods for RwLocks which support recursive read locks and timeouts. -pub unsafe trait RawRwLockRecursiveTimed: RawRwLockRecursive + RawRwLockTimed { - /// Attempts to acquire a shared lock until a timeout is reached, without - /// deadlocking in case of a recursive lock. - fn try_lock_shared_recursive_for(&self, timeout: Self::Duration) -> bool; - - /// Attempts to acquire a shared lock until a timeout is reached, without - /// deadlocking in case of a recursive lock. - fn try_lock_shared_recursive_until(&self, timeout: Self::Instant) -> bool; -} - -/// Additional methods for RwLocks which support atomically upgrading a shared -/// lock to an exclusive lock. -/// -/// This requires acquiring a special "upgradable read lock" instead of a -/// normal shared lock. There may only be one upgradable lock at any time, -/// otherwise deadlocks could occur when upgrading. -pub unsafe trait RawRwLockUpgrade: RawRwLock { - /// Acquires an upgradable lock, blocking the current thread until it is able to do so. - fn lock_upgradable(&self); - - /// Attempts to acquire an upgradable lock without blocking. - fn try_lock_upgradable(&self) -> bool; - - /// Releases an upgradable lock. - /// - /// # Safety - /// - /// This method may only be called if an upgradable lock is held in the current context. - unsafe fn unlock_upgradable(&self); - - /// Upgrades an upgradable lock to an exclusive lock. - /// - /// # Safety - /// - /// This method may only be called if an upgradable lock is held in the current context. - unsafe fn upgrade(&self); - - /// Attempts to upgrade an upgradable lock to an exclusive lock without - /// blocking. - /// - /// # Safety - /// - /// This method may only be called if an upgradable lock is held in the current context. - unsafe fn try_upgrade(&self) -> bool; -} - -/// Additional methods for RwLocks which support upgradable locks and fair -/// unlocking. -pub unsafe trait RawRwLockUpgradeFair: RawRwLockUpgrade + RawRwLockFair { - /// Releases an upgradable lock using a fair unlock protocol. - /// - /// # Safety - /// - /// This method may only be called if an upgradable lock is held in the current context. - unsafe fn unlock_upgradable_fair(&self); - - /// Temporarily yields an upgradable lock to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `unlock_upgradable_fair` followed - /// by `lock_upgradable`, however it can be much more efficient in the case where there - /// are no waiting threads. - /// - /// # Safety - /// - /// This method may only be called if an upgradable lock is held in the current context. - unsafe fn bump_upgradable(&self) { - self.unlock_upgradable_fair(); - self.lock_upgradable(); - } -} - -/// Additional methods for RwLocks which support upgradable locks and lock -/// downgrading. -pub unsafe trait RawRwLockUpgradeDowngrade: RawRwLockUpgrade + RawRwLockDowngrade { - /// Downgrades an upgradable lock to a shared lock. - /// - /// # Safety - /// - /// This method may only be called if an upgradable lock is held in the current context. - unsafe fn downgrade_upgradable(&self); - - /// Downgrades an exclusive lock to an upgradable lock. - /// - /// # Safety - /// - /// This method may only be called if an exclusive lock is held in the current context. - unsafe fn downgrade_to_upgradable(&self); -} - -/// Additional methods for RwLocks which support upgradable locks and locking -/// with timeouts. -pub unsafe trait RawRwLockUpgradeTimed: RawRwLockUpgrade + RawRwLockTimed { - /// Attempts to acquire an upgradable lock until a timeout is reached. - fn try_lock_upgradable_for(&self, timeout: Self::Duration) -> bool; - - /// Attempts to acquire an upgradable lock until a timeout is reached. - fn try_lock_upgradable_until(&self, timeout: Self::Instant) -> bool; - - /// Attempts to upgrade an upgradable lock to an exclusive lock until a - /// timeout is reached. - /// - /// # Safety - /// - /// This method may only be called if an upgradable lock is held in the current context. - unsafe fn try_upgrade_for(&self, timeout: Self::Duration) -> bool; - - /// Attempts to upgrade an upgradable lock to an exclusive lock until a - /// timeout is reached. - /// - /// # Safety - /// - /// This method may only be called if an upgradable lock is held in the current context. - unsafe fn try_upgrade_until(&self, timeout: Self::Instant) -> bool; -} - -/// 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). -/// -/// 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. -pub struct RwLock<R, T: ?Sized> { - raw: R, - data: UnsafeCell<T>, -} - -// Copied and modified from serde -#[cfg(feature = "serde")] -impl<R, T> Serialize for RwLock<R, T> -where - R: RawRwLock, - T: Serialize + ?Sized, -{ - fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> - where - S: Serializer, - { - self.read().serialize(serializer) - } -} - -#[cfg(feature = "serde")] -impl<'de, R, T> Deserialize<'de> for RwLock<R, T> -where - R: RawRwLock, - T: Deserialize<'de> + ?Sized, -{ - fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> - where - D: Deserializer<'de>, - { - Deserialize::deserialize(deserializer).map(RwLock::new) - } -} - -unsafe impl<R: RawRwLock + Send, T: ?Sized + Send> Send for RwLock<R, T> {} -unsafe impl<R: RawRwLock + Sync, T: ?Sized + Send + Sync> Sync for RwLock<R, T> {} - -impl<R: RawRwLock, T> RwLock<R, T> { - /// Creates a new instance of an `RwLock<T>` which is unlocked. - #[cfg(has_const_fn_trait_bound)] - #[inline] - pub const fn new(val: T) -> RwLock<R, T> { - RwLock { - data: UnsafeCell::new(val), - raw: R::INIT, - } - } - - /// Creates a new instance of an `RwLock<T>` which is unlocked. - #[cfg(not(has_const_fn_trait_bound))] - #[inline] - pub fn new(val: T) -> RwLock<R, T> { - RwLock { - data: UnsafeCell::new(val), - raw: R::INIT, - } - } - - /// Consumes this `RwLock`, returning the underlying data. - #[inline] - #[allow(unused_unsafe)] - pub fn into_inner(self) -> T { - unsafe { self.data.into_inner() } - } -} - -impl<R, T> RwLock<R, T> { - /// Creates a new new instance of an `RwLock<T>` based on a pre-existing - /// `RawRwLock<T>`. - /// - /// This allows creating a `RwLock<T>` in a constant context on stable - /// Rust. - #[inline] - pub const fn const_new(raw_rwlock: R, val: T) -> RwLock<R, T> { - RwLock { - data: UnsafeCell::new(val), - raw: raw_rwlock, - } - } -} - -impl<R: RawRwLock, T: ?Sized> RwLock<R, T> { - /// Creates a new `RwLockReadGuard` without checking if the lock is held. - /// - /// # Safety - /// - /// This method must only be called if the thread logically holds a read lock. - /// - /// This function does not increment the read count of the lock. Calling this function when a - /// guard has already been produced is undefined behaviour unless the guard was forgotten - /// with `mem::forget`.` - #[inline] - pub unsafe fn make_read_guard_unchecked(&self) -> RwLockReadGuard<'_, R, T> { - RwLockReadGuard { - rwlock: self, - marker: PhantomData, - } - } - - /// Creates a new `RwLockReadGuard` without checking if the lock is held. - /// - /// # Safety - /// - /// This method must only be called if the thread logically holds a write lock. - /// - /// Calling this function when a guard has already been produced is undefined behaviour unless - /// the guard was forgotten with `mem::forget`. - #[inline] - pub unsafe fn make_write_guard_unchecked(&self) -> RwLockWriteGuard<'_, R, T> { - RwLockWriteGuard { - rwlock: self, - marker: PhantomData, - } - } - - /// Locks this `RwLock` 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. - /// - /// Note that attempts to recursively acquire a read lock on a `RwLock` when - /// the current thread already holds one may result in a deadlock. - /// - /// Returns an RAII guard which will release this thread's shared access - /// once it is dropped. - #[inline] - pub fn read(&self) -> RwLockReadGuard<'_, R, T> { - self.raw.lock_shared(); - // SAFETY: The lock is held, as required. - unsafe { self.make_read_guard_unchecked() } - } - - /// Attempts to acquire this `RwLock` with shared read access. - /// - /// If the access could not be granted at this time, then `None` is returned. - /// Otherwise, an RAII guard is returned which will release the shared access - /// when it is dropped. - /// - /// This function does not block. - #[inline] - pub fn try_read(&self) -> Option<RwLockReadGuard<'_, R, T>> { - if self.raw.try_lock_shared() { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_read_guard_unchecked() }) - } else { - None - } - } - - /// Locks this `RwLock` with exclusive write access, blocking the current - /// thread until it can be acquired. - /// - /// This function will not return while other writers or other readers - /// currently have access to the lock. - /// - /// Returns an RAII guard which will drop the write access of this `RwLock` - /// when dropped. - #[inline] - pub fn write(&self) -> RwLockWriteGuard<'_, R, T> { - self.raw.lock_exclusive(); - // SAFETY: The lock is held, as required. - unsafe { self.make_write_guard_unchecked() } - } - - /// Attempts to lock this `RwLock` with exclusive write access. - /// - /// If the lock could not be acquired at this time, then `None` is returned. - /// Otherwise, an RAII guard is returned which will release the lock when - /// it is dropped. - /// - /// This function does not block. - #[inline] - pub fn try_write(&self) -> Option<RwLockWriteGuard<'_, R, T>> { - if self.raw.try_lock_exclusive() { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_write_guard_unchecked() }) - } else { - None - } - } - - /// Returns a mutable reference to the underlying data. - /// - /// Since this call borrows the `RwLock` mutably, no actual locking needs to - /// take place---the mutable borrow statically guarantees no locks exist. - #[inline] - pub fn get_mut(&mut self) -> &mut T { - unsafe { &mut *self.data.get() } - } - - /// Checks whether this `RwLock` is currently locked in any way. - #[inline] - pub fn is_locked(&self) -> bool { - self.raw.is_locked() - } - - /// Check if this `RwLock` is currently exclusively locked. - #[inline] - pub fn is_locked_exclusive(&self) -> bool { - self.raw.is_locked_exclusive() - } - - /// Forcibly unlocks a read lock. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `RwLockReadGuard` object alive, for example when - /// dealing with FFI. - /// - /// # Safety - /// - /// This method must only be called if the current thread logically owns a - /// `RwLockReadGuard` but that guard has be discarded using `mem::forget`. - /// Behavior is undefined if a rwlock is read-unlocked when not read-locked. - #[inline] - pub unsafe fn force_unlock_read(&self) { - self.raw.unlock_shared(); - } - - /// Forcibly unlocks a write lock. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `RwLockWriteGuard` object alive, for example when - /// dealing with FFI. - /// - /// # Safety - /// - /// This method must only be called if the current thread logically owns a - /// `RwLockWriteGuard` but that guard has be discarded using `mem::forget`. - /// Behavior is undefined if a rwlock is write-unlocked when not write-locked. - #[inline] - pub unsafe fn force_unlock_write(&self) { - self.raw.unlock_exclusive(); - } - - /// Returns the underlying raw reader-writer lock object. - /// - /// Note that you will most likely need to import the `RawRwLock` trait from - /// `lock_api` to be able to call functions on the raw - /// reader-writer lock. - /// - /// # Safety - /// - /// This method is unsafe because it allows unlocking a mutex while - /// still holding a reference to a lock guard. - pub unsafe fn raw(&self) -> &R { - &self.raw - } - - /// Returns a raw pointer to the underlying data. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `RwLockReadGuard` or `RwLockWriteGuard` object - /// alive, for example when dealing with FFI. - /// - /// # Safety - /// - /// You must ensure that there are no data races when dereferencing the - /// returned pointer, for example if the current thread logically owns a - /// `RwLockReadGuard` or `RwLockWriteGuard` but that guard has been discarded - /// using `mem::forget`. - #[inline] - pub fn data_ptr(&self) -> *mut T { - self.data.get() - } - - /// Creates a new `RwLockReadGuard` without checking if the lock is held. - /// - /// # Safety - /// - /// This method must only be called if the thread logically holds a read lock. - /// - /// This function does not increment the read count of the lock. Calling this function when a - /// guard has already been produced is undefined behaviour unless the guard was forgotten - /// with `mem::forget`.` - #[cfg(feature = "arc_lock")] - #[inline] - pub unsafe fn make_arc_read_guard_unchecked(self: &Arc<Self>) -> ArcRwLockReadGuard<R, T> { - ArcRwLockReadGuard { - rwlock: self.clone(), - marker: PhantomData, - } - } - - /// Creates a new `RwLockWriteGuard` without checking if the lock is held. - /// - /// # Safety - /// - /// This method must only be called if the thread logically holds a write lock. - /// - /// Calling this function when a guard has already been produced is undefined behaviour unless - /// the guard was forgotten with `mem::forget`. - #[cfg(feature = "arc_lock")] - #[inline] - pub unsafe fn make_arc_write_guard_unchecked(self: &Arc<Self>) -> ArcRwLockWriteGuard<R, T> { - ArcRwLockWriteGuard { - rwlock: self.clone(), - marker: PhantomData, - } - } - - /// Locks this `RwLock` with read access, through an `Arc`. - /// - /// This method is similar to the `read` method; however, it requires the `RwLock` to be inside of an `Arc` - /// and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn read_arc(self: &Arc<Self>) -> ArcRwLockReadGuard<R, T> { - self.raw.lock_shared(); - // SAFETY: locking guarantee is upheld - unsafe { self.make_arc_read_guard_unchecked() } - } - - /// Attempts to lock this `RwLock` with read access, through an `Arc`. - /// - /// This method is similar to the `try_read` method; however, it requires the `RwLock` to be inside of an - /// `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_read_arc(self: &Arc<Self>) -> Option<ArcRwLockReadGuard<R, T>> { - if self.raw.try_lock_shared() { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_read_guard_unchecked() }) - } else { - None - } - } - - /// Locks this `RwLock` with write access, through an `Arc`. - /// - /// This method is similar to the `write` method; however, it requires the `RwLock` to be inside of an `Arc` - /// and the resulting write guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn write_arc(self: &Arc<Self>) -> ArcRwLockWriteGuard<R, T> { - self.raw.lock_exclusive(); - // SAFETY: locking guarantee is upheld - unsafe { self.make_arc_write_guard_unchecked() } - } - - /// Attempts to lock this `RwLock` with writ access, through an `Arc`. - /// - /// This method is similar to the `try_write` method; however, it requires the `RwLock` to be inside of an - /// `Arc` and the resulting write guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_write_arc(self: &Arc<Self>) -> Option<ArcRwLockWriteGuard<R, T>> { - if self.raw.try_lock_exclusive() { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_write_guard_unchecked() }) - } else { - None - } - } -} - -impl<R: RawRwLockFair, T: ?Sized> RwLock<R, T> { - /// Forcibly unlocks a read lock using a fair unlock procotol. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `RwLockReadGuard` object alive, for example when - /// dealing with FFI. - /// - /// # Safety - /// - /// This method must only be called if the current thread logically owns a - /// `RwLockReadGuard` but that guard has be discarded using `mem::forget`. - /// Behavior is undefined if a rwlock is read-unlocked when not read-locked. - #[inline] - pub unsafe fn force_unlock_read_fair(&self) { - self.raw.unlock_shared_fair(); - } - - /// Forcibly unlocks a write lock using a fair unlock procotol. - /// - /// This is useful when combined with `mem::forget` to hold a lock without - /// the need to maintain a `RwLockWriteGuard` object alive, for example when - /// dealing with FFI. - /// - /// # Safety - /// - /// This method must only be called if the current thread logically owns a - /// `RwLockWriteGuard` but that guard has be discarded using `mem::forget`. - /// Behavior is undefined if a rwlock is write-unlocked when not write-locked. - #[inline] - pub unsafe fn force_unlock_write_fair(&self) { - self.raw.unlock_exclusive_fair(); - } -} - -impl<R: RawRwLockTimed, T: ?Sized> RwLock<R, T> { - /// Attempts to acquire this `RwLock` with shared read access until a timeout - /// is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. Otherwise, an RAII guard is returned which will - /// release the shared access when it is dropped. - #[inline] - pub fn try_read_for(&self, timeout: R::Duration) -> Option<RwLockReadGuard<'_, R, T>> { - if self.raw.try_lock_shared_for(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_read_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this `RwLock` with shared read access until a timeout - /// is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. Otherwise, an RAII guard is returned which will - /// release the shared access when it is dropped. - #[inline] - pub fn try_read_until(&self, timeout: R::Instant) -> Option<RwLockReadGuard<'_, R, T>> { - if self.raw.try_lock_shared_until(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_read_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this `RwLock` with exclusive write access until a - /// timeout is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. Otherwise, an RAII guard is returned which will - /// release the exclusive access when it is dropped. - #[inline] - pub fn try_write_for(&self, timeout: R::Duration) -> Option<RwLockWriteGuard<'_, R, T>> { - if self.raw.try_lock_exclusive_for(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_write_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this `RwLock` with exclusive write access until a - /// timeout is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. Otherwise, an RAII guard is returned which will - /// release the exclusive access when it is dropped. - #[inline] - pub fn try_write_until(&self, timeout: R::Instant) -> Option<RwLockWriteGuard<'_, R, T>> { - if self.raw.try_lock_exclusive_until(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_write_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this `RwLock` with read access until a timeout is reached, through an `Arc`. - /// - /// This method is similar to the `try_read_for` method; however, it requires the `RwLock` to be inside of an - /// `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_read_arc_for( - self: &Arc<Self>, - timeout: R::Duration, - ) -> Option<ArcRwLockReadGuard<R, T>> { - if self.raw.try_lock_shared_for(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_read_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this `RwLock` with read access until a timeout is reached, through an `Arc`. - /// - /// This method is similar to the `try_read_until` method; however, it requires the `RwLock` to be inside of - /// an `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_read_arc_until( - self: &Arc<Self>, - timeout: R::Instant, - ) -> Option<ArcRwLockReadGuard<R, T>> { - if self.raw.try_lock_shared_until(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_read_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this `RwLock` with write access until a timeout is reached, through an `Arc`. - /// - /// This method is similar to the `try_write_for` method; however, it requires the `RwLock` to be inside of - /// an `Arc` and the resulting write guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_write_arc_for( - self: &Arc<Self>, - timeout: R::Duration, - ) -> Option<ArcRwLockWriteGuard<R, T>> { - if self.raw.try_lock_exclusive_for(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_write_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this `RwLock` with read access until a timeout is reached, through an `Arc`. - /// - /// This method is similar to the `try_write_until` method; however, it requires the `RwLock` to be inside of - /// an `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_write_arc_until( - self: &Arc<Self>, - timeout: R::Instant, - ) -> Option<ArcRwLockWriteGuard<R, T>> { - if