Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

23 files changed, 3950 insertions, 0 deletions

diff --git a/third_party/rust/dashmap/.cargo-checksum.json b/third_party/rust/dashmap/.cargo-checksum.json
new file mode 100644
index 0000000000..3c80118c4c
--- /dev/null
+++ b/third_party/rust/dashmap/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{"Cargo.toml":"5c8eee21158a25c0f9a586e1739dbf956a8a514dce1b7f5001ddbff5bac35065","LICENSE":"16692e8cee4aa06e3913787497eba2d47c42002014136f5da67be6ee640e28a3","README.md":"666c5a8c9b9404937a193fdf0a1648ac5370723661d55f3804406cfef2c0df1c","rust-toolchain":"e043627c837e03bbb64749ab458b0eb0c93249b2aa4fcd8b2d2d8dd9be1ccfd3","src/iter.rs":"12e09b86c3cc7e8e0db058c31af00a166f46e2c2c182cea5034e43dc6a3d54a2","src/iter_set.rs":"5327da951dc93d30b293aeb7a805666ee4b8e6364881348ab5d86b23c29a0e13","src/lib.rs":"409d1993a6b60e93f7092de111673500e82f0689752a4ef1ecb15149e6bed2ec","src/lock.rs":"a22f2cac6262c729e62a9597b0dae4a04b7662ace5f0960f669f57f9e756e9f1","src/mapref/entry.rs":"290a3f5e1eb49e049286e7de3724130b0c8f2aa69d735b2d8a51e79d08aefe28","src/mapref/mod.rs":"15bd45cfc642a9e3e77bbfbf2d9fad9c5fac0ff6904214a3c501e262242ec8b0","src/mapref/multiple.rs":"3fe7dac633ef085381b7d0c899a4ebeec0b88da7adb4088d1c6c735e9ab05845","src/mapref/one.rs":"ccfd10ca6ca56bae8dcf4c0ac5683b66ecd881b6c1a9883a2d97c02dce6d1bd5","src/rayon/map.rs":"edfe572719ed30a4213993c42a3e1eac9657f12ba27a11e80829519d6a7bfd74","src/rayon/set.rs":"21fe2ca8c58c8ff1bc753f5e2eb6131afd598211eea375f2ac7190cd0f9abcba","src/read_only.rs":"6d3d2d6d3ed13bedc8ece1ed7522acf9d2fb216395adcfa76df8c1dbf52327bd","src/serde.rs":"9a7d240a9c5d093cb8d4ff02ffb4dcdfb4cbac47bac66412bb74fb801f3623f6","src/set.rs":"332df646590e398452b251440d9b2df3e58597799d7c1c016ffefdd5c0c66964","src/setref/mod.rs":"cc39e406a333dc6c04398f4b1336fb400e3a8360c387466d8a91f5d7f4ed40a7","src/setref/multiple.rs":"2270749e83f80dbb4761448f0629ecd02b0b4268f76834236d1167844e6d5e37","src/setref/one.rs":"2af9493c296a3d59dac3a9fed0298d9ca27fa50b0693f82f4377c571e28691c5","src/t.rs":"1e9567ebb665cd422d8934e79a024232ba1a7cb88a48471d47b05653509226bd","src/util.rs":"7a8096a713cf04e60d6c9e38cd366314ed74472abab4bb8a3a9ed081a0e0301b"},"package":"e77a43b28d0668df09411cb0bc9a8c2adc40f9a048afe863e05fd43251e8e39c"}
\ No newline at end of file
diff --git a/third_party/rust/dashmap/Cargo.toml b/third_party/rust/dashmap/Cargo.toml
new file mode 100644
index 0000000000..4b309ef8d5
--- /dev/null
+++ b/third_party/rust/dashmap/Cargo.toml
@@ -0,0 +1,45 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies
+#
+# If you believe there's an error in this file please file an
+# issue against the rust-lang/cargo repository. If you're
+# editing this file be aware that the upstream Cargo.toml
+# will likely look very different (and much more reasonable)
+
+[package]
+edition = "2018"
+name = "dashmap"
+version = "4.0.2"
+authors = ["Acrimon <joel.wejdenstal@gmail.com>"]
+description = "Blazing fast concurrent HashMap for Rust."
+homepage = "https://github.com/xacrimon/dashmap"
+documentation = "https://docs.rs/dashmap"
+readme = "README.md"
+keywords = ["atomic", "concurrent", "hashmap"]
+categories = ["concurrency", "algorithms", "data-structures"]
+license = "MIT"
+repository = "https://github.com/xacrimon/dashmap"
+[package.metadata.docs.rs]
+features = ["rayon", "raw-api", "serde"]
+[dependencies.cfg-if]
+version = "1.0.0"
+
+[dependencies.num_cpus]
+version = "1.13.0"
+
+[dependencies.rayon]
+version = "1.5.0"
+optional = true
+
+[dependencies.serde]
+version = "1.0.118"
+features = ["derive"]
+optional = true
+
+[features]
+default = []
+raw-api = []
diff --git a/third_party/rust/dashmap/LICENSE b/third_party/rust/dashmap/LICENSE
new file mode 100644
index 0000000000..5a8b9ef869
--- /dev/null
+++ b/third_party/rust/dashmap/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2019 Acrimon
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/third_party/rust/dashmap/README.md b/third_party/rust/dashmap/README.md
new file mode 100644
index 0000000000..b517d8e416
--- /dev/null
+++ b/third_party/rust/dashmap/README.md
@@ -0,0 +1,73 @@
+# DashMap
+
+Blazingly fast concurrent map in Rust.
+
+DashMap is an implementation of a concurrent associative array/hashmap in Rust.
+
+DashMap tries to implement an easy to use API similar to `std::collections::HashMap`
+with some slight changes to handle concurrency.
+
+DashMap tries to be very simple to use and to be a direct replacement for `RwLock<HashMap<K, V>>`.
+To accomplish these all methods take `&self` instead modifying methods taking `&mut self`.
+This allows you to put a DashMap in an `Arc<T>` and share it between threads while being able to modify it.
+
+DashMap puts great effort into performance and aims to be as fast as possible.
+If you have any suggestions or tips do not hesitate to open an issue or a PR.
+
+[![version](https://img.shields.io/crates/v/dashmap)](https://crates.io/crates/dashmap)
+
+[![documentation](https://docs.rs/dashmap/badge.svg)](https://docs.rs/dashmap)
+
+[![downloads](https://img.shields.io/crates/d/dashmap)](https://crates.io/crates/dashmap)
+
+[![minimum rustc version](https://img.shields.io/badge/rustc-1.44.1-orange.svg)](https://crates.io/crates/dashmap)
+
+## Cargo features
+
+- `serde` - Enables serde support.
+
+- `raw-api` - Enables the unstable raw-shard api.
+
+- `rayon` - Enables rayon support.
+
+## Support me
+
+[![Foo](https://c5.patreon.com/external/logo/become_a_patron_button@2x.png)](https://patreon.com/acrimon)
+
+Creating and testing open-source software like DashMap takes up a large portion of my time
+and comes with costs such as test hardware. Please consider supporting me and everything I make for the public
+to enable me to continue doing this.
+
+If you want to support me please head over and take a look at my [patreon](https://www.patreon.com/acrimon).
+
+## Contributing
+
+DashMap is gladly accepts contributions!
+Do not hesitate to open issues or PR's.
+
+I will take a look as soon as I have time for it.
+
+That said I do not get paid (yet) to work on open-source. This means
+that my time is limited and my work here comes after my personal life.
+
+## Performance
+
+A comprehensive benchmark suite including DashMap can be found [here](https://github.com/xacrimon/conc-map-bench).
+
+## Special thanks
+
+- [Jon Gjengset](https://github.com/jonhoo)
+
+- [Yato](https://github.com/RustyYato) 
+
+- [Karl Bergström](https://github.com/kabergstrom)
+
+- [Dylan DPC](https://github.com/Dylan-DPC)
+
+- [Lokathor](https://github.com/Lokathor)
+
+- [namibj](https://github.com/namibj)
+
+## License
+
+This project is licensed under MIT.
diff --git a/third_party/rust/dashmap/rust-toolchain b/third_party/rust/dashmap/rust-toolchain
new file mode 100644
index 0000000000..a7d77a96a9
--- /dev/null
+++ b/third_party/rust/dashmap/rust-toolchain
@@ -0,0 +1 @@
+stable-2020-06-18
diff --git a/third_party/rust/dashmap/src/iter.rs b/third_party/rust/dashmap/src/iter.rs
new file mode 100644
index 0000000000..e88c1cae1d
--- /dev/null
+++ b/third_party/rust/dashmap/src/iter.rs
@@ -0,0 +1,309 @@
+use super::mapref::multiple::{RefMulti, RefMutMulti};
+use super::util;
+use crate::lock::{RwLockReadGuard, RwLockWriteGuard};
+use crate::t::Map;
+use crate::util::SharedValue;
+use crate::{DashMap, HashMap};
+use core::hash::{BuildHasher, Hash};
+use core::mem;
+use std::collections::hash_map;
+use std::collections::hash_map::RandomState;
+use std::sync::Arc;
+
+/// Iterator over a DashMap yielding key value pairs.
+///
+/// # Examples
+///
+/// ```
+/// use dashmap::DashMap;
+///
+/// let map = DashMap::new();
+/// map.insert("hello", "world");
+/// map.insert("alex", "steve");
+/// let pairs: Vec<(&'static str, &'static str)> = map.into_iter().collect();
+/// assert_eq!(pairs.len(), 2);
+/// ```
+pub struct OwningIter<K, V, S = RandomState> {
+    map: DashMap<K, V, S>,
+    shard_i: usize,
+    current: Option<GuardOwningIter<K, V>>,
+}
+
+impl<K: Eq + Hash, V, S: BuildHasher + Clone> OwningIter<K, V, S> {
+    pub(crate) fn new(map: DashMap<K, V, S>) -> Self {
+        Self {
+            map,
+            shard_i: 0,
+            current: None,
+        }
+    }
+}
+
+type GuardOwningIter<K, V> = hash_map::IntoIter<K, SharedValue<V>>;
+
+impl<K: Eq + Hash, V, S: BuildHasher + Clone> Iterator for OwningIter<K, V, S> {
+    type Item = (K, V);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            if let Some(current) = self.current.as_mut() {
+                if let Some((k, v)) = current.next() {
+                    return Some((k, v.into_inner()));
+                }
+            }
+
+            if self.shard_i == self.map._shard_count() {
+                return None;
+            }
+
+            //let guard = unsafe { self.map._yield_read_shard(self.shard_i) };
+            let mut shard_wl = unsafe { self.map._yield_write_shard(self.shard_i) };
+
+            let hasher = self.map._hasher();
+
+            let map = mem::replace(&mut *shard_wl, HashMap::with_hasher(hasher));
+
+            drop(shard_wl);
+
+            let iter = map.into_iter();
+
+            //unsafe { ptr::write(&mut self.current, Some((arcee, iter))); }
+            self.current = Some(iter);
+
+            self.shard_i += 1;
+        }
+    }
+}
+
+unsafe impl<K, V, S> Send for OwningIter<K, V, S>
+where
+    K: Eq + Hash + Send,
+    V: Send,
+    S: BuildHasher + Clone + Send,
+{
+}
+
+unsafe impl<K, V, S> Sync for OwningIter<K, V, S>
+where
+    K: Eq + Hash + Sync,
+    V: Sync,
+    S: BuildHasher + Clone + Sync,
+{
+}
+
+type GuardIter<'a, K, V, S> = (
+    Arc<RwLockReadGuard<'a, HashMap<K, V, S>>>,
+    hash_map::Iter<'a, K, SharedValue<V>>,
+);
+
+type GuardIterMut<'a, K, V, S> = (
+    Arc<RwLockWriteGuard<'a, HashMap<K, V, S>>>,
+    hash_map::IterMut<'a, K, SharedValue<V>>,
+);
+
+/// Iterator over a DashMap yielding immutable references.
+///
+/// # Examples
+///
+/// ```
+/// use dashmap::DashMap;
+///
+/// let map = DashMap::new();
+/// map.insert("hello", "world");
+/// assert_eq!(map.iter().count(), 1);
+/// ```
+pub struct Iter<'a, K, V, S = RandomState, M = DashMap<K, V, S>> {
+    map: &'a M,
+    shard_i: usize,
+    current: Option<GuardIter<'a, K, V, S>>,
+}
+
+unsafe impl<'a, 'i, K, V, S, M> Send for Iter<'i, K, V, S, M>
+where
+    K: 'a + Eq + Hash + Send,
+    V: 'a + Send,
+    S: 'a + BuildHasher + Clone,
+    M: Map<'a, K, V, S>,
+{
+}
+
+unsafe impl<'a, 'i, K, V, S, M> Sync for Iter<'i, K, V, S, M>
+where
+    K: 'a + Eq + Hash + Sync,
+    V: 'a + Sync,
+    S: 'a + BuildHasher + Clone,
+    M: Map<'a, K, V, S>,
+{
+}
+
+impl<'a, K: Eq + Hash, V, S: 'a + BuildHasher + Clone, M: Map<'a, K, V, S>> Iter<'a, K, V, S, M> {
+    pub(crate) fn new(map: &'a M) -> Self {
+        Self {
+            map,
+            shard_i: 0,
+            current: None,
+        }
+    }
+}
+
+impl<'a, K: Eq + Hash, V, S: 'a + BuildHasher + Clone, M: Map<'a, K, V, S>> Iterator
+    for Iter<'a, K, V, S, M>
+{
+    type Item = RefMulti<'a, K, V, S>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            if let Some(current) = self.current.as_mut() {
+                if let Some((k, v)) = current.1.next() {
+                    let guard = current.0.clone();
+
+                    return Some(RefMulti::new(guard, k, v.get()));
+                }
+            }
+
+            if self.shard_i == self.map._shard_count() {
+                return None;
+            }
+
+            let guard = unsafe { self.map._yield_read_shard(self.shard_i) };
+
+            let sref: &HashMap<K, V, S> = unsafe { util::change_lifetime_const(&*guard) };
+
+            let iter = sref.iter();
+
+            self.current = Some((Arc::new(guard), iter));
+
+            self.shard_i += 1;
+        }
+    }
+}
+
+/// Iterator over a DashMap yielding mutable references.
