diff options
Diffstat (limited to 'library/alloc/src/rc.rs')
| -rw-r--r-- | library/alloc/src/rc.rs | 162 |
1 files changed, 83 insertions, 79 deletions
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs index 0e2c35845e8..e98ae7c31ad 100644 --- a/library/alloc/src/rc.rs +++ b/library/alloc/src/rc.rs @@ -282,19 +282,19 @@ mod tests; // would interfere with otherwise safe [into|from]_raw() of transmutable // inner types. #[repr(C)] -struct RcBox<T: ?Sized> { +struct RcInner<T: ?Sized> { strong: Cell<usize>, weak: Cell<usize>, value: T, } -/// Calculate layout for `RcBox<T>` using the inner value's layout -fn rcbox_layout_for_value_layout(layout: Layout) -> Layout { +/// Calculate layout for `RcInner<T>` using the inner value's layout +fn rc_inner_layout_for_value_layout(layout: Layout) -> Layout { // Calculate layout using the given value layout. // Previously, layout was calculated on the expression - // `&*(ptr as *const RcBox<T>)`, but this created a misaligned + // `&*(ptr as *const RcInner<T>)`, but this created a misaligned // reference (see #54908). - Layout::new::<RcBox<()>>().extend(layout).unwrap().0.pad_to_align() + Layout::new::<RcInner<()>>().extend(layout).unwrap().0.pad_to_align() } /// A single-threaded reference-counting pointer. 'Rc' stands for 'Reference @@ -314,8 +314,8 @@ pub struct Rc< T: ?Sized, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global, > { - ptr: NonNull<RcBox<T>>, - phantom: PhantomData<RcBox<T>>, + ptr: NonNull<RcInner<T>>, + phantom: PhantomData<RcInner<T>>, alloc: A, } @@ -343,37 +343,37 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Rc<U>> for Rc<T> {} impl<T: ?Sized> Rc<T> { #[inline] - unsafe fn from_inner(ptr: NonNull<RcBox<T>>) -> Self { + unsafe fn from_inner(ptr: NonNull<RcInner<T>>) -> Self { unsafe { Self::from_inner_in(ptr, Global) } } #[inline] - unsafe fn from_ptr(ptr: *mut RcBox<T>) -> Self { + unsafe fn from_ptr(ptr: *mut RcInner<T>) -> Self { unsafe { Self::from_inner(NonNull::new_unchecked(ptr)) } } } impl<T: ?Sized, A: Allocator> Rc<T, A> { #[inline(always)] - fn inner(&self) -> &RcBox<T> { + fn inner(&self) -> &RcInner<T> { // This unsafety is ok because while this Rc is alive we're guaranteed // that the inner pointer is valid. unsafe { self.ptr.as_ref() } } #[inline] - fn into_inner_with_allocator(this: Self) -> (NonNull<RcBox<T>>, A) { + fn into_inner_with_allocator(this: Self) -> (NonNull<RcInner<T>>, A) { let this = mem::ManuallyDrop::new(this); (this.ptr, unsafe { ptr::read(&this.alloc) }) } #[inline] - unsafe fn from_inner_in(ptr: NonNull<RcBox<T>>, alloc: A) -> Self { + unsafe fn from_inner_in(ptr: NonNull<RcInner<T>>, alloc: A) -> Self { Self { ptr, phantom: PhantomData, alloc } } #[inline] - unsafe fn from_ptr_in(ptr: *mut RcBox<T>, alloc: A) -> Self { + unsafe fn from_ptr_in(ptr: *mut RcInner<T>, alloc: A) -> Self { unsafe { Self::from_inner_in(NonNull::new_unchecked(ptr), alloc) } } } @@ -397,7 +397,7 @@ impl<T> Rc<T> { // if the weak pointer is stored inside the strong one. unsafe { Self::from_inner( - Box::leak(Box::new(RcBox { strong: Cell::new(1), weak: Cell::new(1), value })) + Box::leak(Box::new(RcInner { strong: Cell::new(1), weak: Cell::new(1), value })) .into(), ) } @@ -546,8 +546,12 @@ impl<T> Rc<T> { // if the weak pointer is stored inside the strong one. unsafe { Ok(Self::from_inner( - Box::leak(Box::try_new(RcBox { strong: Cell::new(1), weak: Cell::new(1), value })?) - .into(), + Box::leak(Box::try_new(RcInner { + strong: Cell::new(1), + weak: Cell::new(1), + value, + })?) + .into(), )) } } @@ -646,7 +650,7 @@ impl<T, A: Allocator> Rc<T, A> { // That would make code size bigger. match