tustvold commented on code in PR #3920:
URL: https://github.com/apache/arrow-rs/pull/3920#discussion_r1148349944
##########
arrow-buffer/src/buffer/mutable.rs:
##########
@@ -89,35 +97,46 @@ impl MutableBuffer {
/// let data = buffer.as_slice_mut();
/// assert_eq!(data[126], 0u8);
/// ```
- #[allow(deprecated)]
pub fn from_len_zeroed(len: usize) -> Self {
- let new_capacity = bit_util::round_upto_multiple_of_64(len);
- let ptr = alloc::allocate_aligned_zeroed(new_capacity);
- Self {
- data: ptr,
- len,
- capacity: new_capacity,
- }
+ let layout = Layout::from_size_align(len, ALIGNMENT).unwrap();
+ let data = match layout.size() {
+ 0 => dangling_ptr(),
+ _ => {
+ // Safety: Verified size != 0
+ let raw_ptr = unsafe { std::alloc::alloc_zeroed(layout) };
+ NonNull::new(raw_ptr).unwrap_or_else(||
handle_alloc_error(layout))
+ }
+ };
+ Self { data, len, layout }
+ }
+
+ /// Create a [`MutableBuffer`] from the provided [`Vec`] without copying
+ #[inline]
+ pub fn from_vec<T: ArrowNativeType>(vec: Vec<T>) -> Self {
+ // Safety
+ // Vec::as_ptr guaranteed to not be null and ArrowNativeType are
trivially transmutable
+ let data = unsafe { NonNull::new_unchecked(vec.as_ptr() as _) };
+ let len = vec.len() * mem::size_of::<T>();
+ // Safety
+ // Vec guaranteed to have a valid layout matching that of
`Layout::array`
+ // This is based on `RawVec::current_memory`
+ let layout = unsafe {
Layout::array::<T>(vec.capacity()).unwrap_unchecked() };
+ mem::forget(vec);
+ Self { data, len, layout }
}
/// Allocates a new [MutableBuffer] from given `Bytes`.
pub(crate) fn from_bytes(bytes: Bytes) -> Result<Self, Bytes> {
- let capacity = match bytes.deallocation() {
- Deallocation::Standard(layout) if layout.align() == ALIGNMENT => {
- layout.size()
- }
+ let layout = match bytes.deallocation() {
Review Comment:
Correct, we can handle any alignment now
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