diff options
Diffstat (limited to 'vendor/rayon/src/slice')
| -rw-r--r-- | vendor/rayon/src/slice/chunks.rs | 389 | ||||
| -rw-r--r-- | vendor/rayon/src/slice/mergesort.rs | 755 | ||||
| -rw-r--r-- | vendor/rayon/src/slice/mod.rs | 1041 | ||||
| -rw-r--r-- | vendor/rayon/src/slice/quicksort.rs | 903 | ||||
| -rw-r--r-- | vendor/rayon/src/slice/rchunks.rs | 386 | ||||
| -rw-r--r-- | vendor/rayon/src/slice/test.rs | 170 |
6 files changed, 0 insertions, 3644 deletions
diff --git a/vendor/rayon/src/slice/chunks.rs b/vendor/rayon/src/slice/chunks.rs deleted file mode 100644 index a3cc709..0000000 --- a/vendor/rayon/src/slice/chunks.rs +++ /dev/null @@ -1,389 +0,0 @@ -use crate::iter::plumbing::*; -use crate::iter::*; -use crate::math::div_round_up; -use std::cmp; - -/// Parallel iterator over immutable non-overlapping chunks of a slice -#[derive(Debug)] -pub struct Chunks<'data, T: Sync> { - chunk_size: usize, - slice: &'data [T], -} - -impl<'data, T: Sync> Chunks<'data, T> { - pub(super) fn new(chunk_size: usize, slice: &'data [T]) -> Self { - Self { chunk_size, slice } - } -} - -impl<'data, T: Sync> Clone for Chunks<'data, T> { - fn clone(&self) -> Self { - Chunks { ..*self } - } -} - -impl<'data, T: Sync + 'data> ParallelIterator for Chunks<'data, T> { - type Item = &'data [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Sync + 'data> IndexedParallelIterator for Chunks<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - div_round_up(self.slice.len(), self.chunk_size) - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(ChunksProducer { - chunk_size: self.chunk_size, - slice: self.slice, - }) - } -} - -struct ChunksProducer<'data, T: Sync> { - chunk_size: usize, - slice: &'data [T], -} - -impl<'data, T: 'data + Sync> Producer for ChunksProducer<'data, T> { - type Item = &'data [T]; - type IntoIter = ::std::slice::Chunks<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.chunks(self.chunk_size) - } - - fn split_at(self, index: usize) -> (Self, Self) { - let elem_index = cmp::min(index * self.chunk_size, self.slice.len()); - let (left, right) = self.slice.split_at(elem_index); - ( - ChunksProducer { - chunk_size: self.chunk_size, - slice: left, - }, - ChunksProducer { - chunk_size: self.chunk_size, - slice: right, - }, - ) - } -} - -/// Parallel iterator over immutable non-overlapping chunks of a slice -#[derive(Debug)] -pub struct ChunksExact<'data, T: Sync> { - chunk_size: usize, - slice: &'data [T], - rem: &'data [T], -} - -impl<'data, T: Sync> ChunksExact<'data, T> { - pub(super) fn new(chunk_size: usize, slice: &'data [T]) -> Self { - let rem_len = slice.len() % chunk_size; - let len = slice.len() - rem_len; - let (slice, rem) = slice.split_at(len); - Self { - chunk_size, - slice, - rem, - } - } - - /// Return the remainder of the original slice that is not going to be - /// returned by the iterator. The returned slice has at most `chunk_size-1` - /// elements. - pub fn remainder(&self) -> &'data [T] { - self.rem - } -} - -impl<'data, T: Sync> Clone for ChunksExact<'data, T> { - fn clone(&self) -> Self { - ChunksExact { ..*self } - } -} - -impl<'data, T: Sync + 'data> ParallelIterator for ChunksExact<'data, T> { - type Item = &'data [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Sync + 'data> IndexedParallelIterator for ChunksExact<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - self.slice.len() / self.chunk_size - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(ChunksExactProducer { - chunk_size: self.chunk_size, - slice: self.slice, - }) - } -} - -struct ChunksExactProducer<'data, T: Sync> { - chunk_size: usize, - slice: &'data [T], -} - -impl<'data, T: 'data + Sync> Producer for ChunksExactProducer<'data, T> { - type Item = &'data [T]; - type IntoIter = ::std::slice::ChunksExact<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.chunks_exact(self.chunk_size) - } - - fn split_at(self, index: usize) -> (Self, Self) { - let elem_index = index * self.chunk_size; - let (left, right) = self.slice.split_at(elem_index); - ( - ChunksExactProducer { - chunk_size: self.chunk_size, - slice: left, - }, - ChunksExactProducer { - chunk_size: self.chunk_size, - slice: right, - }, - ) - } -} - -/// Parallel iterator over mutable non-overlapping chunks of a slice -#[derive(Debug)] -pub struct ChunksMut<'data, T: Send> { - chunk_size: usize, - slice: &'data mut [T], -} - -impl<'data, T: Send> ChunksMut<'data, T> { - pub(super) fn new(chunk_size: usize, slice: &'data mut [T]) -> Self { - Self { chunk_size, slice } - } -} - -impl<'data, T: Send + 'data> ParallelIterator for ChunksMut<'data, T> { - type Item = &'data mut [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Send + 'data> IndexedParallelIterator for ChunksMut<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - div_round_up(self.slice.len(), self.chunk_size) - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(ChunksMutProducer { - chunk_size: self.chunk_size, - slice: self.slice, - }) - } -} - -struct ChunksMutProducer<'data, T: Send> { - chunk_size: usize, - slice: &'data mut [T], -} - -impl<'data, T: 'data + Send> Producer for ChunksMutProducer<'data, T> { - type Item = &'data mut [T]; - type IntoIter = ::std::slice::ChunksMut<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.chunks_mut(self.chunk_size) - } - - fn split_at(self, index: usize) -> (Self, Self) { - let elem_index = cmp::min(index * self.chunk_size, self.slice.len()); - let (left, right) = self.slice.split_at_mut(elem_index); - ( - ChunksMutProducer { - chunk_size: self.chunk_size, - slice: left, - }, - ChunksMutProducer { - chunk_size: self.chunk_size, - slice: right, - }, - ) - } -} - -/// Parallel iterator over mutable non-overlapping chunks of a slice -#[derive(Debug)] -pub struct ChunksExactMut<'data, T: Send> { - chunk_size: usize, - slice: &'data mut [T], - rem: &'data mut [T], -} - -impl<'data, T: Send> ChunksExactMut<'data, T> { - pub(super) fn new(chunk_size: usize, slice: &'data mut [T]) -> Self { - let rem_len = slice.len() % chunk_size; - let len = slice.len() - rem_len; - let (slice, rem) = slice.split_at_mut(len); - Self { - chunk_size, - slice, - rem, - } - } - - /// Return the remainder of the original slice that is not going to be - /// returned by the iterator. The returned slice has at most `chunk_size-1` - /// elements. - /// - /// Note that this has to consume `self` to return the original lifetime of - /// the data, which prevents this from actually being used as a parallel - /// iterator since that also consumes. This method is provided for parity - /// with `std::iter::ChunksExactMut`, but consider calling `remainder()` or - /// `take_remainder()` as alternatives. - pub fn into_remainder(self) -> &'data mut [T] { - self.rem - } - - /// Return the remainder of the original slice that is not going to be - /// returned by the iterator. The returned slice has at most `chunk_size-1` - /// elements. - /// - /// Consider `take_remainder()` if you need access to the data with its - /// original lifetime, rather than borrowing through `&mut self` here. - pub fn remainder(&mut self) -> &mut [T] { - self.rem - } - - /// Return the remainder of the original slice that is not going to be - /// returned by the iterator. The returned slice has at most `chunk_size-1` - /// elements. Subsequent calls will return an empty slice. - pub fn take_remainder(&mut self) -> &'data mut [T] { - std::mem::take(&mut self.rem) - } -} - -impl<'data, T: Send + 'data> ParallelIterator for ChunksExactMut<'data, T> { - type Item = &'data mut [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Send + 'data> IndexedParallelIterator for ChunksExactMut<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - self.slice.len() / self.chunk_size - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(ChunksExactMutProducer { - chunk_size: self.chunk_size, - slice: self.slice, - }) - } -} - -struct ChunksExactMutProducer<'data, T: Send> { - chunk_size: usize, - slice: &'data mut [T], -} - -impl<'data, T: 'data + Send> Producer for ChunksExactMutProducer<'data, T> { - type Item = &'data mut [T]; - type IntoIter = ::std::slice::ChunksExactMut<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.chunks_exact_mut(self.chunk_size) - } - - fn split_at(self, index: usize) -> (Self, Self) { - let elem_index = index * self.chunk_size; - let (left, right) = self.slice.split_at_mut(elem_index); - ( - ChunksExactMutProducer { - chunk_size: self.chunk_size, - slice: left, - }, - ChunksExactMutProducer { - chunk_size: self.chunk_size, - slice: right, - }, - ) - } -} diff --git a/vendor/rayon/src/slice/mergesort.rs b/vendor/rayon/src/slice/mergesort.rs deleted file mode 100644 index fec309d..0000000 --- a/vendor/rayon/src/slice/mergesort.rs +++ /dev/null @@ -1,755 +0,0 @@ -//! Parallel merge sort. -//! -//! This implementation is copied verbatim from `std::slice::sort` and then parallelized. -//! The only difference from the original is that the sequential `mergesort` returns -//! `MergesortResult` and leaves descending arrays intact. - -use crate::iter::*; -use crate::slice::ParallelSliceMut; -use crate::SendPtr; -use std::mem; -use std::mem::size_of; -use std::ptr; -use std::slice; - -unsafe fn get_and_increment<T>(ptr: &mut *mut T) -> *mut T { - let old = *ptr; - *ptr = ptr.offset(1); - old -} - -unsafe fn decrement_and_get<T>(ptr: &mut *mut T) -> *mut T { - *ptr = ptr.offset(-1); - *ptr -} - -/// When dropped, copies from `src` into `dest` a sequence of length `len`. -struct CopyOnDrop<T> { - src: *const T, - dest: *mut T, - len: usize, -} - -impl<T> Drop for CopyOnDrop<T> { - fn drop(&mut self) { - unsafe { - ptr::copy_nonoverlapping(self.src, self.dest, self.len); - } - } -} - -/// Inserts `v[0]` into pre-sorted sequence `v[1..]` so that whole `v[..]` becomes sorted. -/// -/// This is the integral subroutine of insertion sort. -fn insert_head<T, F>(v: &mut [T], is_less: &F) -where - F: Fn(&T, &T) -> bool, -{ - if v.len() >= 2 && is_less(&v[1], &v[0]) { - unsafe { - // There are three ways to implement insertion here: - // - // 1. Swap adjacent elements until the first one gets to its final destination. - // However, this way we copy data around more than is necessary. If elements are big - // structures (costly to copy), this method will be slow. - // - // 2. Iterate until the right place for the first element is found. Then shift the - // elements succeeding it to make room for it and finally place it into the - // remaining hole. This is a good method. - // - // 3. Copy the first element into a temporary variable. Iterate until the right place - // for it is found. As we go along, copy every traversed element into the slot - // preceding it. Finally, copy data from the temporary variable into the remaining - // hole. This method is very good. Benchmarks demonstrated slightly better - // performance than with the 2nd method. - // - // All methods were benchmarked, and the 3rd showed best results. So we chose that one. - let tmp = mem::ManuallyDrop::new(ptr::read(&v[0])); - - // Intermediate state of the insertion process is always tracked by `hole`, which - // serves two purposes: - // 1. Protects integrity of `v` from panics in `is_less`. - // 2. Fills the remaining hole in `v` in the end. - // - // Panic safety: - // - // If `is_less` panics at any point during the process, `hole` will get dropped and - // fill the hole in `v` with `tmp`, thus ensuring that `v` still holds every object it - // initially held exactly once. - let mut hole = InsertionHole { - src: &*tmp, - dest: &mut v[1], - }; - ptr::copy_nonoverlapping(&v[1], &mut v[0], 1); - - for i in 2..v.len() { - if !is_less(&v[i], &*tmp) { - break; - } - ptr::copy_nonoverlapping(&v[i], &mut v[i - 1], 1); - hole.dest = &mut v[i]; - } - // `hole` gets dropped and thus copies `tmp` into the remaining hole in `v`. - } - } - - // When dropped, copies from `src` into `dest`. - struct InsertionHole<T> { - src: *const T, - dest: *mut T, - } - - impl<T> Drop for InsertionHole<T> { - fn drop(&mut self) { - unsafe { - ptr::copy_nonoverlapping(self.src, self.dest, 1); - } - } - } -} - -/// Merges non-decreasing runs `v[..mid]` and `v[mid..]` using `buf` as temporary storage, and -/// stores the result into `v[..]