Auto merge of #432 - Amanieu:rkyv, r=Amanieu

Add support for rkyv serialization and deserialization

This is direct port of the implementation within the `rkyv` crate, which targets an older version of hashbrown.

Cargo.toml

@@ -19,6 +19,7 @@ ahash = { version = "0.8.0", default-features = false, optional = true }
 # For external trait impls
 rayon = { version = "1.0", optional = true }
 serde = { version = "1.0.25", default-features = false, optional = true }
+rkyv = { version = "0.7.42", optional = true, default-features = false, features = ["alloc"]}
 
 # When built as part of libstd
 core = { version = "1.0.0", optional = true, package = "rustc-std-workspace-core" }
@@ -36,20 +37,15 @@ fnv = "1.0.7"
 serde_test = "1.0"
 doc-comment = "0.3.1"
 bumpalo = "3.6.0"
+rkyv = { version = "0.7.42", features = ["validation"] }
 
 [features]
 default = ["ahash", "inline-more", "allocator-api2"]
 
 nightly = ["allocator-api2?/nightly", "bumpalo/allocator_api"]
 
 rustc-internal-api = []
-rustc-dep-of-std = [
-    "nightly",
-    "core",
-    "compiler_builtins",
-    "alloc",
-    "rustc-internal-api",
-]
+rustc-dep-of-std = ["nightly", "core", "compiler_builtins", "alloc", "rustc-internal-api"]
 raw = []
 
 # Enables usage of `#[inline]` on far more functions than by default in this

src/external_trait_impls/mod.rs

@@ -1,4 +1,6 @@
 #[cfg(feature = "rayon")]
 pub(crate) mod rayon;
+#[cfg(feature = "rkyv")]
+mod rkyv;
 #[cfg(feature = "serde")]
 mod serde;

