-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
+#![unstable(feature = "raw_vec_internals", reason = "implementation detail", issue = "0")]
+#![doc(hidden)]
-use core::ptr::Unique;
+use core::cmp;
use core::mem;
-use core::slice;
-use heap;
-use super::oom;
-use super::boxed::Box;
use core::ops::Drop;
-use core::cmp;
+use core::ptr::{self, NonNull, Unique};
+use core::slice;
+
+use crate::alloc::{Alloc, Layout, Global, handle_alloc_error};
+use crate::collections::CollectionAllocErr::{self, *};
+use crate::boxed::Box;
/// 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 heap::EMPTY on zero-sized types
-/// * Produces heap::EMPTY on zero-length allocations
+/// * Produces Unique::empty() on zero-sized types
+/// * Produces Unique::empty() on zero-length allocations
/// * 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
-/// * Aborts on OOM
-/// * Avoids freeing heap::EMPTY
+/// * Aborts on OOM or calls handle_alloc_error as applicable
+/// * Avoids freeing Unique::empty()
/// * Contains a ptr::Unique and thus endows the user with all related benefits
///
/// This type does not in anyway inspect the memory that it manages. When dropped it *will*
/// This enables you to use capacity growing logic catch the overflows in your length
/// that might occur with zero-sized types.
///
-/// However this means that you need to be careful when roundtripping this type
+/// However this means that you need to be careful when round-tripping this type
/// with a `Box<[T]>`: `cap()` won't yield the len. However `with_capacity`,
/// `shrink_to_fit`, and `from_box` will actually set RawVec's private capacity
/// field. This allows zero-sized types to not be special-cased by consumers of
/// this type.
-#[cfg_attr(stage0, unsafe_no_drop_flag)]
-pub struct RawVec<T> {
+#[allow(missing_debug_implementations)]
+pub struct RawVec<T, A: Alloc = Global> {
ptr: Unique<T>,
cap: usize,
+ a: A,
}
-impl<T> RawVec<T> {
- /// Creates the biggest possible RawVec without allocating. If T has positive
- /// size, then this makes a RawVec with capacity 0. If T has 0 size, then it
- /// it makes a RawVec with capacity `usize::MAX`. Useful for implementing
- /// delayed allocation.
- pub fn new() -> Self {
+impl<T, A: Alloc> RawVec<T, A> {
+ /// Like `new` but parameterized over the choice of allocator for
+ /// the returned RawVec.
+ pub const fn new_in(a: A) -> Self {
+ // !0 is usize::MAX. This branch should be stripped at compile time.
+ // FIXME(mark-i-m): use this line when `if`s are allowed in `const`
+ //let cap = if mem::size_of::<T>() == 0 { !0 } else { 0 };
+
+ // Unique::empty() doubles as "unallocated" and "zero-sized allocation"
+ RawVec {
+ ptr: Unique::empty(),
+ // FIXME(mark-i-m): use `cap` when ifs are allowed in const
+ cap: [0, !0][(mem::size_of::<T>() == 0) as usize],
+ a,
+ }
+ }
+
+ /// Like `with_capacity` but parameterized over the choice of
+ /// allocator for the returned RawVec.
+ #[inline]
+ pub fn with_capacity_in(cap: usize, a: A) -> Self {
+ RawVec::allocate_in(cap, false, a)
+ }
+
+ /// Like `with_capacity_zeroed` but parameterized over the choice
+ /// of allocator for the returned RawVec.
+ #[inline]
+ pub fn with_capacity_zeroed_in(cap: usize, a: A) -> Self {
+ RawVec::allocate_in(cap, true, a)
+ }
+
+ fn allocate_in(cap: usize, zeroed: bool, mut a: A) -> Self {
unsafe {
- // !0 is usize::MAX. This branch should be stripped at compile time.
