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//! Rayon extensions for `HashSet`.
use super::map;
use crate::hash_set::HashSet;
use crate::raw::{Allocator, Global};
use core::hash::{BuildHasher, Hash};
use rayon::iter::plumbing::UnindexedConsumer;
use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelExtend, ParallelIterator};
/// Parallel iterator over elements of a consumed set.
///
/// This iterator is created by the [`into_par_iter`] method on [`HashSet`]
/// (provided by the [`IntoParallelIterator`] trait).
/// See its documentation for more.
///
/// [`into_par_iter`]: /hashbrown/struct.HashSet.html#method.into_par_iter
/// [`HashSet`]: /hashbrown/struct.HashSet.html
pub struct IntoParIter<T, A: Allocator = Global> {
inner: map::IntoParIter<T, (), A>,
}
impl<T: Send, A: Allocator + Send> ParallelIterator for IntoParIter<T, A> {
type Item = T;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
self.inner.map(|(k, _)| k).drive_unindexed(consumer)
}
}
/// Parallel draining iterator over entries of a set.
///
/// This iterator is created by the [`par_drain`] method on [`HashSet`].
/// See its documentation for more.
///
/// [`par_drain`]: /hashbrown/struct.HashSet.html#method.par_drain
/// [`HashSet`]: /hashbrown/struct.HashSet.html
pub struct ParDrain<'a, T, A: Allocator = Global> {
inner: map::ParDrain<'a, T, (), A>,
}
impl<T: Send, A: Allocator + Send + Sync> ParallelIterator for ParDrain<'_, T, A> {
type Item = T;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
self.inner.map(|(k, _)| k).drive_unindexed(consumer)
}
}
/// Parallel iterator over shared references to elements in a set.
///
/// This iterator is created by the [`par_iter`] method on [`HashSet`]
/// (provided by the [`IntoParallelRefIterator`] trait).
/// See its documentation for more.
///
/// [`par_iter`]: /hashbrown/struct.HashSet.html#method.par_iter
/// [`HashSet`]: /hashbrown/struct.HashSet.html
/// [`IntoParallelRefIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefIterator.html
pub struct ParIter<'a, T> {
inner: map::ParKeys<'a, T, ()>,
}
impl<'a, T: Sync> ParallelIterator for ParIter<'a, T> {
type Item = &'a T;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
self.inner.drive_unindexed(consumer)
}
}
/// Parallel iterator over shared references to elements in the difference of
/// sets.
///
/// This iterator is created by the [`par_difference`] method on [`HashSet`].
/// See its documentation for more.
///
/// [`par_difference`]: /hashbrown/struct.HashSet.html#method.par_difference
/// [`HashSet`]: /hashbrown/struct.HashSet.html
pub struct ParDifference<'a, T, S, A: Allocator = Global> {
a: &'a HashSet<T, S, A>,
b: &'a HashSet<T, S, A>,
}
impl<'a, T, S, A> ParallelIterator for ParDifference<'a, T, S, A>
where
T: Eq + Hash + Sync,
S: BuildHasher + Sync,
A: Allocator + Sync,
{
type Item = &'a T;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
self.a
.into_par_iter()
.filter(|&x| !self.b.contains(x))
.drive_unindexed(consumer)
}
}
/// Parallel iterator over shared references to elements in the symmetric
/// difference of sets.
///
/// This iterator is created by the [`par_symmetric_difference`] method on
/// [`HashSet`].
/// See its documentation for more.
///
/// [`par_symmetric_difference`]: /hashbrown/struct.HashSet.html#method.par_symmetric_difference
/// [`HashSet`]: /hashbrown/struct.HashSet.html
pub struct ParSymmetricDifference<'a, T, S, A: Allocator = Global> {
a: &'a HashSet<T, S, A>,
b: &'a HashSet<T, S, A>,
}
impl<'a, T, S, A> ParallelIterator for ParSymmetricDifference<'a, T, S, A>
where
T: Eq + Hash + Sync,
S: BuildHasher + Sync,
A: Allocator + Sync,
{
type Item = &'a T;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
self.a
.par_difference(self.b)
.chain(self.b.par_difference(self.a))
.drive_unindexed(consumer)
}
}
/// Parallel iterator over shared references to elements in the intersection of
/// sets.
///
/// This iterator is created by the [`par_intersection`] method on [`HashSet`].
/// See its documentation for more.
