565 lines
22 KiB
Rust
565 lines
22 KiB
Rust
// SPDX-License-Identifier: Apache-2.0 OR MIT
|
|
|
|
#![unstable(feature = "raw_vec_internals", reason = "unstable const warnings", issue = "none")]
|
|
|
|
use core::alloc::LayoutError;
|
|
use core::cmp;
|
|
use core::intrinsics;
|
|
use core::mem::{self, ManuallyDrop, MaybeUninit, SizedTypeProperties};
|
|
use core::ptr::{self, NonNull, Unique};
|
|
use core::slice;
|
|
|
|
#[cfg(not(no_global_oom_handling))]
|
|
use crate::alloc::handle_alloc_error;
|
|
use crate::alloc::{Allocator, Global, Layout};
|
|
use crate::boxed::Box;
|
|
use crate::collections::TryReserveError;
|
|
use crate::collections::TryReserveErrorKind::*;
|
|
|
|
#[cfg(test)]
|
|
mod tests;
|
|
|
|
enum AllocInit {
|
|
/// The contents of the new memory are uninitialized.
|
|
Uninitialized,
|
|
/// The new memory is guaranteed to be zeroed.
|
|
#[allow(dead_code)]
|
|
Zeroed,
|
|
}
|
|
|
|
/// A low-level utility for more ergonomically allocating, reallocating, and deallocating
|
|
/// a buffer of memory on the heap without having to worry about all the corner cases
|
|
/// involved. This type is excellent for building your own data structures like Vec and VecDeque.
|
|
/// In particular:
|
|
///
|
|
/// * Produces `Unique::dangling()` on zero-sized types.
|
|
/// * Produces `Unique::dangling()` on zero-length allocations.
|
|
/// * Avoids freeing `Unique::dangling()`.
|
|
/// * Catches all overflows in capacity computations (promotes them to "capacity overflow" panics).
|
|
/// * Guards against 32-bit systems allocating more than isize::MAX bytes.
|
|
/// * Guards against overflowing your length.
|
|
/// * Calls `handle_alloc_error` for fallible allocations.
|
|
/// * Contains a `ptr::Unique` and thus endows the user with all related benefits.
|
|
/// * Uses the excess returned from the allocator to use the largest available capacity.
|
|
///
|
|
/// This type does not in anyway inspect the memory that it manages. When dropped it *will*
|
|
/// free its memory, but it *won't* try to drop its contents. It is up to the user of `RawVec`
|
|
/// to handle the actual things *stored* inside of a `RawVec`.
|
|
///
|
|
/// Note that the excess of a zero-sized types is always infinite, so `capacity()` always returns
|
|
/// `usize::MAX`. This means that you need to be careful when round-tripping this type with a
|
|
/// `Box<[T]>`, since `capacity()` won't yield the length.
|
|
#[allow(missing_debug_implementations)]
|
|
pub(crate) struct RawVec<T, A: Allocator = Global> {
|
|
ptr: Unique<T>,
|
|
cap: usize,
|
|
alloc: A,
|
|
}
|
|
|
|
impl<T> RawVec<T, Global> {
|
|
/// HACK(Centril): This exists because stable `const fn` can only call stable `const fn`, so
|
|
/// they cannot call `Self::new()`.
|
|
///
|
|
/// If you change `RawVec<T>::new` or dependencies, please take care to not introduce anything
|
|
/// that would truly const-call something unstable.
|
|
pub const NEW: Self = Self::new();
|
|
|
|
/// Creates the biggest possible `RawVec` (on the system heap)
|
|
/// without allocating. If `T` has positive size, then this makes a
|
|
/// `RawVec` with capacity `0`. If `T` is zero-sized, then it makes a
|
|
/// `RawVec` with capacity `usize::MAX`. Useful for implementing
|
|
/// delayed allocation.