Self::try_new_in(value, alloc) { Ok(m) => m, - Err(_) => handle_alloc_error(Layout::new::<RcBox<T>>()), + Err(_) => handle_alloc_error(Layout::new::<RcInner<T>>()), } } @@ -765,7 +769,7 @@ impl<T, A: Allocator> Rc<T, A> { // Construct the inner in the "uninitialized" state with a single // weak reference. let (uninit_raw_ptr, alloc) = Box::into_raw_with_allocator(Box::new_in( - RcBox { + RcInner { strong: Cell::new(0), weak: Cell::new(1), value: mem::MaybeUninit::<T>::uninit(), @@ -773,7 +777,7 @@ impl<T, A: Allocator> Rc<T, A> { alloc, )); let uninit_ptr: NonNull<_> = (unsafe { &mut *uninit_raw_ptr }).into(); - let init_ptr: NonNull<RcBox<T>> = uninit_ptr.cast(); + let init_ptr: NonNull<RcInner<T>> = uninit_ptr.cast(); let weak = Weak { ptr: init_ptr, alloc: alloc }; @@ -826,7 +830,7 @@ impl<T, A: Allocator> Rc<T, A> { // the allocation while the strong destructor is running, even // if the weak pointer is stored inside the strong one. let (ptr, alloc) = Box::into_unique(Box::try_new_in( - RcBox { strong: Cell::new(1), weak: Cell::new(1), value }, + RcInner { strong: Cell::new(1), weak: Cell::new(1), value }, alloc, )?); Ok(unsafe { Self::from_inner_in(ptr.into(), alloc) }) @@ -1059,7 +1063,7 @@ impl<T> Rc<[T]> { |layout| Global.allocate_zeroed(layout), |mem| { ptr::slice_from_raw_parts_mut(mem.cast::<T>(), len) - as *mut RcBox<[mem::MaybeUninit<T>]> + as *mut RcInner<[mem::MaybeUninit<T>]> }, )) } @@ -1132,7 +1136,7 @@ impl<T, A: Allocator> Rc<[T], A> { |layout| alloc.allocate_zeroed(layout), |mem| { ptr::slice_from_raw_parts_mut(mem.cast::<T>(), len) - as *mut RcBox<[mem::MaybeUninit<T>]> + as *mut RcInner<[mem::MaybeUninit<T>]> }, ), alloc, @@ -1437,7 +1441,7 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> { #[stable(feature = "weak_into_raw", since = "1.45.0")] #[rustc_never_returns_null_ptr] pub fn as_ptr(this: &Self) -> *const T { - let ptr: *mut RcBox<T> = NonNull::as_ptr(this.ptr); + let ptr: *mut RcInner<T> = NonNull::as_ptr(this.ptr); // SAFETY: This cannot go through Deref::deref or Rc::inner because // this is required to retain raw/mut provenance such that e.g. `get_mut` can @@ -1516,8 +1520,8 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> { pub unsafe fn from_raw_in(ptr: *const T, alloc: A) -> Self { let offset = unsafe { data_offset(ptr) }; - // Reverse the offset to find the original RcBox. - let rc_ptr = unsafe { ptr.byte_sub(offset) as *mut RcBox<T> }; + // Reverse the offset to find the original RcInner. + let rc_ptr = unsafe { ptr.byte_sub(offset) as *mut RcInner<T> }; unsafe { Self::from_ptr_in(rc_ptr, alloc) } } @@ -2002,43 +2006,43 @@ impl<A: Allocator> Rc<dyn Any, A> { } impl<T: ?Sized> Rc<T> { - /// Allocates an `RcBox<T>` with sufficient space for + /// Allocates an `RcInner<T>` with sufficient space for /// a possibly-unsized inner value where the value has the layout provided. /// - /// The function `mem_to_rcbox` is called with the data pointer - /// and must return back a (potentially fat)-pointer for the `RcBox<T>`. + /// The function `mem_to_rc_inner` is called with the data pointer + /// and must return back a (potentially fat)-pointer for the `RcInner<T>`. #[cfg(not(no_global_oom_handling))] unsafe fn allocate_for_layout( value_layout: Layout, allocate: impl FnOnce(Layout) -> Result<NonNull<[u8]>, AllocError>, - mem_to_rcbox: impl FnOnce(*mut u8) -> *mut RcBox<T>, - ) -> *mut RcBox<T> { - let layout = rcbox_layout_for_value_layout(value_layout); + mem_to_rc_inner: impl FnOnce(*mut u8) -> *mut RcInner<T>, + ) -> *mut RcInner<T> { + let layout = rc_inner_layout_for_value_layout(value_layout); unsafe { - Rc::try_allocate_for_layout(value_layout, allocate, mem_to_rcbox) + Rc::try_allocate_for_layout(value_layout, allocate, mem_to_rc_inner) .unwrap_or_else(|_| handle_alloc_error(layout)) } } - /// Allocates