lock_api-0.3.3/Cargo.toml.orig010064400017500001750000000014621360406725600144220ustar0000000000000000[package] name = "lock_api" version = "0.3.3" authors = ["Amanieu d'Antras "] description = "Wrappers to create fully-featured Mutex and RwLock types. Compatible with no_std." license = "Apache-2.0/MIT" repository = "https://github.com/Amanieu/parking_lot" keywords = ["mutex", "rwlock", "lock", "no_std"] categories = ["concurrency", "no-std"] edition = "2018" [dependencies] scopeguard = { version = "1.0", default-features = false } owning_ref = { version = "0.4", optional = true } # Optional dependency for supporting serde. Optional crates automatically # create a feature with the same name as the crate, so if you need serde # support, just pass "--features serde" when building this crate. serde = {version = "1.0.90", default-features = false, optional = true} [features] nightly = [] lock_api-0.3.3/Cargo.toml0000644000000021631360406732400107230ustar00# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO # # When uploading crates to the registry Cargo will automatically # "normalize" Cargo.toml files for maximal compatibility # with all versions of Cargo and also rewrite `path` dependencies # to registry (e.g., crates.io) dependencies # # If you believe there's an error in this file please file an # issue against the rust-lang/cargo repository. If you're # editing this file be aware that the upstream Cargo.toml # will likely look very different (and much more reasonable) [package] edition = "2018" name = "lock_api" version = "0.3.3" authors = ["Amanieu d'Antras "] description = "Wrappers to create fully-featured Mutex and RwLock types. Compatible with no_std." keywords = ["mutex", "rwlock", "lock", "no_std"] categories = ["concurrency", "no-std"] license = "Apache-2.0/MIT" repository = "https://github.com/Amanieu/parking_lot" [dependencies.owning_ref] version = "0.4" optional = true [dependencies.scopeguard] version = "1.0" default-features = false [dependencies.serde] version = "1.0.90" optional = true default-features = false [features] nightly = [] lock_api-0.3.3/LICENSE-APACHE010064400017500001750000000251371340176713000134550ustar0000000000000000 Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. 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See the License for the specific language governing permissions and limitations under the License. lock_api-0.3.3/LICENSE-MIT010064400017500001750000000020571340176713000131610ustar0000000000000000Copyright (c) 2016 The Rust Project Developers Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. lock_api-0.3.3/src/lib.rs010064400017500001750000000075621343732567600134540ustar0000000000000000// Copyright 2018 Amanieu d'Antras // // Licensed under the Apache License, Version 2.0, or the MIT license , 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.swap(true, Ordering::Acquire) //! } //! //! 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 = lock_api::Mutex; //! 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 two cargo features: //! //! - `owning_ref`: Allows your lock types to be used with the `owning_ref` crate. //! - `nightly`: Enables nightly-only features. At the moment the only such //! feature is `const fn` constructors for lock types. #![no_std] #![warn(missing_docs)] #![warn(rust_2018_idioms)] #![cfg_attr(feature = "nightly", feature(const_fn))] #[macro_use] extern crate scopeguard; /// 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 ()); mod mutex; pub use crate::mutex::*; mod remutex; pub use crate::remutex::*; mod rwlock; pub use crate::rwlock::*; lock_api-0.3.3/src/mutex.rs010064400017500001750000000512701356657730500140440ustar0000000000000000// Copyright 2018 Amanieu d'Antras // // Licensed under the Apache License, Version 2.0, or the MIT license , 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 = "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. fn try_lock(&self) -> bool; /// Unlocks this mutex. fn unlock(&self); } /// 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. 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. 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 { raw: R, data: UnsafeCell, } unsafe impl Send for Mutex {} unsafe impl Sync for Mutex {} impl Mutex { /// Creates a new mutex in an unlocked state ready for use. #[cfg(feature = "nightly")] #[inline] pub const fn new(val: T) -> Mutex { Mutex { raw: R::INIT, data: UnsafeCell::new(val), } } /// Creates a new mutex in an unlocked state ready for use. #[cfg(not(feature = "nightly"))] #[inline] pub fn new(val: T) -> Mutex { 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 Mutex { /// # Safety /// /// The lock must be held when calling this method. #[inline] unsafe fn guard(&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.guard() } } /// 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> { if self.raw.try_lock() { // SAFETY: The lock is held, as required. Some(unsafe { self.guard() }) } 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() } } /// 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 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 `MutexGuard`. #[inline] pub unsafe fn raw(&self) -> &R { &self.raw } } impl Mutex { /// 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 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 Mutex { /// 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> { if self.raw.try_lock_for(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.guard() }) } 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> { if self.raw.try_lock_until(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.guard() }) } else { None } } } impl Default for Mutex { #[inline] fn default() -> Mutex { Mutex::new(Default::default()) } } impl From for Mutex { #[inline] fn from(t: T) -> Mutex { Mutex::new(t) } } impl fmt::Debug for Mutex { 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("") } } f.debug_struct("Mutex") .field("data", &LockedPlaceholder) .finish() } } } } // Copied and modified from serde #[cfg(feature = "serde")] impl Serialize for Mutex where R: RawMutex, T: Serialize + ?Sized, { fn serialize(&self, serializer: S) -> Result where S: Serializer, { self.lock().serialize(serializer) } } #[cfg(feature = "serde")] impl<'de, R, T> Deserialize<'de> for Mutex where R: RawMutex, T: Deserialize<'de> + ?Sized, { fn deserialize(deserializer: D) -> Result 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. #[must_use = "if unused the Mutex will immediately unlock"] pub struct MutexGuard<'a, R: RawMutex, T: ?Sized> { mutex: &'a Mutex, 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 { 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(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(s: Self, f: F) -> Result, 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(s: &mut Self, f: F) -> U where F: FnOnce() -> U, { s.mutex.raw.unlock(); defer!