|
|
#[must_use]
|
|
pub const fn new() -> Self {
|
|
Self::new_in(Global)
|
|
}
|
|
|
|
/// Creates a `RawVec` (on the system heap) with exactly the
|
|
/// capacity and alignment requirements for a `[T; capacity]`. This is
|
|
/// equivalent to calling `RawVec::new` when `capacity` is `0` or `T` is
|
|
/// zero-sized. Note that if `T` is zero-sized this means you will
|
|
/// *not* get a `RawVec` with the requested capacity.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Panics if the requested capacity exceeds `isize::MAX` bytes.
|
|
///
|
|
/// # Aborts
|
|
///
|
|
/// Aborts on OOM.
|
|
#[cfg(not(any(no_global_oom_handling, test)))]
|
|
#[must_use]
|
|
#[inline]
|
|
pub fn with_capacity(capacity: usize) -> Self {
|
|
Self::with_capacity_in(capacity, Global)
|
|
}
|
|
|
|
/// Like `with_capacity`, but guarantees the buffer is zeroed.
|
|
#[cfg(not(any(no_global_oom_handling, test)))]
|
|
#[must_use]
|
|
#[inline]
|
|
pub fn with_capacity_zeroed(capacity: usize) -> Self {
|
|
Self::with_capacity_zeroed_in(capacity, Global)
|
|
}
|
|
}
|
|
|
|
impl<T, A: Allocator> RawVec<T, A> {
|
|
// Tiny Vecs are dumb. Skip to:
|
|
// - 8 if the element size is 1, because any heap allocators is likely
|
|
// to round up a request of less than 8 bytes to at least 8 bytes.
|
|
// - 4 if elements are moderate-sized (<= 1 KiB).
|
|
// - 1 otherwise, to avoid wasting too much space for very short Vecs.
|
|
pub(crate) const MIN_NON_ZERO_CAP: usize = if mem::size_of::<T>() == 1 {
|
|
8
|
|
} else if mem::size_of::<T>() <= 1024 {
|
|
4
|
|
} else {
|
|
1
|
|
};
|
|
|
|
/// Like `new`, but parameterized over the choice of allocator for
|
|
/// the returned `RawVec`.
|
|
pub const fn new_in(alloc: A) -> Self {
|
|
// `cap: 0` means "unallocated". zero-sized types are ignored.
|
|
Self { ptr: Unique::dangling(), cap: 0, alloc }
|
|
}
|
|
|
|
/// Like `with_capacity`, but parameterized over the choice of
|
|
/// allocator for the returned `RawVec`.
|
|
#[cfg(not(no_global_oom_handling))]
|
|
#[inline]
|
|
pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
|
|
Self::allocate_in(capacity, AllocInit::Uninitialized, alloc)
|
|
}
|
|
|
|
/// Like `try_with_capacity`, but parameterized over the choice of
|
|
/// allocator for the returned `RawVec`.
|
|
#[inline]
|
|
pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, TryReserveError> {
|
|
Self::try_allocate_in(capacity, AllocInit::Uninitialized, alloc)
|
|
}
|
|
|
|
/// Like `with_capacity_zeroed`, but parameterized over the choice
|
|
/// of allocator for the returned `RawVec`.
|
|
#[cfg(not(no_global_oom_handling))]
|
|
#[inline]
|
|
pub fn with_capacity_zeroed_in(capacity: usize, alloc: A) -> Self {
|
|
Self::allocate_in(capacity, AllocInit::Zeroed, alloc)
|
|
}
|
|
|
|
/// 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>], A> {
|
|
// 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);
|
|
unsafe {
|
|
let slice = slice::from_raw_parts_mut(me.ptr() as *mut MaybeUninit<T>, len);
|
|
Box::from_raw_in(slice, ptr::read(&me.alloc))
|
|
}
|
|
}
|
|
|
|
#[cfg(not(no_global_oom_handling))]
|
|
fn allocate_in(capacity: usize, init: AllocInit, alloc: A) -> Self {
|
|
// Don't allocate here because `Drop` will not deallocate when `capacity` is 0.