///
/// [`par_intersection`]: /hashbrown/struct.HashSet.html#method.par_intersection
/// [`HashSet`]: /hashbrown/struct.HashSet.html
pub struct ParIntersection<'a, T, S, A: Allocator = Global> {
a: &'a HashSet<T, S, A>,
b: &'a HashSet<T, S, A>,
}
impl<'a, T, S, A> ParallelIterator for ParIntersection<'a, T, S, A>
where
T: Eq + Hash + Sync,
S: BuildHasher + Sync,
A: Allocator + Sync,
{
type Item = &'a T;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
self.a
.into_par_iter()
.filter(|&x| self.b.contains(x))
.drive_unindexed(consumer)
}
}
/// Parallel iterator over shared references to elements in the union of sets.
///
/// This iterator is created by the [`par_union`] method on [`HashSet`].
/// See its documentation for more.
///
/// [`par_union`]: /hashbrown/struct.HashSet.html#method.par_union
/// [`HashSet`]: /hashbrown/struct.HashSet.html
pub struct ParUnion<'a, T, S, A: Allocator = Global> {
a: &'a HashSet<T, S, A>,
b: &'a HashSet<T, S, A>,
}
impl<'a, T, S, A> ParallelIterator for ParUnion<'a, T, S, A>
where
T: Eq + Hash + Sync,
S: BuildHasher + Sync,
A: Allocator + Sync,
{
type Item = &'a T;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
// We'll iterate one set in full, and only the remaining difference from the other.
// Use the smaller set for the difference in order to reduce hash lookups.
let (smaller, larger) = if self.a.len() <= self.b.len() {
(self.a, self.b)
} else {
(self.b, self.a)
};
larger
.into_par_iter()
.chain(smaller.par_difference(larger))
.drive_unindexed(consumer)
}
}
impl<T, S, A> HashSet<T, S, A>
where
T: Eq + Hash + Sync,
S: BuildHasher + Sync,
A: Allocator + Sync,
{
/// Visits (potentially in parallel) the values representing the union,
/// i.e. all the values in `self` or `other`, without duplicates.
#[cfg_attr(feature = "inline-more", inline)]
pub fn par_union<'a>(&'a self, other: &'a Self) -> ParUnion<'a, T, S, A> {
ParUnion { a: self, b: other }
}
/// Visits (potentially in parallel) the values representing the difference,
/// i.e. the values that are in `self` but not in `other`.
#[cfg_attr(feature = "inline-more", inline)]
pub fn par_difference<'a>(&'a self, other: &'a Self) -> ParDifference<'a, T, S, A> {
ParDifference { a: self, b: other }
}
/// Visits (potentially in parallel) the values representing the symmetric
/// difference, i.e. the values that are in `self` or in `other` but not in both.
#[cfg_attr(feature = "inline-more", inline)]
pub fn par_symmetric_difference<'a>(
&'a self,
other: &'a Self,
) -> ParSymmetricDifference<'a, T, S, A> {
ParSymmetricDifference { a: self, b: other }
}
/// Visits (potentially in parallel) the values representing the
/// intersection, i.e. the values that are both in `self` and `other`.
#[cfg_attr(feature = "inline-more", inline)]
pub fn par_intersection<'a>(&'a self, other: &'a Self) -> ParIntersection<'a, T, S, A> {
ParIntersection { a: self, b: other }
}
/// Returns `true` if `self` has no elements in common with `other`.
/// This is equivalent to checking for an empty intersection.
///
/// This method runs in a potentially parallel fashion.
pub fn par_is_disjoint(&self, other: &Self) -> bool {
self.into_par_iter().all(|x| !other.contains(x))
}
/// Returns `true` if the set is a subset of another,
/// i.e. `other` contains at least all the values in `self`.
///
/// This method runs in a potentially parallel fashion.
pub fn par_is_subset(&self, other: &Self) -> bool {
if self.len() <= other.len() {
self.into_par_iter().all(|x| other.contains(x))
} else {
false
}
}
/// Returns `true` if the set is a superset of another,
/// i.e. `self` contains at least all the values in `other`.
///
/// This method runs in a potentially parallel fashion.
pub fn par_is_superset(&self, other: &Self) -> bool {
other.par_is_subset(self)
}
/// Returns `true` if the set is equal to another,
/// i.e. both sets contain the same values.
///
/// This method runs in a potentially parallel fashion.
pub fn par_eq(&self, other: &Self) -> bool {
self.len() == other.len() && self.par_is_subset(other)
}
}
impl<T, S, A> HashSet<T, S, A>
where
T: Eq + Hash + Send,
A: Allocator + Send,
{
/// Consumes (potentially in parallel) all values in an arbitrary order,
/// while preserving the set's allocated memory for reuse.