- let cap = if mem::size_of::<T>() == 0 {
- !0
+ let elem_size = mem::size_of::<T>();
+
+ let alloc_size = cap.checked_mul(elem_size).unwrap_or_else(|| capacity_overflow());
+ alloc_guard(alloc_size).unwrap_or_else(|_| capacity_overflow());
+
+ // handles ZSTs and `cap = 0` alike
+ let ptr = if alloc_size == 0 {
+ NonNull::<T>::dangling()
} else {
- 0
+ let align = mem::align_of::<T>();
+ let layout = Layout::from_size_align(alloc_size, align).unwrap();
+ let result = if zeroed {
+ a.alloc_zeroed(layout)
+ } else {
+ a.alloc(layout)
+ };
+ match result {
+ Ok(ptr) => ptr.cast(),
+ Err(_) => handle_alloc_error(layout),
+ }
};
- // heap::EMPTY doubles as "unallocated" and "zero-sized allocation"
RawVec {
- ptr: Unique::new(heap::EMPTY as *mut T),
- cap: cap,
+ ptr: ptr.into(),
+ cap,
+ a,
}
}
}
+}
+
+impl<T> RawVec<T, Global> {
+ /// 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 has 0 size, then it makes a
+ /// RawVec with capacity `usize::MAX`. Useful for implementing
+ /// delayed allocation.
+ pub const fn new() -> Self {
+ Self::new_in(Global)
+ }
- /// Creates a RawVec with exactly the capacity and alignment requirements
- /// for a `[T; cap]`. This is equivalent to calling RawVec::new when `cap` 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!
+ /// Creates a RawVec (on the system heap) with exactly the
+ /// capacity and alignment requirements for a `[T; cap]`. This is
+ /// equivalent to calling RawVec::new when `cap` 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
///
/// # Aborts
///
/// Aborts on OOM
+ #[inline]
pub fn with_capacity(cap: usize) -> Self {
- unsafe {
- let elem_size = mem::size_of::<T>();
-
- let alloc_size = cap.checked_mul(elem_size).expect("capacity overflow");
- alloc_guard(alloc_size);
+ RawVec::allocate_in(cap, false, Global)
+ }
- // handles ZSTs and `cap = 0` alike
- let ptr = if alloc_size == 0 {
- heap::EMPTY as *mut u8
- } else {
- let align = mem::align_of::<T>();
- let ptr = heap::allocate(alloc_size, align);
- if ptr.is_null() {
- oom()
- }
- ptr
- };
+ /// Like `with_capacity` but guarantees the buffer is zeroed.
+ #[inline]
+ pub fn with_capacity_zeroed(cap: usize) -> Self {
+ RawVec::allocate_in(cap, true, Global)
+ }
+}
- RawVec {
- ptr: Unique::new(ptr as *mut _),
- cap: cap,
- }
+impl<T, A: Alloc> RawVec<T, A> {
+ /// Reconstitutes a RawVec from a pointer, capacity, and allocator.
+ ///
+ /// # Undefined Behavior
+ ///
+ /// The ptr must be allocated (via the given allocator `a`), and with the given capacity. The
+ /// capacity cannot exceed `isize::MAX` (only a concern on 32-bit systems).
+ /// If the ptr and capacity come from a RawVec created via `a`, then this is guaranteed.
+ pub unsafe fn from_raw_parts_in(ptr: *mut T, cap: usize, a: A) -> Self {
+ RawVec {
+ ptr: Unique::new_unchecked(ptr),
+ cap,
+ a,
}
}
+}
- /// Reconstitutes a RawVec from a pointer and capacity.
+impl<T> RawVec<T, Global> {
+ /// Reconstitutes a RawVec from a pointer, capacity.
///
/// # Undefined Behavior
///
- /// The ptr must be allocated, and with the given capacity. The
+ /// The ptr must be allocated (on the system heap), and with the given capacity. The
/// capacity cannot exceed `isize::MAX` (only a concern on 32-bit systems).