|
|
if T::IS_ZST || capacity == 0 {
|
|
Self::new_in(alloc)
|
|
} else {
|
|
// We avoid `unwrap_or_else` here because it bloats the amount of
|
|
// LLVM IR generated.
|
|
let layout = match Layout::array::<T>(capacity) {
|
|
Ok(layout) => layout,
|
|
Err(_) => capacity_overflow(),
|
|
};
|
|
match alloc_guard(layout.size()) {
|
|
Ok(_) => {}
|
|
Err(_) => capacity_overflow(),
|
|
}
|
|
let result = match init {
|
|
AllocInit::Uninitialized => alloc.allocate(layout),
|
|
AllocInit::Zeroed => alloc.allocate_zeroed(layout),
|
|
};
|
|
let ptr = match result {
|
|
Ok(ptr) => ptr,
|
|
Err(_) => handle_alloc_error(layout),
|
|
};
|
|
|
|
// Allocators currently return a `NonNull<[u8]>` whose length
|
|
// matches the size requested. If that ever changes, the capacity
|
|
// here should change to `ptr.len() / mem::size_of::<T>()`.
|
|
Self {
|
|
ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) },
|
|
cap: capacity,
|
|
alloc,
|
|
}
|
|
}
|
|
}
|
|
|
|
fn try_allocate_in(capacity: usize, init: AllocInit, alloc: A) -> Result<Self, TryReserveError> {
|
|
// Don't allocate here because `Drop` will not deallocate when `capacity` is 0.
|
|
if T::IS_ZST || capacity == 0 {
|
|
return Ok(Self::new_in(alloc));
|
|
}
|
|
|
|
let layout = Layout::array::<T>(capacity).map_err(|_| CapacityOverflow)?;
|
|
alloc_guard(layout.size())?;
|
|
let result = match init {
|
|
AllocInit::Uninitialized => alloc.allocate(layout),
|
|
AllocInit::Zeroed => alloc.allocate_zeroed(layout),
|
|
};
|
|
let ptr = result.map_err(|_| AllocError { layout, non_exhaustive: () })?;
|
|
|
|
// Allocators currently return a `NonNull<[u8]>` whose length
|
|
// matches the size requested. If that ever changes, the capacity
|
|
// here should change to `ptr.len() / mem::size_of::<T>()`.
|
|
Ok(Self {
|
|
ptr: unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) },
|
|
cap: capacity,
|
|
alloc,
|
|
})
|
|
}
|
|
|
|
/// Reconstitutes a `RawVec` from a pointer, capacity, and allocator.
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// The `ptr` must be allocated (via the given allocator `alloc`), and with the given
|
|
/// `capacity`.
|
|
/// The `capacity` cannot exceed `isize::MAX` for sized types. (only a concern on 32-bit
|
|
/// systems). ZST vectors may have a capacity up to `usize::MAX`.
|
|
/// If the `ptr` and `capacity` come from a `RawVec` created via `alloc`, then this is
|
|
/// guaranteed.
|
|
#[inline]
|
|
pub unsafe fn from_raw_parts_in(ptr: *mut T, capacity: usize, alloc: A) -> Self {
|
|
Self { ptr: unsafe { Unique::new_unchecked(ptr) }, cap: capacity, alloc }
|
|
}
|
|
|
|
/// Gets a raw pointer to the start of the allocation. Note that this is
|
|
/// `Unique::dangling()` if `capacity == 0` or `T` is zero-sized. In the former case, you must
|
|
/// be careful.
|
|
#[inline]
|
|
pub fn ptr(&self) -> *mut T {
|
|
self.ptr.as_ptr()
|
|
}
|
|
|
|
/// Gets the capacity of the allocation.
|
|
///
|
|
/// This will always be `usize::MAX` if `T` is zero-sized.
