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//! Inherent implementation and trait implementations for the [`Owned`] type. #[cfg(not(feature = "std"))] use alloc::boxed::Box; use core::borrow::{Borrow, BorrowMut}; use core::fmt; use core::marker::PhantomData; use core::mem; use core::ops::{Deref, DerefMut}; use core::ptr::NonNull; use typenum::Unsigned; use crate::internal::Internal; use crate::pointer::{Marked, MarkedNonNull, MarkedPointer, NonNullable}; use crate::{Owned, Reclaim, Record, Shared, Unprotected}; //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Clone //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T: Clone, R: Reclaim, N: Unsigned> Clone for Owned<T, R, N> { #[inline] fn clone(&self) -> Self { let (reference, tag) = unsafe { self.inner.decompose_ref() }; Self::with_tag(reference.clone(), tag) } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Send & Sync //////////////////////////////////////////////////////////////////////////////////////////////////// unsafe impl<T, R: Reclaim, N: Unsigned> Send for Owned<T, R, N> where T: Send {} unsafe impl<T, R: Reclaim, N: Unsigned> Sync for Owned<T, R, N> where T: Sync {} //////////////////////////////////////////////////////////////////////////////////////////////////// // impl MarkedPointer //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, R: Reclaim, N: Unsigned> MarkedPointer for Owned<T, R, N> { impl_trait!(owned); } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl inherent //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, R: Reclaim, N: Unsigned> Owned<T, R, N> { /// Allocates memory for a [`Record<T>`](Record) on the heap and then /// places a record with a default header and `owned` into it. /// /// This does only allocate memory if at least one of /// [`RecordHeader`][header] or `T` are not zero-sized. /// If the [`RecordHeader`][header] is a ZST, this behaves /// identically to `Box::new`. /// /// [header]: crate::LocalReclaim::RecordHeader #[inline] pub fn new(owned: T) -> Self { Self { inner: MarkedNonNull::from(Self::alloc_record(owned)), _marker: PhantomData } } /// Creates a new `Owned` like [`new`](Owned::new) but composes the /// returned pointer with an initial `tag` value. /// /// # Example /// /// The primary use case for this is to pre-mark newly allocated values. /// /// ``` /// use core::sync::atomic::Ordering; /// /// use reclaim::typenum::U1; /// use reclaim::Shared; /// /// type Atomic<T> = reclaim::leak::Atomic<T, U1>; /// type Owned<T> = reclaim::leak::Owned<T, U1>; /// /// let atomic = Atomic::null(); /// let owned = Owned::with_tag("string", 0b1); /// /// atomic.store(owned, Ordering::Relaxed); /// let shared = atomic.load_shared(Ordering::Relaxed); /// /// assert_eq!((&"string", 0b1), Shared::decompose_ref(shared.unwrap())); /// ``` #[inline] pub fn with_tag(owned: T, tag: usize) -> Self { Self { inner: MarkedNonNull::compose(Self::alloc_record(owned), tag), _marker: PhantomData } } impl_inherent!(owned); /// Decomposes the internal marked pointer, returning a reference and the /// separated tag. /// /// # Example /// /// ``` /// use core::sync::atomic::Ordering::Relaxed; /// /// use reclaim::typenum::U1; /// use reclaim::leak::Owned; /// /// type Atomic<T> = reclaim::leak::Atomic<T, U1>; /// /// let mut atomic = Atomic::from(Owned::with_tag("string", 0b1)); /// // ... potential operations by other threads ... /// let owned = atomic.take(); // after all threads have joined /// /// assert_eq!