`. -/// -/// # Safety -/// -/// The two slices must be non-empty and `mid` must be in bounds. Buffer `buf` must be long enough -/// to hold a copy of the shorter slice. Also, `T` must not be a zero-sized type. -unsafe fn merge<T, F>(v: &mut [T], mid: usize, buf: *mut T, is_less: &F) -where - F: Fn(&T, &T) -> bool, -{ - let len = v.len(); - let v = v.as_mut_ptr(); - let v_mid = v.add(mid); - let v_end = v.add(len); - - // The merge process first copies the shorter run into `buf`. Then it traces the newly copied - // run and the longer run forwards (or backwards), comparing their next unconsumed elements and - // copying the lesser (or greater) one into `v`. - // - // As soon as the shorter run is fully consumed, the process is done. If the longer run gets - // consumed first, then we must copy whatever is left of the shorter run into the remaining - // hole in `v`. - // - // Intermediate state of the process is always tracked by `hole`, which serves two purposes: - // 1. Protects integrity of `v` from panics in `is_less`. - // 2. Fills the remaining hole in `v` if the longer run gets consumed first. - // - // Panic safety: - // - // If `is_less` panics at any point during the process, `hole` will get dropped and fill the - // hole in `v` with the unconsumed range in `buf`, thus ensuring that `v` still holds every - // object it initially held exactly once. - let mut hole; - - if mid <= len - mid { - // The left run is shorter. - ptr::copy_nonoverlapping(v, buf, mid); - hole = MergeHole { - start: buf, - end: buf.add(mid), - dest: v, - }; - - // Initially, these pointers point to the beginnings of their arrays. - let left = &mut hole.start; - let mut right = v_mid; - let out = &mut hole.dest; - - while *left < hole.end && right < v_end { - // Consume the lesser side. - // If equal, prefer the left run to maintain stability. - let to_copy = if is_less(&*right, &**left) { - get_and_increment(&mut right) - } else { - get_and_increment(left) - }; - ptr::copy_nonoverlapping(to_copy, get_and_increment(out), 1); - } - } else { - // The right run is shorter. - ptr::copy_nonoverlapping(v_mid, buf, len - mid); - hole = MergeHole { - start: buf, - end: buf.add(len - mid), - dest: v_mid, - }; - - // Initially, these pointers point past the ends of their arrays. - let left = &mut hole.dest; - let right = &mut hole.end; - let mut out = v_end; - - while v < *left && buf < *right { - // Consume the greater side. - // If equal, prefer the right run to maintain stability. - let to_copy = if is_less(&*right.offset(-1), &*left.offset(-1)) { - decrement_and_get(left) - } else { - decrement_and_get(right) - }; - ptr::copy_nonoverlapping(to_copy, decrement_and_get(&mut out), 1); - } - } - // Finally, `hole` gets dropped. If the shorter run was not fully consumed, whatever remains of - // it will now be copied into the hole in `v`. - - // When dropped, copies the range `start..end` into `dest..`. - struct MergeHole<T> { - start: *mut T, - end: *mut T, - dest: *mut T, - } - - impl<T> Drop for MergeHole<T> { - fn drop(&mut self) { - // `T` is not a zero-sized type, so it's okay to divide by its size. - unsafe { - let len = self.end.offset_from(self.start) as usize; - ptr::copy_nonoverlapping(self.start, self.dest, len); - } - } - } -} - -/// The result of merge sort. -#[must_use] -#[derive(Clone, Copy, PartialEq, Eq)] -enum MergesortResult { - /// The slice has already been sorted. - NonDescending, - /// The slice has been descending and therefore it was left intact. - Descending, - /// The slice was sorted. - Sorted, -} - -/// A sorted run that starts at index `start` and is of length `len`. -#[derive(Clone, Copy)] -struct Run { - start: usize, - len: usize, -} - -/// Examines the stack of runs and identifies the next pair of runs to merge. More specifically, -/// if `Some(r)` is returned, that means `runs[r]` and `runs[r + 1]` must be merged next. If the -/// algorithm should continue building a new run instead, `None` is returned. -/// -/// TimSort is infamous for its buggy implementations, as described here: -/// http://envisage-project.eu/timsort-specification-and-verification/ -/// -/// The gist of the story is: we must enforce the invariants on the top four runs on the stack. -/// Enforcing them on just top three is not sufficient to ensure that the invariants will still -/// hold for *all* runs in the stack. -/// -/// This function correctly checks invariants for the top four runs. Additionally, if the top -/// run starts at index 0, it will always demand a merge operation until the stack is fully -/// collapsed, in order to complete the sort. -#[inline] -fn collapse(runs: &[Run]) -> Option<usize> { - let n = runs.len(); - - if n >= 2 - && (runs[n - 1].start == 0 - || runs[n - 2].len <= runs[n - 1].len - || (n >= 3 && runs[n - 3].len <= runs[n - 2].len + runs[n - 1].len) - || (n >= 4 && runs[n - 4].len <= runs[n - 3].len + runs[n - 2].len)) - { - if n >= 3 && runs[n - 3].len < runs[n - 1].len { - Some(n - 3) - } else { - Some(n - 2) - } - } else { - None - } -} - -/// Sorts a slice using merge sort, unless it is already in descending order. -/// -/// This function doesn't modify the slice if it is already non-descending or descending. -/// Otherwise, it sorts the slice into non-descending order. -/// -/// This merge sort borrows some (but not all) ideas from TimSort, which is described in detail -/// [here](https://github.com/python/cpython/blob/main/Objects/listsort.txt). -/// -/// The algorithm identifies strictly descending and non-descending subsequences, which are called -/// natural runs. There is a stack of pending runs yet to be merged. Each newly found run is pushed -/// onto the stack, and then some pairs of adjacent runs are merged until these two invariants are -/// satisfied: -/// -/// 1. for every `i` in `1..runs.len()`: `runs[i - 1].len > runs[i].len` -/// 2. for every `i` in `2..runs.len()`: `runs[i - 2].len > runs[i - 1].len + runs[i].len` -/// -/// The invariants ensure that the total running time is *O*(*n* \* log(*n*)) worst-case. -/// -/// # Safety -/// -/// The argument `buf` is used as a temporary buffer and must be at least as long as `v`. -unsafe fn mergesort<T, F>(v: &mut [T], buf: *mut T, is_less: &F) -> MergesortResult -where - T: Send, - F: Fn(&T, &T) -> bool + Sync, -{ - // Very short runs are extended using insertion sort to span at least this many elements. - const MIN_RUN: usize = 10; - - let len = v.len(); - - // In order to identify natural runs in `v`, we traverse it backwards. That might seem like a - // strange decision, but consider the fact that merges more often go in the opposite direction - // (forwards). According to benchmarks, merging forwards is slightly faster than merging - // backwards. To conclude, identifying runs by traversing backwards improves performance. - let mut runs = vec![]; - let mut end = len; - while end > 0 { - // Find the next natural run, and reverse it if it's strictly descending. - let mut start = end - 1; - - if start > 0 { - start -= 1; - - if is_less(v.get_unchecked(start + 1), v.get_unchecked(start)) { - while start > 0 && is_less(v.get_unchecked(start), v.get_unchecked(start - 1)) { - start -= 1; - } - - // If this descending run covers the whole slice, return immediately. - if start == 0 && end == len { - return MergesortResult::Descending; - } else { - v[start..end].reverse(); - } - } else { - while start > 0 && !is_less(v.get_unchecked(start), v.get_unchecked(start - 1)) { - start -= 1; - } - - // If this non-descending run covers the whole slice, return immediately. - if end - start == len { - return MergesortResult::NonDescending; - } - } - } - - // Insert some more elements into the run if it's too short. Insertion sort is faster than - // merge sort on short sequences, so this significantly improves performance. - while start > 0 && end - start < MIN_RUN { - start -= 1; - insert_head(&mut v[start..end], &is_less); - } - - // Push this run onto the stack. - runs.push(Run { - start, - len: end - start, - }); - end = start; - - // Merge some pairs of adjacent runs to satisfy the invariants. - while let Some(r) = collapse(&runs) { - let left = runs[r + 1]; - let right = runs[r]; - merge( - &mut v[left.start..right.start + right.len], - left.len, - buf, - &is_less, - ); - - runs[r] = Run { - start: left.start, - len: left.len + right.len, - }; - runs.remove(r + 1); - } - } - - // Finally, exactly one run must remain in the stack. - debug_assert!(runs.len() == 1 && runs[0].start == 0 && runs[0].len == len); - - // The original order of the slice was neither non-descending nor descending. - MergesortResult::Sorted -} - -//////////////////////////////////////////////////////////////////////////// -// Everything above this line is copied from `std::slice::sort` (with very minor tweaks). -// Everything below this line is parallelization. -//////////////////////////////////////////////////////////////////////////// - -/// Splits two sorted slices so that they can be merged in parallel. -/// -/// Returns two indices `(a, b)` so that slices `left[..a]` and `right[..b]` come before -/// `left[a..]` and `right[b..]`. -fn split_for_merge<T, F>(left: &[T], right: &[T], is_less: &F) -> (usize, usize) -where - F: Fn(&T, &T) -> bool, -{ - let left_len = left.len(); - let right_len = right.len(); - - if left_len >= right_len { - let left_mid = left_len / 2; - - // Find the first element in `right` that is greater than or equal to `left[left_mid]`. - let mut a = 0; - let mut b = right_len; - while a < b { - let m = a + (b - a) / 2; - if is_less(&right[m], &left[left_mid]) { - a = m + 1; - } else { - b = m; - } - } - - (left_mid, a) - } else { - let right_mid = right_len / 2; - - // Find the first element in `left` that is greater than `right[right_mid]`. - let mut a = 0; - let mut b = left_len; - while a < b { - let m = a + (b - a) / 2; - if is_less(&right[right_mid], &left[m]) { - b = m; - } else { - a = m + 1; - } - } - - (a, right_mid) - } -} - -/// Merges slices `left` and `right` in parallel and stores the result into `dest`. -/// -/// # Safety -/// -/// The `dest` pointer must have enough space to store the result. -/// -/// Even if `is_less` panics at any point during the merge process, this function will fully copy -/// all elements from `left` and `right` into `dest` (not necessarily in sorted order). -unsafe fn par_merge<T, F>(left: &mut [T], right: &mut [T], dest: *mut T, is_less: &F) -where - T: Send, - F: Fn(&T, &T) -> bool + Sync, -{ - // Slices whose lengths sum up to this value are merged sequentially. This number is slightly - // larger than `CHUNK_LENGTH`, and the reason is that merging is faster than merge sorting, so - // merging needs a bit coarser granularity in order to hide the overhead of Rayon's task - // scheduling. - const MAX_SEQUENTIAL: usize = 5000; - - let left_len = left.len(); - let right_len = right.len(); - - // Intermediate state of the merge process, which serves two purposes: - // 1. Protects integrity of `dest` from panics in `is_less`. - // 2. Copies the remaining elements as soon as one of the two sides is exhausted. - // - // Panic safety: - // - // If `is_less` panics at any point during the merge process, `s` will get dropped and copy the - // remaining parts of `left` and `right` into `dest`. - let mut s = State { - left_start: left.as_mut_ptr(), - left_end: left.as_mut_ptr().add(left_len), - right_start: right.as_mut_ptr(), - right_end: right.as_mut_ptr().add(right_len), - dest, - }; - - if left_len == 0 || right_len == 0 || left_len + right_len < MAX_SEQUENTIAL { - while s.left_start < s.left_end && s.right_start < s.right_end { - // Consume the lesser side. - // If equal, prefer the left run to maintain stability. - let to_copy = if is_less(&*s.right_start, &*s.left_start) { - get_and_increment(&mut s.right_start) - } else { - get_and_increment(&mut s.left_start) - }; - ptr::copy_nonoverlapping(to_copy, get_and_increment(&mut s.dest), 1); - } - } else { - // Function `split_for_merge` might panic. If that happens, `s` will get destructed and copy - // the whole `left` and `right` into `dest`. - let (left_mid, right_mid) = split_for_merge(left, right, is_less); - let (left_l, left_r) = left.split_at_mut(left_mid); - let (right_l, right_r) = right.split_at_mut(right_mid); - - // Prevent the destructor of `s` from running. Rayon will ensure that both calls to - // `par_merge` happen. If one of the two calls panics, they will ensure that elements still - // get copied into `dest_left` and `dest_right``. - mem::forget(s); - - // Wrap pointers in SendPtr so that they can be sent to another thread - // See the documentation of SendPtr for a full explanation - let dest_l = SendPtr(dest); - let dest_r = SendPtr(dest.add(left_l.len() + right_l.len())); - rayon_core::join( - move || par_merge(left_l, right_l, dest_l.get(), is_less), - move || par_merge(left_r, right_r, dest_r.get(), is_less), - ); - } - // Finally, `s` gets dropped if we used sequential merge, thus copying the remaining elements - // all at once. - - // When dropped, copies arrays `left_start..left_end` and `right_start..right_end` into `dest`, - // in that order. - struct State<T> { - left_start: *mut T, - left_end: *mut T, - right_start: *mut T, - right_end: *mut T, - dest: *mut T, - } - - impl<T> Drop for State<T> { - fn drop(&mut self) { - let size = size_of::<T>(); - let left_len = (self.left_end as usize - self.left_start as usize) / size; - let right_len = (self.right_end as usize - self.right_start as usize) / size; - - // Copy array `left`, followed by `right`. - unsafe { - ptr::copy_nonoverlapping(self.left_start, self.dest, left_len); - self.dest = self.dest.add(left_len); - ptr::copy_nonoverlapping(self.right_start, self.dest, right_len); - } - } - } -} - -/// Recursively merges pre-sorted chunks inside `v`. -/// -/// Chunks of `v` are stored in `chunks` as intervals (inclusive left and exclusive right bound). -/// Argument `buf` is an auxiliary buffer that will be used during the procedure. -/// If `into_buf` is true, the result will be stored into `buf`, otherwise it will be in `v`. -/// -/// # Safety -/// -/// The number of chunks must be positive and they must be adjacent: the right bound of each chunk -/// must equal the left bound of the following chunk. -/// -/// The buffer must be at least as long as `v`. -unsafe fn recurse<T, F>( - v: *mut T, - buf: *mut T, - chunks: &[(usize, usize)], - into_buf: bool, - is_less: &F, -) where - T: Send, - F: Fn(&T, &T) -> bool + Sync, -{ - let len = chunks.len(); - debug_assert!