diff options
Diffstat (limited to 'src/liballoc/raw_vec.rs')
| -rw-r--r-- | src/liballoc/raw_vec.rs | 172 |
1 files changed, 60 insertions, 112 deletions
diff --git a/src/liballoc/raw_vec.rs b/src/liballoc/raw_vec.rs index 56e284a12fa..805dbfe2775 100644 --- a/src/liballoc/raw_vec.rs +++ b/src/liballoc/raw_vec.rs @@ -9,7 +9,7 @@ use core::ptr::{NonNull, Unique}; use core::slice; use crate::alloc::{ - handle_alloc_error, AllocErr, + handle_alloc_error, AllocInit::{self, *}, AllocRef, Global, Layout, ReallocPlacement::{self, *}, @@ -118,6 +118,30 @@ impl<T> RawVec<T, Global> { RawVec::from_raw_parts(slice.as_mut_ptr(), slice.len()) } } + + /// Converts the entire buffer into `Box<[MaybeUninit<T>]>` with the specified `len`. + /// + /// Note that this will correctly reconstitute any `cap` changes + /// that may have been performed. (See description of type for details.) + /// + /// # Safety + /// + /// * `len` must be greater than or equal to the most recently requested capacity, and + /// * `len` must be less than or equal to `self.capacity()`. + /// + /// Note, that the requested capacity and `self.capacity()` could differ, as + /// an allocator could overallocate and return a greater memory block than requested. + pub unsafe fn into_box(self, len: usize) -> Box<[MaybeUninit<T>]> { + // Sanity-check one half of the safety requirement (we cannot check the other half). + debug_assert!( + len <= self.capacity(), + "`len` must be smaller than or equal to `self.capacity()`" + ); + + let me = ManuallyDrop::new(self); + let slice = slice::from_raw_parts_mut(me.ptr() as *mut MaybeUninit<T>, len); + Box::from_raw(slice) + } } impl<T, A: AllocRef> RawVec<T, A> { @@ -211,13 +235,13 @@ impl<T, A: AllocRef> RawVec<T, A> { } } - /// Ensures that the buffer contains at least enough space to hold - /// `used_capacity + needed_extra_capacity` elements. If it doesn't already have - /// enough capacity, will reallocate enough space plus comfortable slack - /// space to get amortized `O(1)` behavior. Will limit this behavior - /// if it would needlessly cause itself to panic. + /// Ensures that the buffer contains at least enough space to hold `len + + /// additional` elements. If it doesn't already have enough capacity, will + /// reallocate enough space plus comfortable slack space to get amortized + /// `O(1)` behavior. Will limit this behavior if it would needlessly cause + /// itself to panic. /// - /// If `used_capacity` exceeds `self.capacity()`, this may fail to actually allocate + /// If `len` exceeds `self.capacity()`, this may fail to actually allocate /// the requested space. This is not really unsafe, but the unsafe /// code *you* write that relies on the behavior of this function may break. /// @@ -263,8 +287,8 @@ impl<T, A: AllocRef> RawVec<T, A> { /// # vector.push_all(&[1, 3, 5, 7, 9]); /// # } /// ``` - pub fn reserve(&mut self, used_capacity: usize, needed_extra_capacity: usize) { - match self.try_reserve(used_capacity, needed_extra_capacity) { + pub fn reserve(&mut self, len: usize, additional: usize) { + match self.try_reserve(len, additional) { Err(CapacityOverflow) => capacity_overflow(), Err(AllocError { layout, .. }) => handle_alloc_error(layout), Ok(()) => { /* yay */ } @@ -272,55 +296,23 @@ impl<T, A: AllocRef> RawVec<T, A> { } /// The same as `reserve`, but returns on errors instead of panicking or aborting. - pub fn try_reserve( - &mut self, - used_capacity: usize, - needed_extra_capacity: usize, - ) -> Result<(), TryReserveError> { - if self.needs_to_grow(used_capacity, needed_extra_capacity) { - self.grow_amortized(used_capacity, needed_extra_capacity, MayMove) + pub fn try_reserve(&mut self, len: usize, additional: usize) -> Result<(), TryReserveError> { + if self.needs_to_grow(len, additional) { + self.grow_amortized(len, additional) } else { Ok(()) } } - /// Attempts to ensure that the buffer contains at least enough space to hold - /// `used_capacity + needed_extra_capacity` elements. If it doesn't already have - /// enough capacity, will reallocate in place enough space plus comfortable slack - /// space to get amortized `O(1)` behavior. Will limit this behaviour - /// if it would needlessly cause itself