+///
+/// # Examples
+///
+/// ```
+/// use dashmap::DashMap;
+///
+/// let map = DashMap::new();
+/// map.insert("Johnny", 21);
+/// map.iter_mut().for_each(|mut r| *r += 1);
+/// assert_eq!(*map.get("Johnny").unwrap(), 22);
+/// ```
+pub struct IterMut<'a, K, V, S = RandomState, M = DashMap<K, V, S>> {
+    map: &'a M,
+    shard_i: usize,
+    current: Option<GuardIterMut<'a, K, V, S>>,
+}
+
+unsafe impl<'a, 'i, K, V, S, M> Send for IterMut<'i, K, V, S, M>
+where
+    K: 'a + Eq + Hash + Send,
+    V: 'a + Send,
+    S: 'a + BuildHasher + Clone,
+    M: Map<'a, K, V, S>,
+{
+}
+
+unsafe impl<'a, 'i, K, V, S, M> Sync for IterMut<'i, K, V, S, M>
+where
+    K: 'a + Eq + Hash + Sync,
+    V: 'a + Sync,
+    S: 'a + BuildHasher + Clone,
+    M: Map<'a, K, V, S>,
+{
+}
+
+impl<'a, K: Eq + Hash, V, S: 'a + BuildHasher + Clone, M: Map<'a, K, V, S>>
+    IterMut<'a, K, V, S, M>
+{
+    pub(crate) fn new(map: &'a M) -> Self {
+        Self {
+            map,
+            shard_i: 0,
+            current: None,
+        }
+    }
+}
+
+impl<'a, K: Eq + Hash, V, S: 'a + BuildHasher + Clone, M: Map<'a, K, V, S>> Iterator
+    for IterMut<'a, K, V, S, M>
+{
+    type Item = RefMutMulti<'a, K, V, S>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            if let Some(current) = self.current.as_mut() {
+                if let Some((k, v)) = current.1.next() {
+                    let guard = current.0.clone();
+
+                    unsafe {
+                        let k = util::change_lifetime_const(k);
+
+                        let v = &mut *v.as_ptr();
+
+                        return Some(RefMutMulti::new(guard, k, v));
+                    }
+                }
+            }
+
+            if self.shard_i == self.map._shard_count() {
+                return None;
+            }
+
+            let mut guard = unsafe { self.map._yield_write_shard(self.shard_i) };
+
+            let sref: &mut HashMap<K, V, S> = unsafe { util::change_lifetime_mut(&mut *guard) };
+
+            let iter = sref.iter_mut();
+
+            self.current = Some((Arc::new(guard), iter));
+
+            self.shard_i += 1;
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::DashMap;
+
+    #[test]
+    fn iter_mut_manual_count() {
+        let map = DashMap::new();
+
+        map.insert("Johnny", 21);
+
+        assert_eq!(map.len(), 1);
+
+        let mut c = 0;
+
+        for shard in map.shards() {
+            c += shard.write().iter_mut().count();
+        }
+
+        assert_eq!(c, 1);
+    }
+
+    #[test]
+    fn iter_mut_count() {
+        let map = DashMap::new();
+
+        map.insert("Johnny", 21);
+
+        assert_eq!(map.len(), 1);
+
+        assert_eq!(map.iter_mut().count(), 1);
+    }
+
+    #[test]
+    fn iter_count() {
+        let map = DashMap::new();
+
+        map.insert("Johnny", 21);
+
+        assert_eq!(map.len(), 1);
+
+        assert_eq!(map.iter().count(), 1);
+    }
+}
diff --git a/third_party/rust/dashmap/src/iter_set.rs b/third_party/rust/dashmap/src/iter_set.rs
new file mode 100644
index 0000000000..619a5b500e
--- /dev/null
+++ b/third_party/rust/dashmap/src/iter_set.rs
@@ -0,0 +1,71 @@
+use crate::setref::multiple::RefMulti;
+use crate::t::Map;
+use core::hash::{BuildHasher, Hash};
+
+pub struct OwningIter<K, S> {
+    inner: crate::iter::OwningIter<K, (), S>,
+}
+
+impl<K: Eq + Hash, S: BuildHasher + Clone> OwningIter<K, S> {
+    pub(crate) fn new(inner: crate::iter::OwningIter<K, (), S>) -> Self {
+        Self { inner }
+    }
+}
+
+impl<K: Eq + Hash, S: BuildHasher + Clone> Iterator for OwningIter<K, S> {
+    type Item = K;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next().map(|(k, _)| k)
+    }
+}
+
+unsafe impl<K, S> Send for OwningIter<K, S>
+where
+    K: Eq + Hash + Send,
+    S: BuildHasher + Clone + Send,
+{
+}
+
+unsafe impl<K, S> Sync for OwningIter<K, S>
+where
+    K: Eq + Hash + Sync,
+    S: BuildHasher + Clone + Sync,
+{
+}
+
+pub struct Iter<'a, K, S, M> {
+    inner: crate::iter::Iter<'a, K, (), S, M>,
+}
+
+unsafe impl<'a, 'i, K, S, M> Send for Iter<'i, K, S, M>
+where
+    K: 'a + Eq + Hash + Send,
+    S: 'a + BuildHasher + Clone,
+    M: Map<'a, K, (), S>,
+{
+}
+
+unsafe impl<'a, 'i, K, S, M> Sync for Iter<'i, K, S, M>
+where
+    K: 'a + Eq + Hash + Sync,
+    S: 'a + BuildHasher + Clone,
+    M: Map<'a, K, (), S>,
+{
+}
+
+impl<'a, K: Eq + Hash, S: 'a + BuildHasher + Clone, M: Map<'a, K, (), S>> Iter<'a, K, S, M> {
+    pub(crate) fn new(inner: crate::iter::Iter<'a, K, (), S, M>) -> Self {
+        Self { inner }
+    }
+}
+
+impl<'a, K: Eq + Hash, S: 'a + BuildHasher + Clone, M: Map<'a, K, (), S>> Iterator
+    for Iter<'a, K, S, M>
+{
+    type Item = RefMulti<'a, K, S>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next().map(RefMulti::new)
+    }
+}
diff --git a/third_party/rust/dashmap/src/lib.rs b/third_party/rust/dashmap/src/lib.rs
new file mode 100644
index 0000000000..3507ece5f2
--- /dev/null
+++ b/third_party/rust/dashmap/src/lib.rs
@@ -0,0 +1,993 @@
+#![allow(clippy::type_complexity)]
+
+pub mod iter;
+pub mod iter_set;
+pub mod lock;
+pub mod mapref;
+mod read_only;
+#[cfg(feature = "serde")]
+mod serde;
+mod set;
+pub mod setref;
+mod t;
+mod util;
+
+#[cfg(feature = "rayon")]
+pub mod rayon {
+    pub mod map;
+    pub mod set;
+}
+
+use cfg_if::cfg_if;
+use core::borrow::Borrow;
+use core::fmt;
+use core::hash::{BuildHasher, Hash, Hasher};
+use core::iter::FromIterator;
+use core::ops::{BitAnd, BitOr, Shl, Shr, Sub};
+use iter::{Iter, IterMut, OwningIter};
+use lock::{RwLock, RwLockReadGuard, RwLockWriteGuard};
+use mapref::entry::{Entry, OccupiedEntry, VacantEntry};
+use mapref::multiple::RefMulti;
+use mapref::one::{Ref, RefMut};
+pub use read_only::ReadOnlyView;
+pub use set::DashSet;
+use std::collections::hash_map::RandomState;
+pub use t::Map;
+
+cfg_if! {
+    if #[cfg(feature = "raw-api")] {
+        pub use util::SharedValue;
+    } else {
+        use util::SharedValue;
+    }
+}
+
+pub(crate) type HashMap<K, V, S> = std::collections::HashMap<K, SharedValue<V>, S>;
+
+fn shard_amount() -> usize {
+    (num_cpus::get() * 4).next_power_of_two()
+}
+
+fn ncb(shard_amount: usize) -> usize {
+    shard_amount.trailing_zeros() as usize
+}
+
+/// DashMap is an implementation of a concurrent associative array/hashmap in Rust.
+///
+/// DashMap tries to implement an easy to use API similar to `std::collections::HashMap`
+/// with some slight changes to handle concurrency.
+///
+/// DashMap tries to be very simple to use and to be a direct replacement for `RwLock<HashMap<K, V, S>>`.
+/// To accomplish these all methods take `&self` instead modifying methods taking `&mut self`.
+/// This allows you to put a DashMap in an `Arc<T>` and share it between threads while being able to modify it.
+///
+/// Documentation mentioning locking behaviour acts in the reference frame of the calling thread.
+/// This means that it is safe to ignore it across multiple threads.
+pub struct DashMap<K, V, S = RandomState> {
+    shift: usize,
+    shards: Box<[RwLock<HashMap<K, V, S>>]>,
+    hasher: S,
+}
+
+impl<K: Eq + Hash + Clone, V: Clone, S: Clone> Clone for DashMap<K, V, S> {
+    fn clone(&self) -> Self {
+        let mut inner_shards = Vec::new();
+
+        for shard in self.shards.iter() {
+            let shard = shard.read();
+
+            inner_shards.push(RwLock::new((*shard).clone()));
+        }
+
+        Self {
+            shift: self.shift,
+            shards: inner_shards.into_boxed_slice(),
+            hasher: self.hasher.clone(),
+        }
+    }
+}
+
+impl<K, V, S> Default for DashMap<K, V, S>
+where
+    K: Eq + Hash,
+    S: Default + BuildHasher + Clone,
+{
+    fn default() -> Self {
+        Self::with_hasher(Default::default())
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash, V: 'a> DashMap<K, V, RandomState> {
+    /// Creates a new DashMap with a capacity of 0.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let reviews = DashMap::new();
+    /// reviews.insert("Veloren", "What a fantastic game!");
+    /// ```
+    pub fn new() -> Self {
+        DashMap::with_hasher(RandomState::default())
+    }
+
+    /// Creates a new DashMap with a specified starting capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let mappings = DashMap::with_capacity(2);
+    /// mappings.insert(2, 4);
+    /// mappings.insert(8, 16);
+    /// ```
+    pub fn with_capacity(capacity: usize) -> Self {
+        DashMap::with_capacity_and_hasher(capacity, RandomState::default())
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> DashMap<K, V, S> {
+    /// Wraps this `DashMap` into a read-only view. This view allows to obtain raw references to the stored values.
+    pub fn into_read_only(self) -> ReadOnlyView<K, V, S> {
+        ReadOnlyView::new(self)
+    }
+
+    /// Creates a new DashMap with a capacity of 0 and the provided hasher.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    /// use std::collections::hash_map::RandomState;
+    ///
+    /// let s = RandomState::new();
+    /// let reviews = DashMap::with_hasher(s);
+    /// reviews.insert("Veloren", "What a fantastic game!");
+    /// ```
+    pub fn with_hasher(hasher: S) -> Self {
+        Self::with_capacity_and_hasher(0, hasher)
+    }
+
+    /// Creates a new DashMap with a specified starting capacity and hasher.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    /// use std::collections::hash_map::RandomState;
+    ///
+    /// let s = RandomState::new();
+    /// let mappings = DashMap::with_capacity_and_hasher(2, s);
+    /// mappings.insert(2, 4);
+    /// mappings.insert(8, 16);
+    /// ```
+    pub fn with_capacity_and_hasher(mut capacity: usize, hasher: S) -> Self {
+        let shard_amount = shard_amount();
+        let shift = util::ptr_size_bits() - ncb(shard_amount);
+
+        if capacity != 0 {
+            capacity = (capacity + (shard_amount - 1)) & !(shard_amount - 1);
+        }
+
+        let cps = capacity / shard_amount;
+
+        let shards = (0..shard_amount)
+            .map(|_| RwLock::new(HashMap::with_capacity_and_hasher(cps, hasher.clone())))
+            .collect();
+
+        Self {
+            shift,
+            shards,
+            hasher,
+        }
+    }
+
+    /// Hash a given item to produce a usize.
+    /// Uses the provided or default HashBuilder.
+    pub fn hash_usize<T: Hash>(&self, item: &T) -> usize {
+        let mut hasher = self.hasher.build_hasher();
+
+        item.hash(&mut hasher);
+
+        hasher.finish() as usize
+    }
+
+    cfg_if! {
+        if #[cfg(feature = "raw-api")] {
+            /// Allows you to peek at the inner shards that store your data.
+            /// You should probably not use this unless you know what you are doing.
+            ///
+            /// Requires the `raw-api` feature to be enabled.
+            ///
+            /// # Examples
+            ///
+            /// ```
+            /// use dashmap::DashMap;
+            ///
+            /// let map = DashMap::<(), ()>::new();
+            /// println!("Amount of shards: {}", map.shards().len());
+            /// ```
+            pub fn shards(&self) -> &[RwLock<HashMap<K, V, S>>] {
+                &self.shards
+            }
+        } else {
+            #[allow(dead_code)]
+            pub(crate) fn shards(&self) -> &[RwLock<HashMap<K, V, S>>] {
+                &self.shards
+            }
+        }
+    }
+
+    cfg_if! {
+        if #[cfg(feature = "raw-api")] {
+            /// Finds which shard a certain key is stored in.
+            /// You should probably not use this unless you know what you are doing.
+            /// Note that shard selection is dependent on the default or provided HashBuilder.
+            ///
+            /// Requires the `raw-api` feature to be enabled.
+            ///
+            /// # Examples
+            ///
+            /// ```
+            /// use dashmap::DashMap;
+            ///
+            /// let map = DashMap::new();
+            /// map.insert("coca-cola", 1.4);
+            /// println!("coca-cola is stored in shard: {}", map.determine_map("coca-cola"));
+            /// ```
+            pub fn determine_map<Q>(&self, key: &Q) -> usize
+            where
+                K: Borrow<Q>,
+                Q: Hash + Eq + ?Sized,
+            {
+                let hash = self.hash_usize(&key);
+                self.determine_shard(hash)
+            }
+        }
+    }
+
+    cfg_if! {
+        if #[cfg(feature = "raw-api")] {
+            /// Finds which shard a certain hash is stored in.
+            ///
+            /// Requires the `raw-api` feature to be enabled.
+            ///
+            /// # Examples
+            ///
+            /// ```
+            /// use dashmap::DashMap;
+            ///
+            /// let map: DashMap<i32, i32> = DashMap::new();
+            /// let key = "key";
+            /// let hash = map.hash_usize(&key);
+            /// println!("hash is stored in shard: {}", map.determine_shard(hash));
+            /// ```
+            pub fn determine_shard(&self, hash: usize) -> usize {
+                // Leave the high 7 bits for the HashBrown SIMD tag.
+                (hash << 7) >> self.shift
+            }
+        } else {
+
+            pub(crate) fn determine_shard(&self, hash: usize) -> usize {
+                // Leave the high 7 bits for the HashBrown SIMD tag.
+                (hash << 7) >> self.shift
+            }
+        }
+    }
+
+    /// Returns a reference to the map's [`BuildHasher`].
