introduce the GetQueryGroupStorage trait and use it

components/salsa-macros/Cargo.toml

@@ -16,3 +16,4 @@ heck = "0.3"
 proc-macro2 = "0.4"
 quote = "0.6"
 syn = { version = "0.15", features = ["full", "extra-traits"] }
+

components/salsa-macros/src/database_storage.rs

@@ -50,28 +50,32 @@ pub(crate) fn database_storage(input: TokenStream) -> TokenStream {
         .collect();
 
     let each_query = || {
-        query_groups
+        query_groups.iter().flat_map(|query_group| {
+            query_group
+                .queries
                 .iter()
-            .zip(&query_group_names_snake)
+                .map(move |q| (query_group.group_storage(), q))
-            .flat_map(|(query_group, name_snake)| {
-                query_group.queries.iter().map(move |q| (name_snake, q))
         })
     };
 
     // For each query group `foo::MyGroup` create a link to its
     // `foo::MyGroupGroupStorage`
     let mut storage_fields = proc_macro2::TokenStream::new();
+    let mut storage_impls = proc_macro2::TokenStream::new();
     for (query_group, query_group_name_snake) in query_groups.iter().zip(&query_group_names_snake) {
+        let group_storage = query_group.group_storage();
+
         // rewrite the last identifier (`MyGroup`, above) to
         // (e.g.) `MyGroupGroupStorage`.
-        let mut group_storage = query_group.query_group.clone();
-        let last_ident = &group_storage.segments.last().unwrap().value().ident;
-        let storage_ident = Ident::new(
-            &format!("{}GroupStorage", last_ident.to_string()),
-            Span::call_site(),
-        );
-        group_storage.segments.last_mut().unwrap().value_mut().ident = storage_ident;
         storage_fields.extend(quote! { #query_group_name_snake: #group_storage<#database_name>, });
+        storage_impls.extend(quote! {
+            impl ::salsa::plumbing::GetQueryGroupStorage<#group_storage<#database_name>> for #database_name {
+                fn from(db: &Self) -> &#group_storage<#database_name> {
+                    let runtime = ::salsa::Database::salsa_runtime(db);
+                    &runtime.storage().#query_group_name_snake
+                }
+            }
+        });
     }
 
     let mut attrs = proc_macro2::TokenStream::new();
@@ -132,9 +136,10 @@ pub(crate) fn database_storage(input: TokenStream) -> TokenStream {
 
     //
     let mut for_each_ops = proc_macro2::TokenStream::new();
-    for (group_index, Query { query_name, .. }) in each_query() {
+    for (ref group_storage, Query { query_name, .. }) in each_query() {
         for_each_ops.extend(quote! {
-            op(&::salsa::Database::salsa_runtime(self).storage().#group_index.#query_name);
+            let storage: &#group_storage<#database_name> = ::salsa::plumbing::GetQueryGroupStorage::from(self);
+            op(&storage.#query_name);
         });
     }
     output.extend(quote! {
@@ -150,7 +155,7 @@ pub(crate) fn database_storage(input: TokenStream) -> TokenStream {
 
     let mut for_each_query_desc = proc_macro2::TokenStream::new();
     for (
-        group_index,
+        ref group_storage,
         Query {
             query_name,
             query_type,
@@ -159,8 +164,8 @@ pub(crate) fn database_storage(input: TokenStream) -> TokenStream {
     {
         for_each_query_desc.extend(quote! {
             __SalsaQueryDescriptorKind::#query_name(key) => {
-                let runtime = ::salsa::Database::salsa_runtime(db);
+                let group_storage = ::salsa::plumbing::GetQueryGroupStorage::<#group_storage<#database_name>>::from(db);
-                let storage = &runtime.storage().#group_index.#query_name;
+                let storage = &group_storage.#query_name;
                 <_ as ::salsa::plumbing::QueryStorageOps<#database_name, #query_type>>::maybe_changed_since(
                     storage,
                     db,
@@ -188,7 +193,7 @@ pub(crate) fn database_storage(input: TokenStream) -> TokenStream {
 
     let mut for_each_query_table = proc_macro2::TokenStream::new();
     for (
-        group_index,
+        ref group_storage,
         Query {
             query_name,
             query_type,
@@ -200,12 +205,10 @@ pub(crate) fn database_storage(input: TokenStream) -> TokenStream {
                 fn get_query_table(
                     db: &Self,
                 ) -> ::salsa::QueryTable<'_, Self, #query_type> {
+                    let storage: &#group_storage<#database_name> = ::salsa::plumbing::GetQueryGroupStorage::from(db);
                     ::salsa::QueryTable::new(
                         db,
-                        &::salsa::Database::salsa_runtime(db)
+                        &storage.#query_name,
-                            .storage()
-                            .#group_index
-                            .#query_name,
                     )
                 }
 
@@ -213,12 +216,10 @@ pub(crate) fn database_storage(input: TokenStream) -> TokenStream {
                     db: &mut Self,
                 ) -> ::salsa::QueryTableMut<'_, Self, #query_type> {
                     let db = &*db;
+                    let storage: &#group_storage<#database_name> = ::salsa::plumbing::GetQueryGroupStorage::from(db);
                     ::salsa::QueryTableMut::new(
                         db,
-                        &::salsa::Database::salsa_runtime(db)
+                        &storage.#query_name,
-                            .storage()
-                            .#group_index
-                            .#query_name,
                     )
                 }
 
@@ -235,6 +236,13 @@ pub(crate) fn database_storage(input: TokenStream) -> TokenStream {
     }
 
     output.extend(for_each_query_table);
+    output.extend(storage_impls);
+
+    if std::env::var("SALSA_DUMP").is_ok() {
+        println!("~~~ database_storage");
+        println!("{}", output.to_string());
+        println!("~~~ database_storage");
+    }
 
     output.into()
 }
@@ -251,6 +259,22 @@ struct QueryGroup {
     queries: Vec<Query>,
 }
 
+impl QueryGroup {
+    /// Construct the path to the group storage for a query group. For
+    /// a query group at the path `foo::MyQuery`, this would be
+    /// `foo::MyQueryGroupStorage`.
+    fn group_storage(&self) -> Path {
+        let mut group_storage = self.query_group.clone();
+        let last_ident = &group_storage.segments.last().unwrap().value().ident;
+        let storage_ident = Ident::new(
+            &format!("{}GroupStorage", last_ident.to_string()),
+            Span::call_site(),
+        );
+        group_storage.segments.last_mut().unwrap().value_mut().ident = storage_ident;
+        group_storage
+    }
+}
+
 struct Query {
     query_name: Ident,
     query_type: Path,

src/plumbing.rs

@@ -81,6 +81,10 @@ pub trait GetQueryTable<Q: Query<Self>>: Database {
     fn descriptor(db: &Self, key: Q::Key) -> Self::QueryDescriptor;
 }
 
+pub trait GetQueryGroupStorage<S>: Database {
+    fn from(db: &Self) -> &S;
+}
+
 pub trait QueryStorageOps<DB, Q>: Default
 where
     DB: Database,