[−][src]Struct voluntary_servitude::atomics::AtomicOption
Atomic Option<Box<T>>
It can't provide a reference to the current value since it may be dropped at any time
You must swap the element to access it
FillOnceAtomicOption
provides a API that enables access to the reference, but only enables try_store
to write to it
Methods
impl<T> AtomicOption<T>
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pub fn new<V>(value: V) -> Self where
V: Into<Option<Box<T>>>,
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V: Into<Option<Box<T>>>,
Creates new AtomicOption
let empty: AtomicOption<()> = AtomicOption::new(None); assert!(empty.into_inner().is_none()); let filled = AtomicOption::new(Box::new(10)); assert_eq!(filled.into_inner().map(|a| *a), Some(10));
pub fn try_store<V>(&self, new: V, order: Ordering) -> Result<(), NotEmpty> where
V: Into<Box<T>>,
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V: Into<Box<T>>,
Stores new value if AtomicOption
currently contains a None
This operation is implemented as a single atomic compare_and_swap
.
use std::sync::atomic::Ordering; let option = AtomicOption::default(); let old = option.try_store(5, Ordering::Relaxed); assert!(old.is_ok()); let failed_to_store = option.try_store(10, Ordering::Relaxed); assert!(failed_to_store.is_err()); assert_eq!(option.into_inner().map(|a| *a), Some(5));
pub fn store<V>(&self, new: V, order: Ordering) where
V: Into<Option<Box<T>>>,
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V: Into<Option<Box<T>>>,
Stores value into AtomicOption
and drops old one
use std::sync::atomic::Ordering; let option: AtomicOption<u8> = AtomicOption::new(None); option.store(Box::new(3), Ordering::Relaxed); assert_eq!(option.into_inner().map(|a| *a), Some(3));
pub fn swap<V>(&self, new: V, order: Ordering) -> Option<Box<T>> where
V: Into<Option<Box<T>>>,
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V: Into<Option<Box<T>>>,
Stores value into AtomicOption
returning old value
use std::sync::atomic::Ordering; let option = AtomicOption::default(); assert_eq!(option.swap(Box::new(5), Ordering::Relaxed), None); assert_eq!(option.swap(None, Ordering::Relaxed), Some(Box::new(5)));
pub fn take(&self, order: Ordering) -> Option<Box<T>>
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Replaces AtomicOption
value with None
returning old value
use std::sync::atomic::Ordering; let option = AtomicOption::from(5); assert_eq!(option.take(Ordering::Relaxed), Some(Box::new(5))); assert_eq!(option.take(Ordering::Relaxed), None);
pub unsafe fn atomic_ptr(&self) -> &AtomicPtr<T>
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Gives access to inner AtomicPtr
(AtomicOption
is an abstraction of it).
Safety
This is heavily unsafe.
It's unsafe because you are responsible for making sure T
is not dropped nor replaced with a invalid pointer (or that will be invalidated while still stored).
use std::sync::atomic::Ordering; let ten = AtomicOption::from(10); assert_eq!(unsafe { &*ten.atomic_ptr().load(Ordering::Relaxed) }, &10);
pub fn into_inner(self) -> Option<Box<T>>
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Converts itself into a Option<Box<T>>
let ten = AtomicOption::from(10); assert_eq!(ten.into_inner().map(|a| *a), Some(10));
pub unsafe fn from_raw(ptr: *mut T) -> Self
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Creates new AtomicOption
based on raw pointer
Safety
Unsafe because it uses a raw pointer, so it can't be sure of its origin (and ownership)
You must own the pointer to call this
use std::ptr::null_mut; let empty = unsafe { AtomicOption::<()>::from_raw(null_mut()) }; assert!(empty.into_inner().is_none()); let filled = unsafe { AtomicOption::from_raw(Box::into_raw(10.into())) }; assert_eq!(filled.into_inner().map(|a| *a), Some(10));
pub fn get_raw(&self, order: Ordering) -> *mut T
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Atomically extracts current pointer stored, this function should probably not be called
Safety
It's almost never safe to deref this value, it could have been dropped from the moment you extracted it to the moment you deref/access it in any way, it WILL cause UB
It exists to provide a way of implementing safe wrappers (like FillOnceAtomicOption
)
use std::{sync::atomic::Ordering, ptr::null_mut}; let empty: AtomicOption<()> = AtomicOption::new(None); assert_eq!(empty.get_raw(Ordering::Relaxed), null_mut()); let ptr = Box::into_raw(10u8.into()); let filled = unsafe { AtomicOption::from_raw(ptr) }; assert_eq!(filled.get_raw(Ordering::Relaxed), ptr); // You should probably never deref `ptr` // You should probably never use this method // UB will be everywhere, FillOnceAtomicOption is a safe an alternative
Trait Implementations
impl<T> Drop for AtomicOption<T>
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impl<T> From<T> for AtomicOption<T>
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impl<T> From<Box<T>> for AtomicOption<T>
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impl<T> From<Option<T>> for AtomicOption<T>
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impl<T> From<Option<Box<T>>> for AtomicOption<T>
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impl<T> From<FillOnceAtomicOption<T>> for AtomicOption<T>
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fn from(atomic: FillOnceAtomicOption<T>) -> Self
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impl<T> From<Atomic<T>> for AtomicOption<T>
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impl<T> From<AtomicOption<T>> for FillOnceAtomicOption<T>
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fn from(atomic: AtomicOption<T>) -> Self
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impl<T> Default for AtomicOption<T>
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impl<T: Debug> Debug for AtomicOption<T>
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impl<T> Pointer for AtomicOption<T>
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Auto Trait Implementations
impl<T> Send for AtomicOption<T> where
T: Send,
T: Send,
impl<T> Sync for AtomicOption<T> where
T: Sync,
T: Sync,
Blanket Implementations
impl<T> From for T
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impl<T, U> Into for T where
U: From<T>,
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U: From<T>,
impl<T, U> TryFrom for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T> Borrow for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T, U> TryInto for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,