|
|
#[inline(always)]
|
|
pub fn capacity(&self) -> usize {
|
|
if T::IS_ZST { usize::MAX } else { self.cap }
|
|
}
|
|
|
|
/// Returns a shared reference to the allocator backing this `RawVec`.
|
|
pub fn allocator(&self) -> &A {
|
|
&self.alloc
|
|
}
|
|
|
|
fn current_memory(&self) -> Option<(NonNull<u8>, Layout)> {
|
|
if T::IS_ZST || self.cap == 0 {
|
|
None
|
|
} else {
|
|
// We could use Layout::array here which ensures the absence of isize and usize overflows
|
|
// and could hypothetically handle differences between stride and size, but this memory
|
|
// has already been allocated so we know it can't overflow and currently rust does not
|
|
// support such types. So we can do better by skipping some checks and avoid an unwrap.
|
|
let _: () = const { assert!(mem::size_of::<T>() % mem::align_of::<T>() == 0) };
|
|
unsafe {
|
|
let align = mem::align_of::<T>();
|
|
let size = mem::size_of::<T>().unchecked_mul(self.cap);
|
|
let layout = Layout::from_size_align_unchecked(size, align);
|
|
Some((self.ptr.cast().into(), layout))
|
|
}
|
|
}
|
|
}
|
|
|
|
/// 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 `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.
|
|
///
|
|
/// This is ideal for implementing a bulk-push operation like `extend`.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Panics if the new capacity exceeds `isize::MAX` bytes.
|
|
///
|
|
/// # Aborts
|
|
///
|
|
/// Aborts on OOM.
|
|
#[cfg(not(no_global_oom_handling))]
|
|
#[inline]
|
|
pub fn reserve(&mut self, len: usize, additional: usize) {
|
|
// Callers expect this function to be very cheap when there is already sufficient capacity.
|
|
// Therefore, we move all the resizing and error-handling logic from grow_amortized and
|
|
// handle_reserve behind a call, while making sure that this function is likely to be
|
|
// inlined as just a comparison and a call if the comparison fails.
|
|
#[cold]
|
|
fn do_reserve_and_handle<T, A: Allocator>(
|
|
slf: &mut RawVec<T, A>,
|
|
len: usize,
|
|
additional: usize,
|
|
) {
|
|
handle_reserve(slf.grow_amortized(len, additional));
|
|
}
|
|
|
|
if self.needs_to_grow(len, additional) {
|
|
do_reserve_and_handle(self, len, additional);
|
|
}
|
|
}
|
|
|
|
/// A specialized version of `reserve()` used only by the hot and
|
|
/// oft-instantiated `Vec::push()`, which does its own capacity check.
|
|
#[cfg(not(no_global_oom_handling))]
|
|
#[inline(never)]
|
|
pub fn reserve_for_push(&mut self, len: usize) {
|
|
handle_reserve(self.grow_amortized(len, 1));
|
|
}
|
|
|
|
/// The same as `reserve`, but returns on errors instead of panicking or aborting.
|
|
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(())
|
|
}
|
|
}
|
|
|
|
/// The same as `reserve_for_push`, but returns on errors instead of panicking or aborting.
|
|
#[inline(never)]
|
|
pub fn try_reserve_for_push(&mut self, len: usize) -> Result<(), TryReserveError> {
|
|
self.grow_amortized(len, 1)
|
|
}
|
|
|
|
/// 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 `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
|
|
///
|
|
/// Panics if the new capacity exceeds `isize::MAX` bytes.
|
|
///
|
|
/// # Aborts
|
|
///
|
|
/// Aborts on OOM.
|
|
#[cfg(not(no_global_oom_handling))]
|
|
pub fn reserve_exact(&mut self, len: usize, additional: usize) {
|
|
handle_reserve(self.try_reserve_exact(len, additional));
|
|
}
|
|
|
|
/// The same as `reserve_exact`, but returns on errors instead of panicking or aborting.