/// If the ptr and capacity come from a RawVec, then this is guaranteed.
pub unsafe fn from_raw_parts(ptr: *mut T, cap: usize) -> Self {
RawVec {
- ptr: Unique::new(ptr),
- cap: cap,
+ ptr: Unique::new_unchecked(ptr),
+ cap,
+ a: Global,
}
}
}
}
-impl<T> RawVec<T> {
+impl<T, A: Alloc> RawVec<T, A> {
/// Gets a raw pointer to the start of the allocation. Note that this is
- /// heap::EMPTY if `cap = 0` or T is zero-sized. In the former case, you must
+ /// Unique::empty() if `cap = 0` or T is zero-sized. In the former case, you must
/// be careful.
pub fn ptr(&self) -> *mut T {
- *self.ptr
+ self.ptr.as_ptr()
}
/// Gets the capacity of the allocation.
}
}
+ /// Returns a shared reference to the allocator backing this RawVec.
+ pub fn alloc(&self) -> &A {
+ &self.a
+ }
+
+ /// Returns a mutable reference to the allocator backing this RawVec.
+ pub fn alloc_mut(&mut self) -> &mut A {
+ &mut self.a
+ }
+
+ fn current_layout(&self) -> Option<Layout> {
+ if self.cap == 0 {
+ None
+ } else {
+ // We have an allocated chunk of memory, so we can bypass runtime
+ // checks to get our current layout.
+ unsafe {
+ let align = mem::align_of::<T>();
+ let size = mem::size_of::<T>() * self.cap;
+ Some(Layout::from_size_align_unchecked(size, align))
+ }
+ }
+ }
+
/// Doubles the size of the type's backing allocation. This is common enough
/// to want to do that it's easiest to just have a dedicated method. Slightly
/// more efficient logic can be provided for this than the general case.
///
/// # Examples
///
- /// ```ignore
+ /// ```
+ /// # #![feature(alloc, raw_vec_internals)]
+ /// # extern crate alloc;
+ /// # use std::ptr;
+ /// # use alloc::raw_vec::RawVec;
/// struct MyVec<T> {
/// buf: RawVec<T>,
/// len: usize,
/// // double would have aborted or panicked if the len exceeded
/// // `isize::MAX` so this is safe to do unchecked now.
/// unsafe {
- /// ptr::write(self.buf.ptr().offset(self.len as isize), elem);
+ /// ptr::write(self.buf.ptr().add(self.len), elem);
/// }
/// self.len += 1;
/// }
/// }
+ /// # fn main() {
+ /// # let mut vec = MyVec { buf: RawVec::new(), len: 0 };
+ /// # vec.push(1);
+ /// # }
/// ```
#[inline(never)]
#[cold]
// 0, getting to here necessarily means the RawVec is overfull.
assert!(elem_size != 0, "capacity overflow");
- let align = mem::align_of::<T>();
-
- let (new_cap, ptr) = if self.cap == 0 {
- // skip to 4 because tiny Vec's are dumb; but not if that would cause overflow
- let new_cap = if elem_size > (!0) / 8 {
- 1
- } else {
- 4
- };
- let ptr = heap::allocate(new_cap * elem_size, align);
- (new_cap, ptr)
- } else {
- // Since we guarantee that we never allocate more than isize::MAX bytes,
- // `elem_size * self.cap <= isize::MAX` as a precondition, so this can't overflow
- let new_cap = 2 * self.cap;
- let new_alloc_size = new_cap * elem_size;
- alloc_guard(new_alloc_size);
- let ptr = heap::reallocate(self.ptr() as *mut _,
- self.cap * elem_size,
- new_alloc_size,
- align);
- (new_cap, ptr)
+ let (new_cap, uniq) = match self.current_layout() {
+ Some(cur) => {
+ // Since we guarantee that we never allocate more than
+ // isize::MAX bytes, `elem_size * self.cap <= isize::MAX` as
+ // a precondition, so this can't overflow. Additionally the
+ // alignment will never be too large as to "not be
+ // satisfiable", so `Layout::from_size_align` will always
+ // return `Some`.
+ //
+ // tl;dr; we bypass runtime checks due to dynamic assertions
+ // in this module, allowing us to use
+ // `from_size_align_unchecked`.
