2605 lines
90 KiB
Rust
2605 lines
90 KiB
Rust
// Copyright 2016 Amanieu d'Antras
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//
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// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
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// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
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// http://opensource.org/licenses/MIT>, at your option. This file may not be
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// copied, modified, or distributed except according to those terms.
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use core::cell::UnsafeCell;
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use core::fmt;
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use core::marker::PhantomData;
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use core::mem;
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use core::ops::{Deref, DerefMut};
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#[cfg(feature = "arc_lock")]
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use alloc::sync::Arc;
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#[cfg(feature = "arc_lock")]
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use core::mem::ManuallyDrop;
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#[cfg(feature = "arc_lock")]
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use core::ptr;
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#[cfg(feature = "owning_ref")]
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use owning_ref::StableAddress;
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#[cfg(feature = "serde")]
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use serde::{Deserialize, Deserializer, Serialize, Serializer};
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/// Basic operations for a reader-writer lock.
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///
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/// Types implementing this trait can be used by `RwLock` to form a safe and
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/// fully-functioning `RwLock` type.
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///
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/// # Safety
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///
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/// Implementations of this trait must ensure that the `RwLock` is actually
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/// exclusive: an exclusive lock can't be acquired while an exclusive or shared
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/// lock exists, and a shared lock can't be acquire while an exclusive lock
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/// exists.
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pub unsafe trait RawRwLock {
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/// Initial value for an unlocked `RwLock`.
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// A “non-constant” const item is a legacy way to supply an initialized value to downstream
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// static items. Can hopefully be replaced with `const fn new() -> Self` at some point.
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#[allow(clippy::declare_interior_mutable_const)]
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const INIT: Self;
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/// Marker type which determines whether a lock guard should be `Send`. Use
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/// one of the `GuardSend` or `GuardNoSend` helper types here.
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type GuardMarker;
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/// Acquires a shared lock, blocking the current thread until it is able to do so.
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fn lock_shared(&self);
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/// Attempts to acquire a shared lock without blocking.
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fn try_lock_shared(&self) -> bool;
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/// Releases a shared lock.
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///
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/// # Safety
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///
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/// This method may only be called if a shared lock is held in the current context.
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unsafe fn unlock_shared(&self);
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/// Acquires an exclusive lock, blocking the current thread until it is able to do so.
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fn lock_exclusive(&self);
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/// Attempts to acquire an exclusive lock without blocking.
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fn try_lock_exclusive(&self) -> bool;
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/// Releases an exclusive lock.
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///
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/// # Safety
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///
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/// This method may only be called if an exclusive lock is held in the current context.
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unsafe fn unlock_exclusive(&self);
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/// Checks if this `RwLock` is currently locked in any way.
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#[inline]
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fn is_locked(&self) -> bool {
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let acquired_lock = self.try_lock_exclusive();
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if acquired_lock {
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// Safety: A lock was successfully acquired above.
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unsafe {
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self.unlock_exclusive();
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}
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}
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!acquired_lock
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}
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/// Check if this `RwLock` is currently exclusively locked.
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fn is_locked_exclusive(&self) -> bool {
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let acquired_lock = self.try_lock_shared();
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if acquired_lock {
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// Safety: A shared lock was successfully acquired above.
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unsafe {
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self.unlock_shared();
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}
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}
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!acquired_lock
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}
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}
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/// Additional methods for RwLocks which support fair unlocking.
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///
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/// Fair unlocking means that a lock is handed directly over to the next waiting
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/// thread if there is one, without giving other threads the opportunity to
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/// "steal" the lock in the meantime. This is typically slower than unfair
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/// unlocking, but may be necessary in certain circumstances.
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pub unsafe trait RawRwLockFair: RawRwLock {
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/// Releases a shared lock using a fair unlock protocol.
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///
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/// # Safety
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///
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/// This method may only be called if a shared lock is held in the current context.
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unsafe fn unlock_shared_fair(&self);
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/// Releases an exclusive lock using a fair unlock protocol.
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///
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/// # Safety
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///
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/// This method may only be called if an exclusive lock is held in the current context.
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unsafe fn unlock_exclusive_fair(&self);
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/// Temporarily yields a shared lock to a waiting thread if there is one.
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///
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/// This method is functionally equivalent to calling `unlock_shared_fair` followed
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/// by `lock_shared`, however it can be much more efficient in the case where there
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/// are no waiting threads.
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///
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/// # Safety
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///
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/// This method may only be called if a shared lock is held in the current context.
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unsafe fn bump_shared(&self) {
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self.unlock_shared_fair();
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self.lock_shared();
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}
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/// Temporarily yields an exclusive lock to a waiting thread if there is one.
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///
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/// This method is functionally equivalent to calling `unlock_exclusive_fair` followed
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/// by `lock_exclusive`, however it can be much more efficient in the case where there
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/// are no waiting threads.
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///
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/// # Safety
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///
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/// This method may only be called if an exclusive lock is held in the current context.
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unsafe fn bump_exclusive(&self) {
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self.unlock_exclusive_fair();
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self.lock_exclusive();
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}
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}
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/// Additional methods for RwLocks which support atomically downgrading an
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/// exclusive lock to a shared lock.
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pub unsafe trait RawRwLockDowngrade: RawRwLock {
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/// Atomically downgrades an exclusive lock into a shared lock without
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/// allowing any thread to take an exclusive lock in the meantime.
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///
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/// # Safety
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///
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/// This method may only be called if an exclusive lock is held in the current context.
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unsafe fn downgrade(&self);
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}
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/// Additional methods for RwLocks which support locking with timeouts.
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///
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/// The `Duration` and `Instant` types are specified as associated types so that
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/// this trait is usable even in `no_std` environments.
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pub unsafe trait RawRwLockTimed: RawRwLock {
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/// Duration type used for `try_lock_for`.
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type Duration;
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/// Instant type used for `try_lock_until`.
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type Instant;
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/// Attempts to acquire a shared lock until a timeout is reached.
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fn try_lock_shared_for(&self, timeout: Self::Duration) -> bool;
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/// Attempts to acquire a shared lock until a timeout is reached.
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fn try_lock_shared_until(&self, timeout: Self::Instant) -> bool;
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/// Attempts to acquire an exclusive lock until a timeout is reached.
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fn try_lock_exclusive_for(&self, timeout: Self::Duration) -> bool;
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/// Attempts to acquire an exclusive lock until a timeout is reached.
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fn try_lock_exclusive_until(&self, timeout: Self::Instant) -> bool;
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}
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/// Additional methods for RwLocks which support recursive read locks.
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///
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/// These are guaranteed to succeed without blocking if
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/// another read lock is held at the time of the call. This allows a thread
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/// to recursively lock a `RwLock`. However using this method can cause
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/// writers to starve since readers no longer block if a writer is waiting
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/// for the lock.
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pub unsafe trait RawRwLockRecursive: RawRwLock {
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/// Acquires a shared lock without deadlocking in case of a recursive lock.
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fn lock_shared_recursive(&self);
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/// Attempts to acquire a shared lock without deadlocking in case of a recursive lock.
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fn try_lock_shared_recursive(&self) -> bool;
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}
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/// Additional methods for RwLocks which support recursive read locks and timeouts.
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pub unsafe trait RawRwLockRecursiveTimed: RawRwLockRecursive + RawRwLockTimed {
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/// Attempts to acquire a shared lock until a timeout is reached, without
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/// deadlocking in case of a recursive lock.
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fn try_lock_shared_recursive_for(&self, timeout: Self::Duration) -> bool;
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/// Attempts to acquire a shared lock until a timeout is reached, without
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/// deadlocking in case of a recursive lock.
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fn try_lock_shared_recursive_until(&self, timeout: Self::Instant) -> bool;
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}
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/// Additional methods for RwLocks which support atomically upgrading a shared
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/// lock to an exclusive lock.
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///
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/// This requires acquiring a special "upgradable read lock" instead of a
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/// normal shared lock. There may only be one upgradable lock at any time,
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/// otherwise deadlocks could occur when upgrading.
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pub unsafe trait RawRwLockUpgrade: RawRwLock {
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/// Acquires an upgradable lock, blocking the current thread until it is able to do so.
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fn lock_upgradable(&self);
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/// Attempts to acquire an upgradable lock without blocking.
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fn try_lock_upgradable(&self) -> bool;
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/// Releases an upgradable lock.
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///
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/// # Safety
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///
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/// This method may only be called if an upgradable lock is held in the current context.
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unsafe fn unlock_upgradable(&self);
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/// Upgrades an upgradable lock to an exclusive lock.
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///
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/// # Safety
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///
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/// This method may only be called if an upgradable lock is held in the current context.
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unsafe fn upgrade(&self);
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/// Attempts to upgrade an upgradable lock to an exclusive lock without
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/// blocking.
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///
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/// # Safety
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///
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/// This method may only be called if an upgradable lock is held in the current context.
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unsafe fn try_upgrade(&self) -> bool;
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}
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/// Additional methods for RwLocks which support upgradable locks and fair
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/// unlocking.
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pub unsafe trait RawRwLockUpgradeFair: RawRwLockUpgrade + RawRwLockFair {
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/// Releases an upgradable lock using a fair unlock protocol.
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///
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/// # Safety
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///
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/// This method may only be called if an upgradable lock is held in the current context.
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unsafe fn unlock_upgradable_fair(&self);
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/// Temporarily yields an upgradable lock to a waiting thread if there is one.
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///
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/// This method is functionally equivalent to calling `unlock_upgradable_fair` followed
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/// by `lock_upgradable`, however it can be much more efficient in the case where there
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/// are no waiting threads.
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///
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/// # Safety
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///
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/// This method may only be called if an upgradable lock is held in the current context.
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unsafe fn bump_upgradable(&self) {
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self.unlock_upgradable_fair();
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self.lock_upgradable();
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}
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}
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/// Additional methods for RwLocks which support upgradable locks and lock
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/// downgrading.