|
|
pub fn try_reserve_exact(
|
|
&mut self,
|
|
len: usize,
|
|
additional: usize,
|
|
) -> Result<(), TryReserveError> {
|
|
if self.needs_to_grow(len, additional) { self.grow_exact(len, additional) } else { Ok(()) }
|
|
}
|
|
|
|
/// Shrinks the buffer down to the specified capacity. If the given amount
|
|
/// is 0, actually completely deallocates.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Panics if the given amount is *larger* than the current capacity.
|
|
///
|
|
/// # Aborts
|
|
///
|
|
/// Aborts on OOM.
|
|
#[cfg(not(no_global_oom_handling))]
|
|
pub fn shrink_to_fit(&mut self, cap: usize) {
|
|
handle_reserve(self.shrink(cap));
|
|
}
|
|
}
|
|
|
|
impl<T, A: Allocator> 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, len: usize, additional: usize) -> bool {
|
|
additional > self.capacity().wrapping_sub(len)
|
|
}
|
|
|
|
fn set_ptr_and_cap(&mut self, ptr: NonNull<[u8]>, cap: usize) {
|
|
// Allocators currently return a `NonNull<[u8]>` whose length matches
|
|
// the size requested. If that ever changes, the capacity here should
|
|
// change to `ptr.len() / mem::size_of::<T>()`.
|
|
self.ptr = unsafe { Unique::new_unchecked(ptr.cast().as_ptr()) };
|
|
self.cap = cap;
|
|
}
|
|
|
|
// This method is usually instantiated many times. So we want it to be as
|
|
// small as possible, to improve compile times. But we also want as much of
|
|
// its contents to be statically computable as possible, to make the
|
|
// generated code run faster. Therefore, this method is carefully written
|
|
// 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, len: usize, additional: usize) -> Result<(), TryReserveError> {
|
|
// This is ensured by the calling contexts.
|
|
debug_assert!(additional > 0);
|
|
|
|
if T::IS_ZST {
|
|
// Since we return a capacity of `usize::MAX` when `elem_size` is
|
|
// 0, getting to here necessarily means the `RawVec` is overfull.
|
|
return Err(CapacityOverflow.into());
|
|
}
|
|
|
|
// Nothing we can really do about these checks, sadly.
|
|
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`.
|
|
let cap = cmp::max(self.cap * 2, required_cap);
|
|
let cap = cmp::max(Self::MIN_NON_ZERO_CAP, cap);
|
|
|
|
let new_layout = Layout::array::<T>(cap);
|
|
|
|
// `finish_grow` is non-generic over `T`.
|
|
let ptr = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
|
|
self.set_ptr_and_cap(ptr, cap);
|
|
Ok(())
|
|
}
|
|
|
|
// 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, len: usize, additional: usize) -> Result<(), TryReserveError> {
|
|
if T::IS_ZST {
|
|
// 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.into());
|
|
}
|
|
|
|
let cap = len.checked_add(additional).ok_or(CapacityOverflow)?;
|
|
let new_layout = Layout::array::<T>(cap);
|
|
|
|
// `finish_grow` is non-generic over `T`.
|
|
let ptr = finish_grow(new_layout, self.current_memory(), &mut self.alloc)?;
|
|
self.set_ptr_and_cap(ptr, cap);
|
|
Ok(())
|
|
}
|
|
|
|
#[cfg(not(no_global_oom_handling))]
|
|
fn shrink(&mut self, cap: usize) -> Result<(), TryReserveError> {
|
|
assert!(cap <= self.capacity(), "Tried to shrink to a larger capacity");
|
|
|
|
let (ptr, layout) = if let Some(mem) = self.current_memory() { mem } else { return Ok(()) };
|
|
// See current_memory() why this assert is here
|
|
let _: () = const { assert!(mem::size_of::<T>() % mem::align_of::<T>() == 0) };
|
|
let ptr = unsafe {
|
|
// `Layout::array` cannot overflow here because it would have
|
|
// overflowed earlier when capacity was larger.
