Vendor dependencies for 0.3.0 release

vendor/hashbrown/src/external_trait_impls/mod.rs

@@ -0,0 +1,4 @@
+#[cfg(feature = "rayon")]
+pub(crate) mod rayon;
+#[cfg(feature = "serde")]
+mod serde;

vendor/hashbrown/src/external_trait_impls/rayon/helpers.rs

@@ -0,0 +1,27 @@
+use alloc::collections::LinkedList;
+use alloc::vec::Vec;
+
+use rayon::iter::{IntoParallelIterator, ParallelIterator};
+
+/// Helper for collecting parallel iterators to an intermediary
+#[allow(clippy::linkedlist)] // yes, we need linked list here for efficient appending!
+pub(super) fn collect<I: IntoParallelIterator>(iter: I) -> (LinkedList<Vec<I::Item>>, usize) {
+    let list = iter
+        .into_par_iter()
+        .fold(Vec::new, |mut vec, elem| {
+            vec.push(elem);
+            vec
+        })
+        .map(|vec| {
+            let mut list = LinkedList::new();
+            list.push_back(vec);
+            list
+        })
+        .reduce(LinkedList::new, |mut list1, mut list2| {
+            list1.append(&mut list2);
+            list1
+        });
+
+    let len = list.iter().map(Vec::len).sum();
+    (list, len)
+}