to panic. + /// Ensures that the buffer contains at least enough space to hold `len + + /// additional` elements. If it doesn't already, will reallocate the + /// minimum possible amount of memory necessary. Generally this will be + /// exactly the amount of memory necessary, but in principle the allocator + /// is free to give back more than we asked for. /// - /// If `used_capacity` exceeds `self.capacity()`, this may fail to actually allocate - /// the requested space. This is not really unsafe, but the unsafe - /// code *you* write that relies on the behavior of this function may break. - /// - /// Returns `true` if the reallocation attempt has succeeded. - /// - /// # Panics - /// - /// * Panics if the requested capacity exceeds `usize::MAX` bytes. - /// * Panics on 32-bit platforms if the requested capacity exceeds - /// `isize::MAX` bytes. - pub fn reserve_in_place(&mut self, used_capacity: usize, needed_extra_capacity: usize) -> bool { - // This is more readable than putting this in one line: - // `!self.needs_to_grow(...) || self.grow(...).is_ok()` - if self.needs_to_grow(used_capacity, needed_extra_capacity) { - self.grow_amortized(used_capacity, needed_extra_capacity, InPlace).is_ok() - } else { - true - } - } - - /// Ensures that the buffer contains at least enough space to hold - /// `used_capacity + needed_extra_capacity` elements. If it doesn't already, - /// will reallocate the minimum possible amount of memory necessary. - /// Generally this will be exactly the amount of memory necessary, - /// but in principle the allocator is free to give back more than what - /// we asked for. - /// - /// If `used_capacity` exceeds `self.capacity()`, this may fail to actually allocate - /// the requested space. This is not really unsafe, but the unsafe - /// code *you* write that relies on the behavior of this function may break. + /// If `len` exceeds `self.capacity()`, this may fail to actually allocate + /// the requested space. This is not really unsafe, but the unsafe code + /// *you* write that relies on the behavior of this function may break. /// /// # Panics /// @@ -331,8 +323,8 @@ impl<T, A: AllocRef> RawVec<T, A> { /// # Aborts /// /// Aborts on OOM. - pub fn reserve_exact(&mut self, used_capacity: usize, needed_extra_capacity: usize) { - match self.try_reserve_exact(used_capacity, needed_extra_capacity) { + pub fn reserve_exact(&mut self, len: usize, additional: usize) { + match self.try_reserve_exact(len, additional) { Err(CapacityOverflow) => capacity_overflow(), Err(AllocError { layout, .. }) => handle_alloc_error(layout), Ok(()) => { /* yay */ } @@ -342,14 +334,10 @@ impl<T, A: AllocRef> RawVec<T, A> { /// The same as `reserve_exact`, but returns on errors instead of panicking or aborting. pub fn try_reserve_exact( &mut self, - used_capacity: usize, - needed_extra_capacity: usize, + len: usize, + additional: usize, ) -> Result<(), TryReserveError> { - if self.needs_to_grow(used_capacity, needed_extra_capacity) { - self.grow_exact(used_capacity, needed_extra_capacity) - } else { - Ok(()) - } + if self.needs_to_grow(len, additional) { self.grow_exact(len, additional) } else { Ok(()) } } /// Shrinks the allocation down to the specified amount. If the given amount @@ -374,8 +362,8 @@ impl<T, A: AllocRef> RawVec<T, A> { impl<T, A: AllocRef> RawVec<T, A> { /// Returns if the buffer needs to grow to fulfill the needed extra capacity. /// Mainly used to make inlining reserve-calls possible without inlining `grow`. - fn needs_to_grow(&self, used_capacity: usize, needed_extra_capacity: usize) -> bool { - needed_extra_capacity > self.capacity().wrapping_sub(used_capacity) + fn needs_to_grow(&self, len: usize, additional: usize) -> bool { + additional > self.capacity().wrapping_sub(len) } fn capacity_from_bytes(excess: usize) -> usize { @@ -395,14 +383,9 @@ impl<T, A: AllocRef> RawVec<T, A> { // so that all of the code that depends on `T` is within it, while as much // of the code that doesn't depend on `T` as possible is in functions that // are non-generic over `T`. - fn grow_amortized( - &mut self, - used_capacity: usize, - needed_extra_capacity: usize, - placement: ReallocPlacement, - ) -> Result<(), TryReserveError> { + fn grow_amortized(&mut self, len: usize, additional: usize) -> Result<(), TryReserveError> { // This is ensured by the calling contexts. - debug_assert!