+ let new_cap = 2 * self.cap;
+ let new_size = new_cap * elem_size;
+ alloc_guard(new_size).unwrap_or_else(|_| capacity_overflow());
+ let ptr_res = self.a.realloc(NonNull::from(self.ptr).cast(),
+ cur,
+ new_size);
+ match ptr_res {
+ Ok(ptr) => (new_cap, ptr.cast().into()),
+ Err(_) => handle_alloc_error(
+ Layout::from_size_align_unchecked(new_size, cur.align())
+ ),
+ }
+ }
+ None => {
+ // skip to 4 because tiny Vec's are dumb; but not if that
+ // would cause overflow
+ let new_cap = if elem_size > (!0) / 8 { 1 } else { 4 };
+ match self.a.alloc_array::<T>(new_cap) {
+ Ok(ptr) => (new_cap, ptr.into()),
+ Err(_) => handle_alloc_error(Layout::array::<T>(new_cap).unwrap()),
+ }
+ }
};
-
- // If allocate or reallocate fail, we'll get `null` back
- if ptr.is_null() {
- oom()
- }
-
- self.ptr = Unique::new(ptr as *mut _);
+ self.ptr = uniq;
self.cap = new_cap;
}
}
/// enough to want to do that it's easiest to just have a dedicated method. Slightly
/// more efficient logic can be provided for this than the general case.
///
- /// Returns true if the reallocation attempt has succeeded, or false otherwise.
+ /// Returns `true` if the reallocation attempt has succeeded.
///
/// # Panics
///
pub fn double_in_place(&mut self) -> bool {
unsafe {
let elem_size = mem::size_of::<T>();
- let align = mem::align_of::<T>();
+ let old_layout = match self.current_layout() {
+ Some(layout) => layout,
+ None => return false, // nothing to double
+ };
// since we set the capacity to usize::MAX when elem_size is
// 0, getting to here necessarily means the RawVec is overfull.
assert!(elem_size != 0, "capacity overflow");
- // Since we guarantee that we never allocate more than isize::MAX bytes,
- // `elem_size * self.cap <= isize::MAX` as a precondition, so this can't overflow
+ // Since we guarantee that we never allocate more than isize::MAX
+ // bytes, `elem_size * self.cap <= isize::MAX` as a precondition, so
+ // this can't overflow.
+ //
+ // Similarly like with `double` above we can go straight to
+ // `Layout::from_size_align_unchecked` as we know this won't
+ // overflow and the alignment is sufficiently small.
let new_cap = 2 * self.cap;
- let new_alloc_size = new_cap * elem_size;
-
- alloc_guard(new_alloc_size);
- let size = heap::reallocate_inplace(self.ptr() as *mut _,
- self.cap * elem_size,
- new_alloc_size,
- align);
- if size >= new_alloc_size {
- // We can't directly divide `size`.
- self.cap = new_cap;
+ let new_size = new_cap * elem_size;
+ alloc_guard(new_size).unwrap_or_else(|_| capacity_overflow());
+ match self.a.grow_in_place(NonNull::from(self.ptr).cast(), old_layout, new_size) {
+ Ok(_) => {
+ // We can't directly divide `size`.
+ self.cap = new_cap;
+ true
+ }
+ Err(_) => {
+ false
+ }
}
- size >= new_alloc_size
}
}
+ /// The same as `reserve_exact`, but returns on errors instead of panicking or aborting.
+ pub fn try_reserve_exact(&mut self, used_cap: usize, needed_extra_cap: usize)
+ -> Result<(), CollectionAllocErr> {
+
+ self.reserve_internal(used_cap, needed_extra_cap, Fallible, Exact)
+ }
+
/// Ensures that the buffer contains at least enough space to hold
/// `used_cap + needed_extra_cap` elements. If it doesn't already,
/// will reallocate the minimum possible amount of memory necessary.
///
/// Aborts on OOM
pub fn reserve_exact(&mut self, used_cap: usize, needed_extra_cap: usize) {
- unsafe {
- let elem_size = mem::size_of::<T>();
- let align = mem::align_of::<T>();
-
- // NOTE: we don't early branch on ZSTs here because we want this
- // to actually catch "asking for more than usize::MAX" in that case.