(len > 0); - - // Base case of the algorithm. - // If only one chunk is remaining, there's no more work to split and merge. - if len == 1 { - if into_buf { - // Copy the chunk from `v` into `buf`. - let (start, end) = chunks[0]; - let src = v.add(start); - let dest = buf.add(start); - ptr::copy_nonoverlapping(src, dest, end - start); - } - return; - } - - // Split the chunks into two halves. - let (start, _) = chunks[0]; - let (mid, _) = chunks[len / 2]; - let (_, end) = chunks[len - 1]; - let (left, right) = chunks.split_at(len / 2); - - // After recursive calls finish we'll have to merge chunks `(start, mid)` and `(mid, end)` from - // `src` into `dest`. If the current invocation has to store the result into `buf`, we'll - // merge chunks from `v` into `buf`, and vice versa. - // - // Recursive calls flip `into_buf` at each level of recursion. More concretely, `par_merge` - // merges chunks from `buf` into `v` at the first level, from `v` into `buf` at the second - // level etc. - let (src, dest) = if into_buf { (v, buf) } else { (buf, v) }; - - // Panic safety: - // - // If `is_less` panics at any point during the recursive calls, the destructor of `guard` will - // be executed, thus copying everything from `src` into `dest`. This way we ensure that all - // chunks are in fact copied into `dest`, even if the merge process doesn't finish. - let guard = CopyOnDrop { - src: src.add(start), - dest: dest.add(start), - len: end - start, - }; - - // Wrap pointers in SendPtr so that they can be sent to another thread - // See the documentation of SendPtr for a full explanation - let v = SendPtr(v); - let buf = SendPtr(buf); - rayon_core::join( - move || recurse(v.get(), buf.get(), left, !into_buf, is_less), - move || recurse(v.get(), buf.get(), right, !into_buf, is_less), - ); - - // Everything went all right - recursive calls didn't panic. - // Forget the guard in order to prevent its destructor from running. - mem::forget(guard); - - // Merge chunks `(start, mid)` and `(mid, end)` from `src` into `dest`. - let src_left = slice::from_raw_parts_mut(src.add(start), mid - start); - let src_right = slice::from_raw_parts_mut(src.add(mid), end - mid); - par_merge(src_left, src_right, dest.add(start), is_less); -} - -/// Sorts `v` using merge sort in parallel. -/// -/// The algorithm is stable, allocates memory, and `O(n log n)` worst-case. -/// The allocated temporary buffer is of the same length as is `v`. -pub(super) fn par_mergesort<T, F>(v: &mut [T], is_less: F) -where - T: Send, - F: Fn(&T, &T) -> bool + Sync, -{ - // Slices of up to this length get sorted using insertion sort in order to avoid the cost of - // buffer allocation. - const MAX_INSERTION: usize = 20; - // The length of initial chunks. This number is as small as possible but so that the overhead - // of Rayon's task scheduling is still negligible. - const CHUNK_LENGTH: usize = 2000; - - // Sorting has no meaningful behavior on zero-sized types. - if size_of::<T>() == 0 { - return; - } - - let len = v.len(); - - // Short slices get sorted in-place via insertion sort to avoid allocations. - if len <= MAX_INSERTION { - if len >= 2 { - for i in (0..len - 1).rev() { - insert_head(&mut v[i..], &is_less); - } - } - return; - } - - // Allocate a buffer to use as scratch memory. We keep the length 0 so we can keep in it - // shallow copies of the contents of `v` without risking the dtors running on copies if - // `is_less` panics. - let mut buf = Vec::<T>::with_capacity(len); - let buf = buf.as_mut_ptr(); - - // If the slice is not longer than one chunk would be, do sequential merge sort and return. - if len <= CHUNK_LENGTH { - let res = unsafe { mergesort(v, buf, &is_less) }; - if res == MergesortResult::Descending { - v.reverse(); - } - return; - } - - // Split the slice into chunks and merge sort them in parallel. - // However, descending chunks will not be sorted - they will be simply left intact. - let mut iter = { - // Wrap pointer in SendPtr so that it can be sent to another thread - // See the documentation of SendPtr for a full explanation - let buf = SendPtr(buf); - let is_less = &is_less; - - v.par_chunks_mut(CHUNK_LENGTH) - .with_max_len(1) - .enumerate() - .map(move |(i, chunk)| { - let l = CHUNK_LENGTH * i; - let r = l + chunk.len(); - unsafe { - let buf = buf.get().add(l); - (l, r, mergesort(chunk, buf, is_less)) - } - }) - .collect::<Vec<_>>() - .into_iter() - .peekable() - }; - - // Now attempt to concatenate adjacent chunks that were left intact. - let mut chunks = Vec::with_capacity(iter.len()); - - while let Some((a, mut b, res)) = iter.next() { - // If this chunk was not modified by the sort procedure... - if res != MergesortResult::Sorted { - while let Some(&(x, y, r)) = iter.peek() { - // If the following chunk is of the same type and can be concatenated... - if r == res && (r == MergesortResult::Descending) == is_less(&v[x], &v[x - 1]) { - // Concatenate them. - b = y; - iter.next(); - } else { - break; - } - } - } - - // Descending chunks must be reversed. - if res == MergesortResult::Descending { - v[a..b].reverse(); - } - - chunks.push((a, b)); - } - - // All chunks are properly sorted. - // Now we just have to merge them together. - unsafe { - recurse(v.as_mut_ptr(), buf, &chunks, false, &is_less); - } -} - -#[cfg(test)] -mod tests { - use super::split_for_merge; - use rand::distributions::Uniform; - use rand::{thread_rng, Rng}; - - #[test] - fn test_split_for_merge() { - fn check(left: &[u32], right: &[u32]) { - let (l, r) = split_for_merge(left, right, &|&a, &b| a < b); - assert!(left[..l] - .iter() - .all(|&x| right[r..].iter().all(|&y| x <= y))); - assert!(right[..r].iter().all(|&x| left[l..].iter().all(|&y| x < y))); - } - - check(&[1, 2, 2, 2, 2, 3], &[1, 2, 2, 2, 2, 3]); - check(&[1, 2, 2, 2, 2, 3], &[]); - check(&[], &[1, 2, 2, 2, 2, 3]); - - let rng = &mut thread_rng(); - - for _ in 0..100 { - let limit: u32 = rng.gen_range(1..21); - let left_len: usize = rng.gen_range(0..20); - let right_len: usize = rng.gen_range(0..20); - - let mut left = rng - .sample_iter(&Uniform::new(0, limit)) - .take(left_len) - .collect::<Vec<_>>(); - let mut right = rng - .sample_iter(&Uniform::new(0, limit)) - .take(right_len) - .collect::<Vec<_>>(); - - left.sort(); - right.sort(); - check(&left, &right); - } - } -} diff --git a/vendor/rayon/src/slice/mod.rs b/vendor/rayon/src/slice/mod.rs deleted file mode 100644 index dab56de..0000000 --- a/vendor/rayon/src/slice/mod.rs +++ /dev/null @@ -1,1041 +0,0 @@ -//! Parallel iterator types for [slices][std::slice] -//! -//! You will rarely need to interact with this module directly unless you need -//! to name one of the iterator types. -//! -//! [std::slice]: https://doc.rust-lang.org/stable/std/slice/ - -mod chunks; -mod mergesort; -mod quicksort; -mod rchunks; - -mod test; - -use self::mergesort::par_mergesort; -use self::quicksort::par_quicksort; -use crate::iter::plumbing::*; -use crate::iter::*; -use crate::split_producer::*; -use std::cmp; -use std::cmp::Ordering; -use std::fmt::{self, Debug}; -use std::mem; - -pub use self::chunks::{Chunks, ChunksExact, ChunksExactMut, ChunksMut}; -pub use self::rchunks::{RChunks, RChunksExact, RChunksExactMut, RChunksMut}; - -/// Parallel extensions for slices. -pub trait ParallelSlice<T: Sync> { - /// Returns a plain slice, which is used to implement the rest of the - /// parallel methods. - fn as_parallel_slice(&self) -> &[T]; - - /// Returns a parallel iterator over subslices separated by elements that - /// match the separator. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let smallest = [1, 2, 3, 0, 2, 4, 8, 0, 3, 6, 9] - /// .par_split(|i| *i == 0) - /// .map(|numbers| numbers.iter().min().unwrap()) - /// .min(); - /// assert_eq!(Some(&1), smallest); - /// ``` - fn par_split<P>(&self, separator: P) -> Split<'_, T, P> - where - P: Fn(&T) -> bool + Sync + Send, - { - Split { - slice: self.as_parallel_slice(), - separator, - } - } - - /// Returns a parallel iterator over all contiguous windows of length - /// `window_size`. The windows overlap. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let windows: Vec<_> = [1, 2, 3].par_windows(2).collect(); - /// assert_eq!(vec![[1, 2], [2, 3]], windows); - /// ``` - fn par_windows(&self, window_size: usize) -> Windows<'_, T> { - Windows { - window_size, - slice: self.as_parallel_slice(), - } - } - - /// Returns a parallel iterator over at most `chunk_size` elements of - /// `self` at a time. The chunks do not overlap. - /// - /// If the number of elements in the iterator is not divisible by - /// `chunk_size`, the last chunk may be shorter than `chunk_size`. All - /// other chunks will have that exact length. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let chunks: Vec<_> = [1, 2, 3, 4, 5].par_chunks(2).collect(); - /// assert_eq!(chunks, vec![&[1, 2][..], &[3, 4], &[5]]); - /// ``` - #[track_caller] - fn par_chunks(&self, chunk_size: usize) -> Chunks<'_, T> { - assert!(chunk_size != 0, "chunk_size must not be zero"); - Chunks::new(chunk_size, self.as_parallel_slice()) - } - - /// Returns a parallel iterator over `chunk_size` elements of - /// `self` at a time. The chunks do not overlap. - /// - /// If `chunk_size` does not divide the length of the slice, then the - /// last up to `chunk_size-1` elements will be omitted and can be - /// retrieved from the remainder function of the iterator. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let chunks: Vec<_> = [1, 2, 3, 4, 5].par_chunks_exact(2).collect(); - /// assert_eq!(chunks, vec![&[1, 2][..], &[3, 4]]); - /// ``` - #[track_caller] - fn par_chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T> { - assert!(chunk_size != 0, "chunk_size must not be zero"); - ChunksExact::new(chunk_size, self.as_parallel_slice()) - } - - /// Returns a parallel iterator over at most `chunk_size` elements of `self` at a time, - /// starting at the end. The chunks do not overlap. - /// - /// If the number of elements in the iterator is not divisible by - /// `chunk_size`, the last chunk may be shorter than `chunk_size`. All - /// other chunks will have that exact length. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let chunks: Vec<_> = [1, 2, 3, 4, 5].par_rchunks(2).collect(); - /// assert_eq!(chunks, vec![&[4, 5][..], &[2, 3], &[1]]); - /// ``` - #[track_caller] - fn par_rchunks(&self, chunk_size: usize) -> RChunks<'_, T> { - assert!(chunk_size != 0, "chunk_size must not be zero"); - RChunks::new(chunk_size, self.as_parallel_slice()) - } - - /// Returns a parallel iterator over `chunk_size` elements of `self` at a time, - /// starting at the end. The chunks do not overlap. - /// - /// If `chunk_size` does not divide the length of the slice, then the - /// last up to `chunk_size-1` elements will be omitted and can be - /// retrieved from the remainder function of the iterator. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let chunks: Vec<_> = [1, 2, 3, 4, 5].par_rchunks_exact(2).collect(); - /// assert_eq!(chunks, vec![&[4, 5][..], &[2, 3]]); - /// ``` - #[track_caller] - fn par_rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T> { - assert!(chunk_size != 0, "chunk_size must not be zero"); - RChunksExact::new(chunk_size, self.as_parallel_slice()) - } -} - -impl<T: Sync> ParallelSlice<T> for [T] { - #[inline] - fn as_parallel_slice(&self) -> &[T] { - self - } -} - -/// Parallel extensions for mutable slices. -pub trait ParallelSliceMut<T: Send> { - /// Returns a plain mutable slice, which is used to implement the rest of - /// the parallel methods. - fn as_parallel_slice_mut(&mut self) -> &mut [T]; - - /// Returns a parallel iterator over mutable subslices separated by - /// elements that match the separator. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let mut array = [1, 2, 3, 0, 2, 4, 8, 0, 3, 6, 9]; - /// array.par_split_mut(|i| *i == 0) - /// .for_each(|slice| slice.reverse()); - /// assert_eq!(array, [3, 2, 1, 0, 8, 4, 2, 0, 9, 6, 3]); - /// ``` - fn par_split_mut<P>(&mut self, separator: P) -> SplitMut<'_, T, P> - where - P: Fn(&T) -> bool + Sync + Send, - { - SplitMut { - slice: self.as_parallel_slice_mut(), - separator, - } - } - - /// Returns a parallel iterator over at most `chunk_size` elements of - /// `self` at a time. The chunks are mutable and do not overlap. - /// - /// If the number of elements in the iterator is not divisible by - /// `chunk_size`, the last chunk may be shorter than `chunk_size`. All - /// other chunks will have that exact length. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let mut array = [1, 2, 3, 4, 5]; - /// array.par_chunks_mut(2) - /// .for_each(|slice| slice.reverse()); - /// assert_eq!(array, [2, 1, 4, 3, 5]); - /// ``` - #[track_caller] - fn par_chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T> { - assert!(chunk_size != 0, "chunk_size must not be zero"); - ChunksMut::new(chunk_size, self.as_parallel_slice_mut()) - } - - /// Returns a parallel iterator over `chunk_size` elements of - /// `self` at a time. The chunks are mutable and do not overlap. - /// - /// If `chunk_size` does not divide the length of the slice, then the - /// last up to `chunk_size-1` elements will be omitted and can be - /// retrieved from the remainder function of the iterator. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let mut array = [1, 2, 3, 4, 5]; - /// array.par_chunks_exact_mut(3) - /// .for_each(|slice| slice.reverse()); - /// assert_eq!(array, [3, 2, 1, 4, 5]); - /// ``` - #[track_caller] - fn par_chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T> { - assert!(chunk_size != 0, "chunk_size must not be zero"); - ChunksExactMut::new(chunk_size, self.as_parallel_slice_mut()) - } - - /// Returns a parallel iterator over at most `chunk_size` elements of `self` at a time, - /// starting at the end. The chunks are mutable and do not overlap. - /// - /// If the number of elements in the iterator is not divisible by - /// `chunk_size`, the last chunk may be shorter than `chunk_size`. All - /// other chunks will have that exact length. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let mut array = [1, 2, 3, 4, 5]; - /// array.par_rchunks_mut(2) - /// .for_each(|slice| slice.reverse()); - /// assert_eq!(array, [1, 3, 2, 5, 4]); - /// ``` - #[track_caller] - fn par_rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T> { - assert!(chunk_size != 0, "chunk_size must not be zero"); - RChunksMut::new(chunk_size, self.as_parallel_slice_mut()) - } - - /// Returns a parallel iterator over `chunk_size` elements of `self` at a time, - /// starting at the end. The chunks are mutable and do not overlap. - /// - /// If `chunk_size` does not divide the length of the slice, then the - /// last up to `chunk_size-1` elements will be omitted and can be - /// retrieved from the remainder function of the iterator. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// let mut array = [1, 2, 3, 4, 5]; - /// array.par_rchunks_exact_mut(3) - /// .for_each(|slice| slice.reverse()); - /// assert_eq!(array, [1, 2, 5, 4, 3]); - /// ``` - #[track_caller] - fn par_rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T> { - assert!(chunk_size != 0, "chunk_size must not be zero"); - RChunksExactMut::new(chunk_size, self.as_parallel_slice_mut()) - } - - /// Sorts the slice in parallel. - /// - /// This sort is stable (i.e., does not reorder equal elements) and *O*(*n* \* log(*n*)) worst-case. - /// - /// When applicable, unstable sorting is preferred because it is generally faster than stable - /// sorting and it doesn't allocate auxiliary memory. - /// See [`par_sort_unstable`](#method.par_sort_unstable). - /// - /// # Current implementation - /// - /// The current algorithm is an adaptive merge sort inspired by - /// [timsort](https://en.wikipedia.org/wiki/Timsort). - /// It is designed to be very fast in cases where the slice is nearly sorted, or consists of - /// two or more sorted sequences concatenated one after another. - /// - /// Also, it allocates temporary storage the same size as `self`, but for very short slices a - /// non-allocating insertion sort is used instead. - /// - /// In order to sort the slice in parallel, the slice is first divided into smaller chunks and - /// all chunks are sorted in parallel. Then, adjacent chunks that together form non-descending - /// or descending runs are concatenated. Finally, the remaining chunks are merged together using - /// parallel subdivision of chunks and parallel merge operation. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// - /// let mut v = [-5, 4, 1, -3, 2]; - /// - /// v.par_sort(); - /// assert_eq!(v, [-5, -3, 1, 2, 4]); - /// ``` - fn par_sort(&mut self) - where - T: Ord, - { - par_mergesort(self.as_parallel_slice_mut(), T::lt); - } - - /// Sorts the slice in parallel with a comparator function. - /// - /// This sort is stable (i.e., does not reorder equal elements) and *O*(*n* \* log(*n*)) worst-case. - /// - /// The comparator function must define a total ordering for the elements in the slice. If - /// the ordering is not total, the order of the elements is unspecified. An order is a - /// total order if it is (for all `a`, `b` and `c`): - /// - /// * total and antisymmetric: exactly one of `a < b`, `a == b` or `a > b` is true, and - /// * transitive, `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`. - /// - /// For example, while [`f64`] doesn't implement [`Ord`] because `NaN != NaN`, we can use - /// `partial_cmp` as our sort function when we know the slice doesn't contain a `NaN`. - /// - /// ``` - /// use rayon::prelude::*; - /// - /// let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0]; - /// floats.par_sort_by(|a, b| a.partial_cmp(b).unwrap()); - /// assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]); - /// ``` - /// - /// When applicable, unstable sorting is preferred because it is generally faster than stable - /// sorting and it doesn't allocate auxiliary memory. - /// See [`par_sort_unstable_by`](#method.par_sort_unstable_by). - /// - /// # Current implementation - /// - /// The current algorithm is an adaptive merge sort inspired by - /// [timsort](https://en.wikipedia.org/wiki/Timsort). - /// It is designed to be very fast in cases where the slice is nearly sorted, or consists of - /// two or more sorted sequences concatenated one after another. - /// - /// Also, it allocates temporary storage the same size as `self`, but for very short slices a - /// non-allocating insertion sort is used instead. - /// - /// In order to sort the slice in parallel, the slice is first divided into smaller chunks and - /// all chunks are sorted in parallel. Then, adjacent chunks that together form non-descending - /// or descending runs are concatenated. Finally, the remaining chunks are merged together using - /// parallel subdivision of chunks and parallel merge operation. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// - /// let mut v = [5, 4, 1, 3, 2]; - /// v.par_sort_by(|a, b| a.cmp(b)); - /// assert_eq!(v, [1, 2, 3, 4, 5]); - /// - /// // reverse sorting - /// v.par_sort_by(|a, b| b.cmp(a)); - /// assert_eq!(v, [5, 4, 3, 2, 1]); - /// ``` - fn par_sort_by<F>(&mut self, compare: F) - where - F: Fn(&T, &T) -> Ordering + Sync, - { - par_mergesort(self.as_parallel_slice_mut(), |a, b| { - compare(a, b) == Ordering::Less - }); - } - - /// Sorts the slice in parallel with a key extraction function. - /// - /// This sort is stable (i.e., does not reorder equal elements) and *O*(*m* \* *n* \* log(*n*)) - /// worst-case, where the key function is *O*(*m*). - /// - /// For expensive key functions (e.g. functions that are not simple property accesses or - /// basic operations), [`par_sort_by_cached_key`](#method.par_sort_by_cached_key) is likely to - /// be significantly faster, as it does not recompute element keys. - /// - /// When applicable, unstable sorting is preferred because it is generally faster than stable - /// sorting and it doesn't allocate auxiliary memory. - /// See [`par_sort_unstable_by_key`](#method.par_sort_unstable_by_key). - /// - /// # Current implementation - /// - /// The current algorithm is an adaptive merge sort inspired by - /// [timsort](https://en.wikipedia.org/wiki/Timsort). - /// It is designed to be very fast in cases where the slice is nearly sorted, or consists of - /// two or more sorted sequences concatenated one after another. - /// - /// Also, it allocates temporary storage the same size as `self`, but for very short slices a - /// non-allocating insertion sort is used instead. - /// - /// In order to sort the slice in parallel, the slice is first divided into smaller chunks and - /// all chunks are sorted in parallel. Then, adjacent chunks that together form non-descending - /// or descending runs are concatenated. Finally, the remaining chunks are merged together using - /// parallel subdivision of chunks and parallel merge operation. - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// - /// let mut v = [-5i32, 4, 1, -3, 2]; - /// - /// v.par_sort_by_key(|k| k.abs()); - /// assert_eq!(v, [1, 2, -3, 4, -5]); - /// ``` - fn par_sort_by_key<K, F>(&mut self, f: F) - where - K: Ord, - F: Fn(&T) -> K + Sync, - { - par_mergesort(self.as_parallel_slice_mut(), |a, b| f(a).lt(&f(b))); - } - - /// Sorts the slice in parallel with a key extraction function. - /// - /// During sorting, the key function is called at most once per element, by using - /// temporary storage to remember the results of key evaluation. - /// The key function is called in parallel, so the order of calls is completely unspecified. - /// - /// This sort is stable (i.e., does not reorder equal elements) and *O*(*m* \* *n* + *n* \* log(*n*)) - /// worst-case, where the key function is *O*(*m*). - /// - /// For simple key functions (e.g., functions that are property accesses or - /// basic operations), [`par_sort_by_key`](#method.par_sort_by_key) is likely to be - /// faster. - /// - /// # Current implementation - /// - /// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters, - /// which combines the fast average case of randomized quicksort with the fast worst case of - /// heapsort, while achieving linear time on slices with certain patterns. It uses some - /// randomization to avoid degenerate cases, but with a fixed seed to always provide - /// deterministic behavior. - /// - /// In the worst case, the algorithm allocates temporary storage in a `Vec<(K, usize)>` the - /// length of the slice. - /// - /// All quicksorts work in two stages: partitioning into two halves followed by recursive - /// calls. The partitioning phase is sequential, but the two recursive calls are performed in - /// parallel. Finally, after sorting the cached keys, the item positions are updated sequentially. - /// - /// [pdqsort]: https://github.com/orlp/pdqsort - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// - /// let mut v = [-5i32, 4, 32, -3, 2]; - /// - /// v.par_sort_by_cached_key(|k| k.to_string()); - /// assert!(v == [-3, -5, 2, 32, 4]); - /// ``` - fn par_sort_by_cached_key<K, F>(&mut self, f: F) - where - F: Fn(&T) -> K + Sync, - K: Ord + Send, - { - let slice = self.as_parallel_slice_mut(); - let len = slice.len(); - if len < 2 { - return; - } - - // Helper macro for indexing our vector by the smallest possible type, to reduce allocation. - macro_rules! sort_by_key { - ($t:ty) => {{ - let mut indices: Vec<_> = slice - .par_iter_mut() - .enumerate() - .map(|(i, x)| (f(&*x), i as $t)) - .collect(); - // The elements of `indices` are unique, as they are indexed, so any sort will be - // stable with respect to the original slice. We use `sort_unstable` here because - // it requires less memory allocation. - indices.par_sort_unstable(); - for i in 0..len { - let mut index = indices[i].1; - while (index as usize) < i { - index = indices[index as usize].1; - } - indices[i].1 = index; - slice.swap(i, index as usize); - } - }}; - } - - let sz_u8 = mem::size_of::<(K, u8)>(); - let sz_u16 = mem::size_of::<(K, u16)>(); - let sz_u32 = mem::size_of::<(K, u32)>(); - let sz_usize = mem::size_of::<(K, usize)>(); - - if sz_u8 < sz_u16 && len <= (std::u8::MAX as usize) { - return sort_by_key!(u8); - } - if sz_u16 < sz_u32 && len <= (std::u16::MAX as usize) { - return sort_by_key!(u16); - } - if sz_u32 < sz_usize && len <= (std::u32::MAX as usize) { - return sort_by_key!(u32); - } - sort_by_key!(usize) - } - - /// Sorts the slice in parallel, but might not preserve the order of equal elements. - /// - /// This sort is unstable (i.e., may reorder equal elements), in-place - /// (i.e., does not allocate), and *O*(*n* \* log(*n*)) worst-case. - /// - /// # Current implementation - /// - /// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters, - /// which combines the fast average case of randomized quicksort with the fast worst case of - /// heapsort, while achieving linear time on slices with certain patterns. It uses some - /// randomization to avoid degenerate cases, but with a fixed seed to always provide - /// deterministic behavior. - /// - /// It is typically faster than stable sorting, except in a few special cases, e.g., when the - /// slice consists of several concatenated sorted sequences. - /// - /// All quicksorts work in two stages: partitioning into two halves followed by recursive - /// calls. The partitioning phase is sequential, but the two recursive calls are performed in - /// parallel. - /// - /// [pdqsort]: https://github.com/orlp/pdqsort - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// - /// let mut v = [-5, 4, 1, -3, 2]; - /// - /// v.par_sort_unstable(); - /// assert_eq!(v, [-5, -3, 1, 2, 4]); - /// ``` - fn par_sort_unstable(&mut self) - where - T: Ord, - { - par_quicksort(self.as_parallel_slice_mut(), T::lt); - } - - /// Sorts the slice in parallel with a comparator function, but might not preserve the order of - /// equal elements. - /// - /// This sort is unstable (i.e., may reorder equal elements), in-place - /// (i.e., does not allocate), and *O*(*n* \* log(*n*)) worst-case. - /// - /// The comparator function must define a total ordering for the elements in the slice. If - /// the ordering is not total, the order of the elements is unspecified. An order is a - /// total order if it is (for all `a`, `b` and `c`): - /// - /// * total and antisymmetric: exactly one of `a < b`, `a == b` or `a > b` is true, and - /// * transitive, `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`. - /// - /// For example, while [`f64`] doesn't implement [`Ord`] because `NaN != NaN`, we can use - /// `partial_cmp` as our sort function when we know the slice doesn't contain a `NaN`. - /// - /// ``` - /// use rayon::prelude::*; - /// - /// let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0]; - /// floats.par_sort_unstable_by(|a, b| a.partial_cmp(b).unwrap()); - /// assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]); - /// ``` - /// - /// # Current implementation - /// - /// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters, - /// which combines the fast average case of randomized quicksort with the fast worst case of - /// heapsort, while achieving linear time on slices with certain patterns. It uses some - /// randomization to avoid degenerate cases, but with a fixed seed to always provide - /// deterministic behavior. - /// - /// It is typically faster than stable sorting, except in a few special cases, e.g., when the - /// slice consists of several concatenated sorted sequences. - /// - /// All quicksorts work in two stages: partitioning into two halves followed by recursive - /// calls. The partitioning phase is sequential, but the two recursive calls are performed in - /// parallel. - /// - /// [pdqsort]: https://github.com/orlp/pdqsort - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// - /// let mut v = [5, 4, 1, 3, 2]; - /// v.par_sort_unstable_by(|a, b| a.cmp(b)); - /// assert_eq!