self.raw.try_lock_exclusive_until(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_write_guard_unchecked() }) - } else { - None - } - } -} - -impl<R: RawRwLockRecursive, T: ?Sized> RwLock<R, T> { - /// Locks this `RwLock` 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. - /// - /// Unlike `read`, this method is guaranteed to succeed without blocking if - /// another read lock is held at the time of the call. This allows a thread - /// to recursively lock a `RwLock`. However using this method can cause - /// writers to starve since readers no longer block if a writer is waiting - /// for the lock. - /// - /// Returns an RAII guard which will release this thread's shared access - /// once it is dropped. - #[inline] - pub fn read_recursive(&self) -> RwLockReadGuard<'_, R, T> { - self.raw.lock_shared_recursive(); - // SAFETY: The lock is held, as required. - unsafe { self.make_read_guard_unchecked() } - } - - /// Attempts to acquire this `RwLock` with shared read access. - /// - /// If the access could not be granted at this time, then `None` is returned. - /// Otherwise, an RAII guard is returned which will release the shared access - /// when it is dropped. - /// - /// This method is guaranteed to succeed if another read lock is held at the - /// time of the call. See the documentation for `read_recursive` for details. - /// - /// This function does not block. - #[inline] - pub fn try_read_recursive(&self) -> Option<RwLockReadGuard<'_, R, T>> { - if self.raw.try_lock_shared_recursive() { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_read_guard_unchecked() }) - } else { - None - } - } - - /// Locks this `RwLock` with shared read access, through an `Arc`. - /// - /// This method is similar to the `read_recursive` method; however, it requires the `RwLock` to be inside of - /// an `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn read_arc_recursive(self: &Arc<Self>) -> ArcRwLockReadGuard<R, T> { - self.raw.lock_shared_recursive(); - // SAFETY: locking guarantee is upheld - unsafe { self.make_arc_read_guard_unchecked() } - } - - /// Attempts to lock this `RwLock` with shared read access, through an `Arc`. - /// - /// This method is similar to the `try_read_recursive` method; however, it requires the `RwLock` to be inside - /// of an `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_read_recursive_arc(self: &Arc<Self>) -> Option<ArcRwLockReadGuard<R, T>> { - if self.raw.try_lock_shared_recursive() { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_read_guard_unchecked() }) - } else { - None - } - } -} - -impl<R: RawRwLockRecursiveTimed, T: ?Sized> RwLock<R, T> { - /// Attempts to acquire this `RwLock` with shared read access until a timeout - /// is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. Otherwise, an RAII guard is returned which will - /// release the shared access when it is dropped. - /// - /// This method is guaranteed to succeed without blocking if another read - /// lock is held at the time of the call. See the documentation for - /// `read_recursive` for details. - #[inline] - pub fn try_read_recursive_for( - &self, - timeout: R::Duration, - ) -> Option<RwLockReadGuard<'_, R, T>> { - if self.raw.try_lock_shared_recursive_for(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_read_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this `RwLock` with shared read access until a timeout - /// is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. Otherwise, an RAII guard is returned which will - /// release the shared access when it is dropped. - #[inline] - pub fn try_read_recursive_until( - &self, - timeout: R::Instant, - ) -> Option<RwLockReadGuard<'_, R, T>> { - if self.raw.try_lock_shared_recursive_until(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_read_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to lock this `RwLock` with read access until a timeout is reached, through an `Arc`. - /// - /// This method is similar to the `try_read_recursive_for` method; however, it requires the `RwLock` to be - /// inside of an `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_read_arc_recursive_for( - self: &Arc<Self>, - timeout: R::Duration, - ) -> Option<ArcRwLockReadGuard<R, T>> { - if self.raw.try_lock_shared_recursive_for(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_read_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to lock this `RwLock` with read access until a timeout is reached, through an `Arc`. - /// - /// This method is similar to the `try_read_recursive_until` method; however, it requires the `RwLock` to be - /// inside of an `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_read_arc_recursive_until( - self: &Arc<Self>, - timeout: R::Instant, - ) -> Option<ArcRwLockReadGuard<R, T>> { - if self.raw.try_lock_shared_recursive_until(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_arc_read_guard_unchecked() }) - } else { - None - } - } -} - -impl<R: RawRwLockUpgrade, T: ?Sized> RwLock<R, T> { - /// Creates a new `RwLockUpgradableReadGuard` without checking if the lock is held. - /// - /// # Safety - /// - /// This method must only be called if the thread logically holds an upgradable read lock. - /// - /// This function does not increment the read count of the lock. Calling this function when a - /// guard has already been produced is undefined behaviour unless the guard was forgotten - /// with `mem::forget`.` - #[inline] - pub unsafe fn make_upgradable_guard_unchecked(&self) -> RwLockUpgradableReadGuard<'_, R, T> { - RwLockUpgradableReadGuard { - rwlock: self, - marker: PhantomData, - } - } - - /// Locks this `RwLock` with upgradable read access, blocking the current thread - /// until it can be acquired. - /// - /// The calling thread will be blocked until there are no more writers or other - /// upgradable reads which hold the lock. There may be other readers currently - /// inside the lock when this method returns. - /// - /// Returns an RAII guard which will release this thread's shared access - /// once it is dropped. - #[inline] - pub fn upgradable_read(&self) -> RwLockUpgradableReadGuard<'_, R, T> { - self.raw.lock_upgradable(); - // SAFETY: The lock is held, as required. - unsafe { self.make_upgradable_guard_unchecked() } - } - - /// Attempts to acquire this `RwLock` with upgradable read access. - /// - /// If the access could not be granted at this time, then `None` is returned. - /// Otherwise, an RAII guard is returned which will release the shared access - /// when it is dropped. - /// - /// This function does not block. - #[inline] - pub fn try_upgradable_read(&self) -> Option<RwLockUpgradableReadGuard<'_, R, T>> { - if self.raw.try_lock_upgradable() { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_upgradable_guard_unchecked() }) - } else { - None - } - } - - /// Creates a new `ArcRwLockUpgradableReadGuard` without checking if the lock is held. - /// - /// # Safety - /// - /// This method must only be called if the thread logically holds an upgradable read lock. - /// - /// This function does not increment the read count of the lock. Calling this function when a - /// guard has already been produced is undefined behaviour unless the guard was forgotten - /// with `mem::forget`.` - #[cfg(feature = "arc_lock")] - #[inline] - pub unsafe fn make_upgradable_arc_guard_unchecked( - self: &Arc<Self>, - ) -> ArcRwLockUpgradableReadGuard<R, T> { - ArcRwLockUpgradableReadGuard { - rwlock: self.clone(), - marker: PhantomData, - } - } - - /// Locks this `RwLock` with upgradable read access, through an `Arc`. - /// - /// This method is similar to the `upgradable_read` method; however, it requires the `RwLock` to be - /// inside of an `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn upgradable_read_arc(self: &Arc<Self>) -> ArcRwLockUpgradableReadGuard<R, T> { - self.raw.lock_upgradable(); - // SAFETY: locking guarantee is upheld - unsafe { self.make_upgradable_arc_guard_unchecked() } - } - - /// Attempts to lock this `RwLock` with upgradable read access, through an `Arc`. - /// - /// This method is similar to the `try_upgradable_read` method; however, it requires the `RwLock` to be - /// inside of an `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_upgradable_read_arc(self: &Arc<Self>) -> Option<ArcRwLockUpgradableReadGuard<R, T>> { - if self.raw.try_lock_upgradable() { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_upgradable_arc_guard_unchecked() }) - } else { - None - } - } -} - -impl<R: RawRwLockUpgradeTimed, T: ?Sized> RwLock<R, T> { - /// Attempts to acquire this `RwLock` with upgradable read access until a timeout - /// is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. Otherwise, an RAII guard is returned which will - /// release the shared access when it is dropped. - #[inline] - pub fn try_upgradable_read_for( - &self, - timeout: R::Duration, - ) -> Option<RwLockUpgradableReadGuard<'_, R, T>> { - if self.raw.try_lock_upgradable_for(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_upgradable_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to acquire this `RwLock` with upgradable read access until a timeout - /// is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. Otherwise, an RAII guard is returned which will - /// release the shared access when it is dropped. - #[inline] - pub fn try_upgradable_read_until( - &self, - timeout: R::Instant, - ) -> Option<RwLockUpgradableReadGuard<'_, R, T>> { - if self.raw.try_lock_upgradable_until(timeout) { - // SAFETY: The lock is held, as required. - Some(unsafe { self.make_upgradable_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to lock this `RwLock` with upgradable access until a timeout is reached, through an `Arc`. - /// - /// This method is similar to the `try_upgradable_read_for` method; however, it requires the `RwLock` to be - /// inside of an `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_upgradable_read_arc_for( - self: &Arc<Self>, - timeout: R::Duration, - ) -> Option<ArcRwLockUpgradableReadGuard<R, T>> { - if self.raw.try_lock_upgradable_for(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_upgradable_arc_guard_unchecked() }) - } else { - None - } - } - - /// Attempts to lock