- // If we make it past the first branch then we are guaranteed to
- // panic.
-
- // Don't actually need any more capacity.
- // Wrapping in case they gave a bad `used_cap`.
- if self.cap().wrapping_sub(used_cap) >= needed_extra_cap {
- return;
- }
-
- // Nothing we can really do about these checks :(
- let new_cap = used_cap.checked_add(needed_extra_cap).expect("capacity overflow");
- let new_alloc_size = new_cap.checked_mul(elem_size).expect("capacity overflow");
- alloc_guard(new_alloc_size);
-
- let ptr = if self.cap == 0 {
- heap::allocate(new_alloc_size, align)
- } else {
- heap::reallocate(self.ptr() as *mut _,
- self.cap * elem_size,
- new_alloc_size,
- align)
- };
-
- // If allocate or reallocate fail, we'll get `null` back
- if ptr.is_null() {
- oom()
- }
-
- self.ptr = Unique::new(ptr as *mut _);
- self.cap = new_cap;
- }
- }
+ match self.reserve_internal(used_cap, needed_extra_cap, Infallible, Exact) {
+ Err(CapacityOverflow) => capacity_overflow(),
+ Err(AllocErr) => unreachable!(),
+ Ok(()) => { /* yay */ }
+ }
+ }
/// Calculates the buffer's new size given that it'll hold `used_cap +
/// needed_extra_cap` elements. This logic is used in amortized reserve methods.
/// Returns `(new_capacity, new_alloc_size)`.
- fn amortized_new_size(&self, used_cap: usize, needed_extra_cap: usize) -> (usize, usize) {
- let elem_size = mem::size_of::<T>();
+ fn amortized_new_size(&self, used_cap: usize, needed_extra_cap: usize)
+ -> Result<usize, CollectionAllocErr> {
+
// Nothing we can really do about these checks :(
- let required_cap = used_cap.checked_add(needed_extra_cap)
- .expect("capacity overflow");
+ let required_cap = used_cap.checked_add(needed_extra_cap).ok_or(CapacityOverflow)?;
// Cannot overflow, because `cap <= isize::MAX`, and type of `cap` is `usize`.
let double_cap = self.cap * 2;
// `double_cap` guarantees exponential growth.
- let new_cap = cmp::max(double_cap, required_cap);
- let new_alloc_size = new_cap.checked_mul(elem_size).expect("capacity overflow");
- (new_cap, new_alloc_size)
+ Ok(cmp::max(double_cap, required_cap))
+ }
+
+ /// The same as `reserve`, but returns on errors instead of panicking or aborting.
+ pub fn try_reserve(&mut self, used_cap: usize, needed_extra_cap: usize)
+ -> Result<(), CollectionAllocErr> {
+ self.reserve_internal(used_cap, needed_extra_cap, Fallible, Amortized)
}
/// Ensures that the buffer contains at least enough space to hold
///
/// # Examples
///
- /// ```ignore
+ /// ```
+ /// # #![feature(alloc, raw_vec_internals)]
+ /// # extern crate alloc;
+ /// # use std::ptr;
+ /// # use alloc::raw_vec::RawVec;
/// struct MyVec<T> {
/// buf: RawVec<T>,
/// len: usize,
/// }
///
- /// impl<T> MyVec<T> {
+ /// impl<T: Clone> MyVec<T> {
/// pub fn push_all(&mut self, elems: &[T]) {
/// self.buf.reserve(self.len, elems.len());
/// // reserve would have aborted or panicked if the len exceeded
/// // `isize::MAX` so this is safe to do unchecked now.
/// for x in elems {
/// unsafe {
- /// ptr::write(self.buf.ptr().offset(self.len as isize), x.clone());
+ /// ptr::write(self.buf.ptr().add(self.len), x.clone());
/// }
/// self.len += 1;
/// }
/// }
/// }
+ /// # fn main() {
+ /// # let mut vector = MyVec { buf: RawVec::new(), len: 0 };
+ /// # vector.push_all(&[1, 3, 5, 7, 9]);
+ /// # }
/// ```
pub fn reserve(&mut self, used_cap: usize, needed_extra_cap: usize) {
- unsafe {
- let elem_size = mem::size_of::<T>();
- let align = mem::align_of::<T>();
-
- // NOTE: we don't early branch on ZSTs here because we want this
- // to actually catch "asking for more than usize::MAX" in that case.
