feat: Add parallel iterators (#10075)

**Description:** I introduced `swc_par_iter`, which uses `swc_parallel` for `join` operations. It's not perfect, but this PR looks like a good starting point. I decided to implement it in a separate crate than `chili` because I need the ability to switch parallelization library.

Author: kdy1

Cargo.lock

@@ -0,0 +1,19 @@
+[package]
+description = "Fork of rayon, with chili support"
+edition = { workspace = true }
+license = { workspace = true }
+name = "swc_par_iter"
+repository = { workspace = true }
+version = "1.0.0"
+
+[dependencies]
+either = { workspace = true }
+swc_parallel = { version = "1.3.0", path = "../swc_parallel", default-features = false }
+
+[dev-dependencies]
+chili = { workspace = true }
+rand = { workspace = true }
+rand_xorshift = "0.3"
+swc_parallel = { version = "1.3.0", path = "../swc_parallel", default-features = false, features = [
+ "chili",
+] }

crates/swc_par_iter/Cargo.toml

@@ -0,0 +1,87 @@
+//! Parallel iterator types for [arrays] (`[T; N]`)
+//!
+//! You will rarely need to interact with this module directly unless you need
+//! to name one of the iterator types.
+//!
+//! [arrays]: https://doc.rust-lang.org/std/primitive.array.html
+
+use std::mem::ManuallyDrop;
+
+use crate::{
+ iter::{plumbing::*, *},
+ slice::{Iter, IterMut},
+ vec::DrainProducer,
+};
+
+impl<'data, T: Sync + 'data, const N: usize> IntoParallelIterator for &'data [T; N] {
+ type Item = &'data T;
+ type Iter = Iter<'data, T>;
+
+ fn into_par_iter(self) -> Self::Iter {
+ <&[T]>::into_par_iter(self)
+ }
+}
+
+impl<'data, T: Send + 'data, const N: usize> IntoParallelIterator for &'data mut [T; N] {
+ type Item = &'data mut T;
+ type Iter = IterMut<'data, T>;
+
+ fn into_par_iter(self) -> Self::Iter {
+ <&mut [T]>::into_par_iter(self)
+ }
+}
+
+impl<T: Send, const N: usize> IntoParallelIterator for [T; N] {
+ type Item = T;
+ type Iter = IntoIter<T, N>;
+
+ fn into_par_iter(self) -> Self::Iter {
+ IntoIter { array: self }
+ }
+}
+
+/// Parallel iterator that moves out of an array.
+#[derive(Debug, Clone)]
+pub struct IntoIter<T: Send, const N: usize> {
+ array: [T; N],
+}
+
+impl<T: Send, const N: usize> ParallelIterator for IntoIter<T, N> {
+ type Item = 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(N)
+ }
+}
+
+impl<T: Send, const N: usize> IndexedParallelIterator for IntoIter<T, N> {
+ fn drive<C>(self, consumer: C) -> C::Result
+ where
+ C: Consumer<Self::Item>,
+ {
+ bridge(self, consumer)
+ }
+
+ fn len(&self) -> usize {
+ N
+ }
+
+ fn with_producer<CB>(self, callback: CB) -> CB::Output
+ where
+ CB: ProducerCallback<Self::Item>,
+ {
+ unsafe {
+ // Drain every item, and then the local array can just fall out of scope.
+ let mut array = ManuallyDrop::new(self.array);
+ let producer = DrainProducer::new(array.as_mut_slice());
+ callback.callback(producer)
+ }
+ }
+}

