Add way to intern structs from references

Cargo.toml

@@ -10,7 +10,7 @@ description = "A generic framework for on-demand, incrementalized computation (e
 [dependencies]
 arc-swap = "1"
 crossbeam = "0.8"
-dashmap = "6"
+dashmap = { version = "6", features = ["raw-api"] }
 hashlink = "0.9"
 indexmap = "2"
 append-only-vec = "0.1.5"

components/salsa-macro-rules/src/setup_interned_struct.rs

@@ -32,6 +32,9 @@ macro_rules! setup_interned_struct {
         // Indices for each field from 0..N -- must be unsuffixed (e.g., `0`, `1`).
         field_indices: [$($field_index:tt),*],
 
+        // Indexed types for each field (T0, T1, ...)
+        field_indexed_tys: [$($indexed_ty:ident),*],
+
         // Number of fields
         num_fields: $N:literal,
 
@@ -62,10 +65,30 @@ macro_rules! setup_interned_struct {
 
             type $Configuration = $Struct<'static>;
 
+            type StructData<$db_lt> = ($($field_ty,)*);
+
+            struct StructKey<$db_lt, $($indexed_ty: $zalsa::interned::Lookup<$field_ty>),*>($($indexed_ty,)* std::marker::PhantomData<&$db_lt ()>,);
+
+            impl<$db_lt, $($indexed_ty: $zalsa::interned::Lookup<$field_ty>),*> $zalsa::interned::Lookup<StructData<$db_lt>>
+                for StructKey<$db_lt, $($indexed_ty),*> {
+
+                fn hash<H: std::hash::Hasher>(&self, h: &mut H) {
+                    $($zalsa::interned::Lookup::hash(&self.$field_index, &mut *h);)*
+                }
+
+                fn eq(&self, data: &StructData<$db_lt>) -> bool {
+                    ($($zalsa::interned::Lookup::eq(&self.$field_index, &data.$field_index) && )* true)
+                }
+
+                fn into_owned(self) -> StructData<$db_lt> {
+                    ($($zalsa::interned::Lookup::into_owned(self.$field_index),)*)
+                }
+            }
+
             impl $zalsa_struct::Configuration for $Configuration {
                 const DEBUG_NAME: &'static str = stringify!($Struct);
-                type Data<$db_lt> = ($($field_ty,)*);
-                type Struct<$db_lt> = $Struct<$db_lt>;
+                type Data<'a> = StructData<'a>;
+                type Struct<'a> = $Struct<'a>;
                 fn struct_from_id<'db>(id: salsa::Id) -> Self::Struct<'db> {
                     $Struct(id, std::marker::PhantomData)
                 }
@@ -126,13 +149,14 @@ macro_rules! setup_interned_struct {
             }
 
             impl<$db_lt> $Struct<$db_lt> {
-                pub fn $new_fn<$Db>(db: &$db_lt $Db, $($field_id: $field_ty),*) -> Self
+                pub fn $new_fn<$Db>(db: &$db_lt $Db,  $($field_id: impl $zalsa::interned::Lookup<$field_ty>),*) -> Self
                 where
                     // FIXME(rust-lang/rust#65991): The `db` argument *should* have the type `dyn Database`
                     $Db: ?Sized + salsa::Database,
                 {
                     let current_revision = $zalsa::current_revision(db);
-                    $Configuration::ingredient(db).intern(db.as_dyn_database(), ($($field_id,)*))
+                    $Configuration::ingredient(db).intern(db.as_dyn_database(),
+                        StructKey::<$db_lt>($($field_id,)* std::marker::PhantomData::default()))
                 }
 
                 $(

components/salsa-macros/src/interned.rs

@@ -90,6 +90,7 @@ impl Macro {
         let field_getter_ids = salsa_struct.field_getter_ids();
         let field_options = salsa_struct.field_options();
         let field_tys = salsa_struct.field_tys();
+        let field_indexed_tys = salsa_struct.field_indexed_tys();
         let generate_debug_impl = salsa_struct.generate_debug_impl();
 
         let zalsa = self.hygiene.ident("zalsa");
@@ -112,6 +113,7 @@ impl Macro {
                     field_getters: [#(#field_vis #field_getter_ids),*],
                     field_tys: [#(#field_tys),*],
                     field_indices: [#(#field_indices),*],
+                    field_indexed_tys: [#(#field_indexed_tys),*],
                     num_fields: #num_fields,
                     generate_debug_impl: #generate_debug_impl,
                     unused_names: [

components/salsa-macros/src/salsa_struct.rs

@@ -242,6 +242,14 @@ where
         self.fields.iter().map(|f| &f.field.ty).collect()
     }
 
+    pub(crate) fn field_indexed_tys(&self) -> Vec<syn::Ident> {
+        self.fields
+            .iter()
+            .enumerate()
+            .map(|(i, _)| quote::format_ident!("T{i}"))
+            .collect()
+    }
+
     pub(crate) fn field_options(&self) -> Vec<TokenStream> {
         self.fields
             .iter()

src/interned.rs

@@ -1,5 +1,5 @@
 use std::fmt;
-use std::hash::Hash;
+use std::hash::{BuildHasher, Hash, Hasher};
 use std::marker::PhantomData;
 
 use crate::durability::Durability;
@@ -114,19 +114,19 @@ where
         unsafe { std::mem::transmute(data) }
     }
 