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pub unsafe trait RawRwLockUpgradeDowngrade: RawRwLockUpgrade + RawRwLockDowngrade {
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/// Downgrades an upgradable lock to a shared lock.
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///
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/// # Safety
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///
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/// This method may only be called if an upgradable lock is held in the current context.
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unsafe fn downgrade_upgradable(&self);
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/// Downgrades an exclusive lock to an upgradable lock.
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///
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/// # Safety
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///
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/// This method may only be called if an exclusive lock is held in the current context.
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unsafe fn downgrade_to_upgradable(&self);
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}
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/// Additional methods for RwLocks which support upgradable locks and locking
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/// with timeouts.
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pub unsafe trait RawRwLockUpgradeTimed: RawRwLockUpgrade + RawRwLockTimed {
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/// Attempts to acquire an upgradable lock until a timeout is reached.
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fn try_lock_upgradable_for(&self, timeout: Self::Duration) -> bool;
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/// Attempts to acquire an upgradable lock until a timeout is reached.
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fn try_lock_upgradable_until(&self, timeout: Self::Instant) -> bool;
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/// Attempts to upgrade an upgradable lock to an exclusive lock until a
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/// timeout is reached.
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///
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/// # Safety
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///
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/// This method may only be called if an upgradable lock is held in the current context.
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unsafe fn try_upgrade_for(&self, timeout: Self::Duration) -> bool;
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/// Attempts to upgrade an upgradable lock to an exclusive lock until a
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/// timeout is reached.
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///
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/// # Safety
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///
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/// This method may only be called if an upgradable lock is held in the current context.
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unsafe fn try_upgrade_until(&self, timeout: Self::Instant) -> bool;
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}
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/// A reader-writer lock
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///
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/// This type of lock allows a number of readers or at most one writer at any
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/// point in time. The write portion of this lock typically allows modification
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/// of the underlying data (exclusive access) and the read portion of this lock
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/// typically allows for read-only access (shared access).
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///
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/// The type parameter `T` represents the data that this lock protects. It is
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/// required that `T` satisfies `Send` to be shared across threads and `Sync` to
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/// allow concurrent access through readers. The RAII guards returned from the
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/// locking methods implement `Deref` (and `DerefMut` for the `write` methods)
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/// to allow access to the contained of the lock.
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pub struct RwLock<R, T: ?Sized> {
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raw: R,
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data: UnsafeCell<T>,
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}
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// Copied and modified from serde
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#[cfg(feature = "serde")]
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impl<R, T> Serialize for RwLock<R, T>
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where
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R: RawRwLock,
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T: Serialize + ?Sized,
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{
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fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
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where
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S: Serializer,
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{
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self.read().serialize(serializer)
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}
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}
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#[cfg(feature = "serde")]
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impl<'de, R, T> Deserialize<'de> for RwLock<R, T>
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where
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R: RawRwLock,
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T: Deserialize<'de> + ?Sized,
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{
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fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
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where
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D: Deserializer<'de>,
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{
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Deserialize::deserialize(deserializer).map(RwLock::new)
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}
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}
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unsafe impl<R: RawRwLock + Send, T: ?Sized + Send> Send for RwLock<R, T> {}
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unsafe impl<R: RawRwLock + Sync, T: ?Sized + Send + Sync> Sync for RwLock<R, T> {}
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impl<R: RawRwLock, T> RwLock<R, T> {
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/// Creates a new instance of an `RwLock<T>` which is unlocked.
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#[cfg(feature = "nightly")]
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#[inline]
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pub const fn new(val: T) -> RwLock<R, T> {
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RwLock {
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data: UnsafeCell::new(val),
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raw: R::INIT,
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}
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}
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/// Creates a new instance of an `RwLock<T>` which is unlocked.
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#[cfg(not(feature = "nightly"))]
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#[inline]
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pub fn new(val: T) -> RwLock<R, T> {
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RwLock {
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data: UnsafeCell::new(val),
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raw: R::INIT,
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}
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}
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/// Consumes this `RwLock`, returning the underlying data.
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#[inline]
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#[allow(unused_unsafe)]
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pub fn into_inner(self) -> T {
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unsafe { self.data.into_inner() }
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}
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}
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impl<R, T> RwLock<R, T> {
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/// Creates a new new instance of an `RwLock<T>` based on a pre-existing
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/// `RawRwLock<T>`.
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///
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/// This allows creating a `RwLock<T>` in a constant context on stable
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/// Rust.
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#[inline]
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pub const fn const_new(raw_rwlock: R, val: T) -> RwLock<R, T> {
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RwLock {
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data: UnsafeCell::new(val),
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raw: raw_rwlock,
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}
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}
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}
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impl<R: RawRwLock, T: ?Sized> RwLock<R, T> {
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/// # Safety
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///
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/// The lock must be held when calling this method.
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#[inline]
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unsafe fn read_guard(&self) -> RwLockReadGuard<'_, R, T> {
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RwLockReadGuard {
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rwlock: self,
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marker: PhantomData,
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}
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}
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/// # Safety
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///
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/// The lock must be held when calling this method.
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#[inline]
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unsafe fn write_guard(&self) -> RwLockWriteGuard<'_, R, T> {
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RwLockWriteGuard {
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rwlock: self,
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marker: PhantomData,
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}
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}
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/// Locks this `RwLock` with shared read access, blocking the current thread
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/// until it can be acquired.
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///
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/// The calling thread will be blocked until there are no more writers which
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/// hold the lock. There may be other readers currently inside the lock when
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/// this method returns.
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///
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/// Note that attempts to recursively acquire a read lock on a `RwLock` when
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/// the current thread already holds one may result in a deadlock.
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///
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/// Returns an RAII guard which will release this thread's shared access
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/// once it is dropped.
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#[inline]
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pub fn read(&self) -> RwLockReadGuard<'_, R, T> {
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self.raw.lock_shared();
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// SAFETY: The lock is held, as required.
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unsafe { self.read_guard() }
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}
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/// Attempts to acquire this `RwLock` with shared read access.
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///
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/// If the access could not be granted at this time, then `None` is returned.
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/// Otherwise, an RAII guard is returned which will release the shared access
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/// when it is dropped.
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///
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/// This function does not block.
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#[inline]
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pub fn try_read(&self) -> Option<RwLockReadGuard<'_, R, T>> {
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if self.raw.try_lock_shared() {
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// SAFETY: The lock is held, as required.
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Some(unsafe { self.read_guard() })
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} else {
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None
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}
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}
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/// Locks this `RwLock` with exclusive write access, blocking the current
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/// thread until it can be acquired.
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///
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/// This function will not return while other writers or other readers
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/// currently have access to the lock.
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///
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/// Returns an RAII guard which will drop the write access of this `RwLock`
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/// when dropped.
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#[inline]
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pub fn write(&self) -> RwLockWriteGuard<'_, R, T> {
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self.raw.lock_exclusive();
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// SAFETY: The lock is held, as required.
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unsafe { self.write_guard() }
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}
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/// Attempts to lock this `RwLock` with exclusive write access.
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///
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/// If the lock could not be acquired at this time, then `None` is returned.
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/// Otherwise, an RAII guard is returned which will release the lock when
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/// it is dropped.
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///
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/// This function does not block.
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#[inline]
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pub fn try_write(&self) -> Option<RwLockWriteGuard<'_, R, T>> {
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if self.raw.try_lock_exclusive() {
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// SAFETY: The lock is held, as required.
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Some(unsafe { self.write_guard() })
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} else {
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None
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}
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}
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/// Returns a mutable reference to the underlying data.
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///
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/// Since this call borrows the `RwLock` mutably, no actual locking needs to
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/// take place---the mutable borrow statically guarantees no locks exist.
|
|
#[inline]
|
|
pub fn get_mut(&mut self) -> &mut T {
|
|
unsafe { &mut *self.data.get() }
|
|
}
|
|
|
|
/// Checks whether this `RwLock` is currently locked in any way.
|
|
#[inline]
|
|
pub fn is_locked(&self) -> bool {
|
|
self.raw.is_locked()
|
|
}
|
|
|
|
/// Check if this `RwLock` is currently exclusively locked.
|
|
#[inline]
|
|
pub fn is_locked_exclusive(&self) -> bool {
|
|
self.raw.is_locked_exclusive()
|
|
}
|
|
|
|
/// Forcibly unlocks a read lock.
|
|
///
|
|
/// This is useful when combined with `mem::forget` to hold a lock without
|
|
/// the need to maintain a `RwLockReadGuard` object alive, for example when
|
|
/// dealing with FFI.
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// This method must only be called if the current thread logically owns a
|
|
/// `RwLockReadGuard` but that guard has be discarded using `mem::forget`.
|
|
/// Behavior is undefined if a rwlock is read-unlocked when not read-locked.
|
|
#[inline]
|
|
pub unsafe fn force_unlock_read(&self) {
|
|
self.raw.unlock_shared();
|
|
}
|
|
|
|
/// Forcibly unlocks a write lock.
|
|
///
|
|
/// This is useful when combined with `mem::forget` to hold a lock without
|
|
/// the need to maintain a `RwLockWriteGuard` object alive, for example when
|
|
/// dealing with FFI.
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// This method must only be called if the current thread logically owns a
|
|
/// `RwLockWriteGuard` but that guard has be discarded using `mem::forget`.
|
|
/// Behavior is undefined if a rwlock is write-unlocked when not write-locked.
|
|
#[inline]
|
|
pub unsafe fn force_unlock_write(&self) {
|
|
self.raw.unlock_exclusive();
|
|
}
|
|
|
|
/// Returns the underlying raw reader-writer lock object.
|
|
///
|
|
/// Note that you will most likely need to import the `RawRwLock` trait from
|
|
/// `lock_api` to be able to call functions on the raw
|
|
/// reader-writer lock.