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use dashmap::DashMap;
+    /// use std::collections::hash_map::RandomState;
+    ///
+    /// let hasher = RandomState::new();
+    /// let map: DashMap<i32, i32> = DashMap::new();
+    /// let hasher: &RandomState = map.hasher();
+    /// ```
+    ///
+    /// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
+    pub fn hasher(&self) -> &S {
+        &self.hasher
+    }
+
+    /// Inserts a key and a value into the map. Returns the old value associated with the key if there was one.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let map = DashMap::new();
+    /// map.insert("I am the key!", "And I am the value!");
+    /// ```
+    pub fn insert(&self, key: K, value: V) -> Option<V> {
+        self._insert(key, value)
+    }
+
+    /// Removes an entry from the map, returning the key and value if they existed in the map.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let soccer_team = DashMap::new();
+    /// soccer_team.insert("Jack", "Goalie");
+    /// assert_eq!(soccer_team.remove("Jack").unwrap().1, "Goalie");
+    /// ```
+    pub fn remove<Q>(&self, key: &Q) -> Option<(K, V)>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        self._remove(key)
+    }
+
+    /// Removes an entry from the map, returning the key and value
+    /// if the entry existed and the provided conditional function returned true.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let soccer_team = DashMap::new();
+    /// soccer_team.insert("Sam", "Forward");
+    /// soccer_team.remove_if("Sam", |_, position| position == &"Goalie");
+    /// assert!(soccer_team.contains_key("Sam"));
+    /// ```
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let soccer_team = DashMap::new();
+    /// soccer_team.insert("Sam", "Forward");
+    /// soccer_team.remove_if("Sam", |_, position| position == &"Forward");
+    /// assert!(!soccer_team.contains_key("Sam"));
+    /// ```
+    pub fn remove_if<Q>(&self, key: &Q, f: impl FnOnce(&K, &V) -> bool) -> Option<(K, V)>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        self._remove_if(key, f)
+    }
+
+    /// Creates an iterator over a DashMap yielding immutable references.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding a mutable reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let words = DashMap::new();
+    /// words.insert("hello", "world");
+    /// assert_eq!(words.iter().count(), 1);
+    /// ```
+    pub fn iter(&'a self) -> Iter<'a, K, V, S, DashMap<K, V, S>> {
+        self._iter()
+    }
+
+    /// Iterator over a DashMap yielding mutable references.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let map = DashMap::new();
+    /// map.insert("Johnny", 21);
+    /// map.iter_mut().for_each(|mut r| *r += 1);
+    /// assert_eq!(*map.get("Johnny").unwrap(), 22);
+    /// ```
+    pub fn iter_mut(&'a self) -> IterMut<'a, K, V, S, DashMap<K, V, S>> {
+        self._iter_mut()
+    }
+
+    /// Get a immutable reference to an entry in the map
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding a mutable reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let youtubers = DashMap::new();
+    /// youtubers.insert("Bosnian Bill", 457000);
+    /// assert_eq!(*youtubers.get("Bosnian Bill").unwrap(), 457000);
+    /// ```
+    pub fn get<Q>(&'a self, key: &Q) -> Option<Ref<'a, K, V, S>>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        self._get(key)
+    }
+
+    /// Get a mutable reference to an entry in the map
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let class = DashMap::new();
+    /// class.insert("Albin", 15);
+    /// *class.get_mut("Albin").unwrap() -= 1;
+    /// assert_eq!(*class.get("Albin").unwrap(), 14);
+    /// ```
+    pub fn get_mut<Q>(&'a self, key: &Q) -> Option<RefMut<'a, K, V, S>>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        self._get_mut(key)
+    }
+
+    /// Remove excess capacity to reduce memory usage.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    pub fn shrink_to_fit(&self) {
+        self._shrink_to_fit();
+    }
+
+    /// Retain elements that whose predicates return true
+    /// and discard elements whose predicates return false.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let people = DashMap::new();
+    /// people.insert("Albin", 15);
+    /// people.insert("Jones", 22);
+    /// people.insert("Charlie", 27);
+    /// people.retain(|_, v| *v > 20);
+    /// assert_eq!(people.len(), 2);
+    /// ```
+    pub fn retain(&self, f: impl FnMut(&K, &mut V) -> bool) {
+        self._retain(f);
+    }
+
+    /// Fetches the total number of key-value pairs stored in the map.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding a mutable reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let people = DashMap::new();
+    /// people.insert("Albin", 15);
+    /// people.insert("Jones", 22);
+    /// people.insert("Charlie", 27);
+    /// assert_eq!(people.len(), 3);
+    /// ```
+    pub fn len(&self) -> usize {
+        self._len()
+    }
+
+    /// Checks if the map is empty or not.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding a mutable reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let map = DashMap::<(), ()>::new();
+    /// assert!(map.is_empty());
+    /// ```
+    pub fn is_empty(&self) -> bool {
+        self._is_empty()
+    }
+
+    /// Removes all key-value pairs in the map.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let stats = DashMap::new();
+    /// stats.insert("Goals", 4);
+    /// assert!(!stats.is_empty());
+    /// stats.clear();
+    /// assert!(stats.is_empty());
+    /// ```
+    pub fn clear(&self) {
+        self._clear();
+    }
+
+    /// Returns how many key-value pairs the map can store without reallocating.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding a mutable reference into the map.
+    pub fn capacity(&self) -> usize {
+        self._capacity()
+    }
+
+    /// Modify a specific value according to a function.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let stats = DashMap::new();
+    /// stats.insert("Goals", 4);
+    /// stats.alter("Goals", |_, v| v * 2);
+    /// assert_eq!(*stats.get("Goals").unwrap(), 8);
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// If the given closure panics, then `alter` will abort the process
+    pub fn alter<Q>(&self, key: &Q, f: impl FnOnce(&K, V) -> V)
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        self._alter(key, f);
+    }
+
+    /// Modify every value in the map according to a function.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let stats = DashMap::new();
+    /// stats.insert("Wins", 4);
+    /// stats.insert("Losses", 2);
+    /// stats.alter_all(|_, v| v + 1);
+    /// assert_eq!(*stats.get("Wins").unwrap(), 5);
+    /// assert_eq!(*stats.get("Losses").unwrap(), 3);
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// If the given closure panics, then `alter_all` will abort the process
+    pub fn alter_all(&self, f: impl FnMut(&K, V) -> V) {
+        self._alter_all(f);
+    }
+
+    /// Checks if the map contains a specific key.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding a mutable reference into the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashMap;
+    ///
+    /// let team_sizes = DashMap::new();
+    /// team_sizes.insert("Dakota Cherries", 23);
+    /// assert!(team_sizes.contains_key("Dakota Cherries"));
+    /// ```
+    pub fn contains_key<Q>(&self, key: &Q) -> bool
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        self._contains_key(key)
+    }
+
+    /// Advanced entry API that tries to mimic `std::collections::HashMap`.
+    /// See the documentation on `dashmap::mapref::entry` for more details.
+    ///
+    /// **Locking behaviour:** May deadlock if called when holding any sort of reference into the map.
+    pub fn entry(&'a self, key: K) -> Entry<'a, K, V, S> {
+        self._entry(key)
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
+    for DashMap<K, V, S>
+{
+    fn _shard_count(&self) -> usize {
+        self.shards.len()
+    }
+
+    unsafe fn _get_read_shard(&'a self, i: usize) -> &'a HashMap<K, V, S> {
+        debug_assert!(i < self.shards.len());
+
+        self.shards.get_unchecked(i).get()
+    }
+
+    unsafe fn _yield_read_shard(&'a self, i: usize) -> RwLockReadGuard<'a, HashMap<K, V, S>> {
+        debug_assert!(i < self.shards.len());
+
+        self.shards.get_unchecked(i).read()
+    }
+
+    unsafe fn _yield_write_shard(&'a self, i: usize) -> RwLockWriteGuard<'a, HashMap<K, V, S>> {
+        debug_assert!(i < self.shards.len());
+
+        self.shards.get_unchecked(i).write()
+    }
+
+    fn _insert(&self, key: K, value: V) -> Option<V> {
+        let hash = self.hash_usize(&key);
+
+        let idx = self.determine_shard(hash);
+
+        let mut shard = unsafe { self._yield_write_shard(idx) };
+
+        shard
+            .insert(key, SharedValue::new(value))
+            .map(|v| v.into_inner())
+    }
+
+    fn _remove<Q>(&self, key: &Q) -> Option<(K, V)>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        let hash = self.hash_usize(&key);
+
+        let idx = self.determine_shard(hash);
+
+        let mut shard = unsafe { self._yield_write_shard(idx) };
+
+        shard.remove_entry(key).map(|(k, v)| (k, v.into_inner()))
+    }
+
+    fn _remove_if<Q>(&self, key: &Q, f: impl FnOnce(&K, &V) -> bool) -> Option<(K, V)>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        let hash = self.hash_usize(&key);
+
+        let idx = self.determine_shard(hash);
+
+        let mut shard = unsafe { self._yield_write_shard(idx) };
+
+        if let Some((k, v)) = shard.get_key_value(key) {
+            if f(k, v.get()) {
+                shard.remove_entry(key).map(|(k, v)| (k, v.into_inner()))
+            } else {
+                None
+            }
+        } else {
+            None
+        }
+    }
+
+    fn _iter(&'a self) -> Iter<'a, K, V, S, DashMap<K, V, S>> {
+        Iter::new(self)
+    }
+
+    fn _iter_mut(&'a self) -> IterMut<'a, K, V, S, DashMap<K, V, S>> {
+        IterMut::new(self)
+    }
+
+    fn _get<Q>(&'a self, key: &Q) -> Option<Ref<'a, K, V, S>>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        let hash = self.hash_usize(&key);
+
+        let idx = self.determine_shard(hash);
+
+        let shard = unsafe { self._yield_read_shard(idx) };
+
+        if let Some((kptr, vptr)) = shard.get_key_value(key) {
+            unsafe {
+                let kptr = util::change_lifetime_const(kptr);
+
+                let vptr = util::change_lifetime_const(vptr);
+
+                Some(Ref::new(shard, kptr, vptr.get()))
+            }
+        } else {
+            None
+        }
+    }
+
+    fn _get_mut<Q>(&'a self, key: &Q) -> Option<RefMut<'a, K, V, S>>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        let hash = self.hash_usize(&key);
+
+        let idx = self.determine_shard(hash);
+
+        let shard = unsafe { self._yield_write_shard(idx) };
+
+        if let Some((kptr, vptr)) = shard.get_key_value(key) {
+            unsafe {
+                let kptr = util::change_lifetime_const(kptr);
+
+                let vptr = &mut *vptr.as_ptr();
+
+                Some(RefMut::new(shard, kptr, vptr))
+            }
+        } else {
+            None
+        }
+    }
+
+    fn _shrink_to_fit(&self) {
+        self.shards.iter().for_each(|s| s.write().shrink_to_fit());
+    }
+
+    fn _retain(&self, mut f: impl FnMut(&K, &mut V) -> bool) {
+        self.shards
+            .iter()
+            .for_each(|s| s.write().retain(|k, v| f(k, v.get_mut())));
+    }
+
+    fn _len(&self) -> usize {
+        self.shards.iter().map(|s| s.read().len()).sum()
+    }
+
+    fn _capacity(&self) -> usize {
+        self.shards.iter().map(|s| s.read().capacity()).sum()
+    }
+
+    fn _alter<Q>(&self, key: &Q, f: impl FnOnce(&K, V) -> V)
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        if let Some(mut r) = self.get_mut(key) {
+            util::map_in_place_2(r.pair_mut(), f);
+        }
+    }
+
+    fn _alter_all(&self, mut f: impl FnMut(&K, V) -> V) {
+        self.shards.iter().for_each(|s| {
+            s.write()
+                .iter_mut()
+                .for_each(|(k, v)| util::map_in_place_2((k, v.get_mut()), &mut f));
+        });
+    }
+
+    fn _entry(&'a self, key: K) -> Entry<'a, K, V, S> {
+        let hash = self.hash_usize(&key);
+
+        let idx = self.determine_shard(hash);
+
+        let shard = unsafe { self._yield_write_shard(idx) };
+
+        if let Some((kptr, vptr)) = shard.get_key_value(&key) {
+            unsafe {
+                let kptr = util::change_lifetime_const(kptr);
+
+                let vptr = &mut *vptr.as_ptr();
+
+                Entry::Occupied(OccupiedEntry::new(shard, key, (kptr, vptr)))
+            }
+        } else {
+            Entry::Vacant(VacantEntry::new(shard, key))
+        }
+    }
+
+    fn _hasher(&self) -> S {
+        self.hasher.clone()
+    }
+}
+
+impl<K: Eq + Hash + fmt::Debug, V: fmt::Debug, S: BuildHasher + Clone> fmt::Debug
+    for DashMap<K, V, S>
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut pmap = f.debug_map();
+
+        for r in self {
+            let (k, v) = r.pair();
+
+            pmap.entry(k, v);
+        }
+
+        pmap.finish()
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> Shl<(K, V)> for &'a DashMap<K, V, S> {
+    type Output = Option<V>;
+
+    fn shl(self, pair: (K, V)) -> Self::Output {
+        self.insert(pair.0, pair.1)
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone, Q> Shr<&Q> for &'a DashMap<K, V, S>
+where
+    K: Borrow<Q>,
+    Q: Hash + Eq + ?Sized,
+{
+    type Output = Ref<'a, K, V, S>;
+
+    fn shr(self, key: &Q) -> Self::Output {
+        self.get(key).unwrap()
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone, Q> BitOr<&Q> for &'a DashMap<K, V, S>
+where
+    K: Borrow<Q>,
+    Q: Hash + Eq + ?Sized,
+{
+    type Output = RefMut<'a, K, V, S>;
+
+    fn bitor(self, key: &Q) -> Self::Output {
+        self.get_mut(key).unwrap()
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone, Q> Sub<&Q> for &'a DashMap<K, V, S>
+where
+    K: Borrow<Q>,
+    Q: Hash + Eq + ?Sized,
+{
+    type Output = Option<(K, V)>;
+
+    fn sub(self, key: &Q) -> Self::Output {
+        self.remove(key)
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone, Q> BitAnd<&Q> for &'a DashMap<K, V, S>
+where
+    K: Borrow<Q>,
+    Q: Hash + Eq + ?Sized,
+{
+    type Output = bool;
+
+    fn bitand(self, key: &Q) -> Self::Output {
+        self.contains_key(key)
+    }
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher + Clone> IntoIterator for DashMap<K, V, S> {
+    type Item = (K, V);
+
+    type IntoIter = OwningIter<K, V, S>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        OwningIter::new(self)
+    }
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher + Clone> IntoIterator for &'a DashMap<K, V, S> {
+    type Item = RefMulti<'a, K, V, S>;
+
+    type IntoIter = Iter<'a, K, V, S, DashMap<K, V, S>>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
+impl<K: Eq + Hash, V, S: BuildHasher + Clone> Extend<(K, V)> for DashMap<K, V, S> {
+    fn extend<I: IntoIterator<Item = (K, V)>>(&mut self, intoiter: I) {
+        for pair in intoiter.into_iter() {
+            self.insert(pair.0, pair.1);
+        }
+    }
+}
+
+impl<K: Eq + Hash, V> FromIterator<(K, V)> for DashMap<K, V, RandomState> {
+    fn from_iter<I: IntoIterator<Item = (K, V)>>(intoiter: I) -> Self {
+        let mut map = DashMap::new();
+
+        map.extend(intoiter);
+
+        map
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::DashMap;
+    use std::collections::hash_map::RandomState;
+
+    #[test]
+    fn test_basic() {
+        let dm = DashMap::new();
+
+        dm.insert(0, 0);
+
+        assert_eq!(dm.get(&0).unwrap().value(), &0);
+    }
+
+    #[test]
+    fn test_default() {
+        let dm: DashMap<u32, u32> = DashMap::default();
+
+        dm.insert(0, 0);
+
+        assert_eq!(dm.get(&0).unwrap().value(), &0);
+    }
+
+    #[test]
+    fn test_multiple_hashes() {
+        let dm: DashMap<u32, u32> = DashMap::default();
+
+        for i in 0..100 {
+            dm.insert(0, i);
+
+            dm.insert(i, i);