crates/swc_par_iter/src/array.rs

@@ -0,0 +1,122 @@
+//! This module contains the parallel iterator types for heaps
+//! (`BinaryHeap<T>`). You will rarely need to interact with it directly
+//! unless you have need to name one of the iterator types.
+
+use std::collections::BinaryHeap;
+
+use crate::{
+ iter::{plumbing::*, *},
+ vec,
+};
+
+/// Parallel iterator over a binary heap
+#[derive(Debug, Clone)]
+pub struct IntoIter<T: Ord + Send> {
+ inner: vec::IntoIter<T>,
+}
+
+impl<T: Ord + Send> IntoParallelIterator for BinaryHeap<T> {
+ type Item = T;
+ type Iter = IntoIter<T>;
+
+ fn into_par_iter(self) -> Self::Iter {
+ IntoIter {
+ inner: Vec::from(self).into_par_iter(),
+ }
+ }
+}
+
+delegate_indexed_iterator! {
+ IntoIter<T> => T,
+ impl<T: Ord + Send>
+}
+
+/// Parallel iterator over an immutable reference to a binary heap
+#[derive(Debug)]
+pub struct Iter<'a, T: Ord + Sync> {
+ // TODO (MSRV 1.80): this could use `slice::Iter` built from
+ // `BinaryHeap::as_slice`, rather than using a temp `Vec<&T>`.
+ inner: vec::IntoIter<&'a T>,
+}
+
+impl<'a, T: Ord + Sync> Clone for Iter<'a, T> {
+ fn clone(&self) -> Self {
+ Iter {
+ inner: self.inner.clone(),
+ }
+ }
+}
+
+into_par_vec! {
+ &'a BinaryHeap<T> => Iter<'a, T>,
+ impl<'a, T: Ord + Sync>
+}
+
+delegate_indexed_iterator! {
+ Iter<'a, T> => &'a T,
+ impl<'a, T: Ord + Sync + 'a>
+}
+
+// `BinaryHeap` doesn't have a mutable `Iterator`
+
+/// Draining parallel iterator that moves out of a binary heap,
+/// but keeps the total capacity.
+#[derive(Debug)]
+pub struct Drain<'a, T: Ord + Send> {
+ heap: &'a mut BinaryHeap<T>,
+}
+
+impl<'a, T: Ord + Send> ParallelDrainFull for &'a mut BinaryHeap<T> {
+ type Item = T;
+ type Iter = Drain<'a, T>;
+
+ fn par_drain(self) -> Self::Iter {
+ Drain { heap: self }
+ }
+}
+
+impl<'a, T: Ord + Send> ParallelIterator for Drain<'a, T> {
+ type Item = 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<'a, T: Ord + Send> IndexedParallelIterator for Drain<'a, T> {
+ fn drive<C>(self, consumer: C) -> C::Result
+ where
+ C: Consumer<Self::Item>,
+ {
+ bridge(self, consumer)
+ }
+
+ fn len(&self) -> usize {
+ self.heap.len()
+ }
+
+ fn with_producer<CB>(self, callback: CB) -> CB::Output
+ where
+ CB: ProducerCallback<Self::Item>,
+ {
+ super::DrainGuard::new(self.heap)
+ .par_drain(..)
+ .with_producer(callback)
+ }
+}
+
+impl<'a, T: Ord + Send> Drop for Drain<'a, T> {
+ fn drop(&mut self) {
+ if !self.heap.is_empty() {
+ // We must not have produced, so just call a normal drain to remove the items.
+ self.heap.drain();
+ }
+ }
+}

crates/swc_par_iter/src/collections/binary_heap.rs

@@ -0,0 +1,66 @@
+//! This module contains the parallel iterator types for B-Tree maps
+//! (`BTreeMap<K, V>`). You will rarely need to interact with it directly
+//! unless you have need to name one of the iterator types.
+
+use std::collections::BTreeMap;
+
+use crate::{
+ iter::{plumbing::*, *},
+ vec,
+};
+
+/// Parallel iterator over a B-Tree map
+#[derive(Debug)] // std doesn't Clone
+pub struct IntoIter<K: Ord + Send, V: Send> {
+ inner: vec::IntoIter<(K, V)>,
+}
+
+into_par_vec! {
+ BTreeMap<K, V> => IntoIter<K, V>,
+ impl<K: Ord + Send, V: Send>
+}
+
+delegate_iterator! {
+ IntoIter<K, V> => (K, V),
+ impl<K: Ord + Send, V: Send>
+}
+
+/// Parallel iterator over an immutable reference to a B-Tree map
+#[derive(Debug)]
+pub struct Iter<'a, K: Ord + Sync, V: Sync> {
+ inner: vec::IntoIter<(&'a K, &'a V)>,
+}
+
+impl<'a, K: Ord + Sync, V: Sync> Clone for Iter<'a, K, V> {
+ fn clone(&self) -> Self {
+ Iter {
+ inner: self.inner.clone(),
+ }
+ }
+}
+
+into_par_vec! {
+ &'a BTreeMap<K, V> => Iter<'a, K, V>,
+ impl<'a, K: Ord + Sync, V: Sync>
+}
+
+delegate_iterator! {
+ Iter<'a, K, V> => (&'a K, &'a V),
+ impl<'a, K: Ord + Sync + 'a, V: Sync + 'a>
+}
+
+/// Parallel iterator over a mutable reference to a B-Tree map
+#[derive(Debug)]
+pub struct IterMut<'a, K: Ord + Sync, V: Send> {
+ inner: vec::IntoIter<(&'a K, &'a mut V)>,
+}
+
+into_par_vec! {
+ &'a mut BTreeMap<K, V> => IterMut<'a, K, V>,
+ impl<'a, K: Ord + Sync, V: Send>
+}
+
+delegate_iterator! {
+ IterMut<'a, K, V> => (&'a K, &'a mut V),
+ impl<'a, K: Ord + Sync + 'a, V: Send + 'a>
+}