Code clean up

This commit is contained in:
Paul Masurel
2020-08-20 15:42:50 +09:00
parent cbacdf0de8
commit f355695581

View File

@@ -4,19 +4,6 @@ use crate::{DocId, DocSet, Score, TERMINATED};
use std::ops::Deref;
use std::ops::DerefMut;
fn is_sorted<I: Iterator<Item = DocId>>(mut it: I) -> bool {
if let Some(first) = it.next() {
let mut prev = first;
for doc in it {
if doc < prev {
return false;
}
prev = doc;
}
}
true
}
/// Takes a term_scorers sorted by their current doc() and a threshold and returns
/// Returns (pivot_len, pivot_ord) defined as follows:
/// - `pivot_doc` lowest document that has a chance of exceeding (>) the threshold score.
@@ -55,37 +42,12 @@ fn find_pivot_doc(
Some((before_pivot_len, pivot_len, pivot_doc))
}
struct TermScorerWithMaxScore<'a> {
scorer: &'a mut TermScorer,
max_score: Score,
}
impl<'a> From<&'a mut TermScorer> for TermScorerWithMaxScore<'a> {
fn from(scorer: &'a mut TermScorer) -> Self {
let max_score = scorer.max_score();
TermScorerWithMaxScore { scorer, max_score }
}
}
impl<'a> Deref for TermScorerWithMaxScore<'a> {
type Target = TermScorer;
fn deref(&self) -> &Self::Target {
self.scorer
}
}
impl<'a> DerefMut for TermScorerWithMaxScore<'a> {
fn deref_mut(&mut self) -> &mut Self::Target {
self.scorer
}
}
// Before and after calling this method, scorers need to be sorted by their `.doc()`.
fn block_max_was_too_low_advance_one_scorer(
scorers: &mut Vec<TermScorerWithMaxScore>,
pivot_len: usize,
) {
debug_assert!(is_sorted(scorers.iter().map(|scorer| scorer.doc())));
let mut scorer_to_seek = pivot_len - 1;
let mut doc_to_seek_after = scorers[scorer_to_seek].doc();
for scorer_ord in (0..pivot_len - 1).rev() {
@@ -102,6 +64,7 @@ fn block_max_was_too_low_advance_one_scorer(
}
scorers[scorer_to_seek].seek(doc_to_seek_after + 1);
restore_ordering(scorers, scorer_to_seek);
debug_assert!(is_sorted(scorers.iter().map(|scorer| scorer.doc())));
}
// Given a list of term_scorers and a `ord` and assuming that `term_scorers[ord]` is sorted
@@ -177,64 +140,100 @@ pub fn block_wand(
.map(TermScorerWithMaxScore::from)
.collect();
scorers.sort_by_key(|scorer| scorer.doc());
loop {
// At this point we need to ensure that the scorers are sorted!
// At this point we need to ensure that the scorers are sorted!
debug_assert!(is_sorted(scorers.iter().map(|scorer| scorer.doc())));
while let Some((before_pivot_len, pivot_len, pivot_doc)) =
find_pivot_doc(&scorers[..], threshold)
{
debug_assert!(is_sorted(scorers.iter().map(|scorer| scorer.doc())));
if let Some((before_pivot_len, pivot_len, pivot_doc)) =
find_pivot_doc(&scorers[..], threshold)
{
debug_assert_ne!(pivot_doc, TERMINATED);
debug_assert!(before_pivot_len < pivot_len);
debug_assert_ne!(pivot_doc, TERMINATED);
debug_assert!(before_pivot_len < pivot_len);
let block_max_score_upperbound: Score = scorers[..pivot_len]
.iter_mut()
.map(|scorer| {
scorer.shallow_seek(pivot_doc);
scorer.block_max_score()
})
.sum();
let block_max_score_upperbound: Score = scorers[..pivot_len]
.iter_mut()
.map(|scorer| {
scorer.shallow_seek(pivot_doc);
scorer.block_max_score()
})
.sum();
// Beware after shallow advance, skip readers can be in advance compared to
// the segment posting lists.
//
// `block_segment_postings.load_block()` need to be called separately.
if block_max_score_upperbound <= threshold {
// Block max condition was not reached
// We could get away by simply advancing the scorers to DocId + 1 but it would