+        }
+
+        for i in 1..100 {
+            let r = dm.get(&i).unwrap();
+
+            assert_eq!(i, *r.value());
+
+            assert_eq!(i, *r.key());
+        }
+
+        let r = dm.get(&0).unwrap();
+
+        assert_eq!(99, *r.value());
+    }
+
+    #[test]
+    fn test_more_complex_values() {
+        #[derive(Hash, PartialEq, Debug, Clone)]
+
+        struct T0 {
+            s: String,
+            u: u8,
+        }
+
+        let dm = DashMap::new();
+
+        let range = 0..10;
+
+        for i in range {
+            let t = T0 {
+                s: i.to_string(),
+                u: i as u8,
+            };
+
+            dm.insert(i, t.clone());
+
+            assert_eq!(&t, dm.get(&i).unwrap().value());
+        }
+    }
+
+    #[test]
+    fn test_different_hashers_randomstate() {
+        let dm_hm_default: DashMap<u32, u32, RandomState> =
+            DashMap::with_hasher(RandomState::new());
+
+        for i in 0..10 {
+            dm_hm_default.insert(i, i);
+
+            assert_eq!(i, *dm_hm_default.get(&i).unwrap().value());
+        }
+    }
+}
diff --git a/third_party/rust/dashmap/src/lock.rs b/third_party/rust/dashmap/src/lock.rs
new file mode 100644
index 0000000000..d27b413185
--- /dev/null
+++ b/third_party/rust/dashmap/src/lock.rs
@@ -0,0 +1,557 @@
+use core::cell::UnsafeCell;
+use core::default::Default;
+use core::fmt;
+use core::marker::PhantomData;
+use core::mem;
+use core::ops::{Deref, DerefMut};
+use core::ptr::NonNull;
+use core::sync::atomic::{spin_loop_hint as cpu_relax, AtomicUsize, Ordering};
+
+pub struct RwLock<T: ?Sized> {
+    lock: AtomicUsize,
+    data: UnsafeCell<T>,
+}
+
+const READER: usize = 1 << 2;
+
+const UPGRADED: usize = 1 << 1;
+
+const WRITER: usize = 1;
+
+#[derive(Debug)]
+pub struct RwLockReadGuard<'a, T: 'a + ?Sized> {
+    lock: &'a AtomicUsize,
+    data: NonNull<T>,
+}
+
+unsafe impl<'a, T: Send> Send for RwLockReadGuard<'a, T> {}
+
+unsafe impl<'a, T: Sync> Sync for RwLockReadGuard<'a, T> {}
+
+#[derive(Debug)]
+pub struct RwLockWriteGuard<'a, T: 'a + ?Sized> {
+    lock: &'a AtomicUsize,
+    data: NonNull<T>,
+    #[doc(hidden)]
+    _invariant: PhantomData<&'a mut T>,
+}
+
+unsafe impl<'a, T: Send> Send for RwLockWriteGuard<'a, T> {}
+
+unsafe impl<'a, T: Sync> Sync for RwLockWriteGuard<'a, T> {}
+
+#[derive(Debug)]
+pub struct RwLockUpgradeableGuard<'a, T: 'a + ?Sized> {
+    lock: &'a AtomicUsize,
+    data: NonNull<T>,
+    #[doc(hidden)]
+    _invariant: PhantomData<&'a mut T>,
+}
+
+unsafe impl<T: ?Sized + Send> Send for RwLock<T> {}
+
+unsafe impl<T: ?Sized + Send + Sync> Sync for RwLock<T> {}
+
+impl<T> RwLock<T> {
+    pub const fn new(user_data: T) -> RwLock<T> {
+        RwLock {
+            lock: AtomicUsize::new(0),
+            data: UnsafeCell::new(user_data),
+        }
+    }
+
+    pub fn into_inner(self) -> T {
+        let RwLock { data, .. } = self;
+
+        data.into_inner()
+    }
+}
+
+impl<T: ?Sized> RwLock<T> {
+    pub fn read(&self) -> RwLockReadGuard<T> {
+        loop {
+            match self.try_read() {
+                Some(guard) => return guard,
+                None => cpu_relax(),
+            }
+        }
+    }
+
+    pub fn try_read(&self) -> Option<RwLockReadGuard<T>> {
+        let value = self.lock.fetch_add(READER, Ordering::Acquire);
+
+        // We check the UPGRADED bit here so that new readers are prevented when an UPGRADED lock is held.
+        // This helps reduce writer starvation.
+        if value & (WRITER | UPGRADED) != 0 {
+            // Lock is taken, undo.
+            self.lock.fetch_sub(READER, Ordering::Release);
+
+            None
+        } else {
+            Some(RwLockReadGuard {
+                lock: &self.lock,
+                data: unsafe { NonNull::new_unchecked(self.data.get()) },
+            })
+        }
+    }
+
+    /// # Safety
+    ///
+    /// This is only safe if the lock is currently locked in read mode and the number of readers is not 0.
+    pub unsafe fn force_read_decrement(&self) {
+        debug_assert!(self.lock.load(Ordering::Relaxed) & !WRITER > 0);
+
+        self.lock.fetch_sub(READER, Ordering::Release);
+    }
+
+    /// # Safety
+    ///
+    /// The lock must be locked in write mode.
+    pub unsafe fn force_write_unlock(&self) {
+        debug_assert_eq!(self.lock.load(Ordering::Relaxed) & !(WRITER | UPGRADED), 0);
+
+        self.lock.fetch_and(!(WRITER | UPGRADED), Ordering::Release);
+    }
+
+    fn try_write_internal(&self, strong: bool) -> Option<RwLockWriteGuard<T>> {
+        if compare_exchange(
+            &self.lock,
+            0,
+            WRITER,
+            Ordering::Acquire,
+            Ordering::Relaxed,
+            strong,
+        )
+        .is_ok()
+        {
+            Some(RwLockWriteGuard {
+                lock: &self.lock,
+                data: unsafe { NonNull::new_unchecked(self.data.get()) },
+                _invariant: PhantomData,
+            })
+        } else {
+            None
+        }
+    }
+
+    pub fn write(&self) -> RwLockWriteGuard<T> {
+        loop {
+            match self.try_write_internal(false) {
+                Some(guard) => return guard,
+                None => cpu_relax(),
+            }
+        }
+    }
+
+    pub fn try_write(&self) -> Option<RwLockWriteGuard<T>> {
+        self.try_write_internal(true)
+    }
+
+    pub fn upgradeable_read(&self) -> RwLockUpgradeableGuard<T> {
+        loop {
+            match self.try_upgradeable_read() {
+                Some(guard) => return guard,
+                None => cpu_relax(),
+            }
+        }
+    }
+
+    pub fn try_upgradeable_read(&self) -> Option<RwLockUpgradeableGuard<T>> {
+        if self.lock.fetch_or(UPGRADED, Ordering::Acquire) & (WRITER | UPGRADED) == 0 {
+            Some(RwLockUpgradeableGuard {
+                lock: &self.lock,
+                data: unsafe { NonNull::new_unchecked(self.data.get()) },
+                _invariant: PhantomData,
+            })
+        } else {
+            None
+        }
+    }
+
+    /// # Safety
+    /// Write locks may not be used in combination with this method.
+    pub unsafe fn get(&self) -> &T {
+        &*self.data.get()
+    }
+
+    pub fn get_mut(&mut self) -> &mut T {
+        unsafe { &mut *self.data.get() }
+    }
+}
+
+impl<T: ?Sized + fmt::Debug> fmt::Debug for RwLock<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.try_read() {
+            Some(guard) => write!(f, "RwLock {{ data: ")
+                .and_then(|()| (&*guard).fmt(f))
+                .and_then(|()| write!(f, "}}")),
+            None => write!(f, "RwLock {{ <locked> }}"),
+        }
+    }
+}
+
+impl<T: ?Sized + Default> Default for RwLock<T> {
+    fn default() -> RwLock<T> {
+        RwLock::new(Default::default())
+    }
+}
+
+impl<'rwlock, T: ?Sized> RwLockUpgradeableGuard<'rwlock, T> {
+    fn try_upgrade_internal(self, strong: bool) -> Result<RwLockWriteGuard<'rwlock, T>, Self> {
+        if compare_exchange(
+            &self.lock,
+            UPGRADED,
+            WRITER,
+            Ordering::Acquire,
+            Ordering::Relaxed,
+            strong,
+        )
+        .is_ok()
+        {
+            let out = Ok(RwLockWriteGuard {
+                lock: &self.lock,
+                data: self.data,
+                _invariant: PhantomData,
+            });
+
+            mem::forget(self);
+
+            out
+        } else {
+            Err(self)
+        }
+    }
+
+    pub fn upgrade(mut self) -> RwLockWriteGuard<'rwlock, T> {
+        loop {
+            self = match self.try_upgrade_internal(false) {
+                Ok(guard) => return guard,
+                Err(e) => e,
+            };
+
+            cpu_relax();
+        }
+    }
+
+    pub fn try_upgrade(self) -> Result<RwLockWriteGuard<'rwlock, T>, Self> {
+        self.try_upgrade_internal(true)
+    }
+
+    pub fn downgrade(self) -> RwLockReadGuard<'rwlock, T> {
+        self.lock.fetch_add(READER, Ordering::Acquire);
+
+        RwLockReadGuard {
+            lock: &self.lock,
+            data: self.data,
+        }
+    }
+}
+
+impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> {
+    pub fn downgrade(self) -> RwLockReadGuard<'rwlock, T> {
+        self.lock.fetch_add(READER, Ordering::Acquire);
+
+        RwLockReadGuard {
+            lock: &self.lock,
+            data: self.data,
+        }
+    }
+}
+
+impl<'rwlock, T: ?Sized> Deref for RwLockReadGuard<'rwlock, T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        unsafe { self.data.as_ref() }
+    }
+}
+
+impl<'rwlock, T: ?Sized> Deref for RwLockUpgradeableGuard<'rwlock, T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        unsafe { self.data.as_ref() }
+    }
+}
+
+impl<'rwlock, T: ?Sized> Deref for RwLockWriteGuard<'rwlock, T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        unsafe { self.data.as_ref() }
+    }
+}
+
+impl<'rwlock, T: ?Sized> DerefMut for RwLockWriteGuard<'rwlock, T> {
+    fn deref_mut(&mut self) -> &mut T {
+        unsafe { self.data.as_mut() }
+    }
+}
+
+impl<'rwlock, T: ?Sized> Drop for RwLockReadGuard<'rwlock, T> {
+    fn drop(&mut self) {
+        debug_assert!(self.lock.load(Ordering::Relaxed) & !(WRITER | UPGRADED) > 0);
+
+        self.lock.fetch_sub(READER, Ordering::Release);
+    }
+}
+
+impl<'rwlock, T: ?Sized> Drop for RwLockUpgradeableGuard<'rwlock, T> {
+    fn drop(&mut self) {
+        debug_assert_eq!(
+            self.lock.load(Ordering::Relaxed) & (WRITER | UPGRADED),
+            UPGRADED
+        );
+
+        self.lock.fetch_sub(UPGRADED, Ordering::AcqRel);
+    }
+}
+
+impl<'rwlock, T: ?Sized> Drop for RwLockWriteGuard<'rwlock, T> {
+    fn drop(&mut self) {
+        debug_assert_eq!(self.lock.load(Ordering::Relaxed) & WRITER, WRITER);
+
+        self.lock.fetch_and(!(WRITER | UPGRADED), Ordering::Release);
+    }
+}
+
+fn compare_exchange(
+    atomic: &AtomicUsize,
+    current: usize,
+    new: usize,
+    success: Ordering,
+    failure: Ordering,
+    strong: bool,
+) -> Result<usize, usize> {
+    if strong {
+        atomic.compare_exchange(current, new, success, failure)
+    } else {
+        atomic.compare_exchange_weak(current, new, success, failure)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::prelude::v1::*;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+    use std::sync::mpsc::channel;
+    use std::sync::Arc;
+    use std::thread;
+
+    #[derive(Eq, PartialEq, Debug)]
+    struct NonCopy(i32);
+
+    #[test]
+    fn smoke() {
+        let l = RwLock::new(());
+        drop(l.read());
+        drop(l.write());
+        drop((l.read(), l.read()));
+        drop(l.write());
+    }
+
+    #[cfg(not(target_arch = "wasm32"))]
+    #[test]
+    fn test_rw_arc() {
+        let arc = Arc::new(RwLock::new(0));
+        let arc2 = arc.clone();
+        let (tx, rx) = channel();
+
+        thread::spawn(move || {
+            let mut lock = arc2.write();
+
+            for _ in 0..10 {
+                let tmp = *lock;
+                *lock = -1;
+                thread::yield_now();
+                *lock = tmp + 1;
+            }
+
+            tx.send(()).unwrap();
+        });
+
+        let mut children = Vec::new();
+
+        for _ in 0..5 {
+            let arc3 = arc.clone();
+
+            children.push(thread::spawn(move || {
+                let lock = arc3.read();
+                assert!(*lock >= 0);
+            }));
+        }
+
+        for r in children {
+            assert!(r.join().is_ok());
+        }
+
+        rx.recv().unwrap();
+        let lock = arc.read();
+        assert_eq!(*lock, 10);
+    }
+
+    #[cfg(not(target_arch = "wasm32"))]
+    #[test]
+    fn test_rw_access_in_unwind() {
+        let arc = Arc::new(RwLock::new(1));
+        let arc2 = arc.clone();
+
+        let _ = thread::spawn(move || {
+            struct Unwinder {
+                i: Arc<RwLock<isize>>,
+            }
+
+            impl Drop for Unwinder {
+                fn drop(&mut self) {
+                    let mut lock = self.i.write();
+
+                    *lock += 1;
+                }
+            }
+
+            let _u = Unwinder { i: arc2 };
+
+            panic!();
+        })
+        .join();
+
+        let lock = arc.read();
+        assert_eq!(*lock, 2);
+    }
+
+    #[test]
+    fn test_rwlock_unsized() {
+        let rw: &RwLock<[i32]> = &RwLock::new([1, 2, 3]);
+
+        {
+            let b = &mut *rw.write();
+            b[0] = 4;
+            b[2] = 5;
+        }
+
+        let comp: &[i32] = &[4, 2, 5];
+
+        assert_eq!(&*rw.read(), comp);
+    }
+
+    #[test]
+    fn test_rwlock_try_write() {
+        use std::mem::drop;
+
+        let lock = RwLock::new(0isize);
+        let read_guard = lock.read();
+        let write_result = lock.try_write();
+
+        match write_result {
+            None => (),
+            Some(_) => panic!("try_write should not succeed while read_guard is in scope"),
+        }
+
+        drop(read_guard);
+    }
+
+    #[test]
+    fn test_rw_try_read() {
+        let m = RwLock::new(0);
+
+        mem::forget(m.write());
+
+        assert!(m.try_read().is_none());
+    }
+
+    #[test]
+    fn test_into_inner() {
+        let m = RwLock::new(NonCopy(10));
+
+        assert_eq!(m.into_inner(), NonCopy(10));
+    }
+
+    #[test]
+    fn test_into_inner_drop() {
+        struct Foo(Arc<AtomicUsize>);
+
+        impl Drop for Foo {
+            fn drop(&mut self) {
+                self.0.fetch_add(1, Ordering::SeqCst);
+            }
+        }
+
+        let num_drops = Arc::new(AtomicUsize::new(0));
+        let m = RwLock::new(Foo(num_drops.clone()));
+        assert_eq!(num_drops.load(Ordering::SeqCst), 0);
+
+        {
+            let _inner = m.into_inner();
+            assert_eq!(num_drops.load(Ordering::SeqCst), 0);
+        }
+
+        assert_eq!(num_drops.load(Ordering::SeqCst), 1);
+    }
+
+    #[test]
+    fn test_force_read_decrement() {
+        let m = RwLock::new(());
+        ::std::mem::forget(m.read());
+        ::std::mem::forget(m.read());
+        ::std::mem::forget(m.read());
+        assert!(m.try_write().is_none());
+
+        unsafe {
+            m.force_read_decrement();
+            m.force_read_decrement();
+        }
+
+        assert!(m.try_write().is_none());
+
+        unsafe {
+            m.force_read_decrement();
+        }
+
+        assert!(m.try_write().is_some());
+    }
+
+    #[test]
+    fn test_force_write_unlock() {
+        let m = RwLock::new(());
+
+        ::std::mem::forget(m.write());
+
+        assert!(m.try_read().is_none());
+
+        unsafe {
+            m.force_write_unlock();
+        }
+
+        assert!(m.try_read().is_some());
+    }
+
+    #[test]
+    fn test_upgrade_downgrade() {
+        let m = RwLock::new(());
+
+        {
+            let _r = m.read();
+            let upg = m.try_upgradeable_read().unwrap();
+            assert!(m.try_read().is_none());
+            assert!(m.try_write().is_none());
+            assert!(upg.try_upgrade().is_err());
+        }
+
+        {
+            let w = m.write();
+            assert!(m.try_upgradeable_read().is_none());
+            let _r = w.downgrade();
+            assert!(m.try_upgradeable_read().is_some());
+            assert!(m.try_read().is_some());
+            assert!(m.try_write().is_none());
+        }
+
+        {
+            let _u = m.upgradeable_read();
+            assert!(m.try_upgradeable_read().is_none());
+        }
+
+        assert!(m.try_upgradeable_read().unwrap().try_upgrade().is_ok());
+    }
+}
diff --git a/third_party/rust/dashmap/src/mapref/entry.rs b/third_party/rust/dashmap/src/mapref/entry.rs
new file mode 100644
index 0000000000..7a609ee61a
--- /dev/null
+++ b/third_party/rust/dashmap/src/mapref/entry.rs
@@ -0,0 +1,198 @@
+use super::one::RefMut;
+use crate::lock::RwLockWriteGuard;
+use crate::util;
+use crate::util::SharedValue;
+use crate::HashMap;
+use core::hash::{BuildHasher, Hash};
+use core::mem;
+use core::ptr;
+use std::collections::hash_map::RandomState;
+
+pub enum Entry<'a, K, V, S = RandomState> {
+    Occupied(OccupiedEntry<'a, K, V, S>),
+    Vacant(VacantEntry<'a, K, V, S>),
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> Entry<'a, K, V, S> {
+    /// Apply a function to the stored value if it exists.