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// This method is unsafe because it allows unlocking a mutex while
|
|
/// still holding a reference to a lock guard.
|
|
pub unsafe fn raw(&self) -> &R {
|
|
&self.raw
|
|
}
|
|
|
|
/// Returns a raw pointer to the underlying data.
|
|
///
|
|
/// This is useful when combined with `mem::forget` to hold a lock without
|
|
/// the need to maintain a `RwLockReadGuard` or `RwLockWriteGuard` object
|
|
/// alive, for example when dealing with FFI.
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// You must ensure that there are no data races when dereferencing the
|
|
/// returned pointer, for example if the current thread logically owns a
|
|
/// `RwLockReadGuard` or `RwLockWriteGuard` but that guard has been discarded
|
|
/// using `mem::forget`.
|
|
#[inline]
|
|
pub fn data_ptr(&self) -> *mut T {
|
|
self.data.get()
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// The lock must be held when calling this method.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
unsafe fn read_guard_arc(self: &Arc<Self>) -> ArcRwLockReadGuard<R, T> {
|
|
ArcRwLockReadGuard {
|
|
rwlock: self.clone(),
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// The lock must be held when calling this method.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
unsafe fn write_guard_arc(self: &Arc<Self>) -> ArcRwLockWriteGuard<R, T> {
|
|
ArcRwLockWriteGuard {
|
|
rwlock: self.clone(),
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
|
|
/// Locks this `RwLock` with read access, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `read` method; however, it requires the `RwLock` to be inside of an `Arc`
|
|
/// and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn read_arc(self: &Arc<Self>) -> ArcRwLockReadGuard<R, T> {
|
|
self.raw.lock_shared();
|
|
// SAFETY: locking guarantee is upheld
|
|
unsafe { self.read_guard_arc() }
|
|
}
|
|
|
|
/// Attempts to lock this `RwLock` with read access, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_read` method; however, it requires the `RwLock` to be inside of an
|
|
/// `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_read_arc(self: &Arc<Self>) -> Option<ArcRwLockReadGuard<R, T>> {
|
|
if self.raw.try_lock_shared() {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.read_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Locks this `RwLock` with write access, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `write` method; however, it requires the `RwLock` to be inside of an `Arc`
|
|
/// and the resulting write guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn write_arc(self: &Arc<Self>) -> ArcRwLockWriteGuard<R, T> {
|
|
self.raw.lock_exclusive();
|
|
// SAFETY: locking guarantee is upheld
|
|
unsafe { self.write_guard_arc() }
|
|
}
|
|
|
|
/// Attempts to lock this `RwLock` with writ access, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_write` method; however, it requires the `RwLock` to be inside of an
|
|
/// `Arc` and the resulting write guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_write_arc(self: &Arc<Self>) -> Option<ArcRwLockWriteGuard<R, T>> {
|
|
if self.raw.try_lock_exclusive() {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.write_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<R: RawRwLockFair, T: ?Sized> RwLock<R, T> {
|
|
/// Forcibly unlocks a read lock using a fair unlock procotol.
|
|
///
|
|
/// This is useful when combined with `mem::forget` to hold a lock without
|
|
/// the need to maintain a `RwLockReadGuard` object alive, for example when
|
|
/// dealing with FFI.
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// This method must only be called if the current thread logically owns a
|
|
/// `RwLockReadGuard` but that guard has be discarded using `mem::forget`.
|
|
/// Behavior is undefined if a rwlock is read-unlocked when not read-locked.
|
|
#[inline]
|
|
pub unsafe fn force_unlock_read_fair(&self) {
|
|
self.raw.unlock_shared_fair();
|
|
}
|
|
|
|
/// Forcibly unlocks a write lock using a fair unlock procotol.
|
|
///
|
|
/// This is useful when combined with `mem::forget` to hold a lock without
|
|
/// the need to maintain a `RwLockWriteGuard` object alive, for example when
|
|
/// dealing with FFI.
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// This method must only be called if the current thread logically owns a
|
|
/// `RwLockWriteGuard` but that guard has be discarded using `mem::forget`.
|
|
/// Behavior is undefined if a rwlock is write-unlocked when not write-locked.
|
|
#[inline]
|
|
pub unsafe fn force_unlock_write_fair(&self) {
|
|
self.raw.unlock_exclusive_fair();
|
|
}
|
|
}
|
|
|
|
impl<R: RawRwLockTimed, T: ?Sized> RwLock<R, T> {
|
|
/// Attempts to acquire this `RwLock` with shared read access until a timeout
|
|
/// is reached.
|
|
///
|
|
/// If the access could not be granted before the timeout expires, then
|
|
/// `None` is returned. Otherwise, an RAII guard is returned which will
|
|
/// release the shared access when it is dropped.
|
|
#[inline]
|
|
pub fn try_read_for(&self, timeout: R::Duration) -> Option<RwLockReadGuard<'_, R, T>> {
|
|
if self.raw.try_lock_shared_for(timeout) {
|
|
// SAFETY: The lock is held, as required.
|
|
Some(unsafe { self.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<RwLockReadGuard<'_, R, T>> {
|
|
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<RwLockWriteGuard<'_, R, T>> {
|
|
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<RwLockWriteGuard<'_, R, T>> {
|
|
if self.raw.try_lock_exclusive_until(timeout) {
|
|
// SAFETY: The lock is held, as required.
|
|
Some(unsafe { self.write_guard() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Attempts to acquire this `RwLock` with read access until a timeout is reached, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_read_for` method; however, it requires the `RwLock` to be inside of an
|
|
/// `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_read_arc_for(
|
|
self: &Arc<Self>,
|
|
timeout: R::Duration,
|
|
) -> Option<ArcRwLockReadGuard<R, T>> {
|
|
if self.raw.try_lock_shared_for(timeout) {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.read_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Attempts to acquire this `RwLock` with read access until a timeout is reached, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_read_until` method; however, it requires the `RwLock` to be inside of
|
|
/// an `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_read_arc_until(
|
|
self: &Arc<Self>,
|
|
timeout: R::Instant,
|
|
) -> Option<ArcRwLockReadGuard<R, T>> {
|
|
if self.raw.try_lock_shared_until(timeout) {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.read_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Attempts to acquire this `RwLock` with write access until a timeout is reached, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_write_for` method; however, it requires the `RwLock` to be inside of
|
|
/// an `Arc` and the resulting write guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_write_arc_for(
|
|
self: &Arc<Self>,
|
|
timeout: R::Duration,
|
|
) -> Option<ArcRwLockWriteGuard<R, T>> {
|
|
if self.raw.try_lock_exclusive_for(timeout) {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.write_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Attempts to acquire this `RwLock` with read access until a timeout is reached, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_write_until` method; however, it requires the `RwLock` to be inside of
|
|
/// an `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_write_arc_until(
|
|
self: &Arc<Self>,
|
|
timeout: R::Instant,
|
|
) -> Option<ArcRwLockWriteGuard<R, T>> {
|
|
if self.raw.try_lock_exclusive_until(timeout) {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.write_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<R: RawRwLockRecursive, T: ?Sized> RwLock<R, T> {
|
|
/// Locks this `RwLock` with shared read access, blocking the current thread
|
|
/// until it can be acquired.
|
|
///
|
|
/// The calling thread will be blocked until there are no more writers which
|
|
/// hold the lock. There may be other readers currently inside the lock when
|
|
/// this method returns.
|
|
///
|
|
/// Unlike `read`, this method is guaranteed to succeed without blocking if
|
|
/// another read lock is held at the time of the call. This allows a thread
|
|
/// to recursively lock a `RwLock`. However using this method can cause
|
|
/// writers to starve since readers no longer block if a writer is waiting
|
|
/// for the lock.
|
|
///
|
|
/// Returns an RAII guard which will release this thread's shared access
|
|
/// once it is dropped.
|
|
#[inline]
|
|
pub fn read_recursive(&self) -> RwLockReadGuard<'_, R, T> {
|
|
self.raw.lock_shared_recursive();
|
|
// SAFETY: The lock is held, as required.
|
|
unsafe { self.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<RwLockReadGuard<'_, R, T>> {
|
|
if self.raw.try_lock_shared_recursive() {
|
|
// SAFETY: The lock is held, as required.
|
|
Some(unsafe { self.read_guard() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Locks this `RwLock` with shared read access, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `read_recursive` method; however, it requires the `RwLock` to be inside of
|
|
/// an `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn read_arc_recursive(self: &Arc<Self>) -> ArcRwLockReadGuard<R, T> {
|
|
self.raw.lock_shared_recursive();
|
|
// SAFETY: locking guarantee is upheld
|
|
unsafe { self.read_guard_arc() }
|
|
}
|
|
|
|
/// Attempts to lock this `RwLock` with shared read access, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_read_recursive` method; however, it requires the `RwLock` to be inside
|
|
/// of an `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_read_recursive_arc(self: &Arc<Self>) -> Option<ArcRwLockReadGuard<R, T>> {
|
|
if self.raw.try_lock_shared_recursive() {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.read_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<R: RawRwLockRecursiveTimed, T: ?Sized> RwLock<R, T> {
|
|
/// Attempts to acquire this `RwLock` with shared read access until a timeout
|
|
/// is reached.
|
|
///
|
|
/// If the access could not be granted before the timeout expires, then
|
|
/// `None` is returned. Otherwise, an RAII guard is returned which will
|
|
/// release the shared access when it is dropped.
|
|
///
|
|
/// This method is guaranteed to succeed without blocking if another read
|
|
/// lock is held at the time of the call. See the documentation for
|
|
/// `read_recursive` for details.
|
|
#[inline]
|
|
pub fn try_read_recursive_for(
|
|
&self,
|
|
timeout: R::Duration,
|
|
) -> Option<RwLockReadGuard<'_, R, T>> {
|
|
if self.raw.try_lock_shared_recursive_for(timeout) {
|
|
// SAFETY: The lock is held, as required.