(v, [1, 2, 3, 4, 5]); - /// - /// // reverse sorting - /// v.par_sort_unstable_by(|a, b| b.cmp(a)); - /// assert_eq!(v, [5, 4, 3, 2, 1]); - /// ``` - fn par_sort_unstable_by<F>(&mut self, compare: F) - where - F: Fn(&T, &T) -> Ordering + Sync, - { - par_quicksort(self.as_parallel_slice_mut(), |a, b| { - compare(a, b) == Ordering::Less - }); - } - - /// Sorts the slice in parallel with a key extraction function, but might not preserve the order - /// of equal elements. - /// - /// This sort is unstable (i.e., may reorder equal elements), in-place - /// (i.e., does not allocate), and *O*(m \* *n* \* log(*n*)) worst-case, - /// where the key function is *O*(*m*). - /// - /// # Current implementation - /// - /// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters, - /// which combines the fast average case of randomized quicksort with the fast worst case of - /// heapsort, while achieving linear time on slices with certain patterns. It uses some - /// randomization to avoid degenerate cases, but with a fixed seed to always provide - /// deterministic behavior. - /// - /// Due to its key calling strategy, `par_sort_unstable_by_key` is likely to be slower than - /// [`par_sort_by_cached_key`](#method.par_sort_by_cached_key) in cases where the key function - /// is expensive. - /// - /// All quicksorts work in two stages: partitioning into two halves followed by recursive - /// calls. The partitioning phase is sequential, but the two recursive calls are performed in - /// parallel. - /// - /// [pdqsort]: https://github.com/orlp/pdqsort - /// - /// # Examples - /// - /// ``` - /// use rayon::prelude::*; - /// - /// let mut v = [-5i32, 4, 1, -3, 2]; - /// - /// v.par_sort_unstable_by_key(|k| k.abs()); - /// assert_eq!(v, [1, 2, -3, 4, -5]); - /// ``` - fn par_sort_unstable_by_key<K, F>(&mut self, f: F) - where - K: Ord, - F: Fn(&T) -> K + Sync, - { - par_quicksort(self.as_parallel_slice_mut(), |a, b| f(a).lt(&f(b))); - } -} - -impl<T: Send> ParallelSliceMut<T> for [T] { - #[inline] - fn as_parallel_slice_mut(&mut self) -> &mut [T] { - self - } -} - -impl<'data, T: Sync + 'data> IntoParallelIterator for &'data [T] { - type Item = &'data T; - type Iter = Iter<'data, T>; - - fn into_par_iter(self) -> Self::Iter { - Iter { slice: self } - } -} - -impl<'data, T: Send + 'data> IntoParallelIterator for &'data mut [T] { - type Item = &'data mut T; - type Iter = IterMut<'data, T>; - - fn into_par_iter(self) -> Self::Iter { - IterMut { slice: self } - } -} - -/// Parallel iterator over immutable items in a slice -#[derive(Debug)] -pub struct Iter<'data, T: Sync> { - slice: &'data [T], -} - -impl<'data, T: Sync> Clone for Iter<'data, T> { - fn clone(&self) -> Self { - Iter { ..*self } - } -} - -impl<'data, T: Sync + 'data> ParallelIterator for Iter<'data, T> { - type Item = &'data T; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Sync + 'data> IndexedParallelIterator for Iter<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - self.slice.len() - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(IterProducer { slice: self.slice }) - } -} - -struct IterProducer<'data, T: Sync> { - slice: &'data [T], -} - -impl<'data, T: 'data + Sync> Producer for IterProducer<'data, T> { - type Item = &'data T; - type IntoIter = ::std::slice::Iter<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.iter() - } - - fn split_at(self, index: usize) -> (Self, Self) { - let (left, right) = self.slice.split_at(index); - (IterProducer { slice: left }, IterProducer { slice: right }) - } -} - -/// Parallel iterator over immutable overlapping windows of a slice -#[derive(Debug)] -pub struct Windows<'data, T: Sync> { - window_size: usize, - slice: &'data [T], -} - -impl<'data, T: Sync> Clone for Windows<'data, T> { - fn clone(&self) -> Self { - Windows { ..*self } - } -} - -impl<'data, T: Sync + 'data> ParallelIterator for Windows<'data, T> { - type Item = &'data [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Sync + 'data> IndexedParallelIterator for Windows<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - assert!(self.window_size >= 1); - self.slice.len().saturating_sub(self.window_size - 1) - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(WindowsProducer { - window_size: self.window_size, - slice: self.slice, - }) - } -} - -struct WindowsProducer<'data, T: Sync> { - window_size: usize, - slice: &'data [T], -} - -impl<'data, T: 'data + Sync> Producer for WindowsProducer<'data, T> { - type Item = &'data [T]; - type IntoIter = ::std::slice::Windows<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.windows(self.window_size) - } - - fn split_at(self, index: usize) -> (Self, Self) { - let left_index = cmp::min(self.slice.len(), index + (self.window_size - 1)); - let left = &self.slice[..left_index]; - let right = &self.slice[index..]; - ( - WindowsProducer { - window_size: self.window_size, - slice: left, - }, - WindowsProducer { - window_size: self.window_size, - slice: right, - }, - ) - } -} - -/// Parallel iterator over mutable items in a slice -#[derive(Debug)] -pub struct IterMut<'data, T: Send> { - slice: &'data mut [T], -} - -impl<'data, T: Send + 'data> ParallelIterator for IterMut<'data, T> { - type Item = &'data mut T; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Send + 'data> IndexedParallelIterator for IterMut<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - self.slice.len() - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(IterMutProducer { slice: self.slice }) - } -} - -struct IterMutProducer<'data, T: Send> { - slice: &'data mut [T], -} - -impl<'data, T: 'data + Send> Producer for IterMutProducer<'data, T> { - type Item = &'data mut T; - type IntoIter = ::std::slice::IterMut<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.iter_mut() - } - - fn split_at(self, index: usize) -> (Self, Self) { - let (left, right) = self.slice.split_at_mut(index); - ( - IterMutProducer { slice: left }, - IterMutProducer { slice: right }, - ) - } -} - -/// Parallel iterator over slices separated by a predicate -pub struct Split<'data, T, P> { - slice: &'data [T], - separator: P, -} - -impl<'data, T, P: Clone> Clone for Split<'data, T, P> { - fn clone(&self) -> Self { - Split { - separator: self.separator.clone(), - ..*self - } - } -} - -impl<'data, T: Debug, P> Debug for Split<'data, T, P> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_struct("Split").field("slice", &self.slice).finish() - } -} - -impl<'data, T, P> ParallelIterator for Split<'data, T, P> -where - P: Fn(&T) -> bool + Sync + Send, - T: Sync, -{ - type Item = &'data [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - let producer = SplitProducer::new(self.slice, &self.separator); - bridge_unindexed(producer, consumer) - } -} - -/// Implement support for `SplitProducer`. -impl<'data, T, P> Fissile<P> for &'data [T] -where - P: Fn(&T) -> bool, -{ - fn length(&self) -> usize { - self.len() - } - - fn midpoint(&self, end: usize) -> usize { - end / 2 - } - - fn find(&self, separator: &P, start: usize, end: usize) -> Option<usize> { - self[start..end].iter().position(separator) - } - - fn rfind(&self, separator: &P, end: usize) -> Option<usize> { - self[..end].iter().rposition(separator) - } - - fn split_once(self, index: usize) -> (Self, Self) { - let (left, right) = self.split_at(index); - (left, &right[1..]) // skip the separator - } - - fn fold_splits<F>(self, separator: &P, folder: F, skip_last: bool) -> F - where - F: Folder<Self>, - Self: Send, - { - let mut split = self.split(separator); - if skip_last { - split.next_back(); - } - folder.consume_iter(split) - } -} - -/// Parallel iterator over mutable slices separated by a predicate -pub struct SplitMut<'data, T, P> { - slice: &'data mut [T], - separator: P, -} - -impl<'data, T: Debug, P> Debug for SplitMut<'data, T, P> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_struct("SplitMut") - .field("slice", &self.slice) - .finish() - } -} - -impl<'data, T, P> ParallelIterator for SplitMut<'data, T, P> -where - P: Fn(&T) -> bool + Sync + Send, - T: Send, -{ - type Item = &'data mut [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - let producer = SplitProducer::new(self.slice, &self.separator); - bridge_unindexed(producer, consumer) - } -} - -/// Implement support for `SplitProducer`. -impl<'data, T, P> Fissile<P> for &'data mut [T] -where - P: Fn(&T) -> bool, -{ - fn length(&self) -> usize { - self.len() - } - - fn midpoint(&self, end: usize) -> usize { - end / 2 - } - - fn find(&self, separator: &P, start: usize, end: usize) -> Option<usize> { - self[start..end].iter().position(separator) - } - - fn rfind(&self, separator: &P, end: usize) -> Option<usize> { - self[..end].iter().rposition(separator) - } - - fn split_once(self, index: usize) -> (Self, Self) { - let (left, right) = self.split_at_mut(index); - (left, &mut right[1..]) // skip the separator - } - - fn fold_splits<F>(self, separator: &P, folder: F, skip_last: bool) -> F - where - F: Folder<Self>, - Self: Send, - { - let mut split = self.split_mut(separator); - if skip_last { - split.next_back(); - } - folder.consume_iter(split) - } -} diff --git a/vendor/rayon/src/slice/quicksort.rs b/vendor/rayon/src/slice/quicksort.rs deleted file mode 100644 index 2bfc350..0000000 --- a/vendor/rayon/src/slice/quicksort.rs +++ /dev/null @@ -1,903 +0,0 @@ -//! Parallel quicksort. -//! -//! This implementation is copied verbatim from `std::slice::sort_unstable` and then parallelized. -//! The only difference from the original is that calls to `recurse` are executed in parallel using -//! `rayon_core::join`. - -use std::cmp; -use std::marker::PhantomData; -use std::mem::{self, MaybeUninit}; -use std::ptr; - -/// When dropped, copies from `src` into `dest`. -#[must_use] -struct CopyOnDrop<'a, T> { - src: *const T, - dest: *mut T, - /// `src` is often a local pointer here, make sure we have appropriate - /// PhantomData so that dropck can protect us. - marker: PhantomData<&'a mut T>, -} - -impl<'a, T> CopyOnDrop<'a, T> { - /// Construct from a source pointer and a destination - /// Assumes dest lives longer than src, since there is no easy way to - /// copy down lifetime information from another pointer - unsafe fn new(src: &'a T, dest: *mut T) -> Self { - CopyOnDrop { - src, - dest, - marker: PhantomData, - } - } -} - -impl<T> Drop for CopyOnDrop<'_, T> { - fn drop(&mut self) { - // SAFETY: This is a helper class. - // Please refer to its usage for correctness. - // Namely, one must be sure that `src` and `dst` does not overlap as required by `ptr::copy_nonoverlapping`. - unsafe { - ptr::copy_nonoverlapping(self.src, self.dest, 1); - } - } -} - -/// Shifts the first element to the right until it encounters a greater or equal element. -fn shift_head<T, F>(v: &mut [T], is_less: &F) -where - F: Fn(&T, &T) -> bool, -{ - let len = v.len(); - // SAFETY: The unsafe operations below involves indexing without a bounds check (by offsetting a - // pointer) and copying memory (`ptr::copy_nonoverlapping`). - // - // a. Indexing: - // 1. We checked the size of the array to >=2. - // 2. All the indexing that we will do is always between {0 <= index < len} at most. - // - // b. Memory copying - // 1. We are obtaining pointers to references which are guaranteed to be valid. - // 2. They cannot overlap because we obtain pointers to difference indices of the slice. - // Namely, `i` and `i-1`. - // 3. If the slice is properly aligned, the elements are properly aligned. - // It is the caller's responsibility to make sure the slice is properly aligned. - // - // See comments below for further detail. - unsafe { - // If the first two elements are out-of-order... - if len >= 2 && is_less(v.get_unchecked(1), v.get_unchecked(0)) { - // Read the first element into a stack-allocated variable. If a following comparison - // operation panics, `hole` will get dropped and automatically write the element back - // into the slice. - let tmp = mem::ManuallyDrop::new(ptr::read(v.get_unchecked(0))); - let v = v.as_mut_ptr(); - let mut hole = CopyOnDrop::new(&*tmp, v.add(1)); - ptr::copy_nonoverlapping(v.add(1), v.add(0), 1); - - for i in 2..len { - if !is_less(&*v.add(i), &*tmp) { - break; - } - - // Move `i`-th element one place to the left, thus shifting the hole to the right. - ptr::copy_nonoverlapping(v.add(i), v.add(i - 1), 1); - hole.dest = v.add(i); - } - // `hole` gets dropped and thus copies `tmp` into the remaining hole in `v`. - } - } -} - -/// Shifts the last element to the left until it encounters a smaller or equal element. -fn shift_tail<T, F>(v: &mut [T], is_less: &F) -where - F: Fn(&T, &T) -> bool, -{ - let len = v.len(); - // SAFETY: The unsafe operations below involves indexing without a bound check (by offsetting a - // pointer) and copying memory (`ptr::copy_nonoverlapping`). - // - // a. Indexing: - // 1. We checked the size of the array to >= 2. - // 2. All the indexing that we will do is always between `0 <= index < len-1` at most. - // - // b. Memory copying - // 1. We are obtaining pointers to references which are guaranteed to be valid. - // 2. They cannot overlap because we obtain pointers to difference indices of the slice. - // Namely, `i` and `i+1`. - // 3. If the