vendor/hashbrown/src/external_trait_impls/rayon/map.rs

@@ -0,0 +1,721 @@
+//! Rayon extensions for `HashMap`.
+
+use super::raw::{RawIntoParIter, RawParDrain, RawParIter};
+use crate::hash_map::HashMap;
+use crate::raw::{Allocator, Global};
+use core::fmt;
+use core::hash::{BuildHasher, Hash};
+use core::marker::PhantomData;
+use rayon::iter::plumbing::UnindexedConsumer;
+use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelExtend, ParallelIterator};
+
+/// Parallel iterator over shared references to entries in a map.
+///
+/// This iterator is created by the [`par_iter`] method on [`HashMap`]
+/// (provided by the [`IntoParallelRefIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter`]: /hashbrown/struct.HashMap.html#method.par_iter
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+/// [`IntoParallelRefIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefIterator.html
+pub struct ParIter<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a V)>,
+}
+
+impl<'a, K: Sync, V: Sync> ParallelIterator for ParIter<'a, K, V> {
+    type Item = (&'a K, &'a V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe {
+                let r = x.as_ref();
+                (&r.0, &r.1)
+            })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K, V> Clone for ParIter<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug> fmt::Debug for ParIter<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe {
+            let r = x.as_ref();
+            (&r.0, &r.1)
+        });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over shared references to keys in a map.
+///
+/// This iterator is created by the [`par_keys`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_keys`]: /hashbrown/struct.HashMap.html#method.par_keys
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParKeys<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a V)>,
+}
+
+impl<'a, K: Sync, V: Sync> ParallelIterator for ParKeys<'a, K, V> {
+    type Item = &'a K;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { &x.as_ref().0 })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K, V> Clone for ParKeys<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V> fmt::Debug for ParKeys<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe { &x.as_ref().0 });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over shared references to values in a map.
+///
+/// This iterator is created by the [`par_values`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_values`]: /hashbrown/struct.HashMap.html#method.par_values
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParValues<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a V)>,
+}
+
+impl<'a, K: Sync, V: Sync> ParallelIterator for ParValues<'a, K, V> {
+    type Item = &'a V;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { &x.as_ref().1 })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K, V> Clone for ParValues<'_, K, V> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: Eq + Hash, V: fmt::Debug> fmt::Debug for ParValues<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe { &x.as_ref().1 });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over mutable references to entries in a map.
+///
+/// This iterator is created by the [`par_iter_mut`] method on [`HashMap`]
+/// (provided by the [`IntoParallelRefMutIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter_mut`]: /hashbrown/struct.HashMap.html#method.par_iter_mut
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+/// [`IntoParallelRefMutIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefMutIterator.html
+pub struct ParIterMut<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a mut V)>,
+}
+
+impl<'a, K: Sync, V: Send> ParallelIterator for ParIterMut<'a, K, V> {
+    type Item = (&'a K, &'a mut V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe {
+                let r = x.as_mut();
+                (&r.0, &mut r.1)
+            })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug> fmt::Debug for ParIterMut<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel iterator over mutable references to values in a map.
+///
+/// This iterator is created by the [`par_values_mut`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_values_mut`]: /hashbrown/struct.HashMap.html#method.par_values_mut
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParValuesMut<'a, K, V> {
+    inner: RawParIter<(K, V)>,
+    marker: PhantomData<(&'a K, &'a mut V)>,
+}
+
+impl<'a, K: Sync, V: Send> ParallelIterator for ParValuesMut<'a, K, V> {