(s.mutex.raw.lock()); f() } } 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) { 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(s: &mut Self, f: F) -> U where F: FnOnce() -> U, { 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) { 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) { 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 `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. #[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 + '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(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(s: Self, f: F) -> Result, 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) { 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) { 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> {} lock_api-0.3.3/src/remutex.rs010064400017500001750000000560271356657730500144000ustar0000000000000000// Copyright 2018 Amanieu d'Antras // // Licensed under the Apache License, Version 2.0, or the MIT license , 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 = "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; } struct RawReentrantMutex { owner: AtomicUsize, lock_count: Cell, mutex: R, get_thread_id: G, } impl RawReentrantMutex { #[inline] fn lock_internal 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 } #[inline] fn lock(&self) { self.lock_internal(|| { self.mutex.lock(); true }); } #[inline] fn try_lock(&self) -> bool { self.lock_internal(|| self.mutex.try_lock()) } #[inline] 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(); } } } impl RawReentrantMutex { #[inline] 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(); } } #[inline] fn bump(&self) { if self.lock_count.get() == 1 { let id = self.owner.load(Ordering::Relaxed); self.owner.store(0, Ordering::Relaxed); self.mutex.bump(); self.owner.store(id, Ordering::Relaxed); } } } impl RawReentrantMutex { #[inline] fn try_lock_until(&self, timeout: R::Instant) -> bool { self.lock_internal(|| self.mutex.try_lock_until(timeout)) } #[inline] 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 { raw: RawReentrantMutex, data: UnsafeCell, } unsafe impl Send for ReentrantMutex { } unsafe impl Sync for ReentrantMutex { } impl ReentrantMutex { /// Creates a new reentrant mutex in an unlocked state ready for use. #[cfg(feature = "nightly")] #[inline] pub const fn new(val: T) -> ReentrantMutex { 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(feature = "nightly"))] #[inline] pub fn new(val: T) -> ReentrantMutex { 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 ReentrantMutex { /// # Safety /// /// The lock must be held when calling this method. #[inline] unsafe fn guard(&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.guard() } } /// 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> { if self.raw.try_lock() { // SAFETY: The lock is held, as required. Some(unsafe { self.guard() }) } 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() } } /// 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 } } impl ReentrantMutex { /// 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 ReentrantMutex { /// 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> { if self.raw.try_lock_for(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.guard() }) } 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> { if self.raw.try_lock_until(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.guard() }) } else { None } } } impl Default for ReentrantMutex { #[inline] fn default() -> ReentrantMutex { ReentrantMutex::new(Default::default()) } } impl From for ReentrantMutex { #[inline] fn from(t: T) -> ReentrantMutex { ReentrantMutex::new(t) } } impl fmt::Debug for ReentrantMutex { 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("") } } f.debug_struct("ReentrantMutex") .field("data", &LockedPlaceholder) .finish() } } } } // Copied and modified from serde #[cfg(feature = "serde")] impl Serialize for ReentrantMutex where R: RawMutex, G: GetThreadId, T: Serialize + ?Sized, { fn serialize(&self, serializer: S) -> Result where S: Serializer, { self.lock().serialize(serializer) } } #[cfg(feature = "serde")] impl<'de, R, G, T> Deserialize<'de> for ReentrantMutex where R: RawMutex, G: GetThreadId, T: Deserialize<'de> + ?Sized, { fn deserialize(deserializer: D) -> Result 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. #[must_use = "if unused the ReentrantMutex will immediately unlock"] pub struct ReentrantMutexGuard<'a, R: RawMutex, G: GetThreadId, T: ?Sized> { remutex: &'a ReentrantMutex, 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 { 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(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::map(...)`. A method would interfere with methods of /// the same name on the contents of the locked data. #[inline] pub fn try_map( s: Self, f: F, ) -> Result, Self> where F: FnOnce(&mut T) -> Option<&mut U>, { let raw = &s.remutex.raw; let data = match f(unsafe { &mut *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(s: &mut Self, f: F) -> U where F: FnOnce() -> U, { 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) { 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(s: &mut Self, f: F) -> U where F: FnOnce() -> U, { 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) { 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) { 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 `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. #[must_use = "if unused the ReentrantMutex will immediately unlock"] pub struct MappedReentrantMutexGuard<'a, R: RawMutex, G: GetThreadId, T: ?Sized> { raw: &'a RawReentrantMutex, 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(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::map(...)