slice is properly aligned, the elements are properly aligned. - // It is the caller's responsibility to make sure the slice is properly aligned. - // - // See comments below for further detail. - unsafe { - // If the last two elements are out-of-order... - if len >= 2 && is_less(v.get_unchecked(len - 1), v.get_unchecked(len - 2)) { - // Read the last element into a stack-allocated variable. If a following comparison - // operation panics, `hole` will get dropped and automatically write the element back - // into the slice. - let tmp = mem::ManuallyDrop::new(ptr::read(v.get_unchecked(len - 1))); - let v = v.as_mut_ptr(); - let mut hole = CopyOnDrop::new(&*tmp, v.add(len - 2)); - ptr::copy_nonoverlapping(v.add(len - 2), v.add(len - 1), 1); - - for i in (0..len - 2).rev() { - if !is_less(&*tmp, &*v.add(i)) { - break; - } - - // Move `i`-th element one place to the right, thus shifting the hole to the left. - ptr::copy_nonoverlapping(v.add(i), v.add(i + 1), 1); - hole.dest = v.add(i); - } - // `hole` gets dropped and thus copies `tmp` into the remaining hole in `v`. - } - } -} - -/// Partially sorts a slice by shifting several out-of-order elements around. -/// -/// Returns `true` if the slice is sorted at the end. This function is *O*(*n*) worst-case. -#[cold] -fn partial_insertion_sort<T, F>(v: &mut [T], is_less: &F) -> bool -where - F: Fn(&T, &T) -> bool, -{ - // Maximum number of adjacent out-of-order pairs that will get shifted. - const MAX_STEPS: usize = 5; - // If the slice is shorter than this, don't shift any elements. - const SHORTEST_SHIFTING: usize = 50; - - let len = v.len(); - let mut i = 1; - - for _ in 0..MAX_STEPS { - // SAFETY: We already explicitly did the bound checking with `i < len`. - // All our subsequent indexing is only in the range `0 <= index < len` - unsafe { - // Find the next pair of adjacent out-of-order elements. - while i < len && !is_less(v.get_unchecked(i), v.get_unchecked(i - 1)) { - i += 1; - } - } - - // Are we done? - if i == len { - return true; - } - - // Don't shift elements on short arrays, that has a performance cost. - if len < SHORTEST_SHIFTING { - return false; - } - - // Swap the found pair of elements. This puts them in correct order. - v.swap(i - 1, i); - - // Shift the smaller element to the left. - shift_tail(&mut v[..i], is_less); - // Shift the greater element to the right. - shift_head(&mut v[i..], is_less); - } - - // Didn't manage to sort the slice in the limited number of steps. - false -} - -/// Sorts a slice using insertion sort, which is *O*(*n*^2) worst-case. -fn insertion_sort<T, F>(v: &mut [T], is_less: &F) -where - F: Fn(&T, &T) -> bool, -{ - for i in 1..v.len() { - shift_tail(&mut v[..i + 1], is_less); - } -} - -/// Sorts `v` using heapsort, which guarantees *O*(*n* \* log(*n*)) worst-case. -#[cold] -fn heapsort<T, F>(v: &mut [T], is_less: &F) -where - F: Fn(&T, &T) -> bool, -{ - // This binary heap respects the invariant `parent >= child`. - let sift_down = |v: &mut [T], mut node| { - loop { - // Children of `node`. - let mut child = 2 * node + 1; - if child >= v.len() { - break; - } - - // Choose the greater child. - if child + 1 < v.len() && is_less(&v[child], &v[child + 1]) { - child += 1; - } - - // Stop if the invariant holds at `node`. - if !is_less(&v[node], &v[child]) { - break; - } - - // Swap `node` with the greater child, move one step down, and continue sifting. - v.swap(node, child); - node = child; - } - }; - - // Build the heap in linear time. - for i in (0..v.len() / 2).rev() { - sift_down(v, i); - } - - // Pop maximal elements from the heap. - for i in (1..v.len()).rev() { - v.swap(0, i); - sift_down(&mut v[..i], 0); - } -} - -/// Partitions `v` into elements smaller than `pivot`, followed by elements greater than or equal -/// to `pivot`. -/// -/// Returns the number of elements smaller than `pivot`. -/// -/// Partitioning is performed block-by-block in order to minimize the cost of branching operations. -/// This idea is presented in the [BlockQuicksort][pdf] paper. -/// -/// [pdf]: https://drops.dagstuhl.de/opus/volltexte/2016/6389/pdf/LIPIcs-ESA-2016-38.pdf -fn partition_in_blocks<T, F>(v: &mut [T], pivot: &T, is_less: &F) -> usize -where - F: Fn(&T, &T) -> bool, -{ - // Number of elements in a typical block. - const BLOCK: usize = 128; - - // The partitioning algorithm repeats the following steps until completion: - // - // 1. Trace a block from the left side to identify elements greater than or equal to the pivot. - // 2. Trace a block from the right side to identify elements smaller than the pivot. - // 3. Exchange the identified elements between the left and right side. - // - // We keep the following variables for a block of elements: - // - // 1. `block` - Number of elements in the block. - // 2. `start` - Start pointer into the `offsets` array. - // 3. `end` - End pointer into the `offsets` array. - // 4. `offsets - Indices of out-of-order elements within the block. - - // The current block on the left side (from `l` to `l.add(block_l)`). - let mut l = v.as_mut_ptr(); - let mut block_l = BLOCK; - let mut start_l = ptr::null_mut(); - let mut end_l = ptr::null_mut(); - let mut offsets_l = [MaybeUninit::<u8>::uninit(); BLOCK]; - - // The current block on the right side (from `r.sub(block_r)` to `r`). - // SAFETY: The documentation for .add() specifically mention that `vec.as_ptr().add(vec.len())` is always safe` - let mut r = unsafe { l.add(v.len()) }; - let mut block_r = BLOCK; - let mut start_r = ptr::null_mut(); - let mut end_r = ptr::null_mut(); - let mut offsets_r = [MaybeUninit::<u8>::uninit(); BLOCK]; - - // FIXME: When we get VLAs, try creating one array of length `min(v.len(), 2 * BLOCK)` rather - // than two fixed-size arrays of length `BLOCK`. VLAs might be more cache-efficient. - - // Returns the number of elements between pointers `l` (inclusive) and `r` (exclusive). - fn width<T>(l: *mut T, r: *mut T) -> usize { - assert!(mem::size_of::<T>() > 0); - // FIXME: this should *likely* use `offset_from`, but more - // investigation is needed (including running tests in miri). - // TODO unstable: (r.addr() - l.addr()) / mem::size_of::<T>() - (r as usize - l as usize) / mem::size_of::<T>() - } - - loop { - // We are done with partitioning block-by-block when `l` and `r` get very close. Then we do - // some patch-up work in order to partition the remaining elements in between. - let is_done = width(l, r) <= 2 * BLOCK; - - if is_done { - // Number of remaining elements (still not compared to the pivot). - let mut rem = width(l, r); - if start_l < end_l || start_r < end_r { - rem -= BLOCK; - } - - // Adjust block sizes so that the left and right block don't overlap, but get perfectly - // aligned to cover the whole remaining gap. - if start_l < end_l { - block_r = rem; - } else if start_r < end_r { - block_l = rem; - } else { - // There were the same number of elements to switch on both blocks during the last - // iteration, so there are no remaining elements on either block. Cover the remaining - // items with roughly equally-sized blocks. - block_l = rem / 2; - block_r = rem - block_l; - } - debug_assert!(block_l <= BLOCK && block_r <= BLOCK); - debug_assert!(width(l, r) == block_l + block_r); - } - - if start_l == end_l { - // Trace `block_l` elements from the left side. - // TODO unstable: start_l = MaybeUninit::slice_as_mut_ptr(&mut offsets_l); - start_l = offsets_l.as_mut_ptr() as *mut u8; - end_l = start_l; - let mut elem = l; - - for i in 0..block_l { - // SAFETY: The unsafety operations below involve the usage of the `offset`. - // According to the conditions required by the function, we satisfy them because: - // 1. `offsets_l` is stack-allocated, and thus considered separate allocated object. - // 2. The function `is_less` returns a `bool`. - // Casting a `bool` will never overflow `isize`. - // 3. We have guaranteed that `block_l` will be `<= BLOCK`. - // Plus, `end_l` was initially set to the begin pointer of `offsets_` which was declared on the stack. - // Thus, we know that even in the worst case (all invocations of `is_less` returns false) we will only be at most 1 byte pass the end. - // Another unsafety operation here is dereferencing `elem`. - // However, `elem` was initially the begin pointer to the slice which is always valid. - unsafe { - // Branchless comparison. - *end_l = i as u8; - end_l = end_l.offset(!is_less(&*elem, pivot) as isize); - elem = elem.offset(1); - } - } - } - - if start_r == end_r { - // Trace `block_r` elements from the right side. - // TODO unstable: start_r = MaybeUninit::slice_as_mut_ptr(&mut offsets_r); - start_r = offsets_r.as_mut_ptr() as *mut u8; - end_r = start_r; - let mut elem = r; - - for i in 0..block_r { - // SAFETY: The unsafety operations below involve the usage of the `offset`. - // According to the conditions required by the function, we satisfy them because: - // 1. `offsets_r` is stack-allocated, and thus considered separate allocated object. - // 2. The function `is_less` returns a `bool`. - // Casting a `bool` will never overflow `isize`. - // 3. We have guaranteed that `block_r` will be `<= BLOCK`. - // Plus, `end_r` was initially set to the begin pointer of `offsets_` which was declared on the stack. - // Thus, we know that even in the worst case (all invocations of `is_less` returns true) we will only be at most 1 byte pass the end. - // Another unsafety operation here is dereferencing `elem`. - // However, `elem` was initially `1 * sizeof(T)` past the end and we decrement it by `1 * sizeof(T)` before accessing it. - // Plus, `block_r` was asserted to be less than `BLOCK` and `elem` will therefore at most be pointing to the beginning of the slice. - unsafe { - // Branchless comparison. - elem = elem.offset(-1); - *end_r = i as u8; - end_r = end_r.offset(is_less(&*elem, pivot) as isize); - } - } - } - - // Number of out-of-order elements to swap between the left and right side. - let count = cmp::min(width(start_l, end_l), width(start_r, end_r)); - - if count > 0 { - macro_rules! left { - () => { - l.offset(*start_l as isize) - }; - } - macro_rules! right { - () => { - r.offset(-(*start_r as isize) - 1) - }; - } - - // Instead of swapping one pair at the time, it is more efficient to perform a cyclic - // permutation. This is not strictly equivalent to swapping, but produces a similar - // result using fewer memory operations. - - // SAFETY: The use of `ptr::read` is valid because there is at least one element in - // both `offsets_l` and `offsets_r`, so `left!` is a valid pointer to read from. - // - // The uses of `left!` involve calls to `offset` on `l`, which points to the - // beginning of `v`. All the offsets pointed-to by `start_l` are at most `block_l`, so - // these `offset` calls are safe as all reads are within the block. The same argument - // applies for the uses of `right!`. - // - // The calls to `start_l.offset` are valid because there are at most `count-1` of them, - // plus the final one at the end of the unsafe block, where `count` is the minimum number - // of collected offsets in `offsets_l` and `offsets_r`, so there is no risk of there not - // being enough elements. The same reasoning applies to the calls to `start_r.offset`. - // - // The calls to `copy_nonoverlapping` are safe because `left!` and `right!` are guaranteed - // not to overlap, and are valid because of the reasoning above. - unsafe { - let tmp = ptr::read(left!()); - ptr::copy_nonoverlapping(right!(), left!(), 1); - - for _ in 1..count { - start_l = start_l.offset(1); - ptr::copy_nonoverlapping(left!(), right!(), 1); - start_r = start_r.offset(1); - ptr::copy_nonoverlapping(right!(), left!(), 1); - } - - ptr::copy_nonoverlapping(&tmp, right!(), 1); - mem::forget(tmp); - start_l = start_l.offset(1); - start_r = start_r.offset(1); - } - } - - if start_l == end_l { - // All out-of-order elements in the left block were moved. Move to the next block. - - // block-width-guarantee - // SAFETY: if `!is_done` then the slice width is guaranteed to be at least `2*BLOCK` wide. There - // are at most `BLOCK` elements in `offsets_l` because of its size, so the `offset` operation is - // safe. Otherwise, the debug assertions in the `is_done` case guarantee that - // `width(l, r) == block_l + block_r`, namely, that the block sizes have been adjusted to account - // for the smaller number of remaining elements. - l = unsafe { l.add(block_l) }; - } - - if start_r == end_r { - // All out-of-order elements in the right block were moved. Move to the previous block. - - // SAFETY: Same argument as [block-width-guarantee]. Either this is a full block `2*BLOCK`-wide, - // or `block_r` has been adjusted for the last handful of elements. - r = unsafe { r.offset(-(block_r as isize)) }; - } - - if is_done { - break; - } - } - - // All that remains now is at most one block (either the left or the right) with out-of-order - // elements that need to be moved. Such remaining elements can be simply shifted to the end - // within their block. - - if start_l < end_l { - // The left block remains. - // Move its remaining out-of-order elements to the far right. - debug_assert_eq!