Serialization support (#79)

Cargo.toml

@@ -26,6 +26,7 @@ sanitize = ['crossbeam-epoch/sanitize']
 crossbeam-epoch = "0.8.2"
 parking_lot = "0.10"
 num_cpus = "1.12.0"
+serde = {version = "1.0.105", optional = true}
 
 [dependencies.ahash]
 version = "0.3.2"
@@ -35,6 +36,7 @@ default-features = false
 rand = "0.7"
 rayon = "1.3"
 criterion = "0.3"
+serde_json = "1.0.50"
 
 [[bench]]
 name = "flurry_dashmap" 

src/lib.rs

@@ -223,6 +223,9 @@ mod raw;
 mod set;
 mod set_ref;
 
+#[cfg(feature = "serde")]
+mod serde_impls;
+
 /// Iterator types.
 pub mod iter;
 

src/serde_impls.rs

@@ -0,0 +1,216 @@
+use crate::{HashMap, HashMapRef, HashSet, HashSetRef};
+use serde::{
+    de::{MapAccess, SeqAccess, Visitor},
+    Deserialize, Deserializer, Serialize, Serializer,
+};
+use std::fmt::{self, Formatter};
+use std::hash::{BuildHasher, Hash};
+use std::marker::PhantomData;
+
+struct HashMapVisitor<K, V, S> {
+    key_marker: PhantomData<K>,
+    value_marker: PhantomData<V>,
+    hash_builder_marker: PhantomData<S>,
+}
+
+impl<K, V, S> Serialize for HashMapRef<'_, K, V, S>
+where
+    K: Serialize,
+    V: Serialize,
+{
+    fn serialize<Sr>(&self, serializer: Sr) -> Result<Sr::Ok, Sr::Error>
+    where
+        Sr: Serializer,
+    {
+        serializer.collect_map(self.iter())
+    }
+}
+
+impl<K, V, S> Serialize for HashMap<K, V, S>
+where
+    K: Serialize,
+    V: Serialize,
+{
+    fn serialize<Sr>(&self, serializer: Sr) -> Result<Sr::Ok, Sr::Error>
+    where
+        Sr: Serializer,
+    {
+        self.pin().serialize(serializer)
+    }
+}
+
+impl<'de, K, V, S> Deserialize<'de> for HashMap<K, V, S>
+where
+    K: 'static + Deserialize<'de> + Send + Sync + Hash + Clone + Eq,
+    V: 'static + Deserialize<'de> + Send + Sync + Eq,
+    S: Default + BuildHasher,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_map(HashMapVisitor::new())
+    }
+}
+
+impl<K, V, S> HashMapVisitor<K, V, S> {
+    pub(crate) fn new() -> Self {
+        Self {
+            key_marker: PhantomData,
+            value_marker: PhantomData,
+            hash_builder_marker: PhantomData,
+        }
+    }
+}
+
+impl<'de, K, V, S> Visitor<'de> for HashMapVisitor<K, V, S>
+where
+    K: 'static + Deserialize<'de> + Send + Sync + Hash + Clone + Eq,
+    V: 'static + Deserialize<'de> + Send + Sync + Eq,
+    S: Default + BuildHasher,
+{
+    type Value = HashMap<K, V, S>;
+
+    fn expecting(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        write!(f, "a map")
+    }
+
+    fn visit_map<M>(self, mut access: M) -> Result<Self::Value, M::Error>
+    where
+        M: MapAccess<'de>,
+    {
+        let map = match access.size_hint() {
+            Some(n) => HashMap::with_capacity_and_hasher(n, S::default()),
+            None => HashMap::with_hasher(S::default()),
+        };
+        let guard = map.guard();
+
+        while let Some((key, value)) = access.next_entry()? {
+            if let Some(_old_value) = map.insert(key, value, &guard) {
+                unreachable!("Serialized map held two values with the same key");
+            }
+        }
+
+        Ok(map)
+    }
+}
+
+impl<T, S> Serialize for HashSetRef<'_, T, S>
+where
+    T: Serialize,
+{
+    fn serialize<Sr>(&self, serilizer: Sr) -> Result<Sr::Ok, Sr::Error>
+    where