an `RcBox<T>` with sufficient space for + /// Allocates an `RcInner<T>` with sufficient space for /// a possibly-unsized inner value where the value has the layout provided, /// returning an error if allocation fails. /// - /// The function `mem_to_rcbox` is called with the data pointer - /// and must return back a (potentially fat)-pointer for the `RcBox<T>`. + /// The function `mem_to_rc_inner` is called with the data pointer + /// and must return back a (potentially fat)-pointer for the `RcInner<T>`. #[inline] unsafe fn try_allocate_for_layout( value_layout: Layout, allocate: impl FnOnce(Layout) -> Result<NonNull<[u8]>, AllocError>, - mem_to_rcbox: impl FnOnce(*mut u8) -> *mut RcBox<T>, - ) -> Result<*mut RcBox<T>, AllocError> { - let layout = rcbox_layout_for_value_layout(value_layout); + mem_to_rc_inner: impl FnOnce(*mut u8) -> *mut RcInner<T>, + ) -> Result<*mut RcInner<T>, AllocError> { + let layout = rc_inner_layout_for_value_layout(value_layout); // Allocate for the layout. let ptr = allocate(layout)?; - // Initialize the RcBox - let inner = mem_to_rcbox(ptr.as_non_null_ptr().as_ptr()); + // Initialize the RcInner + let inner = mem_to_rc_inner(ptr.as_non_null_ptr().as_ptr()); unsafe { debug_assert_eq!(Layout::for_value_raw(inner), layout); @@ -2051,15 +2055,15 @@ impl<T: ?Sized> Rc<T> { } impl<T: ?Sized, A: Allocator> Rc<T, A> { - /// Allocates an `RcBox<T>` with sufficient space for an unsized inner value + /// Allocates an `RcInner<T>` with sufficient space for an unsized inner value #[cfg(not(no_global_oom_handling))] - unsafe fn allocate_for_ptr_in(ptr: *const T, alloc: &A) -> *mut RcBox<T> { - // Allocate for the `RcBox<T>` using the given value. + unsafe fn allocate_for_ptr_in(ptr: *const T, alloc: &A) -> *mut RcInner<T> { + // Allocate for the `RcInner<T>` using the given value. unsafe { Rc::<T>::allocate_for_layout( Layout::for_value_raw(ptr), |layout| alloc.allocate(layout), - |mem| mem.with_metadata_of(ptr as *const RcBox<T>), + |mem| mem.with_metadata_of(ptr as *const RcInner<T>), ) } } @@ -2088,14 +2092,14 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> { } impl<T> Rc<[T]> { - /// Allocates an `RcBox<[T]>` with the given length. + /// Allocates an `RcInner<[T]>` with the given length. #[cfg(not(no_global_oom_handling))] - unsafe fn allocate_for_slice(len: usize) -> *mut RcBox<[T]> { + unsafe fn allocate_for_slice(len: usize) -> *mut RcInner<[T]> { unsafe { Self::allocate_for_layout( Layout::array::<T>(len).unwrap(), |layout| Global.allocate(layout), - |mem| ptr::slice_from_raw_parts_mut(mem.cast::<T>(), len) as *mut RcBox<[T]>, + |mem| ptr::slice_from_raw_parts_mut(mem.cast::<T>(), len) as *mut RcInner<[T]>, ) } } @@ -2119,7 +2123,7 @@ impl<T> Rc<[T]> { unsafe fn from_iter_exact(iter: impl Iterator<Item = T>, len: usize) -> Rc<[T]> { // Panic guard while cloning T elements. // In the event of a panic, elements that have been written - // into the new RcBox will be dropped, then the memory freed. + // into the new RcInner will be dropped, then the memory freed. struct Guard<T> { mem: NonNull<u8>, elems: *mut T, @@ -2154,7 +2158,7 @@ impl<T> Rc<[T]> { guard.n_elems += 1; } - // All clear. Forget the guard so it doesn't free the new RcBox. + // All clear. Forget the guard so it doesn't free the new RcInner. mem::forget(guard); Self::from_ptr(ptr) @@ -2163,15 +2167,15 @@ impl<T> Rc<[T]> { } impl<T, A: Allocator> Rc<[T], A> { - /// Allocates an `RcBox<[T]>` with the given length. + /// Allocates an `RcInner<[T]>` with the given length. #[inline] #[cfg(not(no_global_oom_handling))] - unsafe fn