+    type Item = &'a mut V;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { &mut x.as_mut().1 })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<K: Eq + Hash, V: fmt::Debug> fmt::Debug for ParValuesMut<'_, K, V> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParValues {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel iterator over entries of a consumed map.
+///
+/// This iterator is created by the [`into_par_iter`] method on [`HashMap`]
+/// (provided by the [`IntoParallelIterator`] trait).
+/// See its documentation for more.
+///
+/// [`into_par_iter`]: /hashbrown/struct.HashMap.html#method.into_par_iter
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+/// [`IntoParallelIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelIterator.html
+pub struct IntoParIter<K, V, A: Allocator = Global> {
+    inner: RawIntoParIter<(K, V), A>,
+}
+
+impl<K: Send, V: Send, A: Allocator + Send> ParallelIterator for IntoParIter<K, V, A> {
+    type Item = (K, V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator> fmt::Debug for IntoParIter<K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: unsafe { self.inner.par_iter() },
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel draining iterator over entries of a map.
+///
+/// This iterator is created by the [`par_drain`] method on [`HashMap`].
+/// See its documentation for more.
+///
+/// [`par_drain`]: /hashbrown/struct.HashMap.html#method.par_drain
+/// [`HashMap`]: /hashbrown/struct.HashMap.html
+pub struct ParDrain<'a, K, V, A: Allocator = Global> {
+    inner: RawParDrain<'a, (K, V), A>,
+}
+
+impl<K: Send, V: Send, A: Allocator + Sync> ParallelIterator for ParDrain<'_, K, V, A> {
+    type Item = (K, V);
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+impl<K: fmt::Debug + Eq + Hash, V: fmt::Debug, A: Allocator> fmt::Debug for ParDrain<'_, K, V, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: unsafe { self.inner.par_iter() },
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+impl<K: Sync, V: Sync, S, A: Allocator> HashMap<K, V, S, A> {
+    /// Visits (potentially in parallel) immutably borrowed keys in an arbitrary order.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_keys(&self) -> ParKeys<'_, K, V> {
+        ParKeys {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+
+    /// Visits (potentially in parallel) immutably borrowed values in an arbitrary order.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_values(&self) -> ParValues<'_, K, V> {
+        ParValues {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<K: Send, V: Send, S, A: Allocator> HashMap<K, V, S, A> {
+    /// Visits (potentially in parallel) mutably borrowed values in an arbitrary order.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_values_mut(&mut self) -> ParValuesMut<'_, K, V> {
+        ParValuesMut {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+
+    /// Consumes (potentially in parallel) all values in an arbitrary order,
+    /// while preserving the map's allocated memory for reuse.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_drain(&mut self) -> ParDrain<'_, K, V, A> {
+        ParDrain {
+            inner: self.table.par_drain(),
+        }
+    }
+}
+
+impl<K, V, S, A> HashMap<K, V, S, A>
+where
+    K: Eq + Hash + Sync,
+    V: PartialEq + Sync,
+    S: BuildHasher + Sync,
+    A: Allocator + Sync,
+{
+    /// Returns `true` if the map is equal to another,
+    /// i.e. both maps contain the same keys mapped to the same values.
+    ///
+    /// This method runs in a potentially parallel fashion.
+    pub fn par_eq(&self, other: &Self) -> bool {
+        self.len() == other.len()
+            && self
+                .into_par_iter()
+                .all(|(key, value)| other.get(key).map_or(false, |v| *value == *v))
+    }
+}
+
+impl<K: Send, V: Send, S, A: Allocator + Send> IntoParallelIterator for HashMap<K, V, S, A> {
+    type Item = (K, V);
+    type Iter = IntoParIter<K, V, A>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        IntoParIter {
+            inner: self.table.into_par_iter(),
+        }
+    }
+}
+
+impl<'a, K: Sync, V: Sync, S, A: Allocator> IntoParallelIterator for &'a HashMap<K, V, S, A> {
+    type Item = (&'a K, &'a V);
+    type Iter = ParIter<'a, K, V>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIter {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'a, K: Sync, V: Send, S, A: Allocator> IntoParallelIterator for &'a mut HashMap<K, V, S, A> {
+    type Item = (&'a K, &'a mut V);
+    type Iter = ParIterMut<'a, K, V>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIterMut {
+            inner: unsafe { self.table.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+/// Collect (key, value) pairs from a parallel iterator into a
+/// hashmap. If multiple pairs correspond to the same key, then the
+/// ones produced earlier in the parallel iterator will be
+/// overwritten, just as with a sequential iterator.
+impl<K, V, S> FromParallelIterator<(K, V)> for HashMap<K, V, S, Global>
+where
+    K: Eq + Hash + Send,
+    V: Send,
+    S: BuildHasher + Default,
+{
+    fn from_par_iter<P>(par_iter: P) -> Self
+    where
+        P: IntoParallelIterator<Item = (K, V)>,
+    {
+        let mut map = HashMap::default();
+        map.par_extend(par_iter);
+        map
+    }
+}
+
+/// Extend a hash map with items from a parallel iterator.
+impl<K, V, S, A> ParallelExtend<(K, V)> for HashMap<K, V, S, A>
+where
+    K: Eq + Hash + Send,
+    V: Send,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = (K, V)>,
+    {
+        extend(self, par_iter);
+    }
+}
+
+/// Extend a hash map with copied items from a parallel iterator.
+impl<'a, K, V, S, A> ParallelExtend<(&'a K, &'a V)> for HashMap<K, V, S, A>
+where
+    K: Copy + Eq + Hash + Sync,
+    V: Copy + Sync,
+    S: BuildHasher,
+    A: Allocator,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = (&'a K, &'a V)>,
+    {
+        extend(self, par_iter);
+    }
+}
+
+// This is equal to the normal `HashMap` -- no custom advantage.
+fn extend<K, V, S, A, I>(map: &mut HashMap<K, V, S, A>, par_iter: I)
+where
+    K: Eq + Hash,
+    S: BuildHasher,
+    I: IntoParallelIterator,
+    A: Allocator,
+    HashMap<K, V, S, A>: Extend<I::Item>,
+{
+    let (list, len) = super::helpers::collect(par_iter);
+
+    // Keys may be already present or show multiple times in the iterator.
+    // Reserve the entire length if the map is empty.
+    // Otherwise reserve half the length (rounded up), so the map
+    // will only resize twice in the worst case.
+    let reserve = if map.is_empty() { len } else { (len + 1) / 2 };
+    map.reserve(reserve);
+    for vec in list {
+        map.extend(vec);
+    }
+}
+
+#[cfg(test)]
+mod test_par_map {
+    use alloc::vec::Vec;
+    use core::hash::{Hash, Hasher};
+    use core::sync::atomic::{AtomicUsize, Ordering};
+
+    use rayon::prelude::*;
+
+    use crate::hash_map::HashMap;
+
+    struct Droppable<'a> {
+        k: usize,
+        counter: &'a AtomicUsize,
+    }
+
+    impl Droppable<'_> {
+        fn new(k: usize, counter: &AtomicUsize) -> Droppable<'_> {
+            counter.fetch_add(1, Ordering::Relaxed);
+
+            Droppable { k, counter }
+        }
+    }
+
+    impl Drop for Droppable<'_> {
+        fn drop(&mut self) {
+            self.counter.fetch_sub(1, Ordering::Relaxed);
+        }
+    }
+
+    impl Clone for Droppable<'_> {
+        fn clone(&self) -> Self {
+            Droppable::new(self.k, self.counter)
+        }
+    }
+
+    impl Hash for Droppable<'_> {
+        fn hash<H>(&self, state: &mut H)
+        where
+            H: Hasher,
+        {
+            self.k.hash(state);
+        }
+    }
+
+    impl PartialEq for Droppable<'_> {
+        fn eq(&self, other: &Self) -> bool {
+            self.k == other.k
+        }
+    }
+
+    impl Eq for Droppable<'_> {}
+
+    #[test]
+    fn test_into_iter_drops() {
+        let key = AtomicUsize::new(0);
+        let value = AtomicUsize::new(0);
+
+        let hm = {
+            let mut hm = HashMap::new();
+
+            assert_eq!(key.load(Ordering::Relaxed), 0);
+            assert_eq!(value.load(Ordering::Relaxed), 0);
+
+            for i in 0..100 {
+                let d1 = Droppable::new(i, &key);
+                let d2 = Droppable::new(i + 100, &value);
+                hm.insert(d1, d2);
+            }
+
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            hm
+        };
+
+        // By the way, ensure that cloning doesn't screw up the dropping.
+        drop(hm.clone());
+
+        assert_eq!(key.load(Ordering::Relaxed), 100);
+        assert_eq!(value.load(Ordering::Relaxed), 100);
+
+        // Ensure that dropping the iterator does not leak anything.
+        drop(hm.clone().into_par_iter());
+
+        {
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            // retain only half
+            let _v: Vec<_> = hm.into_par_iter().filter(|(key, _)| key.k < 50).collect();
+
+            assert_eq!(key.load(Ordering::Relaxed), 50);
+            assert_eq!(value.load(Ordering::Relaxed), 50);
+        };
+
+        assert_eq!(key.load(Ordering::Relaxed), 0);
+        assert_eq!(value.load(Ordering::Relaxed), 0);
+    }
+
+    #[test]
+    fn test_drain_drops() {
+        let key = AtomicUsize::new(0);