|
|
Some(unsafe { self.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<RwLockReadGuard<'_, R, T>> {
|
|
if self.raw.try_lock_shared_recursive_until(timeout) {
|
|
// SAFETY: The lock is held, as required.
|
|
Some(unsafe { self.read_guard() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Attempts to lock this `RwLock` with read access until a timeout is reached, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_read_recursive_for` method; however, it requires the `RwLock` to be
|
|
/// inside of an `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_read_arc_recursive_for(
|
|
self: &Arc<Self>,
|
|
timeout: R::Duration,
|
|
) -> Option<ArcRwLockReadGuard<R, T>> {
|
|
if self.raw.try_lock_shared_recursive_for(timeout) {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.read_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Attempts to lock this `RwLock` with read access until a timeout is reached, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_read_recursive_until` method; however, it requires the `RwLock` to be
|
|
/// inside of an `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_read_arc_recursive_until(
|
|
self: &Arc<Self>,
|
|
timeout: R::Instant,
|
|
) -> Option<ArcRwLockReadGuard<R, T>> {
|
|
if self.raw.try_lock_shared_recursive_until(timeout) {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.read_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<R: RawRwLockUpgrade, T: ?Sized> RwLock<R, T> {
|
|
/// # 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<RwLockUpgradableReadGuard<'_, R, T>> {
|
|
if self.raw.try_lock_upgradable() {
|
|
// SAFETY: The lock is held, as required.
|
|
Some(unsafe { self.upgradable_guard() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// The lock must be held when calling this method.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
unsafe fn upgradable_guard_arc(self: &Arc<Self>) -> ArcRwLockUpgradableReadGuard<R, T> {
|
|
ArcRwLockUpgradableReadGuard {
|
|
rwlock: self.clone(),
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
|
|
/// Locks this `RwLock` with upgradable read access, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `upgradable_read` method; however, it requires the `RwLock` to be
|
|
/// inside of an `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn upgradable_read_arc(self: &Arc<Self>) -> ArcRwLockUpgradableReadGuard<R, T> {
|
|
self.raw.lock_upgradable();
|
|
// SAFETY: locking guarantee is upheld
|
|
unsafe { self.upgradable_guard_arc() }
|
|
}
|
|
|
|
/// Attempts to lock this `RwLock` with upgradable read access, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_upgradable_read` method; however, it requires the `RwLock` to be
|
|
/// inside of an `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_upgradable_read_arc(self: &Arc<Self>) -> Option<ArcRwLockUpgradableReadGuard<R, T>> {
|
|
if self.raw.try_lock_upgradable() {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.upgradable_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<R: RawRwLockUpgradeTimed, T: ?Sized> RwLock<R, T> {
|
|
/// Attempts to acquire this `RwLock` with upgradable read access until a timeout
|
|
/// is reached.
|
|
///
|
|
/// If the access could not be granted before the timeout expires, then
|
|
/// `None` is returned. Otherwise, an RAII guard is returned which will
|
|
/// release the shared access when it is dropped.
|
|
#[inline]
|
|
pub fn try_upgradable_read_for(
|
|
&self,
|
|
timeout: R::Duration,
|
|
) -> Option<RwLockUpgradableReadGuard<'_, R, T>> {
|
|
if self.raw.try_lock_upgradable_for(timeout) {
|
|
// SAFETY: The lock is held, as required.
|
|
Some(unsafe { self.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<RwLockUpgradableReadGuard<'_, R, T>> {
|
|
if self.raw.try_lock_upgradable_until(timeout) {
|
|
// SAFETY: The lock is held, as required.
|
|
Some(unsafe { self.upgradable_guard() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Attempts to lock this `RwLock` with upgradable access until a timeout is reached, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_upgradable_read_for` method; however, it requires the `RwLock` to be
|
|
/// inside of an `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_upgradable_read_arc_for(
|
|
self: &Arc<Self>,
|
|
timeout: R::Duration,
|
|
) -> Option<ArcRwLockUpgradableReadGuard<R, T>> {
|
|
if self.raw.try_lock_upgradable_for(timeout) {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.upgradable_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
|
|
/// Attempts to lock this `RwLock` with upgradable access until a timeout is reached, through an `Arc`.
|
|
///
|
|
/// This method is similar to the `try_upgradable_read_until` method; however, it requires the `RwLock` to be
|
|
/// inside of an `Arc` and the resulting read guard has no lifetime requirements.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[inline]
|
|
pub fn try_upgradable_read_arc_until(
|
|
self: &Arc<Self>,
|
|
timeout: R::Instant,
|
|
) -> Option<ArcRwLockUpgradableReadGuard<R, T>> {
|
|
if self.raw.try_lock_upgradable_until(timeout) {
|
|
// SAFETY: locking guarantee is upheld
|
|
Some(unsafe { self.upgradable_guard_arc() })
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<R: RawRwLock, T: ?Sized + Default> Default for RwLock<R, T> {
|
|
#[inline]
|
|
fn default() -> RwLock<R, T> {
|
|
RwLock::new(Default::default())
|
|
}
|
|
}
|
|
|
|
impl<R: RawRwLock, T> From<T> for RwLock<R, T> {
|
|
#[inline]
|
|
fn from(t: T) -> RwLock<R, T> {
|
|
RwLock::new(t)
|
|
}
|
|
}
|
|
|
|
impl<R: RawRwLock, T: ?Sized + fmt::Debug> fmt::Debug for RwLock<R, T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
match self.try_read() {
|
|
Some(guard) => f.debug_struct("RwLock").field("data", &&*guard).finish(),
|
|
None => {
|
|
struct LockedPlaceholder;
|
|
impl fmt::Debug for LockedPlaceholder {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
f.write_str("<locked>")
|
|
}
|
|
}
|
|
|
|
f.debug_struct("RwLock")
|
|
.field("data", &LockedPlaceholder)
|
|
.finish()
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// RAII structure used to release the shared read access of a lock when
|
|
/// dropped.
|
|
#[must_use = "if unused the RwLock will immediately unlock"]
|
|
pub struct RwLockReadGuard<'a, R: RawRwLock, T: ?Sized> {
|
|
rwlock: &'a RwLock<R, T>,
|
|
marker: PhantomData<(&'a T, R::GuardMarker)>,
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> RwLockReadGuard<'a, R, T> {
|
|
/// Returns a reference to the original reader-writer lock object.
|
|
pub fn rwlock(s: &Self) -> &'a RwLock<R, T> {
|
|
s.rwlock
|
|
}
|
|
|
|
/// Make a new `MappedRwLockReadGuard` for a component of the locked data.
|
|
///
|
|
/// This operation cannot fail as the `RwLockReadGuard` passed
|
|
/// in already locked the data.
|
|
///
|
|
/// This is an associated function that needs to be
|
|
/// used as `RwLockReadGuard::map(...)`. A method would interfere with methods of
|
|
/// the same name on the contents of the locked data.
|
|
#[inline]
|
|
pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedRwLockReadGuard<'a, R, U>
|
|
where
|
|
F: FnOnce(&T) -> &U,
|
|
{
|
|
let raw = &s.rwlock.raw;
|
|
let data = f(unsafe { &*s.rwlock.data.get() });
|
|
mem::forget(s);
|
|
MappedRwLockReadGuard {
|
|
raw,
|
|
data,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
|
|
/// Attempts to make a new `MappedRwLockReadGuard` for a component of the
|
|
/// locked data. 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<U: ?Sized, F>(s: Self, f: F) -> Result<MappedRwLockReadGuard<'a, R, U>, Self>
|
|
where
|
|
F: FnOnce(&T) -> Option<&U>,
|
|
{
|
|
let raw = &s.rwlock.raw;
|
|
let data = match f(unsafe { &*s.rwlock.data.get() }) {
|
|
Some(data) => data,
|
|
None => return Err(s),
|
|
};
|
|
mem::forget(s);
|
|
Ok(MappedRwLockReadGuard {
|
|
raw,
|
|
data,
|
|
marker: PhantomData,
|
|
})
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// 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<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_shared();
|
|
}
|
|
defer!(s.rwlock.raw.lock_shared());
|
|
f()
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockFair + 'a, T: ?Sized + 'a> RwLockReadGuard<'a, R, T> {
|
|
/// Unlocks the `RwLock` using a fair unlock protocol.
|
|
///
|
|
/// By default, `RwLock` is unfair and allow the current thread to re-lock
|
|
/// the `RwLock` before another has the chance to acquire the lock, even if
|
|
/// that thread has been blocked on the `RwLock` for a long time. This is
|
|
/// the default because it allows much higher throughput as it avoids
|
|
/// forcing a context switch on every `RwLock` unlock. This can result in one
|
|
/// thread acquiring a `RwLock` many more times than other threads.
|
|
///
|
|
/// However in some cases it can be beneficial to ensure fairness by forcing
|
|
/// the lock to pass on to a waiting thread if there is one. This is done by
|
|
/// using this method instead of dropping the `RwLockReadGuard` normally.
|
|
#[inline]
|
|
pub fn unlock_fair(s: Self) {
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_shared_fair();
|
|
}
|
|
mem::forget(s);
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// The `RwLock` is unlocked a fair unlock protocol.
|
|
///
|
|
/// This is safe because `&mut` guarantees that there exist no other
|
|
/// references to the data protected by the `RwLock`.
|
|
#[inline]
|
|
pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_shared_fair();
|
|
}
|
|
defer!(s.rwlock.raw.lock_shared());
|
|
f()
|
|
}
|
|
|
|
/// Temporarily yields the `RwLock` to a waiting thread if there is one.
|
|
///
|
|
/// This method is functionally equivalent to calling `unlock_fair` followed
|
|
/// by `read`, however it can be much more efficient in the case where there
|
|
/// are no waiting threads.