`. A method would interfere with methods of /// the same name on the contents of the locked data. #[inline] pub fn try_map( s: Self, f: F, ) -> Result, 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) { 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) { 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> { } lock_api-0.3.3/src/rwlock.rs010064400017500001750000001603711360406725600141760ustar0000000000000000// Copyright 2016 Amanieu d'Antras // // Licensed under the Apache License, Version 2.0, or the MIT license , 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 = "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. 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. fn unlock_exclusive(&self); } /// 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. fn unlock_shared_fair(&self); /// Releases an exclusive lock using a fair unlock protocol. 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. 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. 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. 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. fn unlock_upgradable(&self); /// Upgrades an upgradable lock to an exclusive lock. fn upgrade(&self); /// Attempts to upgrade an upgradable lock to an exclusive lock without /// blocking. 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. 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. 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. fn downgrade_upgradable(&self); /// Downgrades an exclusive lock to an upgradable lock. 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. fn try_upgrade_for(&self, timeout: Self::Duration) -> bool; /// Attempts to upgrade an upgradable lock to an exclusive lock until a /// timeout is reached. 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 { raw: R, data: UnsafeCell, } // Copied and modified from serde #[cfg(feature = "serde")] impl Serialize for RwLock where R: RawRwLock, T: Serialize + ?Sized, { fn serialize(&self, serializer: S) -> Result where S: Serializer, { self.read().serialize(serializer) } } #[cfg(feature = "serde")] impl<'de, R, T> Deserialize<'de> for RwLock where R: RawRwLock, T: Deserialize<'de> + ?Sized, { fn deserialize(deserializer: D) -> Result where D: Deserializer<'de>, { Deserialize::deserialize(deserializer).map(RwLock::new) } } unsafe impl Send for RwLock {} unsafe impl Sync for RwLock {} impl RwLock { /// Creates a new instance of an `RwLock` which is unlocked. #[cfg(feature = "nightly")] #[inline] pub const fn new(val: T) -> RwLock { RwLock { data: UnsafeCell::new(val), raw: R::INIT, } } /// Creates a new instance of an `RwLock` which is unlocked. #[cfg(not(feature = "nightly"))] #[inline] pub fn new(val: T) -> RwLock { 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 RwLock { /// # Safety /// /// The lock must be held when calling this method. #[inline] unsafe fn read_guard(&self) -> RwLockReadGuard<'_, R, T> { RwLockReadGuard { rwlock: self, marker: PhantomData, } } /// # Safety /// /// The lock must be held when calling this method. #[inline] unsafe fn write_guard(&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.read_guard() } } /// 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> { if self.raw.try_lock_shared() { // SAFETY: The lock is held, as required. Some(unsafe { self.read_guard() }) } 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.write_guard() } } /// 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> { if self.raw.try_lock_exclusive() { // SAFETY: The lock is held, as required. Some(unsafe { self.write_guard() }) } 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() } } /// 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 } } impl RwLock { /// 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 RwLock { /// 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> { if self.raw.try_lock_shared_for(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.read_guard() }) } 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> { if self.raw.try_lock_shared_until(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.read_guard() }) } 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> { if self.raw.try_lock_exclusive_for(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.write_guard() }) } 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> { if self.raw.try_lock_exclusive_until(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.write_guard() }) } else { None } } } impl RwLock { /// 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.read_guard() } } /// 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> { if self.raw.try_lock_shared_recursive() { // SAFETY: The lock is held, as required. Some(unsafe { self.read_guard() }) } else { None } } } impl RwLock { /// 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> { if self.raw.try_lock_shared_recursive_for(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.read_guard() }) } 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> { if self.raw.try_lock_shared_recursive_until(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.read_guard() }) } else { None } } } impl RwLock { /// # Safety /// /// The lock must be held when calling this method. #[inline] unsafe fn upgradable_guard(&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.upgradable_guard() } } /// 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> { if self.raw.try_lock_upgradable() { // SAFETY: The lock is held, as required. Some(unsafe { self.upgradable_guard() }) } else { None } } } impl RwLock { /// 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> { if self.raw.try_lock_upgradable_for(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.upgradable_guard() }) } 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> { if self.raw.try_lock_upgradable_until(timeout) { // SAFETY: The lock is held, as required. Some(unsafe { self.upgradable_guard() }) } else { None } } } impl Default for RwLock { #[inline] fn default() -> RwLock { RwLock::new(Default::default()) } } impl From for RwLock { #[inline] fn from(t: T) -> RwLock { RwLock::new(t) } } impl fmt::Debug for RwLock { 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("") } } f.debug_struct("RwLock") .field("data", &LockedPlaceholder) .finish() } } } } /// RAII structure used to release the shared read access of a lock when /// dropped. #[must_use = "if unused the RwLock will immediately unlock"] pub struct RwLockReadGuard<'a, R: RawRwLock, T: ?Sized> { rwlock: &'a RwLock, marker: PhantomData<(&'a T, R::GuardMarker)>, } unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + Sync + 'a> Sync for RwLockReadGuard<'a, 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 { 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(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. The original guard is return 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::map(...)