// be inefficient. The optimization requires proper explanation and was
// isolated in a different function.
block_max_was_too_low_advance_one_scorer(&mut scorers, pivot_len);
continue;
}
// Block max condition is observed.
//
// Let's try and advance all scorers before the pivot to the pivot.
if !align_scorers(&mut scorers, pivot_doc, before_pivot_len) {
// At least of the scorer does not contain the pivot.
//
// Let's stop scoring this pivot and go through the pivot selection again.
// Note that the current pivot is not necessarily a bad candidate and it
// may be picked again.
continue;
}
// At this point, all scorers are positioned on the doc.
let score = scorers[..pivot_len]
.iter_mut()
.map(|scorer| scorer.score())
.sum();
if score > threshold {
threshold = callback(pivot_doc, score);
}
// let's advance all of the scorers that are currently positioned on the pivot.
advance_all_scorers_on_pivot(&mut scorers, pivot_len);
} else {
return;
// Beware after shallow advance, skip readers can be in advance compared to
// the segment posting lists.
//
// `block_segment_postings.load_block()` need to be called separately.
if block_max_score_upperbound <= threshold {
// Block max condition was not reached
// We could get away by simply advancing the scorers to DocId + 1 but it would
// be inefficient. The optimization requires proper explanation and was
// isolated in a different function.
block_max_was_too_low_advance_one_scorer(&mut scorers, pivot_len);
continue;
}
// Block max condition is observed.
//
// Let's try and advance all scorers before the pivot to the pivot.
if !align_scorers(&mut scorers, pivot_doc, before_pivot_len) {
// At least of the scorer does not contain the pivot.
//
// Let's stop scoring this pivot and go through the pivot selection again.
// Note that the current pivot is not necessarily a bad candidate and it
// may be picked again.
continue;
}
// At this point, all scorers are positioned on the doc.
let score = scorers[..pivot_len]
.iter_mut()
.map(|scorer| scorer.score())
.sum();
if score > threshold {
threshold = callback(pivot_doc, score);
}
// let's advance all of the scorers that are currently positioned on the pivot.
advance_all_scorers_on_pivot(&mut scorers, pivot_len);
}
}
struct TermScorerWithMaxScore<'a> {
scorer: &'a mut TermScorer,
max_score: Score,
}
impl<'a> From<&'a mut TermScorer> for TermScorerWithMaxScore<'a> {
fn from(scorer: &'a mut TermScorer) -> Self {
let max_score = scorer.max_score();
TermScorerWithMaxScore { scorer, max_score }
}
}
impl<'a> Deref for TermScorerWithMaxScore<'a> {
type Target = TermScorer;
fn deref(&self) -> &Self::Target {
self.scorer
}
}
impl<'a> DerefMut for TermScorerWithMaxScore<'a> {
fn deref_mut(&mut self) -> &mut Self::Target {
self.scorer
}
}
#[cfg(debug_assertions)]
fn is_sorted<I: Iterator<Item = DocId>>(mut it: I) -> bool {
if let Some(first) = it.next() {
let mut prev = first;
for doc in it {
if doc < prev {
return false;
}
prev = doc;
}
}
true
}
#[cfg(test)]
mod tests {
use crate::query::score_combiner::SumCombiner;
@@ -248,17 +247,21 @@ mod tests {
use std::iter;
struct Float(Score);
impl Eq for Float {}
impl PartialEq for Float {
fn eq(&self, other: &Self) -> bool {
self.cmp(&other) == Ordering::Equal
}
}
impl PartialOrd for Float {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for Float {
fn cmp(&self, other: &Self) -> Ordering {
other.0.partial_cmp(&self.0).unwrap_or(Ordering::Equal)