this `RwLock` with upgradable access until a timeout is reached, through an `Arc`. - /// - /// This method is similar to the `try_upgradable_read_until` method; however, it requires the `RwLock` to be - /// inside of an `Arc` and the resulting read guard has no lifetime requirements. - #[cfg(feature = "arc_lock")] - #[inline] - pub fn try_upgradable_read_arc_until( - self: &Arc<Self>, - timeout: R::Instant, - ) -> Option<ArcRwLockUpgradableReadGuard<R, T>> { - if self.raw.try_lock_upgradable_until(timeout) { - // SAFETY: locking guarantee is upheld - Some(unsafe { self.make_upgradable_arc_guard_unchecked() }) - } else { - None - } - } -} - -impl<R: RawRwLock, T: ?Sized + Default> Default for RwLock<R, T> { - #[inline] - fn default() -> RwLock<R, T> { - RwLock::new(Default::default()) - } -} - -impl<R: RawRwLock, T> From<T> for RwLock<R, T> { - #[inline] - fn from(t: T) -> RwLock<R, T> { - RwLock::new(t) - } -} - -impl<R: RawRwLock, T: ?Sized + fmt::Debug> fmt::Debug for RwLock<R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match self.try_read() { - Some(guard) => f.debug_struct("RwLock").field("data", &&*guard).finish(), - None => { - struct LockedPlaceholder; - impl fmt::Debug for LockedPlaceholder { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.write_str("<locked>") - } - } - - f.debug_struct("RwLock") - .field("data", &LockedPlaceholder) - .finish() - } - } - } -} - -/// RAII structure used to release the shared read access of a lock when -/// dropped. -#[clippy::has_significant_drop] -#[must_use = "if unused the RwLock will immediately unlock"] -pub struct RwLockReadGuard<'a, R: RawRwLock, T: ?Sized> { - rwlock: &'a RwLock<R, T>, - marker: PhantomData<(&'a T, R::GuardMarker)>, -} - -unsafe impl<R: RawRwLock + Sync, T: Sync + ?Sized> Sync for RwLockReadGuard<'_, R, T> {} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> RwLockReadGuard<'a, R, T> { - /// Returns a reference to the original reader-writer lock object. - pub fn rwlock(s: &Self) -> &'a RwLock<R, T> { - s.rwlock - } - - /// Make a new `MappedRwLockReadGuard` for a component of the locked data. - /// - /// This operation cannot fail as the `RwLockReadGuard` passed - /// in already locked the data. - /// - /// This is an associated function that needs to be - /// used as `RwLockReadGuard::map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedRwLockReadGuard<'a, R, U> - where - F: FnOnce(&T) -> &U, - { - let raw = &s.rwlock.raw; - let data = f(unsafe { &*s.rwlock.data.get() }); - mem::forget(s); - MappedRwLockReadGuard { - raw, - data, - marker: PhantomData, - } - } - - /// Attempts to make a new `MappedRwLockReadGuard` for a component of the - /// locked data. Returns the original guard if the closure returns `None`. - /// - /// This operation cannot fail as the `RwLockReadGuard` passed - /// in already locked the data. - /// - /// This is an associated function that needs to be - /// used as `RwLockReadGuard::try_map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn try_map<U: ?Sized, F>(s: Self, f: F) -> Result<MappedRwLockReadGuard<'a, R, U>, Self> - where - F: FnOnce(&T) -> Option<&U>, - { - let raw = &s.rwlock.raw; - let data = match f(unsafe { &*s.rwlock.data.get() }) { - Some(data) => data, - None => return Err(s), - }; - mem::forget(s); - Ok(MappedRwLockReadGuard { - raw, - data, - marker: PhantomData, - }) - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the `RwLock`. - #[inline] - pub fn unlocked<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - s.rwlock.raw.unlock_shared(); - } - defer!(s.rwlock.raw.lock_shared()); - f() - } -} - -impl<'a, R: RawRwLockFair + 'a, T: ?Sized + 'a> RwLockReadGuard<'a, R, T> { - /// Unlocks the `RwLock` using a fair unlock protocol. - /// - /// By default, `RwLock` is unfair and allow the current thread to re-lock - /// the `RwLock` before another has the chance to acquire the lock, even if - /// that thread has been blocked on the `RwLock` for a long time. This is - /// the default because it allows much higher throughput as it avoids - /// forcing a context switch on every `RwLock` unlock. This can result in one - /// thread acquiring a `RwLock` many more times than other threads. - /// - /// However in some cases it can be beneficial to ensure fairness by forcing - /// the lock to pass on to a waiting thread if there is one. This is done by - /// using this method instead of dropping the `RwLockReadGuard` normally. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - s.rwlock.raw.unlock_shared_fair(); - } - mem::forget(s); - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// The `RwLock` is unlocked a fair unlock protocol. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the `RwLock`. - #[inline] - pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - s.rwlock.raw.unlock_shared_fair(); - } - defer!(s.rwlock.raw.lock_shared()); - f() - } - - /// Temporarily yields the `RwLock` to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `unlock_fair` followed - /// by `read`, however it can be much more efficient in the case where there - /// are no waiting threads. - #[inline] - pub fn bump(s: &mut Self) { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - s.rwlock.raw.bump_shared(); - } - } -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for RwLockReadGuard<'a, R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.rwlock.data.get() } - } -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Drop for RwLockReadGuard<'a, R, T> { - #[inline] - fn drop(&mut self) { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - self.rwlock.raw.unlock_shared(); - } - } -} - -impl<'a, R: RawRwLock + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug for RwLockReadGuard<'a, R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -impl<'a, R: RawRwLock + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display - for RwLockReadGuard<'a, R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -#[cfg(feature = "owning_ref")] -unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> StableAddress for RwLockReadGuard<'a, R, T> {} - -/// An RAII rwlock guard returned by the `Arc` locking operations on `RwLock`. -/// -/// This is similar to the `RwLockReadGuard` struct, except instead of using a reference to unlock the `RwLock` -/// it uses an `Arc<RwLock>`. This has several advantages, most notably that it has an `'static` lifetime. -#[cfg(feature = "arc_lock")] -#[clippy::has_significant_drop] -#[must_use = "if unused the RwLock will immediately unlock"] -pub struct ArcRwLockReadGuard<R: RawRwLock, T: ?Sized> { - rwlock: Arc<RwLock<R, T>>, - marker: PhantomData<R::GuardMarker>, -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: ?Sized> ArcRwLockReadGuard<R, T> { - /// Returns a reference to the rwlock, contained in its `Arc`. - pub fn rwlock(s: &Self) -> &Arc<RwLock<R, T>> { - &s.rwlock - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// This is functionally identical to the `unlocked` method on [`RwLockReadGuard`]. - #[inline] - pub fn unlocked<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - s.rwlock.raw.unlock_shared(); - } - defer!(s.rwlock.raw.lock_shared()); - f() - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockFair, T: ?Sized> ArcRwLockReadGuard<R, T> { - /// Unlocks the `RwLock` using a fair unlock protocol. - /// - /// This is functionally identical to the `unlock_fair` method on [`RwLockReadGuard`]. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - s.rwlock.raw.unlock_shared_fair(); - } - - // SAFETY: ensure the Arc has its refcount decremented - let mut s = ManuallyDrop::new(s); - unsafe { ptr::drop_in_place(&mut s.rwlock) }; - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// This is functionally identical to the `unlocked_fair` method on [`RwLockReadGuard`]. - #[inline] - pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - s.rwlock.raw.unlock_shared_fair(); - } - defer!(s.rwlock.raw.lock_shared()); - f() - } - - /// Temporarily yields the `RwLock` to a waiting thread if there is one. - /// - /// This is functionally identical to the `bump` method on [`RwLockReadGuard`]. - #[inline] - pub fn bump(s: &mut Self) { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - s.rwlock.raw.bump_shared(); - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: ?Sized> Deref for ArcRwLockReadGuard<R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.rwlock.data.get() } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: ?Sized> Drop for ArcRwLockReadGuard<R, T> { - #[inline] - fn drop(&mut self) { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - self.rwlock.raw.unlock_shared(); - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: fmt::Debug + ?Sized> fmt::Debug for ArcRwLockReadGuard<R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: fmt::Display + ?Sized> fmt::Display for ArcRwLockReadGuard<R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -/// RAII structure used to release the exclusive write access of a lock when -/// dropped. -#[clippy::has_significant_drop] -#[must_use = "if unused the RwLock will immediately unlock"] -pub struct RwLockWriteGuard<'a, R: RawRwLock, T: ?Sized> { - rwlock: &'a RwLock<R, T>, - marker: PhantomData<(&'a mut T, R::GuardMarker)>, -} - -unsafe impl<R: RawRwLock + Sync, T: Sync + ?Sized> Sync for RwLockWriteGuard<'_, R, T> {} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T> { - /// Returns a reference to the original reader-writer lock object. - pub fn rwlock(s: &Self) -> &'a RwLock<R, T> { - s.rwlock - } - - /// Make a new `MappedRwLockWriteGuard` for a component of the locked data. - /// - /// This operation cannot fail as the `RwLockWriteGuard` passed - /// in already locked the data. - /// - /// This is an associated function that needs to be - /// used as `RwLockWriteGuard::map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedRwLockWriteGuard<'a, R, U> - where - F: FnOnce(&mut T) -> &mut U, - { - let raw = &s.rwlock.raw; - let data = f(unsafe { &mut *s.rwlock.data.get() }); - mem::forget(s); - MappedRwLockWriteGuard { - raw, - data, - marker: PhantomData, - } - } - - /// Attempts to make a new `MappedRwLockWriteGuard` for a component of the - /// locked data. The original guard is return if the closure returns `None`. - /// - /// This operation cannot fail as the `RwLockWriteGuard` passed - /// in already locked the data. - /// - /// This is an associated function that needs to be - /// used as `RwLockWriteGuard::try_map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn try_map<U: ?Sized, F>(s: Self, f: F) -> Result<MappedRwLockWriteGuard<'a, R, U>, Self> - where - F: FnOnce(&mut T) -> Option<&mut U>, - { - let raw = &s.rwlock.raw; - let data = match f(unsafe { &mut *s.rwlock.data.get() }) { - Some(data) => data, - None => return Err(s), - }; - mem::forget(s); - Ok(MappedRwLockWriteGuard { - raw, - data, - marker: PhantomData, - }) - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the `RwLock`. - #[inline] - pub fn unlocked<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockReadGuard always holds a shared lock. - unsafe { - s.rwlock.raw.unlock_exclusive(); - } - defer!