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The following commit(s) were added to refs/heads/main by this push:
new 63b54706b1 Remove `len` field from buffer builder (#9750)
63b54706b1 is described below
commit 63b54706b1c0e7aeebf3d2ba8c1a815ef803deb3
Author: Peter L <[email protected]>
AuthorDate: Wed Apr 22 22:11:59 2026 +0930
Remove `len` field from buffer builder (#9750)
# Which issue does this PR close?
- Split out of https://github.com/apache/arrow-rs/pull/9393
# Rationale for this change
The buffer builder doesn't need to keep its own `len` field, as it can
be derived from the inner mutablebuffer
# What changes are included in this PR?
Removes the `len` field from `Bufferbuilder`
# Are these changes tested?
Yes, all tests green
# Are there any user-facing changes?
Nope!
---
arrow-buffer/src/builder/mod.rs | 22 +++++-----------------
1 file changed, 5 insertions(+), 17 deletions(-)
diff --git a/arrow-buffer/src/builder/mod.rs b/arrow-buffer/src/builder/mod.rs
index 72e3865190..843a93c127 100644
--- a/arrow-buffer/src/builder/mod.rs
+++ b/arrow-buffer/src/builder/mod.rs
@@ -58,7 +58,6 @@ use std::marker::PhantomData;
#[derive(Debug)]
pub struct BufferBuilder<T: ArrowNativeType> {
buffer: MutableBuffer,
- len: usize,
_marker: PhantomData<T>,
}
@@ -88,7 +87,6 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
Self {
buffer,
- len: 0,
_marker: PhantomData,
}
}
@@ -99,10 +97,8 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
///
/// - `buffer` bytes must be aligned to type `T`
pub unsafe fn new_from_buffer(buffer: MutableBuffer) -> Self {
- let buffer_len = buffer.len();
Self {
buffer,
- len: buffer_len / std::mem::size_of::<T>(),
_marker: PhantomData,
}
}
@@ -119,7 +115,7 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
/// assert_eq!(builder.len(), 1);
/// ```
pub fn len(&self) -> usize {
- self.len
+ self.buffer.len() / std::mem::size_of::<T>()
}
/// Returns whether the internal buffer is empty.
@@ -134,7 +130,7 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
/// assert_eq!(builder.is_empty(), false);
/// ```
pub fn is_empty(&self) -> bool {
- self.len == 0
+ self.buffer.is_empty()
}
/// Returns the actual capacity (number of elements) of the internal
buffer.
@@ -166,7 +162,6 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
#[inline]
pub fn advance(&mut self, i: usize) {
self.buffer.extend_zeros(i * std::mem::size_of::<T>());
- self.len += i;
}
/// Reserves memory for _at least_ `n` more elements of type `T`.
@@ -201,7 +196,6 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
pub fn append(&mut self, v: T) {
self.reserve(1);
self.buffer.push(v);
- self.len += 1;
}
/// Appends a value of type `T` into the builder N times,
@@ -237,7 +231,6 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
#[inline]
pub fn append_n_zeroed(&mut self, n: usize) {
self.buffer.extend_zeros(n * std::mem::size_of::<T>());
- self.len += n;
}
/// Appends a slice of type `T`, growing the internal buffer as needed.
@@ -254,7 +247,6 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
#[inline]
pub fn append_slice(&mut self, slice: &[T]) {
self.buffer.extend_from_slice(slice);
- self.len += slice.len();
}
/// View the contents of this buffer as a slice
@@ -274,7 +266,7 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
// - MutableBuffer is aligned and initialized for len elements of T
// - MutableBuffer corresponds to a single allocation
// - MutableBuffer does not support modification whilst active
immutable borrows
- unsafe { std::slice::from_raw_parts(self.buffer.as_ptr() as _,
self.len) }
+ unsafe { std::slice::from_raw_parts(self.buffer.as_ptr() as _,
self.len()) }
}
/// View the contents of this buffer as a mutable slice
@@ -298,7 +290,7 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
// - MutableBuffer is aligned and initialized for len elements of T
// - MutableBuffer corresponds to a single allocation
// - MutableBuffer does not support modification whilst active
immutable borrows
- unsafe { std::slice::from_raw_parts_mut(self.buffer.as_mut_ptr() as _,
self.len) }
+ unsafe { std::slice::from_raw_parts_mut(self.buffer.as_mut_ptr() as _,
self.len()) }
}
/// Shorten this BufferBuilder to `len` items
@@ -323,7 +315,6 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
#[inline]
pub fn truncate(&mut self, len: usize) {
self.buffer.truncate(len * std::mem::size_of::<T>());
- self.len = self.len.min(len);
}
/// # Safety
@@ -356,7 +347,6 @@ impl<T: ArrowNativeType> BufferBuilder<T> {
#[inline]
pub fn finish(&mut self) -> Buffer {
let buf = std::mem::take(&mut self.buffer);
- self.len = 0;
buf.into()
}
@@ -387,9 +377,7 @@ impl<T: ArrowNativeType> Default for BufferBuilder<T> {
impl<T: ArrowNativeType> Extend<T> for BufferBuilder<T> {
fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
- self.buffer.extend(iter.into_iter().inspect(|_| {
- self.len += 1;
- }))
+ self.buffer.extend(iter)
}
}
