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authorValentin Popov <valentin@popov.link>2024-07-19 15:37:58 +0300
committerValentin Popov <valentin@popov.link>2024-07-19 15:37:58 +0300
commita990de90fe41456a23e58bd087d2f107d321f3a1 (patch)
tree15afc392522a9e85dc3332235e311b7d39352ea9 /vendor/rayon/src/iter/find_first_last/mod.rs
parent3d48cd3f81164bbfc1a755dc1d4a9a02f98c8ddd (diff)
downloadfparkan-a990de90fe41456a23e58bd087d2f107d321f3a1.tar.xz
fparkan-a990de90fe41456a23e58bd087d2f107d321f3a1.zip
Deleted vendor folder
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diff --git a/vendor/rayon/src/iter/find_first_last/mod.rs b/vendor/rayon/src/iter/find_first_last/mod.rs
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-use super::plumbing::*;
-use super::*;
-use std::cell::Cell;
-use std::sync::atomic::{AtomicUsize, Ordering};
-
-#[cfg(test)]
-mod test;
-
-// The key optimization for find_first is that a consumer can stop its search if
-// some consumer to its left already found a match (and similarly for consumers
-// to the right for find_last). To make this work, all consumers need some
-// notion of their position in the data relative to other consumers, including
-// unindexed consumers that have no built-in notion of position.
-//
-// To solve this, we assign each consumer a lower and upper bound for an
-// imaginary "range" of data that it consumes. The initial consumer starts with
-// the range 0..usize::max_value(). The split divides this range in half so that
-// one resulting consumer has the range 0..(usize::max_value() / 2), and the
-// other has (usize::max_value() / 2)..usize::max_value(). Every subsequent
-// split divides the range in half again until it cannot be split anymore
-// (i.e. its length is 1), in which case the split returns two consumers with
-// the same range. In that case both consumers will continue to consume all
-// their data regardless of whether a better match is found, but the reducer
-// will still return the correct answer.
-
-#[derive(Copy, Clone)]
-enum MatchPosition {
- Leftmost,
- Rightmost,
-}
-
-/// Returns true if pos1 is a better match than pos2 according to MatchPosition
-#[inline]
-fn better_position(pos1: usize, pos2: usize, mp: MatchPosition) -> bool {
- match mp {
- MatchPosition::Leftmost => pos1 < pos2,
- MatchPosition::Rightmost => pos1 > pos2,
- }
-}
-
-pub(super) fn find_first<I, P>(pi: I, find_op: P) -> Option<I::Item>
-where
- I: ParallelIterator,
- P: Fn(&I::Item) -> bool + Sync,
-{
- let best_found = AtomicUsize::new(usize::max_value());
- let consumer = FindConsumer::new(&find_op, MatchPosition::Leftmost, &best_found);
- pi.drive_unindexed(consumer)
-}
-
-pub(super) fn find_last<I, P>(pi: I, find_op: P) -> Option<I::Item>
-where
- I: ParallelIterator,
- P: Fn(&I::Item) -> bool + Sync,
-{
- let best_found = AtomicUsize::new(0);
- let consumer = FindConsumer::new(&find_op, MatchPosition::Rightmost, &best_found);
- pi.drive_unindexed(consumer)
-}
-
-struct FindConsumer<'p, P> {
- find_op: &'p P,
- lower_bound: Cell<usize>,
- upper_bound: usize,
- match_position: MatchPosition,
- best_found: &'p AtomicUsize,
-}
-
-impl<'p, P> FindConsumer<'p, P> {
- fn new(find_op: &'p P, match_position: MatchPosition, best_found: &'p AtomicUsize) -> Self {
- FindConsumer {
- find_op,
- lower_bound: Cell::new(0),
- upper_bound: usize::max_value(),
- match_position,
- best_found,
- }
- }
-
- fn current_index(&self) -> usize {
- match self.match_position {
- MatchPosition::Leftmost => self.lower_bound.get(),
- MatchPosition::Rightmost => self.upper_bound,
- }
- }
-}
-
-impl<'p, T, P> Consumer<T> for FindConsumer<'p, P>
-where
- T: Send,
- P: Fn(&T) -> bool + Sync,