- // If we make it past the first branch then we are guaranteed to
- // panic.
-
- // Don't actually need any more capacity.
- // Wrapping in case they give a bad `used_cap`
- if self.cap().wrapping_sub(used_cap) >= needed_extra_cap {
- return;
- }
-
- let (new_cap, new_alloc_size) = self.amortized_new_size(used_cap, needed_extra_cap);
- // FIXME: may crash and burn on over-reserve
- alloc_guard(new_alloc_size);
-
- let ptr = if self.cap == 0 {
- heap::allocate(new_alloc_size, align)
- } else {
- heap::reallocate(self.ptr() as *mut _,
- self.cap * elem_size,
- new_alloc_size,
- align)
- };
-
- // If allocate or reallocate fail, we'll get `null` back
- if ptr.is_null() {
- oom()
- }
-
- self.ptr = Unique::new(ptr as *mut _);
- self.cap = new_cap;
+ match self.reserve_internal(used_cap, needed_extra_cap, Infallible, Amortized) {
+ Err(CapacityOverflow) => capacity_overflow(),
+ Err(AllocErr) => unreachable!(),
+ Ok(()) => { /* yay */ }
}
}
-
/// Attempts to ensure that the buffer contains at least enough space to hold
/// `used_cap + needed_extra_cap` elements. If it doesn't already have
/// enough capacity, will reallocate in place enough space plus comfortable slack
- /// space to get amortized `O(1)` behaviour. Will limit this behaviour
+ /// space to get amortized `O(1)` behavior. Will limit this behaviour
/// if it would needlessly cause itself to panic.
///
/// If `used_cap` exceeds `self.cap()`, this may fail to actually allocate
/// the requested space. This is not really unsafe, but the unsafe
- /// code *you* write that relies on the behaviour of this function may break.
+ /// code *you* write that relies on the behavior of this function may break.
///
- /// Returns true if the reallocation attempt has succeeded, or false otherwise.
+ /// Returns `true` if the reallocation attempt has succeeded.
///
/// # Panics
///
/// `isize::MAX` bytes.
pub fn reserve_in_place(&mut self, used_cap: usize, needed_extra_cap: usize) -> bool {
unsafe {
- let elem_size = mem::size_of::<T>();
- let align = mem::align_of::<T>();
-
// NOTE: we don't early branch on ZSTs here because we want this
// to actually catch "asking for more than usize::MAX" in that case.
// If we make it past the first branch then we are guaranteed to
// Don't actually need any more capacity. If the current `cap` is 0, we can't
// reallocate in place.
// Wrapping in case they give a bad `used_cap`
- if self.cap().wrapping_sub(used_cap) >= needed_extra_cap || self.cap == 0 {
+ let old_layout = match self.current_layout() {
+ Some(layout) => layout,
+ None => return false,
+ };
+ if self.cap().wrapping_sub(used_cap) >= needed_extra_cap {
return false;
}
- let (_, new_alloc_size) = self.amortized_new_size(used_cap, needed_extra_cap);
+ let new_cap = self.amortized_new_size(used_cap, needed_extra_cap)
+ .unwrap_or_else(|_| capacity_overflow());
+
+ // Here, `cap < used_cap + needed_extra_cap <= new_cap`
+ // (regardless of whether `self.cap - used_cap` wrapped).
+ // Therefore we can safely call grow_in_place.