#[cfg_attr(feature = "inline-more", inline)]
pub fn par_drain(&mut self) -> ParDrain<'_, T, A> {
ParDrain {
inner: self.map.par_drain(),
}
}
}
impl<T: Send, S, A: Allocator + Send> IntoParallelIterator for HashSet<T, S, A> {
type Item = T;
type Iter = IntoParIter<T, A>;
#[cfg_attr(feature = "inline-more", inline)]
fn into_par_iter(self) -> Self::Iter {
IntoParIter {
inner: self.map.into_par_iter(),
}
}
}
impl<'a, T: Sync, S, A: Allocator> IntoParallelIterator for &'a HashSet<T, S, A> {
type Item = &'a T;
type Iter = ParIter<'a, T>;
#[cfg_attr(feature = "inline-more", inline)]
fn into_par_iter(self) -> Self::Iter {
ParIter {
inner: self.map.par_keys(),
}
}
}
/// Collect values from a parallel iterator into a hashset.
impl<T, S> FromParallelIterator<T> for HashSet<T, S, Global>
where
T: Eq + Hash + Send,
S: BuildHasher + Default,
{
fn from_par_iter<P>(par_iter: P) -> Self
where
P: IntoParallelIterator<Item = T>,
{
let mut set = HashSet::default();
set.par_extend(par_iter);
set
}
}
/// Extend a hash set with items from a parallel iterator.
impl<T, S> ParallelExtend<T> for HashSet<T, S, Global>
where
T: Eq + Hash + Send,
S: BuildHasher,
{
fn par_extend<I>(&mut self, par_iter: I)
where
I: IntoParallelIterator<Item = T>,
{
extend(self, par_iter);
}
}
/// Extend a hash set with copied items from a parallel iterator.
impl<'a, T, S> ParallelExtend<&'a T> for HashSet<T, S, Global>
where
T: 'a + Copy + Eq + Hash + Sync,
S: BuildHasher,
{
fn par_extend<I>(&mut self, par_iter: I)
where
I: IntoParallelIterator<Item = &'a T>,
{
extend(self, par_iter);
}
}
// This is equal to the normal `HashSet` -- no custom advantage.
fn extend<T, S, I, A>(set: &mut HashSet<T, S, A>, par_iter: I)
where
T: Eq + Hash,
S: BuildHasher,
A: Allocator,
I: IntoParallelIterator,
HashSet<T, S, A>: Extend<I::Item>,
{
let (list, len) = super::helpers::collect(par_iter);
// Values may be already present or show multiple times in the iterator.
// Reserve the entire length if the set is empty.
// Otherwise reserve half the length (rounded up), so the set
// will only resize twice in the worst case.
let reserve = if set.is_empty() { len } else { (len + 1) / 2 };
set.reserve(reserve);
for vec in list {
set.extend(vec);
}
}
#[cfg(test)]
mod test_par_set {
use alloc::vec::Vec;
use core::sync::atomic::{AtomicUsize, Ordering};
use rayon::prelude::*;
use crate::hash_set::HashSet;
#[test]
fn test_disjoint() {
let mut xs = HashSet::new();
let mut ys = HashSet::new();
assert!(xs.par_is_disjoint(&ys));
assert!(ys.par_is_disjoint(&xs));
assert!(xs.insert(5));
assert!(ys.insert(11));
assert!(xs.par_is_disjoint(&ys));
assert!(ys.par_is_disjoint(&xs));
assert!(xs.insert(7));
assert!(xs.insert(19));
assert!(xs.insert(4));
assert!(ys.insert(2));
assert!(ys.insert(-11));
assert!(xs.par_is_disjoint(&ys));
assert!(ys.par_is_disjoint(&xs));
assert!(ys.insert(7));
assert!(!xs.par_is_disjoint(&ys));
assert!(!ys.par_is_disjoint(&xs));
}
#[test]
fn test_subset_and_superset() {
let mut a = HashSet::new();
assert!(a.insert(0));
assert!(a.insert(5));
assert!(a.insert(11));
assert!(a.insert(7));
let mut b = HashSet::new();
assert!(b.insert(0));
assert!(b.insert(7));
assert!(b.insert(19));
assert!(b.insert(250));
assert!(b.insert(11));
assert!(b.insert(200));
assert!(!a.par_is_subset(&b));
assert!(!a.par_is_superset(&b));
assert!(!b.par_is_subset(&a));
assert!(!b.par_is_superset(&a));
assert!(b.insert(5));
assert!(a.par_is_subset(&b));
assert!(!a.par_is_superset(&b));
assert!(!b.par_is_subset(&a));