allocate_for_slice_in(len: usize, alloc: &A) -> *mut RcBox<[T]> { + unsafe fn allocate_for_slice_in(len: usize, alloc: &A) -> *mut RcInner<[T]> { unsafe { Rc::<[T]>::allocate_for_layout( Layout::array::<T>(len).unwrap(), |layout| alloc.allocate(layout), - |mem| ptr::slice_from_raw_parts_mut(mem.cast::<T>(), len) as *mut RcBox<[T]>, + |mem| ptr::slice_from_raw_parts_mut(mem.cast::<T>(), len) as *mut RcInner<[T]>, ) } } @@ -2901,9 +2905,9 @@ pub struct Weak< // but it is not necessarily a valid pointer. // `Weak::new` sets this to `usize::MAX` so that it doesn’t need // to allocate space on the heap. That's not a value a real pointer - // will ever have because RcBox has alignment at least 2. + // will ever have because RcInner has alignment at least 2. // This is only possible when `T: Sized`; unsized `T` never dangle. - ptr: NonNull<RcBox<T>>, + ptr: NonNull<RcInner<T>>, alloc: A, } @@ -2939,7 +2943,7 @@ impl<T> Weak<T> { pub const fn new() -> Weak<T> { Weak { ptr: unsafe { - NonNull::new_unchecked(ptr::without_provenance_mut::<RcBox<T>>(usize::MAX)) + NonNull::new_unchecked(ptr::without_provenance_mut::<RcInner<T>>(usize::MAX)) }, alloc: Global, } @@ -2966,7 +2970,7 @@ impl<T, A: Allocator> Weak<T, A> { pub fn new_in(alloc: A) -> Weak<T, A> { Weak { ptr: unsafe { - NonNull::new_unchecked(ptr::without_provenance_mut::<RcBox<T>>(usize::MAX)) + NonNull::new_unchecked(ptr::without_provenance_mut::<RcInner<T>>(usize::MAX)) }, alloc, } @@ -3070,11 +3074,11 @@ impl<T: ?Sized, A: Allocator> Weak<T, A> { #[must_use] #[stable(feature = "rc_as_ptr", since = "1.45.0")] pub fn as_ptr(&self) -> *const T { - let ptr: *mut RcBox<T> = NonNull::as_ptr(self.ptr); + let ptr: *mut RcInner<T> = NonNull::as_ptr(self.ptr); if is_dangling(ptr) { // If the pointer is dangling, we return the sentinel directly. This cannot be - // a valid payload address, as the payload is at least as aligned as RcBox (usize). + // a valid payload address, as the payload is at least as aligned as RcInner (usize). ptr as *const T } else { // SAFETY: if is_dangling returns false, then the pointer is dereferenceable. @@ -3206,14 +3210,14 @@ impl<T: ?Sized, A: Allocator> Weak<T, A> { let ptr = if is_dangling(ptr) { // This is a dangling Weak. - ptr as *mut RcBox<T> + ptr as *mut RcInner<T> } else { // Otherwise, we're guaranteed the pointer came from a nondangling Weak. // SAFETY: data_offset is safe to call, as ptr references a real (potentially dropped) T. let offset = unsafe { data_offset(ptr) }; - // Thus, we reverse the offset to get the whole RcBox. + // Thus, we reverse the offset to get the whole RcInner. // SAFETY: the pointer originated from a Weak, so this offset is safe. - unsafe { ptr.byte_sub(offset) as *mut RcBox<T> } + unsafe { ptr.byte_sub(offset) as *mut RcInner<T> } }; // SAFETY: we now have recovered the original Weak pointer, so can create the Weak. @@ -3288,7 +3292,7 @@ impl<T: ?Sized, A: Allocator> Weak<T, A> { } } - /// Returns `None` when the pointer is dangling and there is no allocated `RcBox`, + /// Returns `None` when the pointer is dangling and there is no allocated `RcInner`, /// (i.e., when this `Weak` was created by `Weak::new`). #[inline] fn inner(&self) -> Option<WeakInner<'_>> { @@ -3522,7 +3526,7 @@ trait RcInnerPtr { } } -impl<T: ?Sized> RcInnerPtr for RcBox<T> { +impl<T: ?Sized> RcInnerPtr for RcInner<T> { #[inline(always)] fn weak_ref(&self) -> &Cell<usize> { &self.weak @@ -3563,15 +3567,15 @@ impl<T: ?Sized, A: Allocator> AsRef<T> for Rc<T, A> { #[stable(feature = "pin", since = "1.33.0")] impl<T: ?Sized, A: Allocator> Unpin for Rc<T, A> {} -/// Gets the offset within an `RcBox` for the payload behind a pointer. +/// Gets the