+
+ let new_layout = Layout::new::<T>().repeat(new_cap).unwrap().0;
// FIXME: may crash and burn on over-reserve
- alloc_guard(new_alloc_size);
-
- let size = heap::reallocate_inplace(self.ptr() as *mut _,
- self.cap * elem_size,
- new_alloc_size,
- align);
- if size >= new_alloc_size {
- self.cap = new_alloc_size / elem_size;
+ alloc_guard(new_layout.size()).unwrap_or_else(|_| capacity_overflow());
+ match self.a.grow_in_place(
+ NonNull::from(self.ptr).cast(), old_layout, new_layout.size(),
+ ) {
+ Ok(_) => {
+ self.cap = new_cap;
+ true
+ }
+ Err(_) => {
+ false
+ }
}
- size >= new_alloc_size
}
}
/// Aborts on OOM.
pub fn shrink_to_fit(&mut self, amount: usize) {
let elem_size = mem::size_of::<T>();
- let align = mem::align_of::<T>();
// Set the `cap` because they might be about to promote to a `Box<[T]>`
if elem_size == 0 {
assert!(self.cap >= amount, "Tried to shrink to a larger capacity");
if amount == 0 {
- mem::replace(self, RawVec::new());
+ // We want to create a new zero-length vector within the
+ // same allocator. We use ptr::write to avoid an
+ // erroneous attempt to drop the contents, and we use
+ // ptr::read to sidestep condition against destructuring
+ // types that implement Drop.
+
+ unsafe {
+ let a = ptr::read(&self.a as *const A);
+ self.dealloc_buffer();
+ ptr::write(self, RawVec::new_in(a));
+ }
} else if self.cap != amount {
unsafe {
- // Overflow check is unnecessary as the vector is already at
- // least this large.
- let ptr = heap::reallocate(self.ptr() as *mut _,
- self.cap * elem_size,
- amount * elem_size,
- align);
- if ptr.is_null() {
- oom()
+ // We know here that our `amount` is greater than zero. This
+ // implies, via the assert above, that capacity is also greater
+ // than zero, which means that we've got a current layout that
+ // "fits"
+ //
+ // We also know that `self.cap` is greater than `amount`, and
+ // consequently we don't need runtime checks for creating either
+ // layout
+ let old_size = elem_size * self.cap;
+ let new_size = elem_size * amount;
+ let align = mem::align_of::<T>();
+ let old_layout = Layout::from_size_align_unchecked(old_size, align);
+ match self.a.realloc(NonNull::from(self.ptr).cast(),
+ old_layout,
+ new_size) {
+ Ok(p) => self.ptr = p.cast().into(),
+ Err(_) => handle_alloc_error(
+ Layout::from_size_align_unchecked(new_size, align)
+ ),
}
- self.ptr = Unique::new(ptr as *mut _);
}
self.cap = amount;
}
}
+}
+
+enum Fallibility {
+ Fallible,
+ Infallible,
+}
+
+use Fallibility::*;
+
+enum ReserveStrategy {
+ Exact,
+ Amortized,
+}
+use ReserveStrategy::*;
+
+impl<T, A: Alloc> RawVec<T, A> {
+ fn reserve_internal(
+ &mut self,
+ used_cap: usize,
+ needed_extra_cap: usize,
+ fallibility: Fallibility,
+ strategy: ReserveStrategy,
+ ) -> Result<(), CollectionAllocErr> {
+ unsafe {
+ use crate::alloc::AllocErr;
+
+ // NOTE: we don't early branch on ZSTs here because we want this
+ // to actually catch "asking for more than usize::MAX" in that case.
+ // If we make it past the first branch then we are guaranteed to
+ // panic.
+
+ // Don't actually need any more capacity.
+ // Wrapping in case they gave a bad `used_cap`.