(width(l, r), block_l); - while start_l < end_l { - // remaining-elements-safety - // SAFETY: while the loop condition holds there are still elements in `offsets_l`, so it - // is safe to point `end_l` to the previous element. - // - // The `ptr::swap` is safe if both its arguments are valid for reads and writes: - // - Per the debug assert above, the distance between `l` and `r` is `block_l` - // elements, so there can be at most `block_l` remaining offsets between `start_l` - // and `end_l`. This means `r` will be moved at most `block_l` steps back, which - // makes the `r.offset` calls valid (at that point `l == r`). - // - `offsets_l` contains valid offsets into `v` collected during the partitioning of - // the last block, so the `l.offset` calls are valid. - unsafe { - end_l = end_l.offset(-1); - ptr::swap(l.offset(*end_l as isize), r.offset(-1)); - r = r.offset(-1); - } - } - width(v.as_mut_ptr(), r) - } else if start_r < end_r { - // The right block remains. - // Move its remaining out-of-order elements to the far left. - debug_assert_eq!(width(l, r), block_r); - while start_r < end_r { - // SAFETY: See the reasoning in [remaining-elements-safety]. - unsafe { - end_r = end_r.offset(-1); - ptr::swap(l, r.offset(-(*end_r as isize) - 1)); - l = l.offset(1); - } - } - width(v.as_mut_ptr(), l) - } else { - // Nothing else to do, we're done. - width(v.as_mut_ptr(), l) - } -} - -/// Partitions `v` into elements smaller than `v[pivot]`, followed by elements greater than or -/// equal to `v[pivot]`. -/// -/// Returns a tuple of: -/// -/// 1. Number of elements smaller than `v[pivot]`. -/// 2. True if `v` was already partitioned. -fn partition<T, F>(v: &mut [T], pivot: usize, is_less: &F) -> (usize, bool) -where - F: Fn(&T, &T) -> bool, -{ - let (mid, was_partitioned) = { - // Place the pivot at the beginning of slice. - v.swap(0, pivot); - let (pivot, v) = v.split_at_mut(1); - let pivot = &mut pivot[0]; - - // Read the pivot into a stack-allocated variable for efficiency. If a following comparison - // operation panics, the pivot will be automatically written back into the slice. - - // SAFETY: `pivot` is a reference to the first element of `v`, so `ptr::read` is safe. - let tmp = mem::ManuallyDrop::new(unsafe { ptr::read(pivot) }); - let _pivot_guard = unsafe { CopyOnDrop::new(&*tmp, pivot) }; - let pivot = &*tmp; - - // Find the first pair of out-of-order elements. - let mut l = 0; - let mut r = v.len(); - - // SAFETY: The unsafety below involves indexing an array. - // For the first one: We already do the bounds checking here with `l < r`. - // For the second one: We initially have `l == 0` and `r == v.len()` and we checked that `l < r` at every indexing operation. - // From here we know that `r` must be at least `r == l` which was shown to be valid from the first one. - unsafe { - // Find the first element greater than or equal to the pivot. - while l < r && is_less(v.get_unchecked(l), pivot) { - l += 1; - } - - // Find the last element smaller that the pivot. - while l < r && !is_less(v.get_unchecked(r - 1), pivot) { - r -= 1; - } - } - - ( - l + partition_in_blocks(&mut v[l..r], pivot, is_less), - l >= r, - ) - - // `_pivot_guard` goes out of scope and writes the pivot (which is a stack-allocated - // variable) back into the slice where it originally was. This step is critical in ensuring - // safety! - }; - - // Place the pivot between the two partitions. - v.swap(0, mid); - - (mid, was_partitioned) -} - -/// Partitions `v` into elements equal to `v[pivot]` followed by elements greater than `v[pivot]`. -/// -/// Returns the number of elements equal to the pivot. It is assumed that `v` does not contain -/// elements smaller than the pivot. -fn partition_equal<T, F>(v: &mut [T], pivot: usize, is_less: &F) -> usize -where - F: Fn(&T, &T) -> bool, -{ - // Place the pivot at the beginning of slice. - v.swap(0, pivot); - let (pivot, v) = v.split_at_mut(1); - let pivot = &mut pivot[0]; - - // Read the pivot into a stack-allocated variable for efficiency. If a following comparison - // operation panics, the pivot will be automatically written back into the slice. - // SAFETY: The pointer here is valid because it is obtained from a reference to a slice. - let tmp = mem::ManuallyDrop::new(unsafe { ptr::read(pivot) }); - let _pivot_guard = unsafe { CopyOnDrop::new(&*tmp, pivot) }; - let pivot = &*tmp; - - // Now partition the slice. - let mut l = 0; - let mut r = v.len(); - loop { - // SAFETY: The unsafety below involves indexing an array. - // For the first one: We already do the bounds checking here with `l < r`. - // For the second one: We initially have `l == 0` and `r == v.len()` and we checked that `l < r` at every indexing operation. - // From here we know that `r` must be at least `r == l` which was shown to be valid from the first one. - unsafe { - // Find the first element greater than the pivot. - while l < r && !is_less(pivot, v.get_unchecked(l)) { - l += 1; - } - - // Find the last element equal to the pivot. - while l < r && is_less(pivot, v.get_unchecked(r - 1)) { - r -= 1; - } - - // Are we done? - if l >= r { - break; - } - - // Swap the found pair of out-of-order elements. - r -= 1; - let ptr = v.as_mut_ptr(); - ptr::swap(ptr.add(l), ptr.add(r)); - l += 1; - } - } - - // We found `l` elements equal to the pivot. Add 1 to account for the pivot itself. - l + 1 - - // `_pivot_guard` goes out of scope and writes the pivot (which is a stack-allocated variable) - // back into the slice where it originally was. This step is critical in ensuring safety! -} - -/// Scatters some elements around in an attempt to break patterns that might cause imbalanced -/// partitions in quicksort. -#[cold] -fn break_patterns<T>(v: &mut [T]) { - let len = v.len(); - if len >= 8 { - // Pseudorandom number generator from the "Xorshift RNGs" paper by George Marsaglia. - let mut random = len as u32; - let mut gen_u32 = || { - random ^= random << 13; - random ^= random >> 17; - random ^= random << 5; - random - }; - let mut gen_usize = || { - if usize::BITS <= 32 { - gen_u32() as usize - } else { - (((gen_u32() as u64) << 32) | (gen_u32() as u64)) as usize - } - }; - - // Take random numbers modulo this number. - // The number fits into `usize` because `len` is not greater than `isize::MAX`. - let modulus = len.next_power_of_two(); - - // Some pivot candidates will be in the nearby of this index. Let's randomize them. - let pos = len / 4 * 2; - - for i in 0..3 { - // Generate a random number modulo `len`. However, in order to avoid costly operations - // we first take it modulo a power of two, and then decrease by `len` until it fits - // into the range `[0, len - 1]`. - let mut other = gen_usize() & (modulus - 1); - - // `other` is guaranteed to be less than `2 * len`. - if other >= len { - other -= len; - } - - v.swap(pos - 1 + i, other); - } - } -} - -/// Chooses a pivot in `v` and returns the index and `true` if the slice is likely already sorted. -/// -/// Elements in `v` might be reordered in the process. -fn choose_pivot<T, F>(v: &mut [T], is_less: &F) -> (usize, bool) -where - F: Fn(&T, &T) -> bool, -{ - // Minimum length to choose the median-of-medians method. - // Shorter slices use the simple median-of-three method. - const SHORTEST_MEDIAN_OF_MEDIANS: usize = 50; - // Maximum number of swaps that can be performed in this function. - const MAX_SWAPS: usize = 4 * 3; - - let len = v.len(); - - // Three indices near which we are going to choose a pivot. - #[allow(clippy::identity_op)] - let mut a = len / 4 * 1; - let mut b = len / 4 * 2; - let mut c = len / 4 * 3; - - // Counts the total number of swaps we are about to perform while sorting indices. - let mut swaps = 0; - - if len >= 8 { - // Swaps indices so that `v[a] <= v[b]`. - // SAFETY: `len >= 8` so there are at least two elements in the neighborhoods of - // `a`, `b` and `c`. This means the three calls to `sort_adjacent` result in - // corresponding calls to `sort3` with valid 3-item neighborhoods around each - // pointer, which in turn means the calls to `sort2` are done with valid - // references. Thus the `v.get_unchecked` calls are safe, as is the `ptr::swap` - // call. - let mut sort2 = |a: &mut usize, b: &mut usize| unsafe { - if is_less(v.get_unchecked(*b), v.get_unchecked(*a)) { - ptr::swap(a, b); - swaps += 1; - } - }; - - // Swaps indices so that `v[a] <= v[b] <= v[c]`. - let mut sort3 = |a: &mut usize, b: &mut usize, c: &mut usize| { - sort2(a, b); - sort2(b, c); - sort2(a, b); - }; - - if len >= SHORTEST_MEDIAN_OF_MEDIANS { - // Finds the median of `v[a - 1], v[a], v[a + 1]` and stores the index into `a`. - let mut sort_adjacent = |a: &mut usize| { - let tmp = *a; - sort3(&mut (tmp - 1), a, &mut (tmp + 1)); - }; - - // Find medians in the neighborhoods of `a`, `b`, and `c`. - sort_adjacent(&mut a); - sort_adjacent(&mut b); - sort_adjacent(&mut c); - } - - // Find the median among `a`, `b`, and `c`. - sort3(&mut a, &mut b, &mut c); - } - - if swaps < MAX_SWAPS { - (b, swaps == 0) - } else { - // The maximum number of swaps was performed. Chances are the slice is descending or mostly - // descending, so reversing will probably help sort it faster. - v.reverse(); - (len - 1 - b, true) - } -} - -/// Sorts `v` recursively. -/// -/// If the slice had a predecessor in the original array, it is specified as `pred`. -/// -/// `limit` is the number of allowed imbalanced partitions before switching to `heapsort`. If zero, -/// this function will immediately switch to heapsort. -fn recurse<'a, T, F>(mut v: &'a mut [T], is_less: &F, mut pred: Option<&'a mut T>, mut limit: u32) -where - T: Send, - F: Fn(&T, &T) -> bool + Sync, -{ - // Slices of up to this length get sorted using insertion sort. - const MAX_INSERTION: usize = 20; - // If both partitions are up to this length, we continue sequentially. This number is as small - // as possible but so that the overhead of Rayon's task scheduling is still negligible. - const MAX_SEQUENTIAL: usize = 2000; - - // True if the last partitioning was reasonably balanced. - let mut was_balanced = true; - // True if the last partitioning didn't shuffle elements (the slice was already partitioned). - let mut was_partitioned = true; - - loop { - let len = v.len(); - - // Very short slices get sorted using insertion sort. - if len <= MAX_INSERTION { - insertion_sort(v, is_less); - return; - } - - // If too many bad pivot choices were made, simply fall back to heapsort in order to - // guarantee `O(n * log(n))` worst-case. - if limit == 0 { - heapsort(v, is_less); - return; - } - - // If the last partitioning was imbalanced, try breaking patterns in the slice by shuffling - // some elements around. Hopefully we'll choose a better pivot this time. - if !was_balanced { - break_patterns(v); - limit -= 1; - } - - // Choose a pivot and try guessing whether the slice is already sorted. - let (pivot, likely_sorted) = choose_pivot(v, is_less); - - // If the last partitioning was decently balanced and didn't shuffle elements, and if pivot - // selection predicts the slice is likely already sorted... - if was_balanced && was_partitioned && likely_sorted { - // Try identifying several out-of-order elements and shifting them to correct - // positions. If the slice ends up being completely sorted, we're done. - if partial_insertion_sort(v, is_less) { - return; - } - } - - // If the chosen pivot is equal to the predecessor, then it's the smallest element in the - // slice. Partition the slice into elements equal to and elements greater than the pivot. - // This case is usually hit when the slice contains many duplicate elements. - if let Some(ref p) = pred { - if !is_less(p, &v[pivot]) { - let mid = partition_equal(v, pivot, is_less); - - // Continue sorting elements greater than the pivot. - v = &mut v[mid..]; - continue; - } - } - - // Partition the slice. - let (mid, was_p) = partition(v, pivot, is_less); - was_balanced = cmp::min(mid, len - mid) >= len / 8; - was_partitioned = was_p; - - // Split the slice into `left`, `pivot`, and `right`. - let (left, right) = v.split_at_mut(mid); - let (pivot, right) = right.split_at_mut(1); - let pivot = &mut pivot[0]; - - if cmp::max(left.len(), right.len()) <= MAX_SEQUENTIAL { - // Recurse into the shorter side only in order to minimize the total number of recursive - // calls and consume less stack space. Then just continue with the longer side (this is - // akin to tail recursion). - if left.len() < right.len() { - recurse(left, is_less, pred, limit); - v = right; - pred = Some(pivot); - } else { - recurse(right, is_less, Some(pivot), limit); - v = left; - } - } else { - // Sort the left and right half in parallel. - rayon_core::join( - || recurse(left, is_less, pred, limit), - || recurse(right, is_less, Some(pivot), limit), - ); - break; - } - } -} - -/// Sorts `v` using pattern-defeating quicksort in parallel. -/// -/// The algorithm is unstable, in-place, and *O*(*n* \* log(*n*)) worst-case. -pub(super) fn par_quicksort<T, F>(v: &mut [T], is_less: F) -where - T: Send, - F: Fn(&T, &T) -> bool + Sync, -{ - // Sorting has no meaningful behavior on zero-sized types. - if mem::size_of::<T>() == 0 { - return; - } - - // Limit the number of imbalanced partitions to `floor(log2(len)) + 1`. - let limit = usize::BITS - v.len().leading_zeros(); - - recurse(v, &is_less, None, limit); -} - -#[cfg(test)] -mod tests { - use super::heapsort; - use rand::distributions::Uniform; - use rand::{thread_rng, Rng}; - - #[test] - fn test_heapsort() { - let rng = &mut thread_rng(); - - for len in (0..25).chain(500..501) { - for &modulus in &[5, 10, 100] { - let dist = Uniform::new(0, modulus); - for _ in 0..100 { - let v: Vec<i32> = rng.sample_iter(&dist).take(len).collect(); - - // Test heapsort using `<` operator. - let mut tmp = v.clone(); - heapsort(&mut tmp, &|a, b| a < b); - assert!(tmp.windows(2).all(|w| w[0] <= w[1])); - - // Test heapsort using `>` operator. - let mut tmp = v.clone(); - heapsort(&mut tmp, &|a, b| a > b); - assert!