offset within an `RcInner` for the payload behind a pointer. /// /// # Safety /// /// The pointer must point to (and have valid metadata for) a previously /// valid instance of T, but the T is allowed to be dropped. unsafe fn data_offset<T: ?Sized>(ptr: *const T) -> usize { - // Align the unsized value to the end of the RcBox. - // Because RcBox is repr(C), it will always be the last field in memory. + // Align the unsized value to the end of the RcInner. + // Because RcInner is repr(C), it will always be the last field in memory. // SAFETY: since the only unsized types possible are slices, trait objects, // and extern types, the input safety requirement is currently enough to // satisfy the requirements of align_of_val_raw; this is an implementation @@ -3581,7 +3585,7 @@ unsafe fn data_offset<T: ?Sized>(ptr: *const T) -> usize { #[inline] fn data_offset_align(align: usize) -> usize { - let layout = Layout::new::<RcBox<()>>(); + let layout = Layout::new::<RcInner<()>>(); layout.size() + layout.padding_needed_for(align) } @@ -3627,8 +3631,8 @@ pub struct UniqueRc< T: ?Sized, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global, > { - ptr: NonNull<RcBox<T>>, - phantom: PhantomData<RcBox<T>>, + ptr: NonNull<RcInner<T>>, + phantom: PhantomData<RcInner<T>>, alloc: A, } @@ -3664,7 +3668,7 @@ impl<T, A: Allocator> UniqueRc<T, A> { #[unstable(feature = "unique_rc_arc", issue = "112566")] pub fn new_in(value: T, alloc: A) -> Self { let (ptr, alloc) = Box::into_unique(Box::new_in( - RcBox { + RcInner { strong: Cell::new(0), // keep one weak reference so if all the weak pointers that are created are dropped // the UniqueRc still stays valid. @@ -3759,7 +3763,7 @@ unsafe impl<#[may_dangle] T: ?Sized, A: Allocator> Drop for UniqueRc<T, A> { } } -/// A unique owning pointer to a [`RcBox`] **that does not imply the contents are initialized,** +/// A unique owning pointer to a [`RcInner`] **that does not imply the contents are initialized,** /// but will deallocate it (without dropping the value) when dropped. /// /// This is a helper for [`Rc::make_mut()`] to ensure correct cleanup on panic. @@ -3767,21 +3771,21 @@ unsafe impl<#[may_dangle] T: ?Sized, A: Allocator> Drop for UniqueRc<T, A> { /// which `MaybeUninit` does not. #[cfg(not(no_global_oom_handling))] struct UniqueRcUninit<T: ?Sized, A: Allocator> { - ptr: NonNull<RcBox<T>>, + ptr: NonNull<RcInner<T>>, layout_for_value: Layout, alloc: Option<A>, } #[cfg(not(no_global_oom_handling))] impl<T: ?Sized, A: Allocator> UniqueRcUninit<T, A> { - /// Allocates a RcBox with layout suitable to contain `for_value` or a clone of it. + /// Allocates a RcInner with layout suitable to contain `for_value` or a clone of it. fn new(for_value: &T, alloc: A) -> UniqueRcUninit<T, A> { let layout = Layout::for_value(for_value); let ptr = unsafe { Rc::allocate_for_layout( layout, - |layout_for_rcbox| alloc.allocate(layout_for_rcbox), - |mem| mem.with_metadata_of(ptr::from_ref(for_value) as *const RcBox<T>), + |layout_for_rc_inner| alloc.allocate(layout_for_rc_inner), + |mem| mem.with_metadata_of(ptr::from_ref(for_value) as *const RcInner<T>), ) }; Self { ptr: NonNull::new(ptr).unwrap(), layout_for_value: layout, alloc: Some(alloc) } @@ -3816,10 +3820,10 @@ impl<T: ?Sized, A: Allocator> Drop for UniqueRcUninit<T, A> { // * new() produced a pointer safe to deallocate. // * We own the pointer unless into_rc() was called, which forgets us. unsafe { - self.alloc - .take() - .unwrap() - .deallocate(self.ptr.cast(), rcbox_layout_for_value_layout(self.layout_for_value)); + self.alloc.take().unwrap().deallocate( + self.ptr.cast(), + rc_inner_layout_for_value_layout(self.layout_for_value), + ); } } } |