|
|
#[inline]
|
|
pub fn bump(s: &mut Self) {
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
s.rwlock.raw.bump_shared();
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for RwLockReadGuard<'a, R, T> {
|
|
type Target = T;
|
|
#[inline]
|
|
fn deref(&self) -> &T {
|
|
unsafe { &*self.rwlock.data.get() }
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Drop for RwLockReadGuard<'a, R, T> {
|
|
#[inline]
|
|
fn drop(&mut self) {
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
self.rwlock.raw.unlock_shared();
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug for RwLockReadGuard<'a, R, T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
fmt::Debug::fmt(&**self, f)
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display
|
|
for RwLockReadGuard<'a, R, T>
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
(**self).fmt(f)
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "owning_ref")]
|
|
unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> StableAddress for RwLockReadGuard<'a, R, T> {}
|
|
|
|
/// An RAII rwlock guard returned by the `Arc` locking operations on `RwLock`.
|
|
///
|
|
/// This is similar to the `RwLockReadGuard` struct, except instead of using a reference to unlock the `RwLock`
|
|
/// it uses an `Arc<RwLock>`. This has several advantages, most notably that it has an `'static` lifetime.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[must_use = "if unused the RwLock will immediately unlock"]
|
|
pub struct ArcRwLockReadGuard<R: RawRwLock, T: ?Sized> {
|
|
rwlock: Arc<RwLock<R, T>>,
|
|
marker: PhantomData<R::GuardMarker>,
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: ?Sized> ArcRwLockReadGuard<R, T> {
|
|
/// Returns a reference to the rwlock, contained in its `Arc`.
|
|
pub fn rwlock(s: &Self) -> &Arc<RwLock<R, T>> {
|
|
&s.rwlock
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// This is functionally identical to the `unlocked` method on [`RwLockReadGuard`].
|
|
#[inline]
|
|
pub fn unlocked<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_shared();
|
|
}
|
|
defer!(s.rwlock.raw.lock_shared());
|
|
f()
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockFair, T: ?Sized> ArcRwLockReadGuard<R, T> {
|
|
/// Unlocks the `RwLock` using a fair unlock protocol.
|
|
///
|
|
/// This is functionally identical to the `unlock_fair` method on [`RwLockReadGuard`].
|
|
#[inline]
|
|
pub fn unlock_fair(s: Self) {
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_shared_fair();
|
|
}
|
|
|
|
// SAFETY: ensure the Arc has its refcount decremented
|
|
let mut s = ManuallyDrop::new(s);
|
|
unsafe { ptr::drop_in_place(&mut s.rwlock) };
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// This is functionally identical to the `unlocked_fair` method on [`RwLockReadGuard`].
|
|
#[inline]
|
|
pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_shared_fair();
|
|
}
|
|
defer!(s.rwlock.raw.lock_shared());
|
|
f()
|
|
}
|
|
|
|
/// Temporarily yields the `RwLock` to a waiting thread if there is one.
|
|
///
|
|
/// This is functionally identical to the `bump` method on [`RwLockReadGuard`].
|
|
#[inline]
|
|
pub fn bump(s: &mut Self) {
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
s.rwlock.raw.bump_shared();
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: ?Sized> Deref for ArcRwLockReadGuard<R, T> {
|
|
type Target = T;
|
|
#[inline]
|
|
fn deref(&self) -> &T {
|
|
unsafe { &*self.rwlock.data.get() }
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: ?Sized> Drop for ArcRwLockReadGuard<R, T> {
|
|
#[inline]
|
|
fn drop(&mut self) {
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
self.rwlock.raw.unlock_shared();
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: fmt::Debug + ?Sized> fmt::Debug for ArcRwLockReadGuard<R, T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
fmt::Debug::fmt(&**self, f)
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: fmt::Display + ?Sized> fmt::Display for ArcRwLockReadGuard<R, T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
(**self).fmt(f)
|
|
}
|
|
}
|
|
|
|
/// RAII structure used to release the exclusive write access of a lock when
|
|
/// dropped.
|
|
#[must_use = "if unused the RwLock will immediately unlock"]
|
|
pub struct RwLockWriteGuard<'a, R: RawRwLock, T: ?Sized> {
|
|
rwlock: &'a RwLock<R, T>,
|
|
marker: PhantomData<(&'a mut T, R::GuardMarker)>,
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T> {
|
|
/// Returns a reference to the original reader-writer lock object.
|
|
pub fn rwlock(s: &Self) -> &'a RwLock<R, T> {
|
|
s.rwlock
|
|
}
|
|
|
|
/// Make a new `MappedRwLockWriteGuard` for a component of the locked data.
|
|
///
|
|
/// This operation cannot fail as the `RwLockWriteGuard` passed
|
|
/// in already locked the data.
|
|
///
|
|
/// This is an associated function that needs to be
|
|
/// used as `RwLockWriteGuard::map(...)`. A method would interfere with methods of
|
|
/// the same name on the contents of the locked data.
|
|
#[inline]
|
|
pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedRwLockWriteGuard<'a, R, U>
|
|
where
|
|
F: FnOnce(&mut T) -> &mut U,
|
|
{
|
|
let raw = &s.rwlock.raw;
|
|
let data = f(unsafe { &mut *s.rwlock.data.get() });
|
|
mem::forget(s);
|
|
MappedRwLockWriteGuard {
|
|
raw,
|
|
data,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
|
|
/// Attempts to make a new `MappedRwLockWriteGuard` for a component of the
|
|
/// locked data. The original guard is return if the closure returns `None`.
|
|
///
|
|
/// This operation cannot fail as the `RwLockWriteGuard` passed
|
|
/// in already locked the data.
|
|
///
|
|
/// This is an associated function that needs to be
|
|
/// used as `RwLockWriteGuard::map(...)`. A method would interfere with methods of
|
|
/// the same name on the contents of the locked data.
|
|
#[inline]
|
|
pub fn try_map<U: ?Sized, F>(s: Self, f: F) -> Result<MappedRwLockWriteGuard<'a, R, U>, Self>
|
|
where
|
|
F: FnOnce(&mut T) -> Option<&mut U>,
|
|
{
|
|
let raw = &s.rwlock.raw;
|
|
let data = match f(unsafe { &mut *s.rwlock.data.get() }) {
|
|
Some(data) => data,
|
|
None => return Err(s),
|
|
};
|
|
mem::forget(s);
|
|
Ok(MappedRwLockWriteGuard {
|
|
raw,
|
|
data,
|
|
marker: PhantomData,
|
|
})
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// This is safe because `&mut` guarantees that there exist no other
|
|
/// references to the data protected by the `RwLock`.
|
|
#[inline]
|
|
pub fn unlocked<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_exclusive();
|
|
}
|
|
defer!(s.rwlock.raw.lock_exclusive());
|
|
f()
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockDowngrade + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T> {
|
|
/// Atomically downgrades a write lock into a read lock without allowing any
|
|
/// writers to take exclusive access of the lock in the meantime.
|
|
///
|
|
/// Note that if there are any writers currently waiting to take the lock
|
|
/// then other readers may not be able to acquire the lock even if it was
|
|
/// downgraded.
|
|
pub fn downgrade(s: Self) -> RwLockReadGuard<'a, R, T> {
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.rwlock.raw.downgrade();
|
|
}
|
|
let rwlock = s.rwlock;
|
|
mem::forget(s);
|
|
RwLockReadGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockUpgradeDowngrade + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T> {
|
|
/// Atomically downgrades a write lock into an upgradable read lock without allowing any
|
|
/// writers to take exclusive access of the lock in the meantime.
|
|
///
|
|
/// Note that if there are any writers currently waiting to take the lock
|
|
/// then other readers may not be able to acquire the lock even if it was
|
|
/// downgraded.
|
|
pub fn downgrade_to_upgradable(s: Self) -> RwLockUpgradableReadGuard<'a, R, T> {
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.rwlock.raw.downgrade_to_upgradable();
|
|
}
|
|
let rwlock = s.rwlock;
|
|
mem::forget(s);
|
|
RwLockUpgradableReadGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockFair + 'a, T: ?Sized + 'a> RwLockWriteGuard<'a, R, T> {
|
|
/// Unlocks the `RwLock` using a fair unlock protocol.
|
|
///
|
|
/// By default, `RwLock` is unfair and allow the current thread to re-lock
|
|
/// the `RwLock` before another has the chance to acquire the lock, even if
|
|
/// that thread has been blocked on the `RwLock` for a long time. This is
|
|
/// the default because it allows much higher throughput as it avoids
|
|
/// forcing a context switch on every `RwLock` unlock. This can result in one
|
|
/// thread acquiring a `RwLock` many more times than other threads.
|
|
///
|
|
/// However in some cases it can be beneficial to ensure fairness by forcing
|
|
/// the lock to pass on to a waiting thread if there is one. This is done by
|
|
/// using this method instead of dropping the `RwLockWriteGuard` normally.
|
|
#[inline]
|
|
pub fn unlock_fair(s: Self) {
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_exclusive_fair();
|
|
}
|
|
mem::forget(s);
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// The `RwLock` is unlocked a fair unlock protocol.
|
|
///
|
|
/// This is safe because `&mut` guarantees that there exist no other
|
|
/// references to the data protected by the `RwLock`.
|
|
#[inline]
|
|
pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_exclusive_fair();
|
|
}
|
|
defer!(s.rwlock.raw.lock_exclusive());
|
|
f()
|
|
}
|
|
|
|
/// Temporarily yields the `RwLock` to a waiting thread if there is one.
|
|
///
|
|
/// This method is functionally equivalent to calling `unlock_fair` followed
|
|
/// by `write`, however it can be much more efficient in the case where there
|
|
/// are no waiting threads.