+        Sr: Serializer,
+    {
+        serilizer.collect_seq(self.iter())
+    }
+}
+
+impl<T, S> Serialize for HashSet<T, S>
+where
+    T: Serialize,
+{
+    fn serialize<Sr>(&self, serializer: Sr) -> Result<Sr::Ok, Sr::Error>
+    where
+        Sr: Serializer,
+    {
+        self.pin().serialize(serializer)
+    }
+}
+
+impl<'de, T, S> Deserialize<'de> for HashSet<T, S>
+where
+    T: 'static + Deserialize<'de> + Send + Sync + Hash + Clone + Eq,
+    S: Default + BuildHasher,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        deserializer.deserialize_seq(HashSetVisitor::new())
+    }
+}
+
+struct HashSetVisitor<T, S> {
+    type_marker: PhantomData<T>,
+    hash_builder_marker: PhantomData<S>,
+}
+
+impl<T, S> HashSetVisitor<T, S> {
+    pub(crate) fn new() -> Self {
+        Self {
+            type_marker: PhantomData,
+            hash_builder_marker: PhantomData,
+        }
+    }
+}
+
+impl<'de, T, S> Visitor<'de> for HashSetVisitor<T, S>
+where
+    T: 'static + Deserialize<'de> + Send + Sync + Hash + Clone + Eq,
+    S: Default + BuildHasher,
+{
+    type Value = HashSet<T, S>;
+
+    fn expecting(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        write!(f, "a set")
+    }
+
+    fn visit_seq<A>(self, mut access: A) -> Result<Self::Value, A::Error>
+    where
+        A: SeqAccess<'de>,
+    {
+        let set = HashSet::default();
+        let guard = set.guard();
+
+        while let Some(value) = access.next_element()? {
+            let _ = set.insert(value, &guard);
+        }
+
+        Ok(set)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::{HashMap, HashSet};
+
+    #[test]
+    fn test_map() {
+        let map: HashMap<u8, u8> = HashMap::with_capacity(5);
+        let guard = map.guard();
+
+        let _ = map.insert(0, 4, &guard);
+        let _ = map.insert(1, 3, &guard);
+        let _ = map.insert(2, 2, &guard);
+        let _ = map.insert(3, 1, &guard);
+        let _ = map.insert(4, 0, &guard);
+
+        let serialized = serde_json::to_string(&map).expect("Couldn't serialize map");
+
+        let deserialized: HashMap<u8, u8> =
+            serde_json::from_str(&serialized).expect("Couldn't deserialize map");
+
+        assert_eq!(map, deserialized);
+    }
+
+    #[test]
+    fn test_set() {
+        let set: HashSet<u8> = HashSet::with_capacity(5);
+        let guard = set.guard();
+
+        let _ = set.insert(0, &guard);
+        let _ = set.insert(1, &guard);
+        let _ = set.insert(2, &guard);
+        let _ = set.insert(3, &guard);
+        let _ = set.insert(4, &guard);
+
+        let serialized = serde_json::to_string(&set).expect("Couldn't serialize map");
+
+        let deserialized: HashSet<u8> =
+            serde_json::from_str(&serialized).expect("Couldn't deserialize map");
+
+        assert_eq!(set, deserialized);
+    }
+}

src/set.rs

@@ -2,15 +2,14 @@
 //!
 //! See `HashSet` for details.
 
+use crate::epoch::Guard;
+use crate::iter::Keys;
+use crate::HashMap;
 use std::borrow::Borrow;
 use std::fmt::{self, Debug, Formatter};
 use std::hash::{BuildHasher, Hash};
 use std::iter::FromIterator;
 
-use crate::epoch::Guard;
-use crate::iter::Keys;
-use crate::HashMap;
-
 /// A concurrent hash set implemented as a `HashMap` where the value is `()`.
 ///
 /// # Examples