-    pub fn intern_id<'db>(
+    pub fn intern_id<'db, T: Lookup<C::Data<'db>>>(
         &'db self,
         db: &'db dyn crate::Database,
-        data: C::Data<'db>,
+        data: T,
     ) -> crate::Id {
         C::deref_struct(self.intern(db, data)).as_id()
     }
 
     /// Intern data to a unique reference.
-    pub fn intern<'db>(
+    pub fn intern<'db, T: Lookup<C::Data<'db>>>(
         &'db self,
         db: &'db dyn crate::Database,
-        data: C::Data<'db>,
+        data: T,
     ) -> C::Struct<'db> {
         let zalsa_local = db.zalsa_local();
         zalsa_local.report_tracked_read(
@@ -137,7 +137,25 @@ where
 
         // Optimisation to only get read lock on the map if the data has already
         // been interned.
+        let mut hasher = self.key_map.hasher().build_hasher();
+        data.hash(&mut hasher);
+        let data_hash = hasher.finish();
+        let shard = self.key_map.determine_shard(data_hash as _);
+        {
+            let lock = self.key_map.shards()[shard].read();
+            if let Some(bucket) = lock.find(data_hash, |(a, _)| {
+                // lifetime shrink
+                let a: &C::Data<'db> = unsafe { std::mem::transmute(a) };
+                Lookup::eq(&data, a)
+            }) {
+                return C::struct_from_id(unsafe { *bucket.as_ref().1.get() });
+            }
+        };
+
+        let data = data.into_owned();
+
         let internal_data = unsafe { self.to_internal_data(data) };
+
         if let Some(guard) = self.key_map.get(&internal_data) {
             let id = *guard;
             drop(guard);
@@ -288,3 +306,58 @@ where
         &self.syncs
     }
 }
+
+pub trait Lookup<O>
+{
+    fn hash<H: Hasher>(&self, h: &mut H);
+    fn eq(&self, data: &O) -> bool;
+    fn into_owned(self) -> O;
+}
+
+impl<T> Lookup<T> for T
+where
+    T: Hash + Eq
+{
+    fn hash<H: Hasher>(&self, h: &mut H) {
+        Hash::hash(self, &mut *h);
+    }
+
+    fn eq(&self, data: &T) -> bool {
+        self == data
+    }
+
+    fn into_owned(self) -> T {
+        self
+    }
+}
+
+impl<T> Lookup<T> for &T
+where
+    T: Clone + Eq + Hash,
+{
+    fn hash<H: Hasher>(&self, h: &mut H) {
+        Hash::hash(self, &mut *h);
+    }
+
+    fn eq(&self, data: &T) -> bool {
+        *self == data
+    }
+
+    fn into_owned(self) -> T {
+        Clone::clone(self)
+    }
+}
+
+impl Lookup<String> for &str {
+    fn hash<H: Hasher>(&self, h: &mut H) {
+        Hash::hash(self, &mut *h)
+    }
+
+    fn eq(&self, data: &String) -> bool {
+        self == data
+    }
+
+    fn into_owned(self) -> String {
+        self.to_owned()
+    }
+}

src/lib.rs

@@ -133,6 +133,7 @@ pub mod plumbing {
         pub use crate::interned::IngredientImpl;
         pub use crate::interned::JarImpl;
         pub use crate::interned::Value;
+        pub use crate::interned::Lookup;
     }
 
     pub mod function {

tests/interned-struct-with-lifetime.rs

@@ -9,16 +9,24 @@ struct InternedString<'db> {
     data: String,
 }
 
+
 #[salsa::interned]
 struct InternedPair<'db> {
     data: (InternedString<'db>, InternedString<'db>),
 }
 
+#[salsa::interned]
+struct InternedTwoFields<'db> {
+    data1: String,
+    data2: String,
+}
+
 #[salsa::tracked]
 fn intern_stuff(db: &dyn salsa::Database) -> String {
     let s1 = InternedString::new(db, "Hello, ".to_string());
-    let s2 = InternedString::new(db, "World, ".to_string());
+    let s2 = InternedString::new(db, "World, ");
     let s3 = InternedPair::new(db, (s1, s2));
+
     format!("{s3:?}")
 }
 
@@ -29,3 +37,24 @@ fn execute() {
         "InternedPair { data: (InternedString { data: \"Hello, \" }, InternedString { data: \"World, \" }) }"
     "#]].assert_debug_eq(&intern_stuff(&db));
 }
+
+#[test]
+fn interning_returns_equal_keys_for_equal_data() {
+    let db = salsa::DatabaseImpl::new();
+    let s1 = InternedString::new(&db, "Hello, ".to_string());
+    let s2 = InternedString::new(&db, "World, ".to_string());
+    let s1_2 = InternedString::new(&db, "Hello, ");
+    let s2_2 = InternedString::new(&db, "World, ");
+    assert_eq!(s1, s1_2);
+    assert_eq!(s2, s2_2);
+}
+#[test]
+fn interning_returns_equal_keys_for_equal_data_multi_field() {
+    let db = salsa::DatabaseImpl::new();
+    let s1 = InternedTwoFields::new(&db, "Hello, ".to_string(), "World");
+    let s2 = InternedTwoFields::new(&db, "World, ", "Hello".to_string());
+    let s1_2 = InternedTwoFields::new(&db, "Hello, ", "World");
+    let s2_2 = InternedTwoFields::new(&db, "World, ", "Hello");
+    assert_eq!(s1, s1_2);
+    assert_eq!(s2, s2_2);
+}