((&"string", 0b1), Owned::decompose_ref(owned.as_ref().unwrap())); /// ``` #[inline] pub fn decompose_ref(owned: &Self) -> (&T, usize) { // this is safe because is `inner` is guaranteed to be backed by a valid allocation unsafe { owned.inner.decompose_ref() } } /// Decomposes the internal marked pointer, returning a mutable reference /// and the separated tag. #[inline] pub fn decompose_mut(owned: &mut Self) -> (&mut T, usize) { // this is safe because is `inner` is guaranteed to be backed by a valid allocation unsafe { owned.inner.decompose_mut() } } /// Consumes and leaks the `Owned`, returning a mutable reference /// `&'a mut T` and the decomposed tag. /// Note that the type `T` must outlive the chosen lifetime `'a`. /// If the type has only static references, or none at all, then this may /// chosen to be `'static`. #[inline] pub fn leak<'a>(owned: Self) -> (&'a mut T, usize) where T: 'a, { let (ptr, tag) = owned.inner.decompose(); mem::forget(owned); unsafe { (&mut *ptr.as_ptr(), tag) } } /// Leaks the `owned` value and turns it into an [`Unprotected`] value, /// which has copy semantics, but can no longer be safely dereferenced. /// /// # Example /// /// ``` /// use core::sync::atomic::Ordering::Relaxed; /// /// use reclaim::typenum::U0; /// use reclaim::{Owned, Shared}; /// /// type Atomic<T> = reclaim::leak::Atomic<T, U0>; /// /// let atomic = Atomic::null(); /// /// let unprotected = Owned::leak_unprotected(Owned::new("string")); /// /// loop { /// // `unprotected` is simply copied in every loop iteration /// if atomic.compare_exchange_weak(Shared::none(), unprotected, Relaxed, Relaxed).is_ok() { /// break; /// } /// } /// /// # assert_eq!(&"string", &*atomic.load_shared(Relaxed).unwrap()) /// ``` #[inline] pub fn leak_unprotected(owned: Self) -> Unprotected<T, R, N> { let inner = owned.inner; mem::forget(owned); Unprotected { inner, _marker: PhantomData } } /// Leaks the `owned` value and turns it into a "protected" [`Shared`][shared] /// value with arbitrary lifetime `'a`. /// /// Note, that the protection of the [`Shared`][shared] value in this case /// stems from the fact, that the given `owned` could not have previously /// been part of a concurrent data structure (barring unsafe construction). /// This rules out concurrent reclamation by other threads. /// /// # Safety /// /// Once a leaked [`Shared`][shared] has been successfully inserted into a /// concurrent data structure, it must not be accessed any more, if there is /// the possibility for concurrent reclamation of the record. /// /// [shared]: crate::Shared /// /// # Example /// /// The use case for this method is similar to [`leak_unprotected`][Owned::leak_unprotected] /// but the leaked value can be safely dereferenced **before** being /// inserted into a shared data structure. /// /// ``` /// use core::sync::atomic::Ordering::Relaxed; /// /// use reclaim::typenum::U0; /// use reclaim::{Owned, Shared}; /// /// type Atomic<T> = reclaim::leak::Atomic<T, U0>; /// /// let atomic = Atomic::null(); /// /// let shared = unsafe { /// Owned::leak_shared(Owned::new("string")) /// }; /// /// assert_eq!(&"string", &*shared); /// /// loop { /// // `shared` is simply copied in every loop iteration /// if atomic.compare_exchange_weak(Shared::none(), shared, Relaxed, Relaxed).is_ok() { /// // if (non-leaking) reclamation is going on, `shared` must not be accessed /// // anymore after successful insertion! /// break; /// } /// } /// /// # assert_eq!(&"string", &*atomic.load_shared(Relaxed).unwrap()) /// ``` #[inline] pub unsafe fn leak_shared<'a>(owned: Self) -> Shared<'a, T, R, N> { let inner = owned.inner; mem::forget(owned); Shared { inner, _marker: PhantomData } } /// Allocates a records wrapping `owned` and returns the pointer to the /// wrapped value. #[inline] fn alloc_record(owned: T) -> NonNull<T> { let record = Box::leak(Box::new(Record::<_, R>::new(owned))); NonNull::from(&record.elem) } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl AsRef & AsMut //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, R: Reclaim, N: Unsigned> AsRef<T> for Owned<T, R, N> { #[inline] fn as_ref(&self) -> &T { &**self } } impl<T, R: Reclaim, N: Unsigned> AsMut<T> for Owned<T, R, N> { #[inline] fn as_mut(&mut self) -> &mut T { &mut **self } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Borrow & BorrowMut //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, R: Reclaim, N: Unsigned> Borrow<T> for Owned<T, R, N> { #[inline] fn borrow(&self) -> &T { &**self } } impl<T, R: Reclaim, N: Unsigned> BorrowMut<T> for Owned<T, R, N> { #[inline] fn borrow_mut(&mut self) -> &mut T { &mut **self } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Default //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T: Default, R: Reclaim, N: Unsigned> Default for Owned<T, R, N> { #[inline] fn default() -> Self { Owned::new(T::default()) } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Deref & DerefMut //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, R: Reclaim, N: Unsigned> Deref for Owned<T, R, N> { type Target = T; #[inline] fn deref(&self) -> &Self::Target { unsafe { self.inner.as_ref() } } } impl<T, R: Reclaim, N: Unsigned> DerefMut for Owned<T, R, N> { #[inline] fn deref_mut(&mut self) -> &mut Self::Target { unsafe { self.inner.as_mut() } } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Drop //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, R: Reclaim, N: Unsigned> Drop for Owned<T, R, N> { #[inline] fn drop(&mut self) { unsafe { let record = Record::<_, R>::from_raw(self.inner.decompose_ptr()); mem::drop(Box::from_raw(record.as_ptr())); } } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl From //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, R: Reclaim, N: Unsigned> From<T> for Owned<T, R, N> { #[inline] fn from(owned: T) -> Self { Owned::new(owned) } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Debug & Pointer //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, R: Reclaim, N: Unsigned> fmt::Debug for Owned<T, R, N> where T: fmt::Debug, { #[inline] fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { let (reference, tag) = unsafe { self.inner.decompose_ref() }; f.debug_struct("Owned").field("value", reference).field("tag", &tag).finish() } } impl<T, R: Reclaim, N: Unsigned> fmt::Pointer for Owned<T, R, N> { #[inline] fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Pointer::fmt(&self.inner.decompose_ptr(), f) } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl NonNullable //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, R: Reclaim, N: Unsigned> NonNullable for Owned<T, R, N> { type Item = T; type MarkBits = N; #[inline] fn into_marked_non_null(self) -> MarkedNonNull<T, N> { let inner = self.inner; mem::forget(self); inner } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Internal //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, R: Reclaim, N: Unsigned> Internal for Owned<T, R, N> {} #[cfg(test)] mod test { use typenum::U2; use crate::leak::Leaking; use crate::pointer::MarkedPointer; type Owned<T> = crate::Owned<T, Leaking, U2>; type Record<T> = crate::Record<T, Leaking>; #[test] fn new() { let o1 = Owned::new(1); let o2 = Owned::new(2); let o3 = Owned::new(3); assert_eq!(1, *o1); assert_eq!(2, *o2); assert_eq!(3, *o3); } #[test] fn from_marked_ptr() { let owned = Owned::new(1); let marked = Owned::into_marked_ptr(owned); let from = unsafe { Owned::from_marked_ptr(marked) }; assert_eq!((&1, 0), Owned::decompose_ref(&from)); } #[test] fn compose() { let owned = Owned::with_tag(1, 0b11); assert_eq!((Some(&1), 0b11), unsafe { Owned::into_marked_ptr(owned).decompose_ref() }); let owned = Owned::with_tag(2, 0); assert_eq!((Some(&2), 0), unsafe { Owned::into_marked_ptr(owned).decompose_ref() }); } #[test] fn header() { let owned = Owned::new(1); let header = unsafe { Record::header_from_raw_non_null(owned.inner.decompose_non_null()) }; assert_eq!(header.checksum, 0xDEAD_BEEF); } }