|
|
#[inline]
|
|
pub fn bump(s: &mut Self) {
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.rwlock.raw.bump_exclusive();
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for RwLockWriteGuard<'a, R, T> {
|
|
type Target = T;
|
|
#[inline]
|
|
fn deref(&self) -> &T {
|
|
unsafe { &*self.rwlock.data.get() }
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> DerefMut for RwLockWriteGuard<'a, R, T> {
|
|
#[inline]
|
|
fn deref_mut(&mut self) -> &mut T {
|
|
unsafe { &mut *self.rwlock.data.get() }
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Drop for RwLockWriteGuard<'a, R, T> {
|
|
#[inline]
|
|
fn drop(&mut self) {
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
self.rwlock.raw.unlock_exclusive();
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug for RwLockWriteGuard<'a, R, T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
fmt::Debug::fmt(&**self, f)
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display
|
|
for RwLockWriteGuard<'a, R, T>
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
(**self).fmt(f)
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "owning_ref")]
|
|
unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> StableAddress for RwLockWriteGuard<'a, R, T> {}
|
|
|
|
/// An RAII rwlock guard returned by the `Arc` locking operations on `RwLock`.
|
|
/// This is similar to the `RwLockWriteGuard` struct, except instead of using a reference to unlock the `RwLock`
|
|
/// it uses an `Arc<RwLock>`. This has several advantages, most notably that it has an `'static` lifetime.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[must_use = "if unused the RwLock will immediately unlock"]
|
|
pub struct ArcRwLockWriteGuard<R: RawRwLock, T: ?Sized> {
|
|
rwlock: Arc<RwLock<R, T>>,
|
|
marker: PhantomData<R::GuardMarker>,
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: ?Sized> ArcRwLockWriteGuard<R, T> {
|
|
/// Returns a reference to the rwlock, contained in its `Arc`.
|
|
pub fn rwlock(s: &Self) -> &Arc<RwLock<R, T>> {
|
|
&s.rwlock
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// This is functionally equivalent to the `unlocked` method on [`RwLockWriteGuard`].
|
|
#[inline]
|
|
pub fn unlocked<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockWriteGuard always holds a shared lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_exclusive();
|
|
}
|
|
defer!(s.rwlock.raw.lock_exclusive());
|
|
f()
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockDowngrade, T: ?Sized> ArcRwLockWriteGuard<R, T> {
|
|
/// Atomically downgrades a write lock into a read lock without allowing any
|
|
/// writers to take exclusive access of the lock in the meantime.
|
|
///
|
|
/// This is functionally equivalent to the `downgrade` method on [`RwLockWriteGuard`].
|
|
pub fn downgrade(s: Self) -> ArcRwLockReadGuard<R, T> {
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.rwlock.raw.downgrade();
|
|
}
|
|
|
|
// SAFETY: prevent the arc's refcount from changing using ManuallyDrop and ptr::read
|
|
let s = ManuallyDrop::new(s);
|
|
let rwlock = unsafe { ptr::read(&s.rwlock) };
|
|
|
|
ArcRwLockReadGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockUpgradeDowngrade, T: ?Sized> ArcRwLockWriteGuard<R, T> {
|
|
/// Atomically downgrades a write lock into an upgradable read lock without allowing any
|
|
/// writers to take exclusive access of the lock in the meantime.
|
|
///
|
|
/// This is functionally identical to the `downgrade_to_upgradable` method on [`RwLockWriteGuard`].
|
|
pub fn downgrade_to_upgradable(s: Self) -> ArcRwLockUpgradableReadGuard<R, T> {
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.rwlock.raw.downgrade_to_upgradable();
|
|
}
|
|
|
|
// SAFETY: same as above
|
|
let s = ManuallyDrop::new(s);
|
|
let rwlock = unsafe { ptr::read(&s.rwlock) };
|
|
|
|
ArcRwLockUpgradableReadGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockFair, T: ?Sized> ArcRwLockWriteGuard<R, T> {
|
|
/// Unlocks the `RwLock` using a fair unlock protocol.
|
|
///
|
|
/// This is functionally equivalent to the `unlock_fair` method on [`RwLockWriteGuard`].
|
|
#[inline]
|
|
pub fn unlock_fair(s: Self) {
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_exclusive_fair();
|
|
}
|
|
|
|
// SAFETY: prevent the Arc from leaking memory
|
|
let mut s = ManuallyDrop::new(s);
|
|
unsafe { ptr::drop_in_place(&mut s.rwlock) };
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// This is functionally equivalent to the `unlocked_fair` method on [`RwLockWriteGuard`].
|
|
#[inline]
|
|
pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_exclusive_fair();
|
|
}
|
|
defer!(s.rwlock.raw.lock_exclusive());
|
|
f()
|
|
}
|
|
|
|
/// Temporarily yields the `RwLock` to a waiting thread if there is one.
|
|
///
|
|
/// This method is functionally equivalent to the `bump` method on [`RwLockWriteGuard`].
|
|
#[inline]
|
|
pub fn bump(s: &mut Self) {
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.rwlock.raw.bump_exclusive();
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: ?Sized> Deref for ArcRwLockWriteGuard<R, T> {
|
|
type Target = T;
|
|
#[inline]
|
|
fn deref(&self) -> &T {
|
|
unsafe { &*self.rwlock.data.get() }
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: ?Sized> DerefMut for ArcRwLockWriteGuard<R, T> {
|
|
#[inline]
|
|
fn deref_mut(&mut self) -> &mut T {
|
|
unsafe { &mut *self.rwlock.data.get() }
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: ?Sized> Drop for ArcRwLockWriteGuard<R, T> {
|
|
#[inline]
|
|
fn drop(&mut self) {
|
|
// Safety: An RwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
self.rwlock.raw.unlock_exclusive();
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: fmt::Debug + ?Sized> fmt::Debug for ArcRwLockWriteGuard<R, T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
fmt::Debug::fmt(&**self, f)
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLock, T: fmt::Display + ?Sized> fmt::Display for ArcRwLockWriteGuard<R, T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
(**self).fmt(f)
|
|
}
|
|
}
|
|
|
|
/// RAII structure used to release the upgradable read access of a lock when
|
|
/// dropped.
|
|
#[must_use = "if unused the RwLock will immediately unlock"]
|
|
pub struct RwLockUpgradableReadGuard<'a, R: RawRwLockUpgrade, T: ?Sized> {
|
|
rwlock: &'a RwLock<R, T>,
|
|
marker: PhantomData<(&'a T, R::GuardMarker)>,
|
|
}
|
|
|
|
unsafe impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + Sync + 'a> Sync
|
|
for RwLockUpgradableReadGuard<'a, R, T>
|
|
{
|
|
}
|
|
|
|
impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T> {
|
|
/// Returns a reference to the original reader-writer lock object.
|
|
pub fn rwlock(s: &Self) -> &'a RwLock<R, T> {
|
|
s.rwlock
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// This is safe because `&mut` guarantees that there exist no other
|
|
/// references to the data protected by the `RwLock`.
|
|
#[inline]
|
|
pub fn unlocked<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_upgradable();
|
|
}
|
|
defer!(s.rwlock.raw.lock_upgradable());
|
|
f()
|
|
}
|
|
|
|
/// Atomically upgrades an upgradable read lock lock into a exclusive write lock,
|
|
/// blocking the current thread until it can be acquired.
|
|
pub fn upgrade(s: Self) -> RwLockWriteGuard<'a, R, T> {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.upgrade();
|
|
}
|
|
let rwlock = s.rwlock;
|
|
mem::forget(s);
|
|
RwLockWriteGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
|
|
/// Tries to atomically upgrade an upgradable read lock into 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<RwLockWriteGuard<'a, R, T>, Self> {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
if unsafe { s.rwlock.raw.try_upgrade() } {
|
|
let rwlock = s.rwlock;
|
|
mem::forget(s);
|
|
Ok(RwLockWriteGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
})
|
|
} else {
|
|
Err(s)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockUpgradeFair + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T> {
|
|
/// Unlocks the `RwLock` using a fair unlock protocol.
|
|
///
|
|
/// By default, `RwLock` is unfair and allow the current thread to re-lock
|
|
/// the `RwLock` before another has the chance to acquire the lock, even if
|
|
/// that thread has been blocked on the `RwLock` for a long time. This is
|
|
/// the default because it allows much higher throughput as it avoids
|
|
/// forcing a context switch on every `RwLock` unlock. This can result in one
|
|
/// thread acquiring a `RwLock` many more times than other threads.
|
|
///
|
|
/// However in some cases it can be beneficial to ensure fairness by forcing
|
|
/// the lock to pass on to a waiting thread if there is one. This is done by
|
|
/// using this method instead of dropping the `RwLockUpgradableReadGuard` normally.
|
|
#[inline]
|
|
pub fn unlock_fair(s: Self) {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_upgradable_fair();
|
|
}
|
|
mem::forget(s);
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// The `RwLock` is unlocked a fair unlock protocol.
|
|
///
|
|
/// This is safe because `&mut` guarantees that there exist no other
|
|
/// references to the data protected by the `RwLock`.
|
|
#[inline]
|
|
pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_upgradable_fair();
|
|
}
|
|
defer!(s.rwlock.raw.lock_upgradable());
|
|
f()
|
|
}
|
|
|
|
/// Temporarily yields the `RwLock` to a waiting thread if there is one.
|
|
///
|
|
/// This method is functionally equivalent to calling `unlock_fair` followed
|
|
/// by `upgradable_read`, however it can be much more efficient in the case where there
|
|
/// are no waiting threads.
|
|
#[inline]
|
|
pub fn bump(s: &mut Self) {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.bump_upgradable();
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockUpgradeDowngrade + 'a, T: ?Sized + 'a> RwLockUpgradableReadGuard<'a, R, T> {
|
|
/// Atomically downgrades an upgradable read lock lock into a shared read lock
|
|
/// without allowing any writers to take exclusive access of the lock in the
|
|
/// meantime.