+    pub fn and_modify(self, f: impl FnOnce(&mut V)) -> Self {
+        match self {
+            Entry::Occupied(mut entry) => {
+                f(entry.get_mut());
+
+                Entry::Occupied(entry)
+            }
+
+            Entry::Vacant(entry) => Entry::Vacant(entry),
+        }
+    }
+
+    /// Get the key of the entry.
+    pub fn key(&self) -> &K {
+        match *self {
+            Entry::Occupied(ref entry) => entry.key(),
+            Entry::Vacant(ref entry) => entry.key(),
+        }
+    }
+
+    /// Into the key of the entry.
+    pub fn into_key(self) -> K {
+        match self {
+            Entry::Occupied(entry) => entry.into_key(),
+            Entry::Vacant(entry) => entry.into_key(),
+        }
+    }
+
+    /// Return a mutable reference to the element if it exists,
+    /// otherwise insert the default and return a mutable reference to that.
+    pub fn or_default(self) -> RefMut<'a, K, V, S>
+    where
+        V: Default,
+    {
+        match self {
+            Entry::Occupied(entry) => entry.into_ref(),
+            Entry::Vacant(entry) => entry.insert(V::default()),
+        }
+    }
+
+    /// Return a mutable reference to the element if it exists,
+    /// otherwise a provided value and return a mutable reference to that.
+    pub fn or_insert(self, value: V) -> RefMut<'a, K, V, S> {
+        match self {
+            Entry::Occupied(entry) => entry.into_ref(),
+            Entry::Vacant(entry) => entry.insert(value),
+        }
+    }
+
+    /// Return a mutable reference to the element if it exists,
+    /// otherwise insert the result of a provided function and return a mutable reference to that.
+    pub fn or_insert_with(self, value: impl FnOnce() -> V) -> RefMut<'a, K, V, S> {
+        match self {
+            Entry::Occupied(entry) => entry.into_ref(),
+            Entry::Vacant(entry) => entry.insert(value()),
+        }
+    }
+
+    pub fn or_try_insert_with<E>(
+        self,
+        value: impl FnOnce() -> Result<V, E>,
+    ) -> Result<RefMut<'a, K, V, S>, E> {
+        match self {
+            Entry::Occupied(entry) => Ok(entry.into_ref()),
+            Entry::Vacant(entry) => Ok(entry.insert(value()?)),
+        }
+    }
+}
+
+pub struct VacantEntry<'a, K, V, S> {
+    shard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
+    key: K,
+}
+
+unsafe impl<'a, K: Eq + Hash + Send, V: Send, S: BuildHasher> Send for VacantEntry<'a, K, V, S> {}
+
+unsafe impl<'a, K: Eq + Hash + Send + Sync, V: Send + Sync, S: BuildHasher> Sync
+    for VacantEntry<'a, K, V, S>
+{
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> VacantEntry<'a, K, V, S> {
+    pub(crate) fn new(shard: RwLockWriteGuard<'a, HashMap<K, V, S>>, key: K) -> Self {
+        Self { shard, key }
+    }
+
+    pub fn insert(mut self, value: V) -> RefMut<'a, K, V, S> {
+        unsafe {
+            let c: K = ptr::read(&self.key);
+
+            self.shard.insert(self.key, SharedValue::new(value));
+
+            let (k, v) = self.shard.get_key_value(&c).unwrap();
+
+            let k = util::change_lifetime_const(k);
+
+            let v = &mut *v.as_ptr();
+
+            let r = RefMut::new(self.shard, k, v);
+
+            mem::forget(c);
+
+            r
+        }
+    }
+
+    pub fn into_key(self) -> K {
+        self.key
+    }
+
+    pub fn key(&self) -> &K {
+        &self.key
+    }
+}
+
+pub struct OccupiedEntry<'a, K, V, S> {
+    shard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
+    elem: (&'a K, &'a mut V),
+    key: K,
+}
+
+unsafe impl<'a, K: Eq + Hash + Send, V: Send, S: BuildHasher> Send for OccupiedEntry<'a, K, V, S> {}
+
+unsafe impl<'a, K: Eq + Hash + Send + Sync, V: Send + Sync, S: BuildHasher> Sync
+    for OccupiedEntry<'a, K, V, S>
+{
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> OccupiedEntry<'a, K, V, S> {
+    pub(crate) fn new(
+        shard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
+        key: K,
+        elem: (&'a K, &'a mut V),
+    ) -> Self {
+        Self { shard, elem, key }
+    }
+
+    pub fn get(&self) -> &V {
+        self.elem.1
+    }
+
+    pub fn get_mut(&mut self) -> &mut V {
+        self.elem.1
+    }
+
+    pub fn insert(&mut self, value: V) -> V {
+        mem::replace(self.elem.1, value)
+    }
+
+    pub fn into_ref(self) -> RefMut<'a, K, V, S> {
+        RefMut::new(self.shard, self.elem.0, self.elem.1)
+    }
+
+    pub fn into_key(self) -> K {
+        self.key
+    }
+
+    pub fn key(&self) -> &K {
+        self.elem.0
+    }
+
+    pub fn remove(mut self) -> V {
+        self.shard.remove(self.elem.0).unwrap().into_inner()
+    }
+
+    pub fn remove_entry(mut self) -> (K, V) {
+        let (k, v) = self.shard.remove_entry(self.elem.0).unwrap();
+
+        (k, v.into_inner())
+    }
+
+    pub fn replace_entry(mut self, value: V) -> (K, V) {
+        let nk = self.key;
+
+        let (k, v) = self.shard.remove_entry(self.elem.0).unwrap();
+
+        self.shard.insert(nk, SharedValue::new(value));
+
+        (k, v.into_inner())
+    }
+}
diff --git a/third_party/rust/dashmap/src/mapref/mod.rs b/third_party/rust/dashmap/src/mapref/mod.rs
new file mode 100644
index 0000000000..8897547e01
--- /dev/null
+++ b/third_party/rust/dashmap/src/mapref/mod.rs
@@ -0,0 +1,3 @@
+pub mod entry;
+pub mod multiple;
+pub mod one;
diff --git a/third_party/rust/dashmap/src/mapref/multiple.rs b/third_party/rust/dashmap/src/mapref/multiple.rs
new file mode 100644
index 0000000000..4d30aee46f
--- /dev/null
+++ b/third_party/rust/dashmap/src/mapref/multiple.rs
@@ -0,0 +1,120 @@
+use crate::lock::{RwLockReadGuard, RwLockWriteGuard};
+use crate::HashMap;
+use core::hash::BuildHasher;
+use core::hash::Hash;
+use core::ops::{Deref, DerefMut};
+use std::collections::hash_map::RandomState;
+use std::sync::Arc;
+
+// -- Shared
+pub struct RefMulti<'a, K, V, S = RandomState> {
+    _guard: Arc<RwLockReadGuard<'a, HashMap<K, V, S>>>,
+    k: &'a K,
+    v: &'a V,
+}
+
+unsafe impl<'a, K: Eq + Hash + Send, V: Send, S: BuildHasher> Send for RefMulti<'a, K, V, S> {}
+
+unsafe impl<'a, K: Eq + Hash + Send + Sync, V: Send + Sync, S: BuildHasher> Sync
+    for RefMulti<'a, K, V, S>
+{
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> RefMulti<'a, K, V, S> {
+    pub(crate) fn new(
+        guard: Arc<RwLockReadGuard<'a, HashMap<K, V, S>>>,
+        k: &'a K,
+        v: &'a V,
+    ) -> Self {
+        Self {
+            _guard: guard,
+            k,
+            v,
+        }
+    }
+
+    pub fn key(&self) -> &K {
+        self.k
+    }
+
+    pub fn value(&self) -> &V {
+        self.v
+    }
+
+    pub fn pair(&self) -> (&K, &V) {
+        (self.k, self.v)
+    }
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> Deref for RefMulti<'a, K, V, S> {
+    type Target = V;
+
+    fn deref(&self) -> &V {
+        self.value()
+    }
+}
+
+// --
+// -- Unique
+pub struct RefMutMulti<'a, K, V, S = RandomState> {
+    _guard: Arc<RwLockWriteGuard<'a, HashMap<K, V, S>>>,
+    k: &'a K,
+    v: &'a mut V,
+}
+
+unsafe impl<'a, K: Eq + Hash + Send, V: Send, S: BuildHasher> Send for RefMutMulti<'a, K, V, S> {}
+
+unsafe impl<'a, K: Eq + Hash + Send + Sync, V: Send + Sync, S: BuildHasher> Sync
+    for RefMutMulti<'a, K, V, S>
+{
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> RefMutMulti<'a, K, V, S> {
+    pub(crate) fn new(
+        guard: Arc<RwLockWriteGuard<'a, HashMap<K, V, S>>>,
+        k: &'a K,
+        v: &'a mut V,
+    ) -> Self {
+        Self {
+            _guard: guard,
+            k,
+            v,
+        }
+    }
+
+    pub fn key(&self) -> &K {
+        self.k
+    }
+
+    pub fn value(&self) -> &V {
+        self.v
+    }
+
+    pub fn value_mut(&mut self) -> &mut V {
+        self.v
+    }
+
+    pub fn pair(&self) -> (&K, &V) {
+        (self.k, self.v)
+    }
+
+    pub fn pair_mut(&mut self) -> (&K, &mut V) {
+        (self.k, self.v)
+    }
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> Deref for RefMutMulti<'a, K, V, S> {
+    type Target = V;
+
+    fn deref(&self) -> &V {
+        self.value()
+    }
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> DerefMut for RefMutMulti<'a, K, V, S> {
+    fn deref_mut(&mut self) -> &mut V {
+        self.value_mut()
+    }
+}
+
+// --
diff --git a/third_party/rust/dashmap/src/mapref/one.rs b/third_party/rust/dashmap/src/mapref/one.rs
new file mode 100644
index 0000000000..67c1706ef8
--- /dev/null
+++ b/third_party/rust/dashmap/src/mapref/one.rs
@@ -0,0 +1,114 @@
+use crate::lock::{RwLockReadGuard, RwLockWriteGuard};
+use crate::HashMap;
+use core::hash::{BuildHasher, Hash};
+use core::ops::{Deref, DerefMut};
+use std::collections::hash_map::RandomState;
+
+// -- Shared
+pub struct Ref<'a, K, V, S = RandomState> {
+    _guard: RwLockReadGuard<'a, HashMap<K, V, S>>,
+    k: &'a K,
+    v: &'a V,
+}
+
+unsafe impl<'a, K: Eq + Hash + Send, V: Send, S: BuildHasher> Send for Ref<'a, K, V, S> {}
+
+unsafe impl<'a, K: Eq + Hash + Send + Sync, V: Send + Sync, S: BuildHasher> Sync
+    for Ref<'a, K, V, S>
+{
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> Ref<'a, K, V, S> {
+    pub(crate) fn new(guard: RwLockReadGuard<'a, HashMap<K, V, S>>, k: &'a K, v: &'a V) -> Self {
+        Self {
+            _guard: guard,
+            k,
+            v,
+        }
+    }
+
+    pub fn key(&self) -> &K {
+        self.k
+    }
+
+    pub fn value(&self) -> &V {
+        self.v
+    }
+
+    pub fn pair(&self) -> (&K, &V) {
+        (self.k, self.v)
+    }
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> Deref for Ref<'a, K, V, S> {
+    type Target = V;
+
+    fn deref(&self) -> &V {
+        self.value()
+    }
+}
+
+// --
+// -- Unique
+pub struct RefMut<'a, K, V, S = RandomState> {
+    guard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
+    k: &'a K,
+    v: &'a mut V,
+}
+
+unsafe impl<'a, K: Eq + Hash + Send, V: Send, S: BuildHasher> Send for RefMut<'a, K, V, S> {}
+
+unsafe impl<'a, K: Eq + Hash + Send + Sync, V: Send + Sync, S: BuildHasher> Sync
+    for RefMut<'a, K, V, S>
+{
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> RefMut<'a, K, V, S> {
+    pub(crate) fn new(
+        guard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
+        k: &'a K,
+        v: &'a mut V,
+    ) -> Self {
+        Self { guard, k, v }
+    }
+
+    pub fn key(&self) -> &K {
+        self.k
+    }
+
+    pub fn value(&self) -> &V {
+        self.v
+    }
+
+    pub fn value_mut(&mut self) -> &mut V {
+        self.v
+    }
+
+    pub fn pair(&self) -> (&K, &V) {
+        (self.k, self.v)
+    }
+
+    pub fn pair_mut(&mut self) -> (&K, &mut V) {
+        (self.k, self.v)
+    }
+
+    pub fn downgrade(self) -> Ref<'a, K, V, S> {
+        Ref::new(self.guard.downgrade(), self.k, self.v)
+    }
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> Deref for RefMut<'a, K, V, S> {
+    type Target = V;
+
+    fn deref(&self) -> &V {
+        self.value()
+    }
+}
+
+impl<'a, K: Eq + Hash, V, S: BuildHasher> DerefMut for RefMut<'a, K, V, S> {
+    fn deref_mut(&mut self) -> &mut V {
+        self.value_mut()
+    }
+}
+
+// --
diff --git a/third_party/rust/dashmap/src/rayon/map.rs b/third_party/rust/dashmap/src/rayon/map.rs
new file mode 100644
index 0000000000..48fdeacf14
--- /dev/null
+++ b/third_party/rust/dashmap/src/rayon/map.rs
@@ -0,0 +1,221 @@
+use crate::lock::RwLock;
+use crate::mapref::multiple::{RefMulti, RefMutMulti};
+use crate::util;
+use crate::{DashMap, HashMap};
+use core::hash::{BuildHasher, Hash};
+use rayon::iter::plumbing::UnindexedConsumer;
+use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelExtend, ParallelIterator};
+use std::collections::hash_map::RandomState;
+use std::sync::Arc;
+
+impl<K, V, S> ParallelExtend<(K, V)> for DashMap<K, V, S>
+where
+    K: Send + Sync + Eq + Hash,
+    V: Send + Sync,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = (K, V)>,
+    {
+        (&*self).par_extend(par_iter);
+    }
+}
+
+// Since we don't actually need mutability, we can implement this on a
+// reference, similar to `io::Write for &File`.