(s.rwlock.raw.lock_exclusive()); - f() - } -} - -impl<'a, R: RawRwLockDowngrade + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T> { - /// Atomically downgrades a write lock into a read lock without allowing any - /// writers to take exclusive access of the lock in the meantime. - /// - /// Note that if there are any writers currently waiting to take the lock - /// then other readers may not be able to acquire the lock even if it was - /// downgraded. - pub fn downgrade(s: Self) -> RwLockReadGuard<'a, R, T> { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - s.rwlock.raw.downgrade(); - } - let rwlock = s.rwlock; - mem::forget(s); - RwLockReadGuard { - rwlock, - marker: PhantomData, - } - } -} - -impl<'a, R: RawRwLockUpgradeDowngrade + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T> { - /// Atomically downgrades a write lock into an upgradable read lock without allowing any - /// writers to take exclusive access of the lock in the meantime. - /// - /// Note that if there are any writers currently waiting to take the lock - /// then other readers may not be able to acquire the lock even if it was - /// downgraded. - pub fn downgrade_to_upgradable(s: Self) -> RwLockUpgradableReadGuard<'a, R, T> { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - s.rwlock.raw.downgrade_to_upgradable(); - } - let rwlock = s.rwlock; - mem::forget(s); - RwLockUpgradableReadGuard { - rwlock, - marker: PhantomData, - } - } -} - -impl<'a, R: RawRwLockFair + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T> { - /// Unlocks the `RwLock` using a fair unlock protocol. - /// - /// By default, `RwLock` is unfair and allow the current thread to re-lock - /// the `RwLock` before another has the chance to acquire the lock, even if - /// that thread has been blocked on the `RwLock` for a long time. This is - /// the default because it allows much higher throughput as it avoids - /// forcing a context switch on every `RwLock` unlock. This can result in one - /// thread acquiring a `RwLock` many more times than other threads. - /// - /// However in some cases it can be beneficial to ensure fairness by forcing - /// the lock to pass on to a waiting thread if there is one. This is done by - /// using this method instead of dropping the `RwLockWriteGuard` normally. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - s.rwlock.raw.unlock_exclusive_fair(); - } - mem::forget(s); - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// The `RwLock` is unlocked a fair unlock protocol. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the `RwLock`. - #[inline] - pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - s.rwlock.raw.unlock_exclusive_fair(); - } - defer!(s.rwlock.raw.lock_exclusive()); - f() - } - - /// Temporarily yields the `RwLock` to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `unlock_fair` followed - /// by `write`, however it can be much more efficient in the case where there - /// are no waiting threads. - #[inline] - pub fn bump(s: &mut Self) { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - s.rwlock.raw.bump_exclusive(); - } - } -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for RwLockWriteGuard<'a, R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.rwlock.data.get() } - } -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> DerefMut for RwLockWriteGuard<'a, R, T> { - #[inline] - fn deref_mut(&mut self) -> &mut T { - unsafe { &mut *self.rwlock.data.get() } - } -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Drop for RwLockWriteGuard<'a, R, T> { - #[inline] - fn drop(&mut self) { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - self.rwlock.raw.unlock_exclusive(); - } - } -} - -impl<'a, R: RawRwLock + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug for RwLockWriteGuard<'a, R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -impl<'a, R: RawRwLock + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display - for RwLockWriteGuard<'a, R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -#[cfg(feature = "owning_ref")] -unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> StableAddress for RwLockWriteGuard<'a, R, T> {} - -/// An RAII rwlock guard returned by the `Arc` locking operations on `RwLock`. -/// This is similar to the `RwLockWriteGuard` struct, except instead of using a reference to unlock the `RwLock` -/// it uses an `Arc<RwLock>`. This has several advantages, most notably that it has an `'static` lifetime. -#[cfg(feature = "arc_lock")] -#[clippy::has_significant_drop] -#[must_use = "if unused the RwLock will immediately unlock"] -pub struct ArcRwLockWriteGuard<R: RawRwLock, T: ?Sized> { - rwlock: Arc<RwLock<R, T>>, - marker: PhantomData<R::GuardMarker>, -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: ?Sized> ArcRwLockWriteGuard<R, T> { - /// Returns a reference to the rwlock, contained in its `Arc`. - pub fn rwlock(s: &Self) -> &Arc<RwLock<R, T>> { - &s.rwlock - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// This is functionally equivalent to the `unlocked` method on [`RwLockWriteGuard`]. - #[inline] - pub fn unlocked<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockWriteGuard always holds a shared lock. - unsafe { - s.rwlock.raw.unlock_exclusive(); - } - defer!(s.rwlock.raw.lock_exclusive()); - f() - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockDowngrade, T: ?Sized> ArcRwLockWriteGuard<R, T> { - /// Atomically downgrades a write lock into a read lock without allowing any - /// writers to take exclusive access of the lock in the meantime. - /// - /// This is functionally equivalent to the `downgrade` method on [`RwLockWriteGuard`]. - pub fn downgrade(s: Self) -> ArcRwLockReadGuard<R, T> { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - s.rwlock.raw.downgrade(); - } - - // SAFETY: prevent the arc's refcount from changing using ManuallyDrop and ptr::read - let s = ManuallyDrop::new(s); - let rwlock = unsafe { ptr::read(&s.rwlock) }; - - ArcRwLockReadGuard { - rwlock, - marker: PhantomData, - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockUpgradeDowngrade, T: ?Sized> ArcRwLockWriteGuard<R, T> { - /// Atomically downgrades a write lock into an upgradable read lock without allowing any - /// writers to take exclusive access of the lock in the meantime. - /// - /// This is functionally identical to the `downgrade_to_upgradable` method on [`RwLockWriteGuard`]. - pub fn downgrade_to_upgradable(s: Self) -> ArcRwLockUpgradableReadGuard<R, T> { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - s.rwlock.raw.downgrade_to_upgradable(); - } - - // SAFETY: same as above - let s = ManuallyDrop::new(s); - let rwlock = unsafe { ptr::read(&s.rwlock) }; - - ArcRwLockUpgradableReadGuard { - rwlock, - marker: PhantomData, - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockFair, T: ?Sized> ArcRwLockWriteGuard<R, T> { - /// Unlocks the `RwLock` using a fair unlock protocol. - /// - /// This is functionally equivalent to the `unlock_fair` method on [`RwLockWriteGuard`]. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - s.rwlock.raw.unlock_exclusive_fair(); - } - - // SAFETY: prevent the Arc from leaking memory - let mut s = ManuallyDrop::new(s); - unsafe { ptr::drop_in_place(&mut s.rwlock) }; - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// This is functionally equivalent to the `unlocked_fair` method on [`RwLockWriteGuard`]. - #[inline] - pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - s.rwlock.raw.unlock_exclusive_fair(); - } - defer!(s.rwlock.raw.lock_exclusive()); - f() - } - - /// Temporarily yields the `RwLock` to a waiting thread if there is one. - /// - /// This method is functionally equivalent to the `bump` method on [`RwLockWriteGuard`]. - #[inline] - pub fn bump(s: &mut Self) { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - s.rwlock.raw.bump_exclusive(); - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: ?Sized> Deref for ArcRwLockWriteGuard<R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.rwlock.data.get() } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: ?Sized> DerefMut for ArcRwLockWriteGuard<R, T> { - #[inline] - fn deref_mut(&mut self) -> &mut T { - unsafe { &mut *self.rwlock.data.get() } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: ?Sized> Drop for ArcRwLockWriteGuard<R, T> { - #[inline] - fn drop(&mut self) { - // Safety: An RwLockWriteGuard always holds an exclusive lock. - unsafe { - self.rwlock.raw.unlock_exclusive(); - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: fmt::Debug + ?Sized> fmt::Debug for ArcRwLockWriteGuard<R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLock, T: fmt::Display + ?Sized> fmt::Display for ArcRwLockWriteGuard<R, T> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -/// RAII structure used to release the upgradable read access of a lock when -/// dropped. -#[clippy::has_significant_drop] -#[must_use = "if unused the RwLock will immediately unlock"] -pub struct RwLockUpgradableReadGuard<'a, R: RawRwLockUpgrade, T: ?Sized> { - rwlock: &'a RwLock<R, T>, - marker: PhantomData<(&'a T, R::GuardMarker)>, -} - -unsafe impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + Sync + 'a> Sync - for RwLockUpgradableReadGuard<'a, R, T> -{ -} - -impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T> { - /// Returns a reference to the original reader-writer lock object. - pub fn rwlock(s: &Self) -> &'a RwLock<R, T> { - s.rwlock - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the `RwLock`. - #[inline] - pub fn unlocked<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.unlock_upgradable(); - } - defer!