src/external_trait_impls/rkyv/hash_map.rs

@@ -0,0 +1,125 @@
+use crate::HashMap;
+use core::{
+    borrow::Borrow,
+    hash::{BuildHasher, Hash},
+};
+use rkyv::{
+    collections::hash_map::{ArchivedHashMap, HashMapResolver},
+    ser::{ScratchSpace, Serializer},
+    Archive, Deserialize, Fallible, Serialize,
+};
+
+impl<K: Archive + Hash + Eq, V: Archive, S> Archive for HashMap<K, V, S>
+where
+    K::Archived: Hash + Eq,
+{
+    type Archived = ArchivedHashMap<K::Archived, V::Archived>;
+    type Resolver = HashMapResolver;
+
+    #[inline]
+    unsafe fn resolve(&self, pos: usize, resolver: Self::Resolver, out: *mut Self::Archived) {
+        ArchivedHashMap::resolve_from_len(self.len(), pos, resolver, out);
+    }
+}
+
+impl<K, V, S, RandomState> Serialize<S> for HashMap<K, V, RandomState>
+where
+    K: Serialize<S> + Hash + Eq,
+    K::Archived: Hash + Eq,
+    V: Serialize<S>,
+    S: Serializer + ScratchSpace + ?Sized,
+{
+    #[inline]
+    fn serialize(&self, serializer: &mut S) -> Result<Self::Resolver, S::Error> {
+        unsafe { ArchivedHashMap::serialize_from_iter(self.iter(), serializer) }
+    }
+}
+
+impl<K: Archive + Hash + Eq, V: Archive, D: Fallible + ?Sized, S: Default + BuildHasher>
+    Deserialize<HashMap<K, V, S>, D> for ArchivedHashMap<K::Archived, V::Archived>
+where
+    K::Archived: Deserialize<K, D> + Hash + Eq,
+    V::Archived: Deserialize<V, D>,
+{
+    #[inline]
+    fn deserialize(&self, deserializer: &mut D) -> Result<HashMap<K, V, S>, D::Error> {
+        let mut result = HashMap::with_capacity_and_hasher(self.len(), S::default());
+        for (k, v) in self.iter() {
+            result.insert(k.deserialize(deserializer)?, v.deserialize(deserializer)?);
+        }
+        Ok(result)
+    }
+}
+
+impl<K: Hash + Eq + Borrow<AK>, V, AK: Hash + Eq, AV: PartialEq<V>, S: BuildHasher>
+    PartialEq<HashMap<K, V, S>> for ArchivedHashMap<AK, AV>
+{
+    #[inline]
+    fn eq(&self, other: &HashMap<K, V, S>) -> bool {
+        if self.len() != other.len() {
+            false
+        } else {
+            self.iter()
+                .all(|(key, value)| other.get(key).map_or(false, |v| value.eq(v)))
+        }
+    }
+}
+
+impl<K: Hash + Eq + Borrow<AK>, V, AK: Hash + Eq, AV: PartialEq<V>>
+    PartialEq<ArchivedHashMap<AK, AV>> for HashMap<K, V>
+{
+    #[inline]
+    fn eq(&self, other: &ArchivedHashMap<AK, AV>) -> bool {
+        other.eq(self)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::HashMap;
+    use alloc::string::String;
+    use rkyv::{
+        archived_root, check_archived_root,
+        ser::{serializers::AllocSerializer, Serializer},
+        Deserialize, Infallible,
+    };
+
+    #[test]
+    fn index_map() {
+        let mut value = HashMap::new();
+        value.insert(String::from("foo"), 10);
+        value.insert(String::from("bar"), 20);
+        value.insert(String::from("baz"), 40);
+        value.insert(String::from("bat"), 80);
+
+        let mut serializer = AllocSerializer::<4096>::default();
+        serializer.serialize_value(&value).unwrap();
+        let result = serializer.into_serializer().into_inner();
+        let archived = unsafe { archived_root::<HashMap<String, i32>>(result.as_ref()) };
+
+        assert_eq!(value.len(), archived.len());
+        for (k, v) in value.iter() {
+            let (ak, av) = archived.get_key_value(k.as_str()).unwrap();
+            assert_eq!(k, ak);
+            assert_eq!(v, av);
+        }
+
+        let deserialized: HashMap<String, i32> = archived.deserialize(&mut Infallible).unwrap();
+        assert_eq!(value, deserialized);
+    }
+
+    #[test]
+    fn validate_index_map() {
+        let mut value = HashMap::new();
+        value.insert(String::from("foo"), 10);
+        value.insert(String::from("bar"), 20);
+        value.insert(String::from("baz"), 40);
+        value.insert(String::from("bat"), 80);
+
+        let mut serializer = AllocSerializer::<4096>::default();
+        serializer.serialize_value(&value).unwrap();
+        let result = serializer.into_serializer().into_inner();
+        check_archived_root::<HashMap<String, i32>>(result.as_ref())
+            .expect("failed to validate archived index map");
+    }
+}