+        let value = AtomicUsize::new(0);
+
+        let mut hm = {
+            let mut hm = HashMap::new();
+
+            assert_eq!(key.load(Ordering::Relaxed), 0);
+            assert_eq!(value.load(Ordering::Relaxed), 0);
+
+            for i in 0..100 {
+                let d1 = Droppable::new(i, &key);
+                let d2 = Droppable::new(i + 100, &value);
+                hm.insert(d1, d2);
+            }
+
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            hm
+        };
+
+        // By the way, ensure that cloning doesn't screw up the dropping.
+        drop(hm.clone());
+
+        assert_eq!(key.load(Ordering::Relaxed), 100);
+        assert_eq!(value.load(Ordering::Relaxed), 100);
+
+        // Ensure that dropping the drain iterator does not leak anything.
+        drop(hm.clone().par_drain());
+
+        {
+            assert_eq!(key.load(Ordering::Relaxed), 100);
+            assert_eq!(value.load(Ordering::Relaxed), 100);
+
+            // retain only half
+            let _v: Vec<_> = hm.drain().filter(|(key, _)| key.k < 50).collect();
+            assert!(hm.is_empty());
+
+            assert_eq!(key.load(Ordering::Relaxed), 50);
+            assert_eq!(value.load(Ordering::Relaxed), 50);
+        };
+
+        assert_eq!(key.load(Ordering::Relaxed), 0);
+        assert_eq!(value.load(Ordering::Relaxed), 0);
+    }
+
+    #[test]
+    fn test_empty_iter() {
+        let mut m: HashMap<isize, bool> = HashMap::new();
+        assert_eq!(m.par_drain().count(), 0);
+        assert_eq!(m.par_keys().count(), 0);
+        assert_eq!(m.par_values().count(), 0);
+        assert_eq!(m.par_values_mut().count(), 0);
+        assert_eq!(m.par_iter().count(), 0);
+        assert_eq!(m.par_iter_mut().count(), 0);
+        assert_eq!(m.len(), 0);
+        assert!(m.is_empty());
+        assert_eq!(m.into_par_iter().count(), 0);
+    }
+
+    #[test]
+    fn test_iterate() {
+        let mut m = HashMap::with_capacity(4);
+        for i in 0..32 {
+            assert!(m.insert(i, i * 2).is_none());
+        }
+        assert_eq!(m.len(), 32);
+
+        let observed = AtomicUsize::new(0);
+
+        m.par_iter().for_each(|(k, v)| {
+            assert_eq!(*v, *k * 2);
+            observed.fetch_or(1 << *k, Ordering::Relaxed);
+        });
+        assert_eq!(observed.into_inner(), 0xFFFF_FFFF);
+    }
+
+    #[test]
+    fn test_keys() {
+        let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+        let map: HashMap<_, _> = vec.into_par_iter().collect();
+        let keys: Vec<_> = map.par_keys().cloned().collect();
+        assert_eq!(keys.len(), 3);
+        assert!(keys.contains(&1));
+        assert!(keys.contains(&2));
+        assert!(keys.contains(&3));
+    }
+
+    #[test]
+    fn test_values() {
+        let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
+        let map: HashMap<_, _> = vec.into_par_iter().collect();
+        let values: Vec<_> = map.par_values().cloned().collect();
+        assert_eq!(values.len(), 3);
+        assert!(values.contains(&'a'));
+        assert!(values.contains(&'b'));
+        assert!(values.contains(&'c'));
+    }
+
+    #[test]
+    fn test_values_mut() {
+        let vec = vec![(1, 1), (2, 2), (3, 3)];
+        let mut map: HashMap<_, _> = vec.into_par_iter().collect();
+        map.par_values_mut().for_each(|value| *value *= 2);
+        let values: Vec<_> = map.par_values().cloned().collect();
+        assert_eq!(values.len(), 3);
+        assert!(values.contains(&2));
+        assert!(values.contains(&4));
+        assert!(values.contains(&6));
+    }
+
+    #[test]
+    fn test_eq() {
+        let mut m1 = HashMap::new();
+        m1.insert(1, 2);
+        m1.insert(2, 3);
+        m1.insert(3, 4);
+
+        let mut m2 = HashMap::new();
+        m2.insert(1, 2);
+        m2.insert(2, 3);
+
+        assert!(!m1.par_eq(&m2));
+
+        m2.insert(3, 4);
+
+        assert!(m1.par_eq(&m2));
+    }
+
+    #[test]
+    fn test_from_iter() {
+        let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
+
+        let map: HashMap<_, _> = xs.par_iter().cloned().collect();
+
+        for &(k, v) in &xs {
+            assert_eq!(map.get(&k), Some(&v));
+        }
+    }
+
+    #[test]
+    fn test_extend_ref() {
+        let mut a = HashMap::new();
+        a.insert(1, "one");
+        let mut b = HashMap::new();
+        b.insert(2, "two");
+        b.insert(3, "three");
+
+        a.par_extend(&b);
+
+        assert_eq!(a.len(), 3);
+        assert_eq!(a[&1], "one");
+        assert_eq!(a[&2], "two");
+        assert_eq!(a[&3], "three");
+    }
+}