`. A method would interfere with methods of /// the same name on the contents of the locked data. #[inline] pub fn try_map(s: Self, f: F) -> Result, 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. /// /// 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(s: &mut Self, f: F) -> U where F: FnOnce() -> U, { 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) { 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(s: &mut Self, f: F) -> U where F: FnOnce() -> U, { 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) { 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) { 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> {} /// RAII structure used to release the exclusive write access of a lock when /// dropped. #[must_use = "if unused the RwLock will immediately unlock"] pub struct RwLockWriteGuard<'a, R: RawRwLock, T: ?Sized> { rwlock: &'a RwLock, marker: PhantomData<(&'a mut T, R::GuardMarker)>, } unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + Sync + 'a> Sync for RwLockWriteGuard<'a, 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 { 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(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::map(...)`. A method would interfere with methods of /// the same name on the contents of the locked data. #[inline] pub fn try_map(s: Self, f: F) -> Result, 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(s: &mut Self, f: F) -> U where F: FnOnce() -> U, { 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> { 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> { 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) { 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(s: &mut Self, f: F) -> U where F: FnOnce() -> U, { 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) { 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) { 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> {} /// RAII structure used to release the upgradable read access of a lock when /// dropped. #[must_use = "if unused the RwLock will immediately unlock"] pub struct RwLockUpgradableReadGuard<'a, R: RawRwLockUpgrade, T: ?Sized> { rwlock: &'a RwLock, 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 { 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(s: &mut Self, f: F) -> U where F: FnOnce() -> U, { s.rwlock.raw.unlock_upgradable(); defer!(s.rwlock.raw.lock_upgradable()); f() } /// Atomically upgrades an upgradable read lock lock into a exclusive write lock, /// blocking the current thread until it can be acquired. pub fn upgrade(s: Self) -> RwLockWriteGuard<'a, R, T> { s.rwlock.raw.upgrade(); let rwlock = s.rwlock; mem::forget(s); RwLockWriteGuard { rwlock, marker: PhantomData, } } /// Tries to atomically upgrade an upgradable read lock into a 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, Self> { if 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) { 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(s: &mut Self, f: F) -> U where F: FnOnce() -> U, { 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) { 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> { s.rwlock.raw.downgrade_upgradable(); let rwlock = s.rwlock; mem::forget(s); RwLockReadGuard { rwlock, marker: PhantomData, } } } impl<'a, R: RawRwLockUpgradeTimed + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T> { /// Tries to atomically upgrade an upgradable read lock into a 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, Self> { if 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 a 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, Self> { if 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: 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) { 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 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. #[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 + '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(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::map(...)`. A method would interfere with methods of /// the same name on the contents of the locked data. #[inline] pub fn try_map(s: Self, f: F) -> Result, 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) { 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) { 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. #[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 + '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(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::map(...)`. A method would interfere with methods of /// the same name on the contents of the locked data. #[inline] pub fn try_map(s: Self, f: F) -> Result, 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: RawRwLockDowngrade + 'a, T: ?Sized + 'a> MappedRwLockWriteGuard<'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. #[deprecated( since = "0.3.3", note = "This function is unsound and will be removed in the future, see issue #198" )] pub fn downgrade(s: Self) -> MappedRwLockReadGuard<'a, R, T> { s.raw.downgrade(); let raw = s.raw; let data = s.data; mem::forget(s); MappedRwLockReadGuard { 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) { 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) { 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> { } lock_api-0.3.3/.cargo_vcs_info.json0000644000000001121360406732400127150ustar00{ "git": { "sha1": "8f69413ae8271a2a2e9067e61392938f6dadd59c" } }