+impl<K, V, S> ParallelExtend<(K, V)> for &'_ DashMap<K, V, S>
+where
+    K: Send + Sync + Eq + Hash,
+    V: Send + Sync,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = (K, V)>,
+    {
+        let &mut map = self;
+        par_iter.into_par_iter().for_each(move |(key, value)| {
+            map.insert(key, value);
+        });
+    }
+}
+
+impl<K, V, S> FromParallelIterator<(K, V)> for DashMap<K, V, S>
+where
+    K: Send + Sync + Eq + Hash,
+    V: Send + Sync,
+    S: Send + Sync + Clone + Default + BuildHasher,
+{
+    fn from_par_iter<I>(par_iter: I) -> Self
+    where
+        I: IntoParallelIterator<Item = (K, V)>,
+    {
+        let map = Self::default();
+        (&map).par_extend(par_iter);
+        map
+    }
+}
+
+// Implementation note: while the shards will iterate in parallel, we flatten
+// sequentially within each shard (`flat_map_iter`), because the standard
+// `HashMap` only implements `ParallelIterator` by collecting to a `Vec` first.
+// There is real parallel support in the `hashbrown/rayon` feature, but we don't
+// always use that map.
+
+impl<K, V, S> IntoParallelIterator for DashMap<K, V, S>
+where
+    K: Send + Eq + Hash,
+    V: Send,
+    S: Send + Clone + BuildHasher,
+{
+    type Iter = OwningIter<K, V, S>;
+    type Item = (K, V);
+
+    fn into_par_iter(self) -> Self::Iter {
+        OwningIter {
+            shards: self.shards,
+        }
+    }
+}
+
+pub struct OwningIter<K, V, S = RandomState> {
+    shards: Box<[RwLock<HashMap<K, V, S>>]>,
+}
+
+impl<K, V, S> ParallelIterator for OwningIter<K, V, S>
+where
+    K: Send + Eq + Hash,
+    V: Send,
+    S: Send + Clone + BuildHasher,
+{
+    type Item = (K, V);
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        Vec::from(self.shards)
+            .into_par_iter()
+            .flat_map_iter(|shard| {
+                shard
+                    .into_inner()
+                    .into_iter()
+                    .map(|(k, v)| (k, v.into_inner()))
+            })
+            .drive_unindexed(consumer)
+    }
+}
+
+// This impl also enables `IntoParallelRefIterator::par_iter`
+impl<'a, K, V, S> IntoParallelIterator for &'a DashMap<K, V, S>
+where
+    K: Send + Sync + Eq + Hash,
+    V: Send + Sync,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    type Iter = Iter<'a, K, V, S>;
+    type Item = RefMulti<'a, K, V, S>;
+
+    fn into_par_iter(self) -> Self::Iter {
+        Iter {
+            shards: &self.shards,
+        }
+    }
+}
+
+pub struct Iter<'a, K, V, S = RandomState> {
+    shards: &'a [RwLock<HashMap<K, V, S>>],
+}
+
+impl<'a, K, V, S> ParallelIterator for Iter<'a, K, V, S>
+where
+    K: Send + Sync + Eq + Hash,
+    V: Send + Sync,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    type Item = RefMulti<'a, K, V, S>;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.shards
+            .into_par_iter()
+            .flat_map_iter(|shard| {
+                let guard = shard.read();
+                let sref: &'a HashMap<K, V, S> = unsafe { util::change_lifetime_const(&*guard) };
+
+                let guard = Arc::new(guard);
+                sref.iter().map(move |(k, v)| {
+                    let guard = Arc::clone(&guard);
+                    RefMulti::new(guard, k, v.get())
+                })
+            })
+            .drive_unindexed(consumer)
+    }
+}
+
+// This impl also enables `IntoParallelRefMutIterator::par_iter_mut`
+impl<'a, K, V, S> IntoParallelIterator for &'a mut DashMap<K, V, S>
+where
+    K: Send + Sync + Eq + Hash,
+    V: Send + Sync,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    type Iter = IterMut<'a, K, V, S>;
+    type Item = RefMutMulti<'a, K, V, S>;
+
+    fn into_par_iter(self) -> Self::Iter {
+        IterMut {
+            shards: &self.shards,
+        }
+    }
+}
+
+impl<'a, K, V, S> DashMap<K, V, S>
+where
+    K: Send + Sync + Eq + Hash,
+    V: Send + Sync,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    // Unlike `IntoParallelRefMutIterator::par_iter_mut`, we only _need_ `&self`.
+    pub fn par_iter_mut(&self) -> IterMut<'_, K, V, S> {
+        IterMut {
+            shards: &self.shards,
+        }
+    }
+}
+
+pub struct IterMut<'a, K, V, S = RandomState> {
+    shards: &'a [RwLock<HashMap<K, V, S>>],
+}
+
+impl<'a, K, V, S> ParallelIterator for IterMut<'a, K, V, S>
+where
+    K: Send + Sync + Eq + Hash,
+    V: Send + Sync,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    type Item = RefMutMulti<'a, K, V, S>;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.shards
+            .into_par_iter()
+            .flat_map_iter(|shard| {
+                let mut guard = shard.write();
+                let sref: &'a mut HashMap<K, V, S> =
+                    unsafe { util::change_lifetime_mut(&mut *guard) };
+
+                let guard = Arc::new(guard);
+                sref.iter_mut().map(move |(k, v)| {
+                    let guard = Arc::clone(&guard);
+                    RefMutMulti::new(guard, k, v.get_mut())
+                })
+            })
+            .drive_unindexed(consumer)
+    }
+}
diff --git a/third_party/rust/dashmap/src/rayon/set.rs b/third_party/rust/dashmap/src/rayon/set.rs
new file mode 100644
index 0000000000..11c06ccbd1
--- /dev/null
+++ b/third_party/rust/dashmap/src/rayon/set.rs
@@ -0,0 +1,121 @@
+use crate::setref::multiple::RefMulti;
+use crate::DashSet;
+use core::hash::{BuildHasher, Hash};
+use rayon::iter::plumbing::UnindexedConsumer;
+use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelExtend, ParallelIterator};
+use std::collections::hash_map::RandomState;
+
+impl<K, S> ParallelExtend<K> for DashSet<K, S>
+where
+    K: Send + Sync + Eq + Hash,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = K>,
+    {
+        (&*self).par_extend(par_iter);
+    }
+}
+
+// Since we don't actually need mutability, we can implement this on a
+// reference, similar to `io::Write for &File`.
+impl<K, S> ParallelExtend<K> for &'_ DashSet<K, S>
+where
+    K: Send + Sync + Eq + Hash,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    fn par_extend<I>(&mut self, par_iter: I)
+    where
+        I: IntoParallelIterator<Item = K>,
+    {
+        let &mut set = self;
+        par_iter.into_par_iter().for_each(move |key| {
+            set.insert(key);
+        });
+    }
+}
+
+impl<K, S> FromParallelIterator<K> for DashSet<K, S>
+where
+    K: Send + Sync + Eq + Hash,
+    S: Send + Sync + Clone + Default + BuildHasher,
+{
+    fn from_par_iter<I>(par_iter: I) -> Self
+    where
+        I: IntoParallelIterator<Item = K>,
+    {
+        let set = Self::default();
+        (&set).par_extend(par_iter);
+        set
+    }
+}
+
+impl<K, S> IntoParallelIterator for DashSet<K, S>
+where
+    K: Send + Eq + Hash,
+    S: Send + Clone + BuildHasher,
+{
+    type Iter = OwningIter<K, S>;
+    type Item = K;
+
+    fn into_par_iter(self) -> Self::Iter {
+        OwningIter {
+            inner: self.inner.into_par_iter(),
+        }
+    }
+}
+
+pub struct OwningIter<K, S = RandomState> {
+    inner: super::map::OwningIter<K, (), S>,
+}
+
+impl<K, S> ParallelIterator for OwningIter<K, S>
+where
+    K: Send + Eq + Hash,
+    S: Send + Clone + BuildHasher,
+{
+    type Item = K;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.map(|(k, _)| k).drive_unindexed(consumer)
+    }
+}
+
+// This impl also enables `IntoParallelRefIterator::par_iter`
+impl<'a, K, S> IntoParallelIterator for &'a DashSet<K, S>
+where
+    K: Send + Sync + Eq + Hash,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    type Iter = Iter<'a, K, S>;
+    type Item = RefMulti<'a, K, S>;
+
+    fn into_par_iter(self) -> Self::Iter {
+        Iter {
+            inner: (&self.inner).into_par_iter(),
+        }
+    }
+}
+
+pub struct Iter<'a, K, S = RandomState> {
+    inner: super::map::Iter<'a, K, (), S>,
+}
+
+impl<'a, K, S> ParallelIterator for Iter<'a, K, S>
+where
+    K: Send + Sync + Eq + Hash,
+    S: Send + Sync + Clone + BuildHasher,
+{
+    type Item = RefMulti<'a, K, S>;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.inner.map(RefMulti::new).drive_unindexed(consumer)
+    }
+}
diff --git a/third_party/rust/dashmap/src/read_only.rs b/third_party/rust/dashmap/src/read_only.rs
new file mode 100644
index 0000000000..b0e7a65e19
--- /dev/null
+++ b/third_party/rust/dashmap/src/read_only.rs
@@ -0,0 +1,243 @@
+use crate::t::Map;
+use crate::{DashMap, HashMap};
+use core::borrow::Borrow;
+use core::fmt;
+use core::hash::{BuildHasher, Hash};
+use std::collections::hash_map::RandomState;
+
+/// A read-only view into a `DashMap`. Allows to obtain raw references to the stored values.
+pub struct ReadOnlyView<K, V, S = RandomState> {
+    map: DashMap<K, V, S>,
+}
+
+impl<K: Eq + Hash + Clone, V: Clone, S: Clone> Clone for ReadOnlyView<K, V, S> {
+    fn clone(&self) -> Self {
+        Self {
+            map: self.map.clone(),
+        }
+    }
+}
+
+impl<K: Eq + Hash + fmt::Debug, V: fmt::Debug, S: BuildHasher + Clone> fmt::Debug
+    for ReadOnlyView<K, V, S>
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.map.fmt(f)
+    }
+}
+
+impl<K, V, S> ReadOnlyView<K, V, S> {
+    pub(crate) fn new(map: DashMap<K, V, S>) -> Self {
+        Self { map }
+    }
+
+    /// Consumes this `ReadOnlyView`, returning the underlying `DashMap`.
+    pub fn into_inner(self) -> DashMap<K, V, S> {
+        self.map
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> ReadOnlyView<K, V, S> {
+    /// Returns the number of elements in the map.
+    pub fn len(&self) -> usize {
+        self.map.len()
+    }
+
+    /// Returns `true` if the map contains no elements.
+    pub fn is_empty(&self) -> bool {
+        self.map.is_empty()
+    }
+
+    /// Returns the number of elements the map can hold without reallocating.
+    pub fn capacity(&self) -> usize {
+        self.map.capacity()
+    }
+
+    /// Returns `true` if the map contains a value for the specified key.
+    pub fn contains_key<Q>(&'a self, key: &Q) -> bool
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        let hash = self.map.hash_usize(&key);
+
+        let idx = self.map.determine_shard(hash);
+
+        let shard = unsafe { self.map._get_read_shard(idx) };
+
+        shard.contains_key(key)
+    }
+
+    /// Returns a reference to the value corresponding to the key.