assert!(b.par_is_superset(&a));
}
#[test]
fn test_iterate() {
let mut a = HashSet::new();
for i in 0..32 {
assert!(a.insert(i));
}
let observed = AtomicUsize::new(0);
a.par_iter().for_each(|k| {
observed.fetch_or(1 << *k, Ordering::Relaxed);
});
assert_eq!(observed.into_inner(), 0xFFFF_FFFF);
}
#[test]
fn test_intersection() {
let mut a = HashSet::new();
let mut b = HashSet::new();
assert!(a.insert(11));
assert!(a.insert(1));
assert!(a.insert(3));
assert!(a.insert(77));
assert!(a.insert(103));
assert!(a.insert(5));
assert!(a.insert(-5));
assert!(b.insert(2));
assert!(b.insert(11));
assert!(b.insert(77));
assert!(b.insert(-9));
assert!(b.insert(-42));
assert!(b.insert(5));
assert!(b.insert(3));
let expected = [3, 5, 11, 77];
let i = a
.par_intersection(&b)
.map(|x| {
assert!(expected.contains(x));
1
})
.sum::<usize>();
assert_eq!(i, expected.len());
}
#[test]
fn test_difference() {
let mut a = HashSet::new();
let mut b = HashSet::new();
assert!(a.insert(1));
assert!(a.insert(3));
assert!(a.insert(5));
assert!(a.insert(9));
assert!(a.insert(11));
assert!(b.insert(3));
assert!(b.insert(9));
let expected = [1, 5, 11];
let i = a
.par_difference(&b)
.map(|x| {
assert!(expected.contains(x));
1
})
.sum::<usize>();
assert_eq!(i, expected.len());
}
#[test]
fn test_symmetric_difference() {
let mut a = HashSet::new();
let mut b = HashSet::new();
assert!(a.insert(1));
assert!(a.insert(3));
assert!(a.insert(5));
assert!(a.insert(9));
assert!(a.insert(11));
assert!(b.insert(-2));
assert!(b.insert(3));
assert!(b.insert(9));
assert!(b.insert(14));
assert!(b.insert(22));
let expected = [-2, 1, 5, 11, 14, 22];
let i = a
.par_symmetric_difference(&b)
.map(|x| {
assert!(expected.contains(x));
1
})
.sum::<usize>();
assert_eq!(i, expected.len());
}
#[test]
fn test_union() {
let mut a = HashSet::new();
let mut b = HashSet::new();
assert!(a.insert(1));
assert!(a.insert(3));
assert!(a.insert(5));
assert!(a.insert(9));
assert!(a.insert(11));
assert!(a.insert(16));
assert!(a.insert(19));
assert!(a.insert(24));
assert!(b.insert(-2));
assert!(b.insert(1));
assert!(b.insert(5));
assert!(b.insert(9));
assert!(b.insert(13));
assert!(b.insert(19));
let expected = [-2, 1, 3, 5, 9, 11, 13, 16, 19, 24];
let i = a
.par_union(&b)
.map(|x| {
assert!(expected.contains(x));
1
})
.sum::<usize>();
assert_eq!(i, expected.len());
}
#[test]
fn test_from_iter() {
let xs = [1, 2, 3, 4, 5, 6, 7, 8, 9];
let set: HashSet<_> = xs.par_iter().cloned().collect();
for x in &xs {
assert!(set.contains(x));
}
}
#[test]
fn test_move_iter() {
let hs = {
let mut hs = HashSet::new();
hs.insert('a');
hs.insert('b');
hs
};
let v = hs.into_par_iter().collect::<Vec<char>>();
assert!(v == ['a', 'b'] || v == ['b', 'a']);
}
#[test]
fn test_eq() {
// These constants once happened to expose a bug in insert().
// I'm keeping them around to prevent a regression.
let mut s1 = HashSet::new();
s1.insert(1);
s1.insert(2);
s1.insert(3);
let mut s2 = HashSet::new();
s2.insert(1);
s2.insert(2);
assert!(!s1.par_eq(&s2));
s2.insert(3);
assert!(s1.par_eq(&s2));
}
#[test]
fn test_extend_ref() {
let mut a = HashSet::new();
a.insert(1);
a.par_extend(&[2, 3, 4][..]);
assert_eq!(a.len(), 4);
assert!(a.contains(&1));
assert!(a.contains(&2));
assert!(a.contains(&3));
assert!(a.contains(&4));
let mut b = HashSet::new();
b.insert(5);
b.insert(6);
a.par_extend(&b);
assert_eq!(a.len(), 6);
assert!(a.contains(&1));
assert!(a.contains(&2));
assert!(a.contains(&3));
assert!(a.contains(&4));
assert!(a.contains(&5));
assert!(a.contains(&6));
}
}