(s.rwlock.raw.lock_upgradable()); - f() - } - - /// Atomically upgrades an upgradable read lock lock into an exclusive write lock, - /// blocking the current thread until it can be acquired. - pub fn upgrade(s: Self) -> RwLockWriteGuard<'a, R, T> { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.upgrade(); - } - let rwlock = s.rwlock; - mem::forget(s); - RwLockWriteGuard { - rwlock, - marker: PhantomData, - } - } - - /// Tries to atomically upgrade an upgradable read lock into an exclusive write lock. - /// - /// If the access could not be granted at this time, then the current guard is returned. - pub fn try_upgrade(s: Self) -> Result<RwLockWriteGuard<'a, R, T>, Self> { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - if unsafe { s.rwlock.raw.try_upgrade() } { - let rwlock = s.rwlock; - mem::forget(s); - Ok(RwLockWriteGuard { - rwlock, - marker: PhantomData, - }) - } else { - Err(s) - } - } -} - -impl<'a, R: RawRwLockUpgradeFair + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T> { - /// Unlocks the `RwLock` using a fair unlock protocol. - /// - /// By default, `RwLock` is unfair and allow the current thread to re-lock - /// the `RwLock` before another has the chance to acquire the lock, even if - /// that thread has been blocked on the `RwLock` for a long time. This is - /// the default because it allows much higher throughput as it avoids - /// forcing a context switch on every `RwLock` unlock. This can result in one - /// thread acquiring a `RwLock` many more times than other threads. - /// - /// However in some cases it can be beneficial to ensure fairness by forcing - /// the lock to pass on to a waiting thread if there is one. This is done by - /// using this method instead of dropping the `RwLockUpgradableReadGuard` normally. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.unlock_upgradable_fair(); - } - mem::forget(s); - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// The `RwLock` is unlocked a fair unlock protocol. - /// - /// This is safe because `&mut` guarantees that there exist no other - /// references to the data protected by the `RwLock`. - #[inline] - pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.unlock_upgradable_fair(); - } - defer!(s.rwlock.raw.lock_upgradable()); - f() - } - - /// Temporarily yields the `RwLock` to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `unlock_fair` followed - /// by `upgradable_read`, however it can be much more efficient in the case where there - /// are no waiting threads. - #[inline] - pub fn bump(s: &mut Self) { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.bump_upgradable(); - } - } -} - -impl<'a, R: RawRwLockUpgradeDowngrade + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T> { - /// Atomically downgrades an upgradable read lock lock into a shared read lock - /// without allowing any writers to take exclusive access of the lock in the - /// meantime. - /// - /// Note that if there are any writers currently waiting to take the lock - /// then other readers may not be able to acquire the lock even if it was - /// downgraded. - pub fn downgrade(s: Self) -> RwLockReadGuard<'a, R, T> { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.downgrade_upgradable(); - } - let rwlock = s.rwlock; - mem::forget(s); - RwLockReadGuard { - rwlock, - marker: PhantomData, - } - } - - /// First, atomically upgrades an upgradable read lock lock into an exclusive write lock, - /// blocking the current thread until it can be acquired. - /// - /// Then, calls the provided closure with an exclusive reference to the lock's data. - /// - /// Finally, atomically downgrades the lock back to an upgradable read lock. - /// The closure's return value is wrapped in `Some` and returned. - /// - /// This function only requires a mutable reference to the guard, unlike - /// `upgrade` which takes the guard by value. - pub fn with_upgraded<Ret, F: FnOnce(&mut T) -> Ret>(&mut self, f: F) -> Ret { - unsafe { - self.rwlock.raw.upgrade(); - } - - // Safety: We just upgraded the lock, so we have mutable access to the data. - // This will restore the state the lock was in at the start of the function. - defer!(unsafe { self.rwlock.raw.downgrade_to_upgradable() }); - - // Safety: We upgraded the lock, so we have mutable access to the data. - // When this function returns, whether by drop or panic, - // the drop guard will downgrade it back to an upgradeable lock. - f(unsafe { &mut *self.rwlock.data.get() }) - } - - /// First, tries to atomically upgrade an upgradable read lock into an exclusive write lock. - /// - /// If the access could not be granted at this time, then `None` is returned. - /// - /// Otherwise, calls the provided closure with an exclusive reference to the lock's data, - /// and finally downgrades the lock back to an upgradable read lock. - /// The closure's return value is wrapped in `Some` and returned. - /// - /// This function only requires a mutable reference to the guard, unlike - /// `try_upgrade` which takes the guard by value. - pub fn try_with_upgraded<Ret, F: FnOnce(&mut T) -> Ret>(&mut self, f: F) -> Option<Ret> { - if unsafe { self.rwlock.raw.try_upgrade() } { - // Safety: We just upgraded the lock, so we have mutable access to the data. - // This will restore the state the lock was in at the start of the function. - defer!(unsafe { self.rwlock.raw.downgrade_to_upgradable() }); - - // Safety: We upgraded the lock, so we have mutable access to the data. - // When this function returns, whether by drop or panic, - // the drop guard will downgrade it back to an upgradeable lock. - Some(f(unsafe { &mut *self.rwlock.data.get() })) - } else { - None - } - } -} - -impl<'a, R: RawRwLockUpgradeTimed + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T> { - /// Tries to atomically upgrade an upgradable read lock into an exclusive - /// write lock, until a timeout is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// the current guard is returned. - pub fn try_upgrade_for( - s: Self, - timeout: R::Duration, - ) -> Result<RwLockWriteGuard<'a, R, T>, Self> { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - if unsafe { s.rwlock.raw.try_upgrade_for(timeout) } { - let rwlock = s.rwlock; - mem::forget(s); - Ok(RwLockWriteGuard { - rwlock, - marker: PhantomData, - }) - } else { - Err(s) - } - } - - /// Tries to atomically upgrade an upgradable read lock into an exclusive - /// write lock, until a timeout is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// the current guard is returned. - #[inline] - pub fn try_upgrade_until( - s: Self, - timeout: R::Instant, - ) -> Result<RwLockWriteGuard<'a, R, T>, Self> { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - if unsafe { s.rwlock.raw.try_upgrade_until(timeout) } { - let rwlock = s.rwlock; - mem::forget(s); - Ok(RwLockWriteGuard { - rwlock, - marker: PhantomData, - }) - } else { - Err(s) - } - } -} - -impl<'a, R: RawRwLockUpgradeTimed + RawRwLockUpgradeDowngrade + 'a, T: ?Sized + 'a> - RwLockUpgradableReadGuard<'a, R, T> -{ - /// Tries to atomically upgrade an upgradable read lock into an exclusive - /// write lock, until a timeout is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. - /// - /// Otherwise, calls the provided closure with an exclusive reference to the lock's data, - /// and finally downgrades the lock back to an upgradable read lock. - /// The closure's return value is wrapped in `Some` and returned. - /// - /// This function only requires a mutable reference to the guard, unlike - /// `try_upgrade_for` which takes the guard by value. - pub fn try_with_upgraded_for<Ret, F: FnOnce(&mut T) -> Ret>( - &mut self, - timeout: R::Duration, - f: F, - ) -> Option<Ret> { - if unsafe { self.rwlock.raw.try_upgrade_for(timeout) } { - // Safety: We just upgraded the lock, so we have mutable access to the data. - // This will restore the state the lock was in at the start of the function. - defer!(unsafe { self.rwlock.raw.downgrade_upgradable() }); - - // Safety: We upgraded the lock, so we have mutable access to the data. - // When this function returns, whether by drop or panic, - // the drop guard will downgrade it back to an upgradeable lock. - Some(f(unsafe { &mut *self.rwlock.data.get() })) - } else { - None - } - } - - /// Tries to atomically upgrade an upgradable read lock into an exclusive - /// write lock, until a timeout is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. - /// - /// Otherwise, calls the provided closure with an exclusive reference to the lock's data, - /// and finally downgrades the lock back to an upgradable read lock. - /// The closure's return value is wrapped in `Some` and returned. - /// - /// This function only requires a mutable reference to the guard, unlike - /// `try_upgrade_until` which takes the guard by value. - pub fn try_with_upgraded_until<Ret, F: FnOnce(&mut T) -> Ret>( - &mut self, - timeout: R::Instant, - f: F, - ) -> Option<Ret> { - if unsafe { self.rwlock.raw.try_upgrade_until(timeout) } { - // Safety: We just upgraded the lock, so we have mutable access to the data. - // This will restore the state the lock was in at the start of the function. - defer!