+    pub fn get<Q>(&'a self, key: &Q) -> Option<&'a V>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        let hash = self.map.hash_usize(&key);
+
+        let idx = self.map.determine_shard(hash);
+
+        let shard = unsafe { self.map._get_read_shard(idx) };
+
+        shard.get(key).map(|v| v.get())
+    }
+
+    /// Returns the key-value pair corresponding to the supplied key.
+    pub fn get_key_value<Q>(&'a self, key: &Q) -> Option<(&'a K, &'a V)>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        let hash = self.map.hash_usize(&key);
+
+        let idx = self.map.determine_shard(hash);
+
+        let shard = unsafe { self.map._get_read_shard(idx) };
+
+        shard.get_key_value(key).map(|(k, v)| (k, v.get()))
+    }
+
+    fn shard_read_iter(&'a self) -> impl Iterator<Item = &'a HashMap<K, V, S>> + 'a {
+        (0..self.map._shard_count())
+            .map(move |shard_i| unsafe { self.map._get_read_shard(shard_i) })
+    }
+
+    /// An iterator visiting all key-value pairs in arbitrary order. The iterator element type is `(&'a K, &'a V)`.
+    pub fn iter(&'a self) -> impl Iterator<Item = (&'a K, &'a V)> + 'a {
+        self.shard_read_iter()
+            .flat_map(|shard| shard.iter())
+            .map(|(k, v)| (k, v.get()))
+    }
+
+    /// An iterator visiting all keys in arbitrary order. The iterator element type is `&'a K`.
+    pub fn keys(&'a self) -> impl Iterator<Item = &'a K> + 'a {
+        self.shard_read_iter().flat_map(|shard| shard.keys())
+    }
+
+    /// An iterator visiting all values in arbitrary order. The iterator element type is `&'a V`.
+    pub fn values(&'a self) -> impl Iterator<Item = &'a V> + 'a {
+        self.shard_read_iter()
+            .flat_map(|shard| shard.values())
+            .map(|v| v.get())
+    }
+}
+
+#[cfg(test)]
+
+mod tests {
+
+    use crate::DashMap;
+
+    fn construct_sample_map() -> DashMap<i32, String> {
+        let map = DashMap::new();
+
+        map.insert(1, "one".to_string());
+
+        map.insert(10, "ten".to_string());
+
+        map.insert(27, "twenty seven".to_string());
+
+        map.insert(45, "forty five".to_string());
+
+        map
+    }
+
+    #[test]
+
+    fn test_properties() {
+        let map = construct_sample_map();
+
+        let view = map.clone().into_read_only();
+
+        assert_eq!(view.is_empty(), map.is_empty());
+
+        assert_eq!(view.len(), map.len());
+
+        assert_eq!(view.capacity(), map.capacity());
+
+        let new_map = view.into_inner();
+
+        assert_eq!(new_map.is_empty(), map.is_empty());
+
+        assert_eq!(new_map.len(), map.len());
+
+        assert_eq!(new_map.capacity(), map.capacity());
+    }
+
+    #[test]
+
+    fn test_get() {
+        let map = construct_sample_map();
+
+        let view = map.clone().into_read_only();
+
+        for key in map.iter().map(|entry| *entry.key()) {
+            assert!(view.contains_key(&key));
+
+            let map_entry = map.get(&key).unwrap();
+
+            assert_eq!(view.get(&key).unwrap(), map_entry.value());
+
+            let key_value: (&i32, &String) = view.get_key_value(&key).unwrap();
+
+            assert_eq!(key_value.0, map_entry.key());
+
+            assert_eq!(key_value.1, map_entry.value());
+        }
+    }
+
+    #[test]
+
+    fn test_iters() {
+        let map = construct_sample_map();
+
+        let view = map.clone().into_read_only();
+
+        let mut visited_items = Vec::new();
+
+        for (key, value) in view.iter() {
+            map.contains_key(key);
+
+            let map_entry = map.get(&key).unwrap();
+
+            assert_eq!(key, map_entry.key());
+
+            assert_eq!(value, map_entry.value());
+
+            visited_items.push((key, value));
+        }
+
+        let mut visited_keys = Vec::new();
+
+        for key in view.keys() {
+            map.contains_key(key);
+
+            let map_entry = map.get(&key).unwrap();
+
+            assert_eq!(key, map_entry.key());
+
+            assert_eq!(view.get(key).unwrap(), map_entry.value());
+
+            visited_keys.push(key);
+        }
+
+        let mut visited_values = Vec::new();
+
+        for value in view.values() {
+            visited_values.push(value);
+        }
+
+        for entry in map.iter() {
+            let key = entry.key();
+
+            let value = entry.value();
+
+            assert!(visited_keys.contains(&key));
+
+            assert!(visited_values.contains(&value));
+
+            assert!(visited_items.contains(&(key, value)));
+        }
+    }
+}
diff --git a/third_party/rust/dashmap/src/serde.rs b/third_party/rust/dashmap/src/serde.rs
new file mode 100644
index 0000000000..c0f2bb2c1b
--- /dev/null
+++ b/third_party/rust/dashmap/src/serde.rs
@@ -0,0 +1,148 @@
+use crate::{DashMap, DashSet};
+use core::fmt;
+use core::hash::Hash;
+use core::marker::PhantomData;
+use serde::de::{Deserialize, MapAccess, SeqAccess, Visitor};
+use serde::ser::{Serialize, SerializeMap, SerializeSeq, Serializer};
+use serde::Deserializer;
+
+pub struct DashMapVisitor<K, V> {
+    marker: PhantomData<fn() -> DashMap<K, V>>,
+}
+
+impl<K, V> DashMapVisitor<K, V>
+where
+    K: Eq + Hash,
+{
+    fn new() -> Self {
+        DashMapVisitor {
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'de, K, V> Visitor<'de> for DashMapVisitor<K, V>
+where
+    K: Deserialize<'de> + Eq + Hash,
+    V: Deserialize<'de>,
+{
+    type Value = DashMap<K, V>;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a DashMap")
+    }
+
+    fn visit_map<M>(self, mut access: M) -> Result<Self::Value, M::Error>
+    where
+        M: MapAccess<'de>,
+    {
+        let map = DashMap::with_capacity(access.size_hint().unwrap_or(0));
+
+        while let Some((key, value)) = access.next_entry()? {
+            map.insert(key, value);
+        }
+
+        Ok(map)
+    }
+}
+
+impl<'de, K, V> Deserialize<'de> for DashMap<K, V>
+where
+    K: Deserialize<'de> + Eq + Hash,
+    V: Deserialize<'de>,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_map(DashMapVisitor::<K, V>::new())
+    }
+}
+
+impl<K, V> Serialize for DashMap<K, V>
+where
+    K: Serialize + Eq + Hash,
+    V: Serialize,
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let mut map = serializer.serialize_map(Some(self.len()))?;
+
+        for ref_multi in self.iter() {
+            map.serialize_entry(ref_multi.key(), ref_multi.value())?;
+        }
+
+        map.end()
+    }
+}
+
+pub struct DashSetVisitor<K> {
+    marker: PhantomData<fn() -> DashSet<K>>,
+}
+
+impl<K> DashSetVisitor<K>
+where
+    K: Eq + Hash,
+{
+    fn new() -> Self {
+        DashSetVisitor {
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<'de, K> Visitor<'de> for DashSetVisitor<K>
+where
+    K: Deserialize<'de> + Eq + Hash,
+{
+    type Value = DashSet<K>;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("a DashSet")
+    }
+
+    fn visit_seq<M>(self, mut access: M) -> Result<Self::Value, M::Error>
+    where
+        M: SeqAccess<'de>,
+    {
+        let map = DashSet::with_capacity(access.size_hint().unwrap_or(0));
+
+        while let Some(key) = access.next_element()? {
+            map.insert(key);
+        }
+
+        Ok(map)
+    }
+}
+
+impl<'de, K> Deserialize<'de> for DashSet<K>
+where
+    K: Deserialize<'de> + Eq + Hash,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_seq(DashSetVisitor::<K>::new())
+    }
+}
+
+impl<K> Serialize for DashSet<K>
+where
+    K: Serialize + Eq + Hash,
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        let mut seq = serializer.serialize_seq(Some(self.len()))?;
+
+        for ref_multi in self.iter() {
+            seq.serialize_element(ref_multi.key())?;
+        }
+
+        seq.end()
+    }
+}
diff --git a/third_party/rust/dashmap/src/set.rs b/third_party/rust/dashmap/src/set.rs
new file mode 100644
index 0000000000..e4d77df108
--- /dev/null
+++ b/third_party/rust/dashmap/src/set.rs
@@ -0,0 +1,458 @@
+use crate::iter_set::{Iter, OwningIter};
+#[cfg(feature = "raw-api")]
+use crate::lock::RwLock;
+use crate::setref::one::Ref;
+use crate::DashMap;
+#[cfg(feature = "raw-api")]
+use crate::HashMap;
+use cfg_if::cfg_if;
+use core::borrow::Borrow;
+use core::fmt;
+use core::hash::{BuildHasher, Hash};
+use core::iter::FromIterator;
+use std::collections::hash_map::RandomState;
+
+/// DashSet is a thin wrapper around [`DashMap`] using `()` as the value type. It uses
+/// methods and types which are more convenient to work with on a set.
+///
+/// [`DashMap`]: struct.DashMap.html
+pub struct DashSet<K, S = RandomState> {
+    pub(crate) inner: DashMap<K, (), S>,
+}
+
+impl<K: Eq + Hash + fmt::Debug, S: BuildHasher + Clone> fmt::Debug for DashSet<K, S> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&self.inner, f)
+    }
+}
+
+impl<K: Eq + Hash + Clone, S: Clone> Clone for DashSet<K, S> {
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+        }
+    }
+
+    fn clone_from(&mut self, source: &Self) {
+        self.inner.clone_from(&source.inner)
+    }
+}
+
+impl<K, S> Default for DashSet<K, S>
+where
+    K: Eq + Hash,
+    S: Default + BuildHasher + Clone,
+{
+    fn default() -> Self {
+        Self::with_hasher(Default::default())
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash> DashSet<K, RandomState> {
+    /// Creates a new DashSet with a capacity of 0.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let games = DashSet::new();
+    /// games.insert("Veloren");
+    /// ```
+    pub fn new() -> Self {
+        Self::with_hasher(RandomState::default())
+    }
+
+    /// Creates a new DashMap with a specified starting capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let numbers = DashSet::with_capacity(2);
+    /// numbers.insert(2);
+    /// numbers.insert(8);
+    /// ```
+    pub fn with_capacity(capacity: usize) -> Self {
+        Self::with_capacity_and_hasher(capacity, RandomState::default())
+    }
+}
+
+impl<'a, K: 'a + Eq + Hash, S: BuildHasher + Clone> DashSet<K, S> {
+    /// Creates a new DashMap with a capacity of 0 and the provided hasher.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    /// use std::collections::hash_map::RandomState;
+    ///
+    /// let s = RandomState::new();
+    /// let games = DashSet::with_hasher(s);
+    /// games.insert("Veloren");
+    /// ```
+    pub fn with_hasher(hasher: S) -> Self {
+        Self::with_capacity_and_hasher(0, hasher)
+    }
+
+    /// Creates a new DashMap with a specified starting capacity and hasher.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    /// use std::collections::hash_map::RandomState;
+    ///
+    /// let s = RandomState::new();
+    /// let numbers = DashSet::with_capacity_and_hasher(2, s);
+    /// numbers.insert(2);
+    /// numbers.insert(8);
+    /// ```
+    pub fn with_capacity_and_hasher(capacity: usize, hasher: S) -> Self {
+        Self {
+            inner: DashMap::with_capacity_and_hasher(capacity, hasher),
+        }
+    }
+
+    /// Hash a given item to produce a usize.
+    /// Uses the provided or default HashBuilder.
+    pub fn hash_usize<T: Hash>(&self, item: &T) -> usize {
+        self.inner.hash_usize(item)
+    }
+
+    cfg_if! {
+        if #[cfg(feature = "raw-api")] {
+            /// Allows you to peek at the inner shards that store your data.
+            /// You should probably not use this unless you know what you are doing.
+            ///
+            /// Requires the `raw-api` feature to be enabled.
+            ///
+            /// # Examples
+            ///
+            /// ```
+            /// use dashmap::DashSet;
+            ///
+            /// let set = DashSet::<()>::new();
+            /// println!("Amount of shards: {}", set.shards().len());
+            /// ```
+            pub fn shards(&self) -> &[RwLock<HashMap<K, (), S>>] {
+                self.inner.shards()
+            }
+        }
+    }
+
+    cfg_if! {
+        if #[cfg(feature = "raw-api")] {
+            /// Finds which shard a certain key is stored in.
+            /// You should probably not use this unless you know what you are doing.
+            /// Note that shard selection is dependent on the default or provided HashBuilder.
+            ///
+            /// Requires the `raw-api` feature to be enabled.
+            ///
+            /// # Examples
+            ///
+            /// ```
+            /// use dashmap::DashSet;
+            ///
+            /// let set = DashSet::new();
+            /// set.insert("coca-cola");
+            /// println!("coca-cola is stored in shard: {}", set.determine_map("coca-cola"));
+            /// ```
+            pub fn determine_map<Q>(&self, key: &Q) -> usize
+            where
+                K: Borrow<Q>,
+                Q: Hash + Eq + ?Sized,
+            {
+                self.inner.determine_map(key)
+            }
+        }
+    }
+
+    cfg_if! {
+        if #[cfg(feature = "raw-api")] {
+            /// Finds which shard a certain hash is stored in.
+            ///
+            /// Requires the `raw-api` feature to be enabled.
+            ///
+            /// # Examples
+            ///
+            /// ```
+            /// use dashmap::DashSet;
+            ///
+            /// let set: DashSet<i32> = DashSet::new();
+            /// let key = "key";
+            /// let hash = set.hash_usize(&key);
+            /// println!("hash is stored in shard: {}", set.determine_shard(hash));
+            /// ```
+            pub fn determine_shard(&self, hash: usize) -> usize {
+                self.inner.determine_shard(hash)
+            }
+        }
+    }
+
+    /// Inserts a key into the set. Returns true if the key was not already in the set.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let set = DashSet::new();
+    /// set.insert("I am the key!");
+    /// ```
+    pub fn insert(&self, key: K) -> bool {
+        self.inner.insert(key, ()).is_none()
+    }
+
+    /// Removes an entry from the map, returning the key if it existed in the map.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let soccer_team = DashSet::new();
+    /// soccer_team.insert("Jack");
+    /// assert_eq!(soccer_team.remove("Jack").unwrap(), "Jack");
+    /// ```
+    pub fn remove<Q>(&self, key: &Q) -> Option<K>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        self.inner.remove(key).map(|(k, _)| k)
+    }
+
+    /// Removes an entry from the set, returning the key
+    /// if the entry existed and the provided conditional function returned true.
