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Optimize BitmapIter::next #292

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merged 3 commits into from
Oct 18, 2024
Merged

Optimize BitmapIter::next #292

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c7c3cd5
do not expose a "datasets" benchmark binary
Dr-Emann Oct 1, 2024
385eff7
Speed up bitmap store iterator
Dr-Emann Oct 1, 2024
b39a3c1
use u16 keys for bitmap store iterator
Dr-Emann Oct 1, 2024
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0 benchmarks/benches/datasets.rs → benchmarks/benches/datasets/mod.rs
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48 changes: 26 additions & 22 deletions roaring/src/bitmap/store/bitmap_store.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,4 @@
use core::borrow::Borrow;
use core::cmp::Ordering;
use core::fmt::{Display, Formatter};
use core::ops::{BitAndAssign, BitOrAssign, BitXorAssign, RangeInclusive, SubAssign};

Expand Down Expand Up @@ -404,9 +403,9 @@ impl Display for Error {
impl std::error::Error for Error {}

pub struct BitmapIter<B: Borrow<[u64; BITMAP_LENGTH]>> {
key: usize,
key: u16,
value: u64,
key_back: usize,
key_back: u16,
value_back: u64,
bits: B,
}
Expand All @@ -416,7 +415,7 @@ impl<B: Borrow<[u64; BITMAP_LENGTH]>> BitmapIter<B> {
BitmapIter {
key: 0,
value: bits.borrow()[0],
key_back: BITMAP_LENGTH - 1,
key_back: BITMAP_LENGTH as u16 - 1,
value_back: bits.borrow()[BITMAP_LENGTH - 1],
bits,
}
Expand All @@ -427,24 +426,28 @@ impl<B: Borrow<[u64; BITMAP_LENGTH]>> Iterator for BitmapIter<B> {
type Item = u16;

fn next(&mut self) -> Option<u16> {
loop {
if self.value == 0 {
self.key += 1;
let cmp = self.key.cmp(&self.key_back);
// Match arms can be reordered, this ordering is perf sensitive
self.value = if cmp == Ordering::Less {
unsafe { *self.bits.borrow().get_unchecked(self.key) }
} else if cmp == Ordering::Equal {
self.value_back
} else {
if self.value == 0 {
'get_val: {
if self.key >= self.key_back {
return None;
};
continue;
}
for key in self.key + 1..self.key_back {
self.value = unsafe { *self.bits.borrow().get_unchecked(key as usize) };
if self.value != 0 {
self.key = key;
break 'get_val;
}
}
self.key = self.key_back;
self.value = self.value_back;
if self.value == 0 {
return None;
}
}
let index = self.value.trailing_zeros() as usize;
self.value &= self.value - 1;
return Some((64 * self.key + index) as u16);
}
let index = self.value.trailing_zeros() as u16;
self.value &= self.value - 1;
Some(64 * self.key + index)
}
}

Expand All @@ -458,13 +461,14 @@ impl<B: Borrow<[u64; BITMAP_LENGTH]>> DoubleEndedIterator for BitmapIter<B> {
return None;
}
self.key_back -= 1;
self.value_back = unsafe { *self.bits.borrow().get_unchecked(self.key_back) };
self.value_back =
unsafe { *self.bits.borrow().get_unchecked(self.key_back as usize) };
continue;
}
let index_from_left = value.leading_zeros() as usize;
let index_from_left = value.leading_zeros() as u16;
let index = 63 - index_from_left;
*value &= !(1 << index);
return Some((64 * self.key_back + index) as u16);
return Some(64 * self.key_back + index);
}
}
}
Expand Down
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