|
|
///
|
|
/// Note that if there are any writers currently waiting to take the lock
|
|
/// then other readers may not be able to acquire the lock even if it was
|
|
/// downgraded.
|
|
pub fn downgrade(s: Self) -> RwLockReadGuard<'a, R, T> {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.downgrade_upgradable();
|
|
}
|
|
let rwlock = s.rwlock;
|
|
mem::forget(s);
|
|
RwLockReadGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
}
|
|
|
|
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<RwLockWriteGuard<'a, R, T>, Self> {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
if unsafe { s.rwlock.raw.try_upgrade_for(timeout) } {
|
|
let rwlock = s.rwlock;
|
|
mem::forget(s);
|
|
Ok(RwLockWriteGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
})
|
|
} else {
|
|
Err(s)
|
|
}
|
|
}
|
|
|
|
/// Tries to atomically upgrade an upgradable read lock into 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<RwLockWriteGuard<'a, R, T>, Self> {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
if unsafe { s.rwlock.raw.try_upgrade_until(timeout) } {
|
|
let rwlock = s.rwlock;
|
|
mem::forget(s);
|
|
Ok(RwLockWriteGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
})
|
|
} else {
|
|
Err(s)
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> Deref for RwLockUpgradableReadGuard<'a, R, T> {
|
|
type Target = T;
|
|
#[inline]
|
|
fn deref(&self) -> &T {
|
|
unsafe { &*self.rwlock.data.get() }
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> Drop for RwLockUpgradableReadGuard<'a, R, T> {
|
|
#[inline]
|
|
fn drop(&mut self) {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
self.rwlock.raw.unlock_upgradable();
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockUpgrade + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug
|
|
for RwLockUpgradableReadGuard<'a, R, T>
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
fmt::Debug::fmt(&**self, f)
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockUpgrade + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display
|
|
for RwLockUpgradableReadGuard<'a, R, T>
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
(**self).fmt(f)
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "owning_ref")]
|
|
unsafe impl<'a, R: RawRwLockUpgrade + 'a, T: ?Sized + 'a> StableAddress
|
|
for RwLockUpgradableReadGuard<'a, R, T>
|
|
{
|
|
}
|
|
|
|
/// An RAII rwlock guard returned by the `Arc` locking operations on `RwLock`.
|
|
/// This is similar to the `RwLockUpgradableReadGuard` struct, except instead of using a reference to unlock the
|
|
/// `RwLock` it uses an `Arc<RwLock>`. This has several advantages, most notably that it has an `'static`
|
|
/// lifetime.
|
|
#[cfg(feature = "arc_lock")]
|
|
#[must_use = "if unused the RwLock will immediately unlock"]
|
|
pub struct ArcRwLockUpgradableReadGuard<R: RawRwLockUpgrade, T: ?Sized> {
|
|
rwlock: Arc<RwLock<R, T>>,
|
|
marker: PhantomData<R::GuardMarker>,
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockUpgrade, T: ?Sized> ArcRwLockUpgradableReadGuard<R, T> {
|
|
/// Returns a reference to the rwlock, contained in its original `Arc`.
|
|
pub fn rwlock(s: &Self) -> &Arc<RwLock<R, T>> {
|
|
&s.rwlock
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// This is functionally identical to the `unlocked` method on [`RwLockUpgradableReadGuard`].
|
|
#[inline]
|
|
pub fn unlocked<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_upgradable();
|
|
}
|
|
defer!(s.rwlock.raw.lock_upgradable());
|
|
f()
|
|
}
|
|
|
|
/// Atomically upgrades an upgradable read lock lock into a exclusive write lock,
|
|
/// blocking the current thread until it can be acquired.
|
|
pub fn upgrade(s: Self) -> ArcRwLockWriteGuard<R, T> {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.upgrade();
|
|
}
|
|
|
|
// SAFETY: avoid incrementing or decrementing the refcount using ManuallyDrop and reading the Arc out
|
|
// of the struct
|
|
let s = ManuallyDrop::new(s);
|
|
let rwlock = unsafe { ptr::read(&s.rwlock) };
|
|
|
|
ArcRwLockWriteGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
|
|
/// Tries to atomically upgrade an upgradable read lock into 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<ArcRwLockWriteGuard<R, T>, Self> {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
if unsafe { s.rwlock.raw.try_upgrade() } {
|
|
// SAFETY: same as above
|
|
let s = ManuallyDrop::new(s);
|
|
let rwlock = unsafe { ptr::read(&s.rwlock) };
|
|
|
|
Ok(ArcRwLockWriteGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
})
|
|
} else {
|
|
Err(s)
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockUpgradeFair, T: ?Sized> ArcRwLockUpgradableReadGuard<R, T> {
|
|
/// Unlocks the `RwLock` using a fair unlock protocol.
|
|
///
|
|
/// This is functionally identical to the `unlock_fair` method on [`RwLockUpgradableReadGuard`].
|
|
#[inline]
|
|
pub fn unlock_fair(s: Self) {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_upgradable_fair();
|
|
}
|
|
|
|
// SAFETY: make sure we decrement the refcount properly
|
|
let mut s = ManuallyDrop::new(s);
|
|
unsafe { ptr::drop_in_place(&mut s.rwlock) };
|
|
}
|
|
|
|
/// Temporarily unlocks the `RwLock` to execute the given function.
|
|
///
|
|
/// This is functionally equivalent to the `unlocked_fair` method on [`RwLockUpgradableReadGuard`].
|
|
#[inline]
|
|
pub fn unlocked_fair<F, U>(s: &mut Self, f: F) -> U
|
|
where
|
|
F: FnOnce() -> U,
|
|
{
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.unlock_upgradable_fair();
|
|
}
|
|
defer!(s.rwlock.raw.lock_upgradable());
|
|
f()
|
|
}
|
|
|
|
/// Temporarily yields the `RwLock` to a waiting thread if there is one.
|
|
///
|
|
/// This method is functionally equivalent to calling `bump` on [`RwLockUpgradableReadGuard`].
|
|
#[inline]
|
|
pub fn bump(s: &mut Self) {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.bump_upgradable();
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockUpgradeDowngrade, T: ?Sized> ArcRwLockUpgradableReadGuard<R, T> {
|
|
/// Atomically downgrades an upgradable read lock lock into a shared read lock
|
|
/// without allowing any writers to take exclusive access of the lock in the
|
|
/// meantime.
|
|
///
|
|
/// Note that if there are any writers currently waiting to take the lock
|
|
/// then other readers may not be able to acquire the lock even if it was
|
|
/// downgraded.
|
|
pub fn downgrade(s: Self) -> ArcRwLockReadGuard<R, T> {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
s.rwlock.raw.downgrade_upgradable();
|
|
}
|
|
|
|
// SAFETY: use ManuallyDrop and ptr::read to ensure the refcount is not changed
|
|
let s = ManuallyDrop::new(s);
|
|
let rwlock = unsafe { ptr::read(&s.rwlock) };
|
|
|
|
ArcRwLockReadGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockUpgradeTimed, T: ?Sized> ArcRwLockUpgradableReadGuard<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<ArcRwLockWriteGuard<R, T>, Self> {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
if unsafe { s.rwlock.raw.try_upgrade_for(timeout) } {
|
|
// SAFETY: same as above
|
|
let s = ManuallyDrop::new(s);
|
|
let rwlock = unsafe { ptr::read(&s.rwlock) };
|
|
|
|
Ok(ArcRwLockWriteGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
})
|
|
} else {
|
|
Err(s)
|
|
}
|
|
}
|
|
|
|
/// Tries to atomically upgrade an upgradable read lock into 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<ArcRwLockWriteGuard<R, T>, Self> {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
if unsafe { s.rwlock.raw.try_upgrade_until(timeout) } {
|
|
// SAFETY: same as above
|
|
let s = ManuallyDrop::new(s);
|
|
let rwlock = unsafe { ptr::read(&s.rwlock) };
|
|
|
|
Ok(ArcRwLockWriteGuard {
|
|
rwlock,
|
|
marker: PhantomData,
|
|
})
|
|
} else {
|
|
Err(s)
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockUpgrade, T: ?Sized> Deref for ArcRwLockUpgradableReadGuard<R, T> {
|
|
type Target = T;
|
|
#[inline]
|
|
fn deref(&self) -> &T {
|
|
unsafe { &*self.rwlock.data.get() }
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockUpgrade, T: ?Sized> Drop for ArcRwLockUpgradableReadGuard<R, T> {
|
|
#[inline]
|
|
fn drop(&mut self) {
|
|
// Safety: An RwLockUpgradableReadGuard always holds an upgradable lock.
|
|
unsafe {
|
|
self.rwlock.raw.unlock_upgradable();
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockUpgrade, T: fmt::Debug + ?Sized> fmt::Debug
|
|
for ArcRwLockUpgradableReadGuard<R, T>
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
fmt::Debug::fmt(&**self, f)
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "arc_lock")]
|
|
impl<R: RawRwLockUpgrade, T: fmt::Display + ?Sized> fmt::Display
|
|
for ArcRwLockUpgradableReadGuard<R, T>
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
(**self).fmt(f)
|
|
}
|
|
}
|
|
|
|
/// An RAII read lock guard returned by `RwLockReadGuard::map`, which can point to a
|
|
/// subfield of the protected data.
|
|
///
|
|
/// The main difference between `MappedRwLockReadGuard` and `RwLockReadGuard` is that the
|
|
/// former doesn't support temporarily unlocking and re-locking, since that
|
|
/// could introduce soundness issues if the locked object is modified by another
|
|
/// thread.