+ if self.cap().wrapping_sub(used_cap) >= needed_extra_cap {
+ return Ok(());
+ }
+
+ // Nothing we can really do about these checks :(
+ let new_cap = match strategy {
+ Exact => used_cap.checked_add(needed_extra_cap).ok_or(CapacityOverflow)?,
+ Amortized => self.amortized_new_size(used_cap, needed_extra_cap)?,
+ };
+ let new_layout = Layout::array::<T>(new_cap).map_err(|_| CapacityOverflow)?;
+
+ alloc_guard(new_layout.size())?;
+
+ let res = match self.current_layout() {
+ Some(layout) => {
+ debug_assert!(new_layout.align() == layout.align());
+ self.a.realloc(NonNull::from(self.ptr).cast(), layout, new_layout.size())
+ }
+ None => self.a.alloc(new_layout),
+ };
+
+ match (&res, fallibility) {
+ (Err(AllocErr), Infallible) => handle_alloc_error(new_layout),
+ _ => {}
+ }
+
+ self.ptr = res?.cast().into();
+ self.cap = new_cap;
+
+ Ok(())
+ }
+ }
+
+}
+
+impl<T> RawVec<T, Global> {
/// Converts the entire buffer into `Box<[T]>`.
///
/// While it is not *strictly* Undefined Behavior to call
}
}
-impl<T> Drop for RawVec<T> {
- #[unsafe_destructor_blind_to_params]
+impl<T, A: Alloc> RawVec<T, A> {
/// Frees the memory owned by the RawVec *without* trying to Drop its contents.
- fn drop(&mut self) {
+ pub unsafe fn dealloc_buffer(&mut self) {
let elem_size = mem::size_of::<T>();
- if elem_size != 0 && self.cap != 0 {
- let align = mem::align_of::<T>();
-
- let num_bytes = elem_size * self.cap;
- unsafe {
- heap::deallocate(*self.ptr as *mut _, num_bytes, align);
+ if elem_size != 0 {
+ if let Some(layout) = self.current_layout() {
+ self.a.dealloc(NonNull::from(self.ptr).cast(), layout);
}
}
}
}
+unsafe impl<#[may_dangle] T, A: Alloc> Drop for RawVec<T, A> {
+ /// Frees the memory owned by the RawVec *without* trying to Drop its contents.
+ fn drop(&mut self) {
+ unsafe { self.dealloc_buffer(); }
+ }
+}
+
// We need to guarantee the following:
// 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
+// all 4GB in user-space. e.g., PAE or x32
#[inline]
-fn alloc_guard(alloc_size: usize) {
- if mem::size_of::<usize>() < 8 {
- assert!(alloc_size <= ::core::isize::MAX as usize,
- "capacity overflow");
+fn alloc_guard(alloc_size: usize) -> Result<(), CollectionAllocErr> {
+ if mem::size_of::<usize>() < 8 && alloc_size > core::isize::MAX as usize {
+ Err(CapacityOverflow)
+ } 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.
+fn capacity_overflow() -> ! {
+ panic!("capacity overflow")
+}
#[cfg(test)]
mod tests {
use super::*;
+ #[test]
+ fn allocator_param() {
+ use crate::alloc::AllocErr;
+
+ // Writing a test of integration between third-party
+ // allocators and RawVec is a little tricky because the RawVec
+ // API does not expose fallible allocation methods, so we
+ // cannot check what happens when allocator is exhausted
+ // (beyond detecting a panic).
+ //
+ // Instead, this just checks that the RawVec methods do at
+ // least go through the Allocator API when it reserves
+ // storage.
+
+ // A dumb allocator that consumes a fixed amount of fuel
+ // before allocation attempts start failing.
+ struct BoundedAlloc { fuel: usize }
+ unsafe impl Alloc for BoundedAlloc {
+ unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> {
+ let size = layout.size();
+ if size > self.fuel {
+ return Err(AllocErr);
+ }
+ match Global.alloc(layout) {
+ ok @ Ok(_) => { self.fuel -= size; ok }
+ err @ Err(_) => err,
+ }
+ }
+ unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout) {
+ Global.dealloc(ptr, layout)
+ }
+ }
+
+ let a = BoundedAlloc { fuel: 500 };
+ let mut v: RawVec<u8, _> = RawVec::with_capacity_in(50, a);
+ assert_eq!(v.a.fuel, 450);
+ v.reserve(50, 150); // (causes a realloc, thus using 50 + 150 = 200 units of fuel)
+ assert_eq!(v.a.fuel, 250);
+ }
+
#[test]
fn reserve_does_not_overallocate() {
{
}
}
+
}
projects / rustc.git / blobdiff