(tmp.windows(2).all(|w| w[0] >= w[1])); - } - } - } - - // Sort using a completely random comparison function. - // This will reorder the elements *somehow*, but won't panic. - let mut v: Vec<_> = (0..100).collect(); - heapsort(&mut v, &|_, _| thread_rng().gen()); - heapsort(&mut v, &|a, b| a < b); - - for (i, &entry) in v.iter().enumerate() { - assert_eq!(entry, i); - } - } -} diff --git a/vendor/rayon/src/slice/rchunks.rs b/vendor/rayon/src/slice/rchunks.rs deleted file mode 100644 index 63e765d..0000000 --- a/vendor/rayon/src/slice/rchunks.rs +++ /dev/null @@ -1,386 +0,0 @@ -use crate::iter::plumbing::*; -use crate::iter::*; -use crate::math::div_round_up; - -/// Parallel iterator over immutable non-overlapping chunks of a slice, starting at the end. -#[derive(Debug)] -pub struct RChunks<'data, T: Sync> { - chunk_size: usize, - slice: &'data [T], -} - -impl<'data, T: Sync> RChunks<'data, T> { - pub(super) fn new(chunk_size: usize, slice: &'data [T]) -> Self { - Self { chunk_size, slice } - } -} - -impl<'data, T: Sync> Clone for RChunks<'data, T> { - fn clone(&self) -> Self { - RChunks { ..*self } - } -} - -impl<'data, T: Sync + 'data> ParallelIterator for RChunks<'data, T> { - type Item = &'data [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Sync + 'data> IndexedParallelIterator for RChunks<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - div_round_up(self.slice.len(), self.chunk_size) - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(RChunksProducer { - chunk_size: self.chunk_size, - slice: self.slice, - }) - } -} - -struct RChunksProducer<'data, T: Sync> { - chunk_size: usize, - slice: &'data [T], -} - -impl<'data, T: 'data + Sync> Producer for RChunksProducer<'data, T> { - type Item = &'data [T]; - type IntoIter = ::std::slice::RChunks<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.rchunks(self.chunk_size) - } - - fn split_at(self, index: usize) -> (Self, Self) { - let elem_index = self.slice.len().saturating_sub(index * self.chunk_size); - let (left, right) = self.slice.split_at(elem_index); - ( - RChunksProducer { - chunk_size: self.chunk_size, - slice: right, - }, - RChunksProducer { - chunk_size: self.chunk_size, - slice: left, - }, - ) - } -} - -/// Parallel iterator over immutable non-overlapping chunks of a slice, starting at the end. -#[derive(Debug)] -pub struct RChunksExact<'data, T: Sync> { - chunk_size: usize, - slice: &'data [T], - rem: &'data [T], -} - -impl<'data, T: Sync> RChunksExact<'data, T> { - pub(super) fn new(chunk_size: usize, slice: &'data [T]) -> Self { - let rem_len = slice.len() % chunk_size; - let (rem, slice) = slice.split_at(rem_len); - Self { - chunk_size, - slice, - rem, - } - } - - /// Return the remainder of the original slice that is not going to be - /// returned by the iterator. The returned slice has at most `chunk_size-1` - /// elements. - pub fn remainder(&self) -> &'data [T] { - self.rem - } -} - -impl<'data, T: Sync> Clone for RChunksExact<'data, T> { - fn clone(&self) -> Self { - RChunksExact { ..*self } - } -} - -impl<'data, T: Sync + 'data> ParallelIterator for RChunksExact<'data, T> { - type Item = &'data [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Sync + 'data> IndexedParallelIterator for RChunksExact<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - self.slice.len() / self.chunk_size - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(RChunksExactProducer { - chunk_size: self.chunk_size, - slice: self.slice, - }) - } -} - -struct RChunksExactProducer<'data, T: Sync> { - chunk_size: usize, - slice: &'data [T], -} - -impl<'data, T: 'data + Sync> Producer for RChunksExactProducer<'data, T> { - type Item = &'data [T]; - type IntoIter = ::std::slice::RChunksExact<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.rchunks_exact(self.chunk_size) - } - - fn split_at(self, index: usize) -> (Self, Self) { - let elem_index = self.slice.len() - index * self.chunk_size; - let (left, right) = self.slice.split_at(elem_index); - ( - RChunksExactProducer { - chunk_size: self.chunk_size, - slice: right, - }, - RChunksExactProducer { - chunk_size: self.chunk_size, - slice: left, - }, - ) - } -} - -/// Parallel iterator over mutable non-overlapping chunks of a slice, starting at the end. -#[derive(Debug)] -pub struct RChunksMut<'data, T: Send> { - chunk_size: usize, - slice: &'data mut [T], -} - -impl<'data, T: Send> RChunksMut<'data, T> { - pub(super) fn new(chunk_size: usize, slice: &'data mut [T]) -> Self { - Self { chunk_size, slice } - } -} - -impl<'data, T: Send + 'data> ParallelIterator for RChunksMut<'data, T> { - type Item = &'data mut [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Send + 'data> IndexedParallelIterator for RChunksMut<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - div_round_up(self.slice.len(), self.chunk_size) - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(RChunksMutProducer { - chunk_size: self.chunk_size, - slice: self.slice, - }) - } -} - -struct RChunksMutProducer<'data, T: Send> { - chunk_size: usize, - slice: &'data mut [T], -} - -impl<'data, T: 'data + Send> Producer for RChunksMutProducer<'data, T> { - type Item = &'data mut [T]; - type IntoIter = ::std::slice::RChunksMut<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.rchunks_mut(self.chunk_size) - } - - fn split_at(self, index: usize) -> (Self, Self) { - let elem_index = self.slice.len().saturating_sub(index * self.chunk_size); - let (left, right) = self.slice.split_at_mut(elem_index); - ( - RChunksMutProducer { - chunk_size: self.chunk_size, - slice: right, - }, - RChunksMutProducer { - chunk_size: self.chunk_size, - slice: left, - }, - ) - } -} - -/// Parallel iterator over mutable non-overlapping chunks of a slice, starting at the end. -#[derive(Debug)] -pub struct RChunksExactMut<'data, T: Send> { - chunk_size: usize, - slice: &'data mut [T], - rem: &'data mut [T], -} - -impl<'data, T: Send> RChunksExactMut<'data, T> { - pub(super) fn new(chunk_size: usize, slice: &'data mut [T]) -> Self { - let rem_len = slice.len() % chunk_size; - let (rem, slice) = slice.split_at_mut(rem_len); - Self { - chunk_size, - slice, - rem, - } - } - - /// Return the remainder of the original slice that is not going to be - /// returned by the iterator. The returned slice has at most `chunk_size-1` - /// elements. - /// - /// Note that this has to consume `self` to return the original lifetime of - /// the data, which prevents this from actually being used as a parallel - /// iterator since that also consumes. This method is provided for parity - /// with `std::iter::RChunksExactMut`, but consider calling `remainder()` or - /// `take_remainder()` as alternatives. - pub fn into_remainder(self) -> &'data mut [T] { - self.rem - } - - /// Return the remainder of the original slice that is not going to be - /// returned by the iterator. The returned slice has at most `chunk_size-1` - /// elements. - /// - /// Consider `take_remainder()` if you need access to the data with its - /// original lifetime, rather than borrowing through `&mut self` here. - pub fn remainder(&mut self) -> &mut [T] { - self.rem - } - - /// Return the remainder of the original slice that is not going to be - /// returned by the iterator. The returned slice has at most `chunk_size-1` - /// elements. Subsequent calls will return an empty slice. - pub fn take_remainder(&mut self) -> &'data mut [T] { - std::mem::take(&mut self.rem) - } -} - -impl<'data, T: Send + 'data> ParallelIterator for RChunksExactMut<'data, T> { - type Item = &'data mut [T]; - - fn drive_unindexed<C>(self, consumer: C) -> C::Result - where - C: UnindexedConsumer<Self::Item>, - { - bridge(self, consumer) - } - - fn opt_len(&self) -> Option<usize> { - Some(self.len()) - } -} - -impl<'data, T: Send + 'data> IndexedParallelIterator for RChunksExactMut<'data, T> { - fn drive<C>(self, consumer: C) -> C::Result - where - C: Consumer<Self::Item>, - { - bridge(self, consumer) - } - - fn len(&self) -> usize { - self.slice.len() / self.chunk_size - } - - fn with_producer<CB>(self, callback: CB) -> CB::Output - where - CB: ProducerCallback<Self::Item>, - { - callback.callback(RChunksExactMutProducer { - chunk_size: self.chunk_size, - slice: self.slice, - }) - } -} - -struct RChunksExactMutProducer<'data, T: Send> { - chunk_size: usize, - slice: &'data mut [T], -} - -impl<'data, T: 'data + Send> Producer for RChunksExactMutProducer<'data, T> { - type Item = &'data mut [T]; - type IntoIter = ::std::slice::RChunksExactMut<'data, T>; - - fn into_iter(self) -> Self::IntoIter { - self.slice.rchunks_exact_mut(self.chunk_size) - } - - fn split_at(self, index: usize) -> (Self, Self) { - let elem_index = self.slice.len() - index * self.chunk_size; - let (left, right) = self.slice.split_at_mut(elem_index); - ( - RChunksExactMutProducer { - chunk_size: self.chunk_size, - slice: right, - }, - RChunksExactMutProducer { - chunk_size: self.chunk_size, - slice: left, - }, - ) - } -} diff --git a/vendor/rayon/src/slice/test.rs b/vendor/rayon/src/slice/test.rs deleted file mode 100644 index f74ca0f..0000000 --- a/vendor/rayon/src/slice/test.rs +++ /dev/null @@ -1,170 +0,0 @@ -#![cfg(test)] - -use crate::prelude::*; -use rand::distributions::Uniform; -use rand::seq::SliceRandom; -use rand::{thread_rng, Rng}; -use std::cmp::Ordering::{Equal, Greater, Less}; - -macro_rules! sort { - ($f:ident, $name:ident) => { - #[test] - fn $name() { - let rng = &mut thread_rng(); - - for len in (0..25).chain(500..501) { - for &modulus in &[5, 10, 100] { - let dist = Uniform::new(0, modulus); - for _ in 0..100 { - let v: Vec<i32> = rng.sample_iter(&dist).take(len).collect(); - - // Test sort using `<` operator. - let mut tmp = v.clone(); - tmp.$f(|a, b| a.cmp(b)); - assert!(tmp.windows(2).all(|w| w[0] <= w[1])); - - // Test sort using `>` operator. - let mut tmp = v.clone(); - tmp.$f(|a, b| b.cmp(a)); - assert!(tmp.windows(2).all(|w| w[0] >= w[1])); - } - } - } - - // Test sort with many duplicates. - for &len in &[1_000, 10_000, 100_000] { - for &modulus in &[5, 10, 100, 10_000] { - let dist = Uniform::new(0, modulus); - let mut v: Vec<i32> = rng.sample_iter(&dist).take(len).collect(); - - v.$f(|a, b| a.cmp(b)); - assert!(v.windows(2).all(|w| w[0] <= w[1])); - } - } - - // Test sort with many pre-sorted runs. - for &len in &[1_000, 10_000, 100_000] { - let len_dist = Uniform::new(0, len); - for &modulus in &[5, 10, 1000, 50_000] { - let dist = Uniform::new(0, modulus); - let mut v: Vec<i32> = rng.sample_iter(&dist).take(len).collect(); - - v.sort(); - v.reverse(); - - for _ in 0..5 { - let a = rng.sample(&len_dist); - let b = rng.sample(&len_dist); - if a < b { - v[a..b].reverse(); - } else { - v.swap(a, b); - } - } - - v.$f(|a, b| a.cmp(b)); - assert!(v.windows(2).all(|w| w[0] <= w[1])); - } - } - - // Sort using a completely random comparison function. - // This will reorder the elements *somehow*, but won't panic. - let mut v: Vec<_> = (0..100).collect(); - v.$f(|_, _| *[Less, Equal, Greater].choose(&mut thread_rng()).unwrap()); - v.$f(|a, b| a.cmp(b)); - for i in 0..v.len() { - assert_eq!(v[i], i); - } - - // Should not panic. - [0i32; 0].$f(|a, b| a.cmp(b)); - [(); 10].$f(|a, b| a.cmp(b)); - [(); 100].$f(|a, b| a.cmp(b)); - - let mut v = [0xDEAD_BEEFu64]; - v.$f(|a, b| a.cmp(b)); - assert!(v == [0xDEAD_BEEF]); - } - }; -} - -sort!(par_sort_by, test_par_sort); -sort!(par_sort_unstable_by, test_par_sort_unstable); - -#[test] -fn test_par_sort_stability() { - for len in (2..25).chain(500..510).chain(50_000..50_010) { - for _ in 0..10 { - let mut counts = [0; 10]; - - // Create a vector like [(6, 1), (5, 1), (6, 2), ...], - // where the first item of each tuple is random, but - // the second item represents which occurrence of that - // number this element is, i.e. the second elements - // will occur in sorted order. - let mut rng = thread_rng(); - let mut v: Vec<_> = (0..len) - .map(|_| { - let n: usize = rng.gen_range(0..10); - counts[n] += 1; - (n, counts[n]) - }) - .collect(); - - // Only sort on the first element, so an unstable sort - // may mix up the counts. - v.par_sort_by(|&(a, _), &(b, _)| a.cmp(&b)); - - // This comparison includes the count (the second item - // of the tuple), so elements with equal first items - // will need to be ordered with increasing - // counts... i.e. exactly asserting that this sort is - // stable. - assert!(v.windows(2).all(|w| w[0] <= w[1])); - } - } -} - -#[test] -fn test_par_chunks_exact_remainder() { - let v: &[i32] = &[0, 1, 2, 3, 4]; - let c = v.par_chunks_exact(2); - assert_eq!(c.remainder(), &[4]); - assert_eq!(c.len(), 2); -} - -#[test] -fn test_par_chunks_exact_mut_remainder() { - let v: &mut [i32] = &mut [0, 1, 2, 3, 4]; - let mut c = v.par_chunks_exact_mut(2); - assert_eq!(c.remainder(), &[4]); - assert_eq!(c.len(), 2); - assert_eq!(c.into_remainder(), &[4]); - - let mut c = v.par_chunks_exact_mut(2); - assert_eq!(c.take_remainder(), &[4]); - assert_eq!(c.take_remainder(), &[]); - assert_eq!(c.len(), 2); -} - -#[test] -fn test_par_rchunks_exact_remainder() { - let v: &[i32] = &[0, 1, 2, 3, 4]; - let c = v.par_rchunks_exact(2); - assert_eq!(c.remainder(), &[0]); - assert_eq!(c.len(), 2); -} - -#[test] -fn test_par_rchunks_exact_mut_remainder() { - let v: &mut [i32] = &mut [0, 1, 2, 3, 4]; - let mut c = v.par_rchunks_exact_mut(2); - assert_eq!(c.remainder(), &[0]); - assert_eq!(c.len(), 2); - assert_eq!(c.into_remainder(), &[0]); - - let mut c = v.par_rchunks_exact_mut(2); - assert_eq!(c.take_remainder(), &[0]); - assert_eq!(c.take_remainder(), &[]); - assert_eq!(c.len(), 2); -} |