-{
- type Folder = FindFolder<'p, T, P>;
- type Reducer = FindReducer;
- type Result = Option<T>;
-
- fn split_at(self, _index: usize) -> (Self, Self, Self::Reducer) {
- let dir = self.match_position;
- (
- self.split_off_left(),
- self,
- FindReducer {
- match_position: dir,
- },
- )
- }
-
- fn into_folder(self) -> Self::Folder {
- FindFolder {
- find_op: self.find_op,
- boundary: self.current_index(),
- match_position: self.match_position,
- best_found: self.best_found,
- item: None,
- }
- }
-
- fn full(&self) -> bool {
- // can stop consuming if the best found index so far is *strictly*
- // better than anything this consumer will find
- better_position(
- self.best_found.load(Ordering::Relaxed),
- self.current_index(),
- self.match_position,
- )
- }
-}
-
-impl<'p, T, P> UnindexedConsumer<T> for FindConsumer<'p, P>
-where
- T: Send,
- P: Fn(&T) -> bool + Sync,
-{
- fn split_off_left(&self) -> Self {
- // Upper bound for one consumer will be lower bound for the other. This
- // overlap is okay, because only one of the bounds will be used for
- // comparing against best_found; the other is kept only to be able to
- // divide the range in half.
- //
- // When the resolution of usize has been exhausted (i.e. when
- // upper_bound = lower_bound), both results of this split will have the
- // same range. When that happens, we lose the ability to tell one
- // consumer to stop working when the other finds a better match, but the
- // reducer ensures that the best answer is still returned (see the test
- // above).
- let old_lower_bound = self.lower_bound.get();
- let median = old_lower_bound + ((self.upper_bound - old_lower_bound) / 2);
- self.lower_bound.set(median);
-
- FindConsumer {
- find_op: self.find_op,
- lower_bound: Cell::new(old_lower_bound),
- upper_bound: median,
- match_position: self.match_position,
- best_found: self.best_found,
- }
- }
-
- fn to_reducer(&self) -> Self::Reducer {
- FindReducer {
- match_position: self.match_position,
- }
- }
-}
-
-struct FindFolder<'p, T, P> {
- find_op: &'p P,
- boundary: usize,
- match_position: MatchPosition,
- best_found: &'p AtomicUsize,
- item: Option<T>,
-}
-
-impl<'p, P: 'p + Fn(&T) -> bool, T> Folder<T> for FindFolder<'p, T, P> {
- type Result = Option<T>;
-
- fn consume(mut self, item: T) -> Self {
- let found_best_in_range = match self.match_position {
- MatchPosition::Leftmost => self.item.is_some(),
- MatchPosition::Rightmost => false,
- };
-
- if !found_best_in_range && (self.find_op)(&item) {
- // Continuously try to set best_found until we succeed or we
- // discover a better match was already found.
- let mut current = self.best_found.load(Ordering::Relaxed);
- loop {
- if better_position(current, self.boundary, self.match_position) {
- break;
- }
- match self.best_found.compare_exchange_weak(
- current,
- self.boundary,
- Ordering::Relaxed,
- Ordering::Relaxed,
- ) {
- Ok(_) => {
- self.item = Some(item);
- break;
- }
- Err(v) => current = v,
- }
- }
- }
- self
- }
-
- fn complete(self) -> Self::Result {
- self.item
- }
-
- fn full(&self) -> bool {
- let found_best_in_range = match self.match_position {
- MatchPosition::Leftmost => self.item.is_some(),
- MatchPosition::Rightmost => false,
- };
-
- found_best_in_range
- || better_position(
- self.best_found.load(Ordering::Relaxed),
- self.boundary,
- self.match_position,
- )
- }
-}
-
-struct FindReducer {
- match_position: MatchPosition,
-}
-
-impl<T> Reducer<Option<T>> for FindReducer {
- fn reduce(self, left: Option<T>, right: Option<T>) -> Option<T> {
- match self.match_position {
- MatchPosition::Leftmost => left.or(right),
- MatchPosition::Rightmost => right.or(left),
- }
- }
-}