jorgecarleitao commented on a change in pull request #9076:
URL: https://github.com/apache/arrow/pull/9076#discussion_r550910490
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File path: rust/arrow/src/buffer.rs
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@@ -852,17 +870,34 @@ impl MutableBuffer {
}
}
- /// Extends the buffer from a byte slice, incrementing its capacity if
needed.
+ /// Extends the buffer from a slice, increasing its capacity if needed.
+ #[inline]
+ pub fn extend_from_slice<T: ToByteSlice>(&mut self, items: &[T]) {
+ let additional = items.len() * std::mem::size_of::<T>();
+ let new_len = self.len + additional;
+ if new_len > self.capacity {
+ self.reserve(additional);
+ }
+ unsafe {
+ let dst = self.data.as_ptr().add(self.len) as *mut T;
+ let src = items.as_ptr() as *const T;
+ std::ptr::copy_nonoverlapping(src, dst, items.len())
+ }
+ self.len = new_len;
+ }
+
+ /// Extends the buffer with a new item, increasing its capacity if needed.
#[inline]
- pub fn extend_from_slice(&mut self, bytes: &[u8]) {
- let additional = bytes.len();
- if self.len + additional > self.capacity() {
+ pub fn push<T: ToByteSlice>(&mut self, item: &T) {
+ let additional = std::mem::size_of::<T>();
+ let new_len = self.len + additional;
+ if new_len > self.capacity {
Review comment:
I though about that also, but it requires more investigations. We would
need to make `MutableBuffer` a generic over `T` and that has implications in
our ability to build generic structures.
For example, `builders::FieldData` relies on a generic `MutableBuffer`, and
`MutableArrayData` also.
Note that growing and freezing a `MutableBuffer` is now faster than
`Vec<u32>` to store `u32`. We do still have a performance problem on which
growing a `MutableBuffer` is faster than pre-reserving it.
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