(unsafe { self.rwlock.raw.downgrade_upgradable() }); - - // Safety: We upgraded the lock, so we have mutable access to the data. - // When this function returns, whether by drop or panic, - // the drop guard will downgrade it back to an upgradeable lock. - Some(f(unsafe { &mut *self.rwlock.data.get() })) - } else { - None - } - } -} - -impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> Deref for RwLockUpgradableReadGuard<'a, R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.rwlock.data.get() } - } -} - -impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> Drop for RwLockUpgradableReadGuard<'a, R, T> { - #[inline] - fn drop(&mut self) { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - self.rwlock.raw.unlock_upgradable(); - } - } -} - -impl<'a, R: RawRwLockUpgrade + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug - for RwLockUpgradableReadGuard<'a, R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -impl<'a, R: RawRwLockUpgrade + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display - for RwLockUpgradableReadGuard<'a, R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -#[cfg(feature = "owning_ref")] -unsafe impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> StableAddress - for RwLockUpgradableReadGuard<'a, R, T> -{ -} - -/// An RAII rwlock guard returned by the `Arc` locking operations on `RwLock`. -/// This is similar to the `RwLockUpgradableReadGuard` struct, except instead of using a reference to unlock the -/// `RwLock` it uses an `Arc<RwLock>`. This has several advantages, most notably that it has an `'static` -/// lifetime. -#[cfg(feature = "arc_lock")] -#[clippy::has_significant_drop] -#[must_use = "if unused the RwLock will immediately unlock"] -pub struct ArcRwLockUpgradableReadGuard<R: RawRwLockUpgrade, T: ?Sized> { - rwlock: Arc<RwLock<R, T>>, - marker: PhantomData<R::GuardMarker>, -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockUpgrade, T: ?Sized> ArcRwLockUpgradableReadGuard<R, T> { - /// Returns a reference to the rwlock, contained in its original `Arc`. - pub fn rwlock(s: &Self) -> &Arc<RwLock<R, T>> { - &s.rwlock - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// This is functionally identical to the `unlocked` method on [`RwLockUpgradableReadGuard`]. - #[inline] - pub fn unlocked<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.unlock_upgradable(); - } - defer!(s.rwlock.raw.lock_upgradable()); - f() - } - - /// Atomically upgrades an upgradable read lock lock into an exclusive write lock, - /// blocking the current thread until it can be acquired. - pub fn upgrade(s: Self) -> ArcRwLockWriteGuard<R, T> { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.upgrade(); - } - - // SAFETY: avoid incrementing or decrementing the refcount using ManuallyDrop and reading the Arc out - // of the struct - let s = ManuallyDrop::new(s); - let rwlock = unsafe { ptr::read(&s.rwlock) }; - - ArcRwLockWriteGuard { - rwlock, - marker: PhantomData, - } - } - - /// Tries to atomically upgrade an upgradable read lock into an exclusive write lock. - /// - /// If the access could not be granted at this time, then the current guard is returned. - pub fn try_upgrade(s: Self) -> Result<ArcRwLockWriteGuard<R, T>, Self> { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - if unsafe { s.rwlock.raw.try_upgrade() } { - // SAFETY: same as above - let s = ManuallyDrop::new(s); - let rwlock = unsafe { ptr::read(&s.rwlock) }; - - Ok(ArcRwLockWriteGuard { - rwlock, - marker: PhantomData, - }) - } else { - Err(s) - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockUpgradeFair, T: ?Sized> ArcRwLockUpgradableReadGuard<R, T> { - /// Unlocks the `RwLock` using a fair unlock protocol. - /// - /// This is functionally identical to the `unlock_fair` method on [`RwLockUpgradableReadGuard`]. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.unlock_upgradable_fair(); - } - - // SAFETY: make sure we decrement the refcount properly - let mut s = ManuallyDrop::new(s); - unsafe { ptr::drop_in_place(&mut s.rwlock) }; - } - - /// Temporarily unlocks the `RwLock` to execute the given function. - /// - /// This is functionally equivalent to the `unlocked_fair` method on [`RwLockUpgradableReadGuard`]. - #[inline] - pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U - where - F: FnOnce() -> U, - { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.unlock_upgradable_fair(); - } - defer!(s.rwlock.raw.lock_upgradable()); - f() - } - - /// Temporarily yields the `RwLock` to a waiting thread if there is one. - /// - /// This method is functionally equivalent to calling `bump` on [`RwLockUpgradableReadGuard`]. - #[inline] - pub fn bump(s: &mut Self) { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.bump_upgradable(); - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockUpgradeDowngrade, T: ?Sized> ArcRwLockUpgradableReadGuard<R, T> { - /// Atomically downgrades an upgradable read lock lock into a shared read lock - /// without allowing any writers to take exclusive access of the lock in the - /// meantime. - /// - /// Note that if there are any writers currently waiting to take the lock - /// then other readers may not be able to acquire the lock even if it was - /// downgraded. - pub fn downgrade(s: Self) -> ArcRwLockReadGuard<R, T> { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - s.rwlock.raw.downgrade_upgradable(); - } - - // SAFETY: use ManuallyDrop and ptr::read to ensure the refcount is not changed - let s = ManuallyDrop::new(s); - let rwlock = unsafe { ptr::read(&s.rwlock) }; - - ArcRwLockReadGuard { - rwlock, - marker: PhantomData, - } - } - - /// First, atomically upgrades an upgradable read lock lock into an exclusive write lock, - /// blocking the current thread until it can be acquired. - /// - /// Then, calls the provided closure with an exclusive reference to the lock's data. - /// - /// Finally, atomically downgrades the lock back to an upgradable read lock. - /// The closure's return value is returned. - /// - /// This function only requires a mutable reference to the guard, unlike - /// `upgrade` which takes the guard by value. - pub fn with_upgraded<Ret, F: FnOnce(&mut T) -> Ret>(&mut self, f: F) -> Ret { - unsafe { - self.rwlock.raw.upgrade(); - } - - // Safety: We just upgraded the lock, so we have mutable access to the data. - // This will restore the state the lock was in at the start of the function. - defer!(unsafe { self.rwlock.raw.downgrade_upgradable() }); - - // Safety: We upgraded the lock, so we have mutable access to the data. - // When this function returns, whether by drop or panic, - // the drop guard will downgrade it back to an upgradeable lock. - f(unsafe { &mut *self.rwlock.data.get() }) - } - - /// First, tries to atomically upgrade an upgradable read lock into an exclusive write lock. - /// - /// If the access could not be granted at this time, then `None` is returned. - /// - /// Otherwise, calls the provided closure with an exclusive reference to the lock's data, - /// and finally downgrades the lock back to an upgradable read lock. - /// The closure's return value is wrapped in `Some` and returned. - /// - /// This function only requires a mutable reference to the guard, unlike - /// `try_upgrade` which takes the guard by value. - pub fn try_with_upgraded<Ret, F: FnOnce(&mut T) -> Ret>(&mut self, f: F) -> Option<Ret> { - if unsafe { self.rwlock.raw.try_upgrade() } { - // Safety: We just upgraded the lock, so we have mutable access to the data. - // This will restore the state the lock was in at the start of the function. - defer!(unsafe { self.rwlock.raw.downgrade_upgradable() }); - - // Safety: We upgraded the lock, so we have mutable access to the data. - // When this function returns, whether by drop or panic, - // the drop guard will downgrade it back to an upgradeable lock. - Some(f(unsafe { &mut *self.rwlock.data.get() })) - } else { - None - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockUpgradeTimed, T: ?Sized> ArcRwLockUpgradableReadGuard<R, T> { - /// Tries to atomically upgrade an upgradable read lock into an exclusive - /// write lock, until a timeout is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// the current guard is returned. - pub fn try_upgrade_for( - s: Self, - timeout: R::Duration, - ) -> Result<ArcRwLockWriteGuard<R, T>, Self> { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - if unsafe { s.rwlock.raw.try_upgrade_for(timeout) } { - // SAFETY: same as above - let s = ManuallyDrop::new(s); - let rwlock = unsafe { ptr::read(&s.rwlock) }; - - Ok(ArcRwLockWriteGuard { - rwlock, - marker: PhantomData, - }) - } else { - Err(s) - } - } - - /// Tries to atomically upgrade an upgradable read lock into an exclusive - /// write lock, until a timeout is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// the current guard is returned. - #[inline] - pub fn try_upgrade_until( - s: Self, - timeout: R::Instant, - ) -> Result<ArcRwLockWriteGuard<R, T>, Self> { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - if unsafe { s.rwlock.raw.try_upgrade_until(timeout) } { - // SAFETY: same as above - let s = ManuallyDrop::new(s); - let rwlock = unsafe { ptr::read(&s.rwlock) }; - - Ok(ArcRwLockWriteGuard { - rwlock, - marker: PhantomData, - }) - } else { - Err(s) - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockUpgradeTimed + RawRwLockUpgradeDowngrade, T: ?Sized> - ArcRwLockUpgradableReadGuard<R, T> -{ - /// Tries to atomically upgrade an upgradable read lock into an exclusive - /// write lock, until a timeout is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. - /// - /// Otherwise, calls the provided closure with an exclusive reference to the lock's data, - /// and finally downgrades the lock back to an upgradable read lock. - /// The closure's return value is wrapped in `Some` and returned. - /// - /// This function only requires a mutable reference to the guard, unlike - /// `try_upgrade_for` which takes the guard by value. - pub fn try_with_upgraded_for<Ret, F: FnOnce(&mut T) -> Ret>( - &mut self, - timeout: R::Duration, - f: F, - ) -> Option<Ret> { - if unsafe { self.rwlock.raw.try_upgrade_for(timeout) } { - // Safety: We just upgraded the lock, so we have mutable access to the data. - // This will restore the state the lock was in at the start of the function. - defer!