|
|
#[must_use = "if unused the RwLock will immediately unlock"]
|
|
pub struct MappedRwLockReadGuard<'a, R: RawRwLock, T: ?Sized> {
|
|
raw: &'a R,
|
|
data: *const T,
|
|
marker: PhantomData<&'a T>,
|
|
}
|
|
|
|
unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + Sync + 'a> Sync for MappedRwLockReadGuard<'a, R, T> {}
|
|
unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + Sync + 'a> Send for MappedRwLockReadGuard<'a, R, T> where
|
|
R::GuardMarker: Send
|
|
{
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> MappedRwLockReadGuard<'a, R, T> {
|
|
/// Make a new `MappedRwLockReadGuard` for a component of the locked data.
|
|
///
|
|
/// This operation cannot fail as the `MappedRwLockReadGuard` passed
|
|
/// in already locked the data.
|
|
///
|
|
/// This is an associated function that needs to be
|
|
/// used as `MappedRwLockReadGuard::map(...)`. A method would interfere with methods of
|
|
/// the same name on the contents of the locked data.
|
|
#[inline]
|
|
pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedRwLockReadGuard<'a, R, U>
|
|
where
|
|
F: FnOnce(&T) -> &U,
|
|
{
|
|
let raw = s.raw;
|
|
let data = f(unsafe { &*s.data });
|
|
mem::forget(s);
|
|
MappedRwLockReadGuard {
|
|
raw,
|
|
data,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
|
|
/// Attempts to make a new `MappedRwLockReadGuard` for a component of the
|
|
/// locked data. The original guard is return if the closure returns `None`.
|
|
///
|
|
/// This operation cannot fail as the `MappedRwLockReadGuard` passed
|
|
/// in already locked the data.
|
|
///
|
|
/// This is an associated function that needs to be
|
|
/// used as `MappedRwLockReadGuard::map(...)`. A method would interfere with methods of
|
|
/// the same name on the contents of the locked data.
|
|
#[inline]
|
|
pub fn try_map<U: ?Sized, F>(s: Self, f: F) -> Result<MappedRwLockReadGuard<'a, R, U>, Self>
|
|
where
|
|
F: FnOnce(&T) -> Option<&U>,
|
|
{
|
|
let raw = s.raw;
|
|
let data = match f(unsafe { &*s.data }) {
|
|
Some(data) => data,
|
|
None => return Err(s),
|
|
};
|
|
mem::forget(s);
|
|
Ok(MappedRwLockReadGuard {
|
|
raw,
|
|
data,
|
|
marker: PhantomData,
|
|
})
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockFair + 'a, T: ?Sized + 'a> MappedRwLockReadGuard<'a, R, T> {
|
|
/// Unlocks the `RwLock` using a fair unlock protocol.
|
|
///
|
|
/// By default, `RwLock` is unfair and allow the current thread to re-lock
|
|
/// the `RwLock` before another has the chance to acquire the lock, even if
|
|
/// that thread has been blocked on the `RwLock` for a long time. This is
|
|
/// the default because it allows much higher throughput as it avoids
|
|
/// forcing a context switch on every `RwLock` unlock. This can result in one
|
|
/// thread acquiring a `RwLock` many more times than other threads.
|
|
///
|
|
/// However in some cases it can be beneficial to ensure fairness by forcing
|
|
/// the lock to pass on to a waiting thread if there is one. This is done by
|
|
/// using this method instead of dropping the `MappedRwLockReadGuard` normally.
|
|
#[inline]
|
|
pub fn unlock_fair(s: Self) {
|
|
// Safety: A MappedRwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
s.raw.unlock_shared_fair();
|
|
}
|
|
mem::forget(s);
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for MappedRwLockReadGuard<'a, R, T> {
|
|
type Target = T;
|
|
#[inline]
|
|
fn deref(&self) -> &T {
|
|
unsafe { &*self.data }
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Drop for MappedRwLockReadGuard<'a, R, T> {
|
|
#[inline]
|
|
fn drop(&mut self) {
|
|
// Safety: A MappedRwLockReadGuard always holds a shared lock.
|
|
unsafe {
|
|
self.raw.unlock_shared();
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug
|
|
for MappedRwLockReadGuard<'a, R, T>
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
fmt::Debug::fmt(&**self, f)
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display
|
|
for MappedRwLockReadGuard<'a, R, T>
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
(**self).fmt(f)
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "owning_ref")]
|
|
unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> StableAddress
|
|
for MappedRwLockReadGuard<'a, R, T>
|
|
{
|
|
}
|
|
|
|
/// An RAII write lock guard returned by `RwLockWriteGuard::map`, which can point to a
|
|
/// subfield of the protected data.
|
|
///
|
|
/// The main difference between `MappedRwLockWriteGuard` and `RwLockWriteGuard` is that the
|
|
/// former doesn't support temporarily unlocking and re-locking, since that
|
|
/// could introduce soundness issues if the locked object is modified by another
|
|
/// thread.
|
|
#[must_use = "if unused the RwLock will immediately unlock"]
|
|
pub struct MappedRwLockWriteGuard<'a, R: RawRwLock, T: ?Sized> {
|
|
raw: &'a R,
|
|
data: *mut T,
|
|
marker: PhantomData<&'a mut T>,
|
|
}
|
|
|
|
unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + Sync + 'a> Sync
|
|
for MappedRwLockWriteGuard<'a, R, T>
|
|
{
|
|
}
|
|
unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + Send + 'a> Send for MappedRwLockWriteGuard<'a, R, T> where
|
|
R::GuardMarker: Send
|
|
{
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> MappedRwLockWriteGuard<'a, R, T> {
|
|
/// Make a new `MappedRwLockWriteGuard` for a component of the locked data.
|
|
///
|
|
/// This operation cannot fail as the `MappedRwLockWriteGuard` passed
|
|
/// in already locked the data.
|
|
///
|
|
/// This is an associated function that needs to be
|
|
/// used as `MappedRwLockWriteGuard::map(...)`. A method would interfere with methods of
|
|
/// the same name on the contents of the locked data.
|
|
#[inline]
|
|
pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedRwLockWriteGuard<'a, R, U>
|
|
where
|
|
F: FnOnce(&mut T) -> &mut U,
|
|
{
|
|
let raw = s.raw;
|
|
let data = f(unsafe { &mut *s.data });
|
|
mem::forget(s);
|
|
MappedRwLockWriteGuard {
|
|
raw,
|
|
data,
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
|
|
/// Attempts to make a new `MappedRwLockWriteGuard` for a component of the
|
|
/// locked data. The original guard is return if the closure returns `None`.
|
|
///
|
|
/// This operation cannot fail as the `MappedRwLockWriteGuard` passed
|
|
/// in already locked the data.
|
|
///
|
|
/// This is an associated function that needs to be
|
|
/// used as `MappedRwLockWriteGuard::map(...)`. A method would interfere with methods of
|
|
/// the same name on the contents of the locked data.
|
|
#[inline]
|
|
pub fn try_map<U: ?Sized, F>(s: Self, f: F) -> Result<MappedRwLockWriteGuard<'a, R, U>, Self>
|
|
where
|
|
F: FnOnce(&mut T) -> Option<&mut U>,
|
|
{
|
|
let raw = s.raw;
|
|
let data = match f(unsafe { &mut *s.data }) {
|
|
Some(data) => data,
|
|
None => return Err(s),
|
|
};
|
|
mem::forget(s);
|
|
Ok(MappedRwLockWriteGuard {
|
|
raw,
|
|
data,
|
|
marker: PhantomData,
|
|
})
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLockFair + 'a, T: ?Sized + 'a> MappedRwLockWriteGuard<'a, R, T> {
|
|
/// Unlocks the `RwLock` using a fair unlock protocol.
|
|
///
|
|
/// By default, `RwLock` is unfair and allow the current thread to re-lock
|
|
/// the `RwLock` before another has the chance to acquire the lock, even if
|
|
/// that thread has been blocked on the `RwLock` for a long time. This is
|
|
/// the default because it allows much higher throughput as it avoids
|
|
/// forcing a context switch on every `RwLock` unlock. This can result in one
|
|
/// thread acquiring a `RwLock` many more times than other threads.
|
|
///
|
|
/// However in some cases it can be beneficial to ensure fairness by forcing
|
|
/// the lock to pass on to a waiting thread if there is one. This is done by
|
|
/// using this method instead of dropping the `MappedRwLockWriteGuard` normally.
|
|
#[inline]
|
|
pub fn unlock_fair(s: Self) {
|
|
// Safety: A MappedRwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
s.raw.unlock_exclusive_fair();
|
|
}
|
|
mem::forget(s);
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Deref for MappedRwLockWriteGuard<'a, R, T> {
|
|
type Target = T;
|
|
#[inline]
|
|
fn deref(&self) -> &T {
|
|
unsafe { &*self.data }
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> DerefMut for MappedRwLockWriteGuard<'a, R, T> {
|
|
#[inline]
|
|
fn deref_mut(&mut self) -> &mut T {
|
|
unsafe { &mut *self.data }
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> Drop for MappedRwLockWriteGuard<'a, R, T> {
|
|
#[inline]
|
|
fn drop(&mut self) {
|
|
// Safety: A MappedRwLockWriteGuard always holds an exclusive lock.
|
|
unsafe {
|
|
self.raw.unlock_exclusive();
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: fmt::Debug + ?Sized + 'a> fmt::Debug
|
|
for MappedRwLockWriteGuard<'a, R, T>
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
fmt::Debug::fmt(&**self, f)
|
|
}
|
|
}
|
|
|
|
impl<'a, R: RawRwLock + 'a, T: fmt::Display + ?Sized + 'a> fmt::Display
|
|
for MappedRwLockWriteGuard<'a, R, T>
|
|
{
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
(**self).fmt(f)
|
|
}
|
|
}
|
|
|
|
#[cfg(feature = "owning_ref")]
|
|
unsafe impl<'a, R: RawRwLock + 'a, T: ?Sized + 'a> StableAddress
|
|
for MappedRwLockWriteGuard<'a, R, T>
|
|
{
|
|
}
|