Dandandan commented on code in PR #2646:
URL: https://github.com/apache/arrow-rs/pull/2646#discussion_r962360991
##########
arrow/src/buffer/mutable.rs:
##########
@@ -496,38 +531,9 @@ impl MutableBuffer {
mut iterator: I,
) -> Self {
let (_, upper) = iterator.size_hint();
- let upper = upper.expect("from_trusted_len_iter requires an upper
limit");
-
- let mut result = {
- let byte_capacity: usize = upper.saturating_add(7) / 8;
- MutableBuffer::new(byte_capacity)
- };
+ let len = upper.expect("from_trusted_len_iter requires an upper
limit");
- 'a: loop {
- let mut byte_accum: u8 = 0;
- let mut mask: u8 = 1;
-
- //collect (up to) 8 bits into a byte
- while mask != 0 {
- if let Some(value) = iterator.next() {
- byte_accum |= match value {
- true => mask,
- false => 0,
- };
- mask <<= 1;
- } else {
- if mask != 1 {
- // Add last byte
- result.push_unchecked(byte_accum);
- }
- break 'a;
- }
- }
-
- // Soundness: from_trusted_len
- result.push_unchecked(byte_accum);
- }
- result
+ Self::collect_bool(len, |_| iterator.next().unwrap())
Review Comment:
@tustvold one last thought, I wonder if using `unwrap_unchecked` here would
result in the same performance (as it removes the condition).
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