(needed_extra_capacity > 0); + debug_assert!(additional > 0); if mem::size_of::<T>() == 0 { // Since we return a capacity of `usize::MAX` when `elem_size` is @@ -411,8 +394,7 @@ impl<T, A: AllocRef> RawVec<T, A> { } // Nothing we can really do about these checks, sadly. - let required_cap = - used_capacity.checked_add(needed_extra_capacity).ok_or(CapacityOverflow)?; + let required_cap = len.checked_add(additional).ok_or(CapacityOverflow)?; // This guarantees exponential growth. The doubling cannot overflow // because `cap <= isize::MAX` and the type of `cap` is `usize`. @@ -437,7 +419,7 @@ impl<T, A: AllocRef> RawVec<T, A> { let new_layout = Layout::array::<T>(cap); // `finish_grow` is non-generic over `T`. - let memory = finish_grow(new_layout, placement, self.current_memory(), &mut self.alloc)?; + let memory = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?; self.set_memory(memory); Ok(()) } @@ -445,22 +427,18 @@ impl<T, A: AllocRef> RawVec<T, A> { // The constraints on this method are much the same as those on // `grow_amortized`, but this method is usually instantiated less often so // it's less critical. - fn grow_exact( - &mut self, - used_capacity: usize, - needed_extra_capacity: usize, - ) -> Result<(), TryReserveError> { + fn grow_exact(&mut self, len: usize, additional: usize) -> Result<(), TryReserveError> { if mem::size_of::<T>() == 0 { // Since we return a capacity of `usize::MAX` when the type size is // 0, getting to here necessarily means the `RawVec` is overfull. return Err(CapacityOverflow); } - let cap = used_capacity.checked_add(needed_extra_capacity).ok_or(CapacityOverflow)?; + let cap = len.checked_add(additional).ok_or(CapacityOverflow)?; let new_layout = Layout::array::<T>(cap); // `finish_grow` is non-generic over `T`. - let memory = finish_grow(new_layout, MayMove, self.current_memory(), &mut self.alloc)?; + let memory = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?; self.set_memory(memory); Ok(()) } @@ -494,7 +472,6 @@ impl<T, A: AllocRef> RawVec<T, A> { // much smaller than the number of `T` types.) fn finish_grow<A>( new_layout: Result<Layout, LayoutErr>, - placement: ReallocPlacement, current_memory: Option<(NonNull<u8>, Layout)>, alloc: &mut A, ) -> Result<MemoryBlock, TryReserveError> @@ -508,44 +485,15 @@ where let memory = if let Some((ptr, old_layout)) = current_memory { debug_assert_eq!(old_layout.align(), new_layout.align()); - unsafe { alloc.grow(ptr, old_layout, new_layout.size(), placement, Uninitialized) } + unsafe { alloc.grow(ptr, old_layout, new_layout.size(), MayMove, Uninitialized) } } else { - match placement { - MayMove => alloc.alloc(new_layout, Uninitialized), - InPlace => Err(AllocErr), - } + alloc.alloc(new_layout, Uninitialized) } .map_err(|_| AllocError { layout: new_layout, non_exhaustive: () })?; Ok(memory) } -impl<T> RawVec<T, Global> { - /// Converts the entire buffer into `Box<[MaybeUninit<T>]>` with the specified `len`. - /// - /// Note that this will correctly reconstitute any `cap` changes - /// that may have been performed. (See description of type for details.) - /// - /// # Safety - /// - /// * `len` must be greater than or equal to the most recently requested capacity, and - /// * `len` must be less than or equal to `self.capacity()`. - /// - /// Note, that the requested capacity and `self.capacity()` could differ, as - /// an allocator could overallocate and return a greater memory block than requested. - pub unsafe fn into_box(self, len: usize) -> Box<[MaybeUninit<T>]> { - // Sanity-check one half of the safety requirement (we cannot check the other half). - debug_assert!( - len <= self.capacity(), - "`len` must be smaller than or equal to `self.capacity()`" - ); - - let me = ManuallyDrop::new(self); - let slice = slice::from_raw_parts_mut(me.ptr() as *mut MaybeUninit<T>, len); - Box::from_raw(slice) - } -} - unsafe impl<#[may_dangle] T, A: AllocRef> Drop for RawVec<T, A> { /// Frees the memory owned by the `RawVec` *without* trying to drop its contents. fn drop(&mut self) { |