src/external_trait_impls/rkyv/hash_set.rs

@@ -0,0 +1,123 @@
+use crate::HashSet;
+use core::{
+    borrow::Borrow,
+    hash::{BuildHasher, Hash},
+};
+use rkyv::{
+    collections::hash_set::{ArchivedHashSet, HashSetResolver},
+    ser::{ScratchSpace, Serializer},
+    Archive, Deserialize, Fallible, Serialize,
+};
+
+impl<K: Archive + Hash + Eq, S> Archive for HashSet<K, S>
+where
+    K::Archived: Hash + Eq,
+{
+    type Archived = ArchivedHashSet<K::Archived>;
+    type Resolver = HashSetResolver;
+
+    #[inline]
+    unsafe fn resolve(&self, pos: usize, resolver: Self::Resolver, out: *mut Self::Archived) {
+        ArchivedHashSet::<K::Archived>::resolve_from_len(self.len(), pos, resolver, out);
+    }
+}
+
+impl<K, S, RS> Serialize<S> for HashSet<K, RS>
+where
+    K::Archived: Hash + Eq,
+    K: Serialize<S> + Hash + Eq,
+    S: ScratchSpace + Serializer + ?Sized,
+{
+    #[inline]
+    fn serialize(&self, serializer: &mut S) -> Result<Self::Resolver, S::Error> {
+        unsafe { ArchivedHashSet::serialize_from_iter(self.iter(), serializer) }
+    }
+}
+
+impl<K, D, S> Deserialize<HashSet<K, S>, D> for ArchivedHashSet<K::Archived>
+where
+    K: Archive + Hash + Eq,
+    K::Archived: Deserialize<K, D> + Hash + Eq,
+    D: Fallible + ?Sized,
+    S: Default + BuildHasher,
+{
+    #[inline]
+    fn deserialize(&self, deserializer: &mut D) -> Result<HashSet<K, S>, D::Error> {
+        let mut result = HashSet::with_hasher(S::default());
+        for k in self.iter() {
+            result.insert(k.deserialize(deserializer)?);
+        }
+        Ok(result)
+    }
+}
+
+impl<K: Hash + Eq + Borrow<AK>, AK: Hash + Eq, S: BuildHasher> PartialEq<HashSet<K, S>>
+    for ArchivedHashSet<AK>
+{
+    #[inline]
+    fn eq(&self, other: &HashSet<K, S>) -> bool {
+        if self.len() != other.len() {
+            false
+        } else {
+            self.iter().all(|key| other.get(key).is_some())
+        }
+    }
+}
+
+impl<K: Hash + Eq + Borrow<AK>, AK: Hash + Eq, S: BuildHasher> PartialEq<ArchivedHashSet<AK>>
+    for HashSet<K, S>
+{
+    #[inline]
+    fn eq(&self, other: &ArchivedHashSet<AK>) -> bool {
+        other.eq(self)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::HashSet;
+    use alloc::string::String;
+    use rkyv::{
+        archived_root, check_archived_root,
+        ser::{serializers::AllocSerializer, Serializer},
+        Deserialize, Infallible,
+    };
+
+    #[test]
+    fn index_set() {
+        let mut value = HashSet::new();
+        value.insert(String::from("foo"));
+        value.insert(String::from("bar"));
+        value.insert(String::from("baz"));
+        value.insert(String::from("bat"));
+
+        let mut serializer = AllocSerializer::<4096>::default();
+        serializer.serialize_value(&value).unwrap();
+        let result = serializer.into_serializer().into_inner();
+        let archived = unsafe { archived_root::<HashSet<String>>(result.as_ref()) };
+
+        assert_eq!(value.len(), archived.len());
+        for k in value.iter() {
+            let ak = archived.get(k.as_str()).unwrap();
+            assert_eq!(k, ak);
+        }
+
+        let deserialized: HashSet<String> = archived.deserialize(&mut Infallible).unwrap();
+        assert_eq!(value, deserialized);
+    }
+
+    #[test]
+    fn validate_index_set() {
+        let mut value = HashSet::new();
+        value.insert(String::from("foo"));
+        value.insert(String::from("bar"));
+        value.insert(String::from("baz"));
+        value.insert(String::from("bat"));
+
+        let mut serializer = AllocSerializer::<4096>::default();
+        serializer.serialize_value(&value).unwrap();
+        let result = serializer.into_serializer().into_inner();
+        check_archived_root::<HashSet<String>>(result.as_ref())
+            .expect("failed to validate archived index set");
+    }
+}

src/external_trait_impls/rkyv/mod.rs

@@ -0,0 +1,2 @@
+mod hash_map;
+mod hash_set;

tests/rayon.rs

@@ -356,7 +356,9 @@ fn set_seq_par_equivalence_into_iter_empty() {
     let vec_seq = SET_EMPTY.clone().into_iter().collect::<Vec<_>>();
     let vec_par = SET_EMPTY.clone().into_par_iter().collect::<Vec<_>>();
 
-    assert_eq3!(vec_seq, vec_par, []);
+    // Work around type inference failure introduced by rend dev-dependency.
+    let empty: [char; 0] = [];
+    assert_eq3!(vec_seq, vec_par, empty);
 }
 
 #[test]