vendor/hashbrown/src/external_trait_impls/rayon/mod.rs

@@ -0,0 +1,5 @@
+mod helpers;
+pub(crate) mod map;
+pub(crate) mod raw;
+pub(crate) mod set;
+pub(crate) mod table;

vendor/hashbrown/src/external_trait_impls/rayon/raw.rs

@@ -0,0 +1,230 @@
+use crate::raw::Bucket;
+use crate::raw::{Allocator, Global, RawIter, RawIterRange, RawTable};
+use crate::scopeguard::guard;
+use core::marker::PhantomData;
+use core::mem;
+use core::ptr::NonNull;
+use rayon::iter::{
+    plumbing::{self, Folder, UnindexedConsumer, UnindexedProducer},
+    ParallelIterator,
+};
+
+/// Parallel iterator which returns a raw pointer to every full bucket in the table.
+pub struct RawParIter<T> {
+    iter: RawIterRange<T>,
+}
+
+impl<T> RawParIter<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) unsafe fn iter(&self) -> RawIterRange<T> {
+        self.iter.clone()
+    }
+}
+
+impl<T> Clone for RawParIter<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            iter: self.iter.clone(),
+        }
+    }
+}
+
+impl<T> From<RawIter<T>> for RawParIter<T> {
+    fn from(it: RawIter<T>) -> Self {
+        RawParIter { iter: it.iter }
+    }
+}
+
+impl<T> ParallelIterator for RawParIter<T> {
+    type Item = Bucket<T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let producer = ParIterProducer { iter: self.iter };
+        plumbing::bridge_unindexed(producer, consumer)
+    }
+}
+
+/// Producer which returns a `Bucket<T>` for every element.
+struct ParIterProducer<T> {
+    iter: RawIterRange<T>,
+}
+
+impl<T> UnindexedProducer for ParIterProducer<T> {
+    type Item = Bucket<T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn split(self) -> (Self, Option<Self>) {
+        let (left, right) = self.iter.split();
+        let left = ParIterProducer { iter: left };
+        let right = right.map(|right| ParIterProducer { iter: right });
+        (left, right)
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        folder.consume_iter(self.iter)
+    }
+}
+
+/// Parallel iterator which consumes a table and returns elements.
+pub struct RawIntoParIter<T, A: Allocator = Global> {
+    table: RawTable<T, A>,
+}
+
+impl<T, A: Allocator> RawIntoParIter<T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) unsafe fn par_iter(&self) -> RawParIter<T> {
+        self.table.par_iter()
+    }
+}
+
+impl<T: Send, A: Allocator + Send> ParallelIterator for RawIntoParIter<T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let iter = unsafe { self.table.iter().iter };
+        let _guard = guard(self.table.into_allocation(), |alloc| {
+            if let Some((ptr, layout, ref alloc)) = *alloc {
+                unsafe {
+                    alloc.deallocate(ptr, layout);
+                }
+            }
+        });
+        let producer = ParDrainProducer { iter };
+        plumbing::bridge_unindexed(producer, consumer)
+    }
+}
+
+/// Parallel iterator which consumes elements without freeing the table storage.
+pub struct RawParDrain<'a, T, A: Allocator = Global> {
+    // We don't use a &'a mut RawTable<T> because we want RawParDrain to be
+    // covariant over T.
+    table: NonNull<RawTable<T, A>>,
+    marker: PhantomData<&'a RawTable<T, A>>,
+}
+
+unsafe impl<T: Send, A: Allocator> Send for RawParDrain<'_, T, A> {}
+
+impl<T, A: Allocator> RawParDrain<'_, T, A> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) unsafe fn par_iter(&self) -> RawParIter<T> {
+        self.table.as_ref().par_iter()
+    }
+}
+
+impl<T: Send, A: Allocator> ParallelIterator for RawParDrain<'_, T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let _guard = guard(self.table, |table| unsafe {
+            table.as_mut().clear_no_drop();
+        });
+        let iter = unsafe { self.table.as_ref().iter().iter };
+        mem::forget(self);
+        let producer = ParDrainProducer { iter };
+        plumbing::bridge_unindexed(producer, consumer)
+    }
+}
+
+impl<T, A: Allocator> Drop for RawParDrain<'_, T, A> {
+    fn drop(&mut self) {
+        // If drive_unindexed is not called then simply clear the table.
+        unsafe {
+            self.table.as_mut().clear();
+        }
+    }
+}
+
+/// Producer which will consume all elements in the range, even if it is dropped
+/// halfway through.
+struct ParDrainProducer<T> {
+    iter: RawIterRange<T>,
+}
+
+impl<T: Send> UnindexedProducer for ParDrainProducer<T> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn split(self) -> (Self, Option<Self>) {
+        let (left, right) = self.iter.clone().split();
+        mem::forget(self);
+        let left = ParDrainProducer { iter: left };
+        let right = right.map(|right| ParDrainProducer { iter: right });
+        (left, right)
+    }
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn fold_with<F>(mut self, mut folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        // Make sure to modify the iterator in-place so that any remaining
+        // elements are processed in our Drop impl.
+        for item in &mut self.iter {
+            folder = folder.consume(unsafe { item.read() });
+            if folder.full() {
+                return folder;
+            }
+        }
+
+        // If we processed all elements then we don't need to run the drop.
+        mem::forget(self);
+        folder
+    }
+}
+
+impl<T> Drop for ParDrainProducer<T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drop(&mut self) {
+        // Drop all remaining elements
+        if mem::needs_drop::<T>() {
+            for item in &mut self.iter {
+                unsafe {
+                    item.drop();
+                }
+            }
+        }
+    }
+}
+
+impl<T, A: Allocator> RawTable<T, A> {
+    /// Returns a parallel iterator over the elements in a `RawTable`.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub unsafe fn par_iter(&self) -> RawParIter<T> {
+        RawParIter {
+            iter: self.iter().iter,
+        }
+    }
+
+    /// Returns a parallel iterator over the elements in a `RawTable`.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn into_par_iter(self) -> RawIntoParIter<T, A> {
+        RawIntoParIter { table: self }
+    }
+
+    /// Returns a parallel iterator which consumes all elements of a `RawTable`
+    /// without freeing its memory allocation.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_drain(&mut self) -> RawParDrain<'_, T, A> {
+        RawParDrain {
+            table: NonNull::from(self),
+            marker: PhantomData,
+        }
+    }
+}