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let soccer_team = DashSet::new();
+    /// soccer_team.insert("Sam");
+    /// soccer_team.remove_if("Sam", |player| player.starts_with("Ja"));
+    /// assert!(soccer_team.contains("Sam"));
+    /// ```
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let soccer_team = DashSet::new();
+    /// soccer_team.insert("Sam");
+    /// soccer_team.remove_if("Jacob", |player| player.starts_with("Ja"));
+    /// assert!(!soccer_team.contains("Jacob"));
+    /// ```
+    pub fn remove_if<Q>(&self, key: &Q, f: impl FnOnce(&K) -> bool) -> Option<K>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        // TODO: Don't create another closure around f
+        self.inner.remove_if(key, |k, _| f(k)).map(|(k, _)| k)
+    }
+
+    /// Creates an iterator over a DashMap yielding immutable references.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let words = DashSet::new();
+    /// words.insert("hello");
+    /// assert_eq!(words.iter().count(), 1);
+    /// ```
+    pub fn iter(&'a self) -> Iter<'a, K, S, DashMap<K, (), S>> {
+        let iter = self.inner.iter();
+
+        Iter::new(iter)
+    }
+
+    /// Get a reference to an entry in the set
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let youtubers = DashSet::new();
+    /// youtubers.insert("Bosnian Bill");
+    /// assert_eq!(*youtubers.get("Bosnian Bill").unwrap(), "Bosnian Bill");
+    /// ```
+    pub fn get<Q>(&'a self, key: &Q) -> Option<Ref<'a, K, S>>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        self.inner.get(key).map(Ref::new)
+    }
+
+    /// Remove excess capacity to reduce memory usage.
+    pub fn shrink_to_fit(&self) {
+        self.inner.shrink_to_fit()
+    }
+
+    /// Retain elements that whose predicates return true
+    /// and discard elements whose predicates return false.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let people = DashSet::new();
+    /// people.insert("Albin");
+    /// people.insert("Jones");
+    /// people.insert("Charlie");
+    /// people.retain(|name| name.contains('i'));
+    /// assert_eq!(people.len(), 2);
+    /// ```
+    pub fn retain(&self, mut f: impl FnMut(&K) -> bool) {
+        self.inner.retain(|k, _| f(k))
+    }
+
+    /// Fetches the total number of keys stored in the set.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let people = DashSet::new();
+    /// people.insert("Albin");
+    /// people.insert("Jones");
+    /// people.insert("Charlie");
+    /// assert_eq!(people.len(), 3);
+    /// ```
+    pub fn len(&self) -> usize {
+        self.inner.len()
+    }
+
+    /// Checks if the set is empty or not.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let map = DashSet::<()>::new();
+    /// assert!(map.is_empty());
+    /// ```
+    pub fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+
+    /// Removes all keys in the set.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let people = DashSet::new();
+    /// people.insert("Albin");
+    /// assert!(!people.is_empty());
+    /// people.clear();
+    /// assert!(people.is_empty());
+    /// ```
+    pub fn clear(&self) {
+        self.inner.clear()
+    }
+
+    /// Returns how many keys the set can store without reallocating.
+    pub fn capacity(&self) -> usize {
+        self.inner.capacity()
+    }
+
+    /// Checks if the set contains a specific key.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use dashmap::DashSet;
+    ///
+    /// let people = DashSet::new();
+    /// people.insert("Dakota Cherries");
+    /// assert!(people.contains("Dakota Cherries"));
+    /// ```
+    pub fn contains<Q>(&self, key: &Q) -> bool
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        self.inner.contains_key(key)
+    }
+}
+
+impl<'a, K: Eq + Hash, S: BuildHasher + Clone> IntoIterator for DashSet<K, S> {
+    type Item = K;
+
+    type IntoIter = OwningIter<K, S>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        OwningIter::new(self.inner.into_iter())
+    }
+}
+
+impl<K: Eq + Hash, S: BuildHasher + Clone> Extend<K> for DashSet<K, S> {
+    fn extend<T: IntoIterator<Item = K>>(&mut self, iter: T) {
+        let iter = iter.into_iter().map(|k| (k, ()));
+
+        self.inner.extend(iter)
+    }
+}
+
+impl<K: Eq + Hash> FromIterator<K> for DashSet<K, RandomState> {
+    fn from_iter<I: IntoIterator<Item = K>>(iter: I) -> Self {
+        let mut set = DashSet::new();
+
+        set.extend(iter);
+
+        set
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::DashSet;
+
+    #[test]
+    fn test_basic() {
+        let set = DashSet::new();
+
+        set.insert(0);
+
+        assert_eq!(set.get(&0).as_deref(), Some(&0));
+    }
+
+    #[test]
+    fn test_default() {
+        let set: DashSet<u32> = DashSet::default();
+
+        set.insert(0);
+
+        assert_eq!(set.get(&0).as_deref(), Some(&0));
+    }
+
+    #[test]
+    fn test_multiple_hashes() {
+        let set = DashSet::<u32>::default();
+
+        for i in 0..100 {
+            assert!(set.insert(i));
+        }
+
+        for i in 0..100 {
+            assert!(!set.insert(i));
+        }
+
+        for i in 0..100 {
+            assert_eq!(Some(i), set.remove(&i));
+        }
+
+        for i in 0..100 {
+            assert_eq!(None, set.remove(&i));
+        }
+    }
+}
diff --git a/third_party/rust/dashmap/src/setref/mod.rs b/third_party/rust/dashmap/src/setref/mod.rs
new file mode 100644
index 0000000000..95ae8f47f2
--- /dev/null
+++ b/third_party/rust/dashmap/src/setref/mod.rs
@@ -0,0 +1,2 @@
+pub mod multiple;
+pub mod one;
diff --git a/third_party/rust/dashmap/src/setref/multiple.rs b/third_party/rust/dashmap/src/setref/multiple.rs
new file mode 100644
index 0000000000..21e7ed4a70
--- /dev/null
+++ b/third_party/rust/dashmap/src/setref/multiple.rs
@@ -0,0 +1,25 @@
+use crate::mapref;
+use core::hash::{BuildHasher, Hash};
+use core::ops::Deref;
+use std::collections::hash_map::RandomState;
+pub struct RefMulti<'a, K, S = RandomState> {
+    inner: mapref::multiple::RefMulti<'a, K, (), S>,
+}
+
+impl<'a, K: Eq + Hash, S: BuildHasher> RefMulti<'a, K, S> {
+    pub(crate) fn new(inner: mapref::multiple::RefMulti<'a, K, (), S>) -> Self {
+        Self { inner }
+    }
+
+    pub fn key(&self) -> &K {
+        self.inner.key()
+    }
+}
+
+impl<'a, K: Eq + Hash, S: BuildHasher> Deref for RefMulti<'a, K, S> {
+    type Target = K;
+
+    fn deref(&self) -> &K {
+        self.key()
+    }
+}
diff --git a/third_party/rust/dashmap/src/setref/one.rs b/third_party/rust/dashmap/src/setref/one.rs
new file mode 100644
index 0000000000..ef03421563
--- /dev/null
+++ b/third_party/rust/dashmap/src/setref/one.rs
@@ -0,0 +1,29 @@
+use crate::mapref;
+use core::hash::{BuildHasher, Hash};
+use core::ops::Deref;
+use std::collections::hash_map::RandomState;
+pub struct Ref<'a, K, S = RandomState> {
+    inner: mapref::one::Ref<'a, K, (), S>,
+}
+
+unsafe impl<'a, K: Eq + Hash + Send, S: BuildHasher> Send for Ref<'a, K, S> {}
+
+unsafe impl<'a, K: Eq + Hash + Send + Sync, S: BuildHasher> Sync for Ref<'a, K, S> {}
+
+impl<'a, K: Eq + Hash, S: BuildHasher> Ref<'a, K, S> {
+    pub(crate) fn new(inner: mapref::one::Ref<'a, K, (), S>) -> Self {
+        Self { inner }
+    }
+
+    pub fn key(&self) -> &K {
+        self.inner.key()
+    }
+}
+
+impl<'a, K: Eq + Hash, S: BuildHasher> Deref for Ref<'a, K, S> {
+    type Target = K;
+
+    fn deref(&self) -> &K {
+        self.key()
+    }
+}
diff --git a/third_party/rust/dashmap/src/t.rs b/third_party/rust/dashmap/src/t.rs
new file mode 100644
index 0000000000..6c2e81a6cc
--- /dev/null
+++ b/third_party/rust/dashmap/src/t.rs
@@ -0,0 +1,95 @@
+//! Central map trait to ease modifications and extensions down the road.
+
+use crate::iter::{Iter, IterMut};
+use crate::lock::{RwLockReadGuard, RwLockWriteGuard};
+use crate::mapref::entry::Entry;
+use crate::mapref::one::{Ref, RefMut};
+use crate::HashMap;
+use core::borrow::Borrow;
+use core::hash::{BuildHasher, Hash};
+
+/// Implementation detail that is exposed due to generic constraints in public types.
+pub trait Map<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + Clone + BuildHasher> {
+    fn _shard_count(&self) -> usize;
+
+    /// # Safety
+    ///
+    /// The index must not be out of bounds.
+    unsafe fn _get_read_shard(&'a self, i: usize) -> &'a HashMap<K, V, S>;
+
+    /// # Safety
+    ///
+    /// The index must not be out of bounds.
+    unsafe fn _yield_read_shard(&'a self, i: usize) -> RwLockReadGuard<'a, HashMap<K, V, S>>;
+
+    /// # Safety
+    ///
+    /// The index must not be out of bounds.
+    unsafe fn _yield_write_shard(&'a self, i: usize) -> RwLockWriteGuard<'a, HashMap<K, V, S>>;
+
+    fn _insert(&self, key: K, value: V) -> Option<V>;
+
+    fn _remove<Q>(&self, key: &Q) -> Option<(K, V)>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized;
+
+    fn _remove_if<Q>(&self, key: &Q, f: impl FnOnce(&K, &V) -> bool) -> Option<(K, V)>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized;
+
+    fn _iter(&'a self) -> Iter<'a, K, V, S, Self>
+    where
+        Self: Sized;
+
+    fn _iter_mut(&'a self) -> IterMut<'a, K, V, S, Self>
+    where
+        Self: Sized;
+
+    fn _get<Q>(&'a self, key: &Q) -> Option<Ref<'a, K, V, S>>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized;
+
+    fn _get_mut<Q>(&'a self, key: &Q) -> Option<RefMut<'a, K, V, S>>
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized;
+
+    fn _shrink_to_fit(&self);
+
+    fn _retain(&self, f: impl FnMut(&K, &mut V) -> bool);
+
+    fn _len(&self) -> usize;
+
+    fn _capacity(&self) -> usize;
+
+    fn _alter<Q>(&self, key: &Q, f: impl FnOnce(&K, V) -> V)
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized;
+
+    fn _alter_all(&self, f: impl FnMut(&K, V) -> V);
+
+    fn _entry(&'a self, key: K) -> Entry<'a, K, V, S>;
+
+    fn _hasher(&self) -> S;
+
+    // provided
+    fn _clear(&self) {
+        self._retain(|_, _| false)
+    }
+
+    fn _contains_key<Q>(&'a self, key: &Q) -> bool
+    where
+        K: Borrow<Q>,
+        Q: Hash + Eq + ?Sized,
+    {
+        self._get(key).is_some()
+    }
+
+    fn _is_empty(&self) -> bool {
+        self._len() == 0
+    }
+}
diff --git a/third_party/rust/dashmap/src/util.rs b/third_party/rust/dashmap/src/util.rs
new file mode 100644
index 0000000000..d84e37db9b
--- /dev/null
+++ b/third_party/rust/dashmap/src/util.rs
@@ -0,0 +1,102 @@
+//! This module is full of hackery and dark magic.
+//! Either spend a day fixing it and quietly submit a PR or don't mention it to anybody.
+use core::cell::UnsafeCell;
+use core::{mem, ptr};
+
+pub const fn ptr_size_bits() -> usize {
+    mem::size_of::<usize>() * 8
+}
+
+pub fn map_in_place_2<T, U, F: FnOnce(U, T) -> T>((k, v): (U, &mut T), f: F) {
+    unsafe {
+        // # Safety
+        //
+        // If the closure panics, we must abort otherwise we could double drop `T`
+        let _promote_panic_to_abort = AbortOnPanic;
+
+        ptr::write(v, f(k, ptr::read(v)));
+    }
+}
+
+/// # Safety
+///
+/// Requires that you ensure the reference does not become invalid.
+/// The object has to outlive the reference.
+pub unsafe fn change_lifetime_const<'a, 'b, T>(x: &'a T) -> &'b T {
+    &*(x as *const T)
+}
+
+/// # Safety
+///
+/// Requires that you ensure the reference does not become invalid.
+/// The object has to outlive the reference.
+pub unsafe fn change_lifetime_mut<'a, 'b, T>(x: &'a mut T) -> &'b mut T {
+    &mut *(x as *mut T)
+}
+
+/// A simple wrapper around `T`
+///
+/// This is to prevent UB when using `HashMap::get_key_value`, because
+/// `HashMap` doesn't expose an api to get the key and value, where
+/// the value is a `&mut T`.
+///
+/// See [#10](https://github.com/xacrimon/dashmap/issues/10) for details
+///
+/// This type is meant to be an implementation detail, but must be exposed due to the `Dashmap::shards`
+#[repr(transparent)]
+pub struct SharedValue<T> {
+    value: UnsafeCell<T>,
+}
+
+impl<T: Clone> Clone for SharedValue<T> {
+    fn clone(&self) -> Self {
+        let inner = self.get().clone();
+
+        Self {
+            value: UnsafeCell::new(inner),
+        }
+    }
+}
+
+unsafe impl<T: Send> Send for SharedValue<T> {}
+
+unsafe impl<T: Sync> Sync for SharedValue<T> {}
+
+impl<T> SharedValue<T> {
+    /// Create a new `SharedValue<T>`
+    pub const fn new(value: T) -> Self {
+        Self {
+            value: UnsafeCell::new(value),
+        }
+    }
+
+    /// Get a shared reference to `T`
+    pub fn get(&self) -> &T {
+        unsafe { &*self.value.get() }
+    }
+
+    /// Get an unique reference to `T`
+    pub fn get_mut(&mut self) -> &mut T {
+        unsafe { &mut *self.value.get() }
+    }
+
+    /// Unwraps the value
+    pub fn into_inner(self) -> T {
+        self.value.into_inner()
+    }
+
+    /// Get a mutable raw pointer to the underlying value
+    pub(crate) fn as_ptr(&self) -> *mut T {
+        self.value.get()
+    }
+}
+
+struct AbortOnPanic;
+
+impl Drop for AbortOnPanic {
+    fn drop(&mut self) {
+        if std::thread::panicking() {
+            std::process::abort()
+        }
+    }
+}