(unsafe { self.rwlock.raw.downgrade_upgradable() }); - - // Safety: We upgraded the lock, so we have mutable access to the data. - // When this function returns, whether by drop or panic, - // the drop guard will downgrade it back to an upgradeable lock. - Some(f(unsafe { &mut *self.rwlock.data.get() })) - } else { - None - } - } - - /// Tries to atomically upgrade an upgradable read lock into an exclusive - /// write lock, until a timeout is reached. - /// - /// If the access could not be granted before the timeout expires, then - /// `None` is returned. - /// - /// Otherwise, calls the provided closure with an exclusive reference to the lock's data, - /// and finally downgrades the lock back to an upgradable read lock. - /// The closure's return value is wrapped in `Some` and returned. - /// - /// This function only requires a mutable reference to the guard, unlike - /// `try_upgrade_until` which takes the guard by value. - pub fn try_with_upgraded_until<Ret, F: FnOnce(&mut T) -> Ret>( - &mut self, - timeout: R::Instant, - f: F, - ) -> Option<Ret> { - if unsafe { self.rwlock.raw.try_upgrade_until(timeout) } { - // Safety: We just upgraded the lock, so we have mutable access to the data. - // This will restore the state the lock was in at the start of the function. - defer!(unsafe { self.rwlock.raw.downgrade_upgradable() }); - - // Safety: We upgraded the lock, so we have mutable access to the data. - // When this function returns, whether by drop or panic, - // the drop guard will downgrade it back to an upgradeable lock. - Some(f(unsafe { &mut *self.rwlock.data.get() })) - } else { - None - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockUpgrade, T: ?Sized> Deref for ArcRwLockUpgradableReadGuard<R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.rwlock.data.get() } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockUpgrade, T: ?Sized> Drop for ArcRwLockUpgradableReadGuard<R, T> { - #[inline] - fn drop(&mut self) { - // Safety: An RwLockUpgradableReadGuard always holds an upgradable lock. - unsafe { - self.rwlock.raw.unlock_upgradable(); - } - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockUpgrade, T: fmt::Debug + ?Sized> fmt::Debug - for ArcRwLockUpgradableReadGuard<R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -#[cfg(feature = "arc_lock")] -impl<R: RawRwLockUpgrade, T: fmt::Display + ?Sized> fmt::Display - for ArcRwLockUpgradableReadGuard<R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -/// 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. -#[clippy::has_significant_drop] -#[must_use = "if unused the RwLock will immediately unlock"] -pub struct MappedRwLockReadGuard<'a, R: RawRwLock, T: ?Sized> { - raw: &'a R, - data: *const T, - marker: PhantomData<&'a T>, -} - -unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + Sync + 'a> Sync for MappedRwLockReadGuard<'a, R, T> {} -unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + Sync + 'a> Send for MappedRwLockReadGuard<'a, R, T> where - R::GuardMarker: Send -{ -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> MappedRwLockReadGuard<'a, R, T> { - /// Make a new `MappedRwLockReadGuard` for a component of the locked data. - /// - /// This operation cannot fail as the `MappedRwLockReadGuard` passed - /// in already locked the data. - /// - /// This is an associated function that needs to be - /// used as `MappedRwLockReadGuard::map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedRwLockReadGuard<'a, R, U> - where - F: FnOnce(&T) -> &U, - { - let raw = s.raw; - let data = f(unsafe { &*s.data }); - mem::forget(s); - MappedRwLockReadGuard { - raw, - data, - marker: PhantomData, - } - } - - /// Attempts to make a new `MappedRwLockReadGuard` for a component of the - /// locked data. The original guard is return if the closure returns `None`. - /// - /// This operation cannot fail as the `MappedRwLockReadGuard` passed - /// in already locked the data. - /// - /// This is an associated function that needs to be - /// used as `MappedRwLockReadGuard::try_map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn try_map<U: ?Sized, F>(s: Self, f: F) -> Result<MappedRwLockReadGuard<'a, R, U>, Self> - where - F: FnOnce(&T) -> Option<&U>, - { - let raw = s.raw; - let data = match f(unsafe { &*s.data }) { - Some(data) => data, - None => return Err(s), - }; - mem::forget(s); - Ok(MappedRwLockReadGuard { - raw, - data, - marker: PhantomData, - }) - } -} - -impl<'a, R: RawRwLockFair + 'a, T: ?Sized + 'a> MappedRwLockReadGuard<'a, R, T> { - /// Unlocks the `RwLock` using a fair unlock protocol. - /// - /// By default, `RwLock` is unfair and allow the current thread to re-lock - /// the `RwLock` before another has the chance to acquire the lock, even if - /// that thread has been blocked on the `RwLock` for a long time. This is - /// the default because it allows much higher throughput as it avoids - /// forcing a context switch on every `RwLock` unlock. This can result in one - /// thread acquiring a `RwLock` many more times than other threads. - /// - /// However in some cases it can be beneficial to ensure fairness by forcing - /// the lock to pass on to a waiting thread if there is one. This is done by - /// using this method instead of dropping the `MappedRwLockReadGuard` normally. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: A MappedRwLockReadGuard always holds a shared lock. - unsafe { - s.raw.unlock_shared_fair(); - } - mem::forget(s); - } -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for MappedRwLockReadGuard<'a, R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.data } - } -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Drop for MappedRwLockReadGuard<'a, R, T> { - #[inline] - fn drop(&mut self) { - // Safety: A MappedRwLockReadGuard always holds a shared lock. - unsafe { - self.raw.unlock_shared(); - } - } -} - -impl<'a, R: RawRwLock + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug - for MappedRwLockReadGuard<'a, R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -impl<'a, R: RawRwLock + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display - for MappedRwLockReadGuard<'a, R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -#[cfg(feature = "owning_ref")] -unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> StableAddress - for MappedRwLockReadGuard<'a, R, 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. -#[clippy::has_significant_drop] -#[must_use = "if unused the RwLock will immediately unlock"] -pub struct MappedRwLockWriteGuard<'a, R: RawRwLock, T: ?Sized> { - raw: &'a R, - data: *mut T, - marker: PhantomData<&'a mut T>, -} - -unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + Sync + 'a> Sync - for MappedRwLockWriteGuard<'a, R, T> -{ -} -unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + Send + 'a> Send for MappedRwLockWriteGuard<'a, R, T> where - R::GuardMarker: Send -{ -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> MappedRwLockWriteGuard<'a, R, T> { - /// Make a new `MappedRwLockWriteGuard` for a component of the locked data. - /// - /// This operation cannot fail as the `MappedRwLockWriteGuard` passed - /// in already locked the data. - /// - /// This is an associated function that needs to be - /// used as `MappedRwLockWriteGuard::map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedRwLockWriteGuard<'a, R, U> - where - F: FnOnce(&mut T) -> &mut U, - { - let raw = s.raw; - let data = f(unsafe { &mut *s.data }); - mem::forget(s); - MappedRwLockWriteGuard { - raw, - data, - marker: PhantomData, - } - } - - /// Attempts to make a new `MappedRwLockWriteGuard` for a component of the - /// locked data. The original guard is return if the closure returns `None`. - /// - /// This operation cannot fail as the `MappedRwLockWriteGuard` passed - /// in already locked the data. - /// - /// This is an associated function that needs to be - /// used as `MappedRwLockWriteGuard::try_map(...)`. A method would interfere with methods of - /// the same name on the contents of the locked data. - #[inline] - pub fn try_map<U: ?Sized, F>(s: Self, f: F) -> Result<MappedRwLockWriteGuard<'a, R, U>, Self> - where - F: FnOnce(&mut T) -> Option<&mut U>, - { - let raw = s.raw; - let data = match f(unsafe { &mut *s.data }) { - Some(data) => data, - None => return Err(s), - }; - mem::forget(s); - Ok(MappedRwLockWriteGuard { - raw, - data, - marker: PhantomData, - }) - } -} - -impl<'a, R: RawRwLockFair + 'a, T: ?Sized + 'a> MappedRwLockWriteGuard<'a, R, T> { - /// Unlocks the `RwLock` using a fair unlock protocol. - /// - /// By default, `RwLock` is unfair and allow the current thread to re-lock - /// the `RwLock` before another has the chance to acquire the lock, even if - /// that thread has been blocked on the `RwLock` for a long time. This is - /// the default because it allows much higher throughput as it avoids - /// forcing a context switch on every `RwLock` unlock. This can result in one - /// thread acquiring a `RwLock` many more times than other threads. - /// - /// However in some cases it can be beneficial to ensure fairness by forcing - /// the lock to pass on to a waiting thread if there is one. This is done by - /// using this method instead of dropping the `MappedRwLockWriteGuard` normally. - #[inline] - pub fn unlock_fair(s: Self) { - // Safety: A MappedRwLockWriteGuard always holds an exclusive lock. - unsafe { - s.raw.unlock_exclusive_fair(); - } - mem::forget(s); - } -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for MappedRwLockWriteGuard<'a, R, T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.data } - } -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> DerefMut for MappedRwLockWriteGuard<'a, R, T> { - #[inline] - fn deref_mut(&mut self) -> &mut T { - unsafe { &mut *self.data } - } -} - -impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Drop for MappedRwLockWriteGuard<'a, R, T> { - #[inline] - fn drop(&mut self) { - // Safety: A MappedRwLockWriteGuard always holds an exclusive lock. - unsafe { - self.raw.unlock_exclusive(); - } - } -} - -impl<'a, R: RawRwLock + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug - for MappedRwLockWriteGuard<'a, R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&**self, f) - } -} - -impl<'a, R: RawRwLock + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display - for MappedRwLockWriteGuard<'a, R, T> -{ - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - (**self).fmt(f) - } -} - -#[cfg(feature = "owning_ref")] -unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> StableAddress - for MappedRwLockWriteGuard<'a, R, T> -{ -} |