|
|
let new_size = mem::size_of::<T>().unchecked_mul(cap);
|
|
let new_layout = Layout::from_size_align_unchecked(new_size, layout.align());
|
|
self.alloc
|
|
.shrink(ptr, layout, new_layout)
|
|
.map_err(|_| AllocError { layout: new_layout, non_exhaustive: () })?
|
|
};
|
|
self.set_ptr_and_cap(ptr, cap);
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
// This function is outside `RawVec` to minimize compile times. See the comment
|
|
// above `RawVec::grow_amortized` for details. (The `A` parameter isn't
|
|
// significant, because the number of different `A` types seen in practice is
|
|
// much smaller than the number of `T` types.)
|
|
#[inline(never)]
|
|
fn finish_grow<A>(
|
|
new_layout: Result<Layout, LayoutError>,
|
|
current_memory: Option<(NonNull<u8>, Layout)>,
|
|
alloc: &mut A,
|
|
) -> Result<NonNull<[u8]>, TryReserveError>
|
|
where
|
|
A: Allocator,
|
|
{
|
|
// Check for the error here to minimize the size of `RawVec::grow_*`.
|
|
let new_layout = new_layout.map_err(|_| CapacityOverflow)?;
|
|
|
|
alloc_guard(new_layout.size())?;
|
|
|
|
let memory = if let Some((ptr, old_layout)) = current_memory {
|
|
debug_assert_eq!(old_layout.align(), new_layout.align());
|
|
unsafe {
|
|
// The allocator checks for alignment equality
|
|
intrinsics::assume(old_layout.align() == new_layout.align());
|
|
alloc.grow(ptr, old_layout, new_layout)
|
|
}
|
|
} else {
|
|
alloc.allocate(new_layout)
|
|
};
|
|
|
|
memory.map_err(|_| AllocError { layout: new_layout, non_exhaustive: () }.into())
|
|
}
|
|
|
|
unsafe impl<#[may_dangle] T, A: Allocator> Drop for RawVec<T, A> {
|
|
/// Frees the memory owned by the `RawVec` *without* trying to drop its contents.
|
|
fn drop(&mut self) {
|
|
if let Some((ptr, layout)) = self.current_memory() {
|
|
unsafe { self.alloc.deallocate(ptr, layout) }
|
|
}
|
|
}
|
|
}
|
|
|
|
// Central function for reserve error handling.
|
|
#[cfg(not(no_global_oom_handling))]
|
|
#[inline]
|
|
fn handle_reserve(result: Result<(), TryReserveError>) {
|
|
match result.map_err(|e| e.kind()) {
|
|
Err(CapacityOverflow) => capacity_overflow(),
|
|
Err(AllocError { layout, .. }) => handle_alloc_error(layout),
|
|
Ok(()) => { /* yay */ }
|
|
}
|
|
}
|
|
|
|
// We need to guarantee the following:
|
|
// * We don't ever allocate `> isize::MAX` byte-size objects.
|
|
// * We don't overflow `usize::MAX` and actually allocate too little.
|
|
//
|
|
// On 64-bit we just need to check for overflow since trying to allocate
|
|
// `> isize::MAX` bytes will surely fail. On 32-bit and 16-bit we need to add
|
|
// an extra guard for this in case we're running on a platform which can use
|
|
// all 4GB in user-space, e.g., PAE or x32.
|
|
|
|
#[inline]
|
|
fn alloc_guard(alloc_size: usize) -> Result<(), TryReserveError> {
|
|
if usize::BITS < 64 && alloc_size > isize::MAX as usize {
|
|
Err(CapacityOverflow.into())
|
|
} else {
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
// One central function responsible for reporting capacity overflows. This'll
|
|
// ensure that the code generation related to these panics is minimal as there's
|
|
// only one location which panics rather than a bunch throughout the module.
|
|
#[cfg(not(no_global_oom_handling))]
|
|
fn capacity_overflow() -> ! {
|
|
panic!("capacity overflow");
|
|
}
|