vendor/hashbrown/src/external_trait_impls/rayon/set.rs

@@ -0,0 +1,659 @@
+//! 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
+/// [`IntoParallelIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelIterator.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));
+    }
+}

vendor/hashbrown/src/external_trait_impls/rayon/table.rs

@@ -0,0 +1,249 @@
+//! Rayon extensions for `HashTable`.
+
+use super::raw::{RawIntoParIter, RawParDrain, RawParIter};
+use crate::hash_table::HashTable;
+use crate::raw::{Allocator, Global};
+use core::fmt;
+use core::marker::PhantomData;
+use rayon::iter::plumbing::UnindexedConsumer;
+use rayon::iter::{IntoParallelIterator, ParallelIterator};
+
+/// Parallel iterator over shared references to entries in a map.
+///
+/// This iterator is created by the [`par_iter`] method on [`HashTable`]
+/// (provided by the [`IntoParallelRefIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter`]: /hashbrown/struct.HashTable.html#method.par_iter
+/// [`HashTable`]: /hashbrown/struct.HashTable.html
+/// [`IntoParallelRefIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefIterator.html
+pub struct ParIter<'a, T> {
+    inner: RawParIter<T>,
+    marker: PhantomData<&'a T>,
+}
+
+impl<'a, T: Sync> ParallelIterator for ParIter<'a, T> {
+    type Item = &'a T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { x.as_ref() })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<T> Clone for ParIter<'_, T> {
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<T: fmt::Debug> fmt::Debug for ParIter<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let iter = unsafe { self.inner.iter() }.map(|x| unsafe { x.as_ref() });
+        f.debug_list().entries(iter).finish()
+    }
+}
+
+/// Parallel iterator over mutable references to entries in a map.
+///
+/// This iterator is created by the [`par_iter_mut`] method on [`HashTable`]
+/// (provided by the [`IntoParallelRefMutIterator`] trait).
+/// See its documentation for more.
+///
+/// [`par_iter_mut`]: /hashbrown/struct.HashTable.html#method.par_iter_mut
+/// [`HashTable`]: /hashbrown/struct.HashTable.html
+/// [`IntoParallelRefMutIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelRefMutIterator.html
+pub struct ParIterMut<'a, T> {
+    inner: RawParIter<T>,
+    marker: PhantomData<&'a mut T>,
+}
+
+impl<'a, T: Send> ParallelIterator for ParIterMut<'a, T> {
+    type Item = &'a mut T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner
+            .map(|x| unsafe { x.as_mut() })
+            .drive_unindexed(consumer)
+    }
+}
+
+impl<T: fmt::Debug> fmt::Debug for ParIterMut<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: self.inner.clone(),
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel iterator over entries of a consumed map.
+///
+/// This iterator is created by the [`into_par_iter`] method on [`HashTable`]
+/// (provided by the [`IntoParallelIterator`] trait).
+/// See its documentation for more.
+///
+/// [`into_par_iter`]: /hashbrown/struct.HashTable.html#method.into_par_iter
+/// [`HashTable`]: /hashbrown/struct.HashTable.html
+/// [`IntoParallelIterator`]: https://docs.rs/rayon/1.0/rayon/iter/trait.IntoParallelIterator.html
+pub struct IntoParIter<T, A: Allocator = Global> {
+    inner: RawIntoParIter<T, A>,
+}
+
+impl<T: Send, A: Allocator + Send> ParallelIterator for IntoParIter<T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+impl<T: fmt::Debug, A: Allocator> fmt::Debug for IntoParIter<T, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: unsafe { self.inner.par_iter() },
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+/// Parallel draining iterator over entries of a map.
+///
+/// This iterator is created by the [`par_drain`] method on [`HashTable`].
+/// See its documentation for more.
+///
+/// [`par_drain`]: /hashbrown/struct.HashTable.html#method.par_drain
+/// [`HashTable`]: /hashbrown/struct.HashTable.html
+pub struct ParDrain<'a, T, A: Allocator = Global> {
+    inner: RawParDrain<'a, T, A>,
+}
+
+impl<T: Send, A: Allocator + Sync> ParallelIterator for ParDrain<'_, T, A> {
+    type Item = T;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.drive_unindexed(consumer)
+    }
+}
+
+impl<T: fmt::Debug, A: Allocator> fmt::Debug for ParDrain<'_, T, A> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ParIter {
+            inner: unsafe { self.inner.par_iter() },
+            marker: PhantomData,
+        }
+        .fmt(f)
+    }
+}
+
+impl<T: Send, A: Allocator> HashTable<T, A> {
+    /// Consumes (potentially in parallel) all values in an arbitrary order,
+    /// while preserving the map's allocated memory for reuse.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub fn par_drain(&mut self) -> ParDrain<'_, T, A> {
+        ParDrain {
+            inner: self.raw.par_drain(),
+        }
+    }
+}
+
+impl<T: Send, A: Allocator + Send> IntoParallelIterator for HashTable<T, 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.raw.into_par_iter(),
+        }
+    }
+}
+
+impl<'a, T: Sync, A: Allocator> IntoParallelIterator for &'a HashTable<T, 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: unsafe { self.raw.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'a, T: Send, A: Allocator> IntoParallelIterator for &'a mut HashTable<T, A> {
+    type Item = &'a mut T;
+    type Iter = ParIterMut<'a, T>;
+
+    #[cfg_attr(feature = "inline-more", inline)]
+    fn into_par_iter(self) -> Self::Iter {
+        ParIterMut {
+            inner: unsafe { self.raw.par_iter() },
+            marker: PhantomData,
+        }
+    }
+}
+
+#[cfg(test)]
+mod test_par_table {
+    use alloc::vec::Vec;
+    use core::sync::atomic::{AtomicUsize, Ordering};
+
+    use rayon::prelude::*;
+
+    use crate::{hash_map::make_hash, hash_table::HashTable, DefaultHashBuilder};
+
+    #[test]
+    fn test_iterate() {
+        let hasher = DefaultHashBuilder::default();
+        let mut a = HashTable::new();
+        for i in 0..32 {
+            a.insert_unique(make_hash(&hasher, &i), i, |x| make_hash(&hasher, x));
+        }
+        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_move_iter() {
+        let hasher = DefaultHashBuilder::default();
+        let hs = {
+            let mut hs = HashTable::new();
+
+            hs.insert_unique(make_hash(&hasher, &'a'), 'a', |x| make_hash(&hasher, x));
+            hs.insert_unique(make_hash(&hasher, &'b'), 'b', |x| make_hash(&hasher, x));
+
+            hs
+        };
+
+        let v = hs.into_par_iter().collect::<Vec<char>>();
+        assert!(v == ['a', 'b'] || v == ['b', 'a']);
+    }
+}

vendor/hashbrown/src/external_trait_impls/serde.rs

@@ -0,0 +1,220 @@
+mod size_hint {
+    use core::cmp;
+
+    /// This presumably exists to prevent denial of service attacks.
+    ///
+    /// Original discussion: https://github.com/serde-rs/serde/issues/1114.
+    #[cfg_attr(feature = "inline-more", inline)]
+    pub(super) fn cautious(hint: Option<usize>) -> usize {
+        cmp::min(hint.unwrap_or(0), 4096)
+    }
+}
+
+mod map {
+    use crate::raw::Allocator;
+    use core::fmt;
+    use core::hash::{BuildHasher, Hash};
+    use core::marker::PhantomData;
+    use serde::de::{Deserialize, Deserializer, MapAccess, Visitor};
+    use serde::ser::{Serialize, Serializer};
+
+    use crate::hash_map::HashMap;
+
+    use super::size_hint;
+
+    impl<K, V, H, A> Serialize for HashMap<K, V, H, A>
+    where
+        K: Serialize + Eq + Hash,
+        V: Serialize,
+        H: BuildHasher,
+        A: Allocator,
+    {
+        #[cfg_attr(feature = "inline-more", inline)]
+        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where
+            S: Serializer,
+        {
+            serializer.collect_map(self)
+        }
+    }
+
+    impl<'de, K, V, S, A> Deserialize<'de> for HashMap<K, V, S, A>
+    where
+        K: Deserialize<'de> + Eq + Hash,
+        V: Deserialize<'de>,
+        S: BuildHasher + Default,
+        A: Allocator + Default,
+    {
+        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct MapVisitor<K, V, S, A>
+            where
+                A: Allocator,
+            {
+                marker: PhantomData<HashMap<K, V, S, A>>,
+            }
+
+            impl<'de, K, V, S, A> Visitor<'de> for MapVisitor<K, V, S, A>
+            where
+                K: Deserialize<'de> + Eq + Hash,
+                V: Deserialize<'de>,
+                S: BuildHasher + Default,
+                A: Allocator + Default,
+            {
+                type Value = HashMap<K, V, S, A>;
+
+                fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    formatter.write_str("a map")
+                }
+
+                #[cfg_attr(feature = "inline-more", inline)]
+                fn visit_map<M>(self, mut map: M) -> Result<Self::Value, M::Error>
+                where
+                    M: MapAccess<'de>,
+                {
+                    let mut values = HashMap::with_capacity_and_hasher_in(
+                        size_hint::cautious(map.size_hint()),
+                        S::default(),
+                        A::default(),
+                    );
+
+                    while let Some((key, value)) = map.next_entry()? {
+                        values.insert(key, value);
+                    }
+
+                    Ok(values)
+                }
+            }
+
+            let visitor = MapVisitor {
+                marker: PhantomData,
+            };
+            deserializer.deserialize_map(visitor)
+        }
+    }
+}
+
+mod set {
+    use crate::raw::Allocator;
+    use core::fmt;
+    use core::hash::{BuildHasher, Hash};
+    use core::marker::PhantomData;
+    use serde::de::{Deserialize, Deserializer, SeqAccess, Visitor};
+    use serde::ser::{Serialize, Serializer};
+
+    use crate::hash_set::HashSet;
+
+    use super::size_hint;
+
+    impl<T, H, A> Serialize for HashSet<T, H, A>
+    where
+        T: Serialize + Eq + Hash,
+        H: BuildHasher,
+        A: Allocator,
+    {
+        #[cfg_attr(feature = "inline-more", inline)]
+        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where
+            S: Serializer,
+        {
+            serializer.collect_seq(self)
+        }
+    }
+
+    impl<'de, T, S, A> Deserialize<'de> for HashSet<T, S, A>
+    where
+        T: Deserialize<'de> + Eq + Hash,
+        S: BuildHasher + Default,
+        A: Allocator + Default,
+    {
+        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct SeqVisitor<T, S, A>
+            where
+                A: Allocator,
+            {
+                marker: PhantomData<HashSet<T, S, A>>,
+            }
+
+            impl<'de, T, S, A> Visitor<'de> for SeqVisitor<T, S, A>
+            where
+                T: Deserialize<'de> + Eq + Hash,
+                S: BuildHasher + Default,
+                A: Allocator + Default,
+            {
+                type Value = HashSet<T, S, A>;
+
+                fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    formatter.write_str("a sequence")
+                }
+
+                #[cfg_attr(feature = "inline-more", inline)]
+                fn visit_seq<M>(self, mut seq: M) -> Result<Self::Value, M::Error>
+                where
+                    M: SeqAccess<'de>,
+                {
+                    let mut values = HashSet::with_capacity_and_hasher_in(
+                        size_hint::cautious(seq.size_hint()),
+                        S::default(),
+                        A::default(),
+                    );
+
+                    while let Some(value) = seq.next_element()? {
+                        values.insert(value);
+                    }
+
+                    Ok(values)
+                }
+            }
+
+            let visitor = SeqVisitor {
+                marker: PhantomData,
+            };
+            deserializer.deserialize_seq(visitor)
+        }
+
+        #[allow(clippy::missing_errors_doc)]
+        fn deserialize_in_place<D>(deserializer: D, place: &mut Self) -> Result<(), D::Error>
+        where
+            D: Deserializer<'de>,
+        {
+            struct SeqInPlaceVisitor<'a, T, S, A>(&'a mut HashSet<T, S, A>)
+            where
+                A: Allocator;
+
+            impl<'de, T, S, A> Visitor<'de> for SeqInPlaceVisitor<'_, T, S, A>
+            where
+                T: Deserialize<'de> + Eq + Hash,
+                S: BuildHasher + Default,
+                A: Allocator,
+            {
+                type Value = ();
+
+                fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    formatter.write_str("a sequence")
+                }
+
+                #[cfg_attr(feature = "inline-more", inline)]
+                fn visit_seq<M>(self, mut seq: M) -> Result<Self::Value, M::Error>
+                where
+                    M: SeqAccess<'de>,
+                {
+                    self.0.clear();
+                    self.0.reserve(size_hint::cautious(seq.size_hint()));
+
+                    while let Some(value) = seq.next_element()? {
+                        self.0.insert(value);
+                    }
+
+                    Ok(())
+                }
+            }
+
+            deserializer.deserialize_seq(SeqInPlaceVisitor(place))
+        }
+    }
+}