Revert "introduce Table and use for interned values"

This reverts commit 9a3111c.

Author: nikomatsakis

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

@@ -52,7 +52,7 @@ macro_rules! setup_interned_struct {
         $(#[$attr])*
         #[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
         $vis struct $Struct<$db_lt>(
-            salsa::Id,
+            std::ptr::NonNull<salsa::plumbing::interned::Value < $Struct<'static> >>,
             std::marker::PhantomData < & $db_lt salsa::plumbing::interned::Value < $Struct<'static> > >
         );
 
@@ -66,11 +66,11 @@ macro_rules! setup_interned_struct {
                 const DEBUG_NAME: &'static str = stringify!($Struct);
                 type Data<$db_lt> = ($($field_ty,)*);
                 type Struct<$db_lt> = $Struct<$db_lt>;
-                fn struct_from_id<'db>(id: salsa::Id) -> Self::Struct<'db> {
-                    $Struct(id, std::marker::PhantomData)
+                unsafe fn struct_from_raw<'db>(ptr: std::ptr::NonNull<$zalsa_struct::Value<Self>>) -> Self::Struct<'db> {
+                    $Struct(ptr, std::marker::PhantomData)
                 }
-                fn deref_struct(s: Self::Struct<'_>) -> salsa::Id {
-                    s.0
+                fn deref_struct(s: Self::Struct<'_>) -> &$zalsa_struct::Value<Self> {
+                    unsafe { s.0.as_ref() }
                 }
             }
 
@@ -89,13 +89,13 @@ macro_rules! setup_interned_struct {
 
             impl $zalsa::AsId for $Struct<'_> {
                 fn as_id(&self) -> salsa::Id {
-                    self.0
+                    unsafe { self.0.as_ref() }.as_id()
                 }
             }
 
             impl<$db_lt> $zalsa::LookupId<$db_lt> for $Struct<$db_lt> {
                 fn lookup_id(id: salsa::Id, db: &$db_lt dyn $zalsa::Database) -> Self {
-                    Self(id, std::marker::PhantomData)
+                    $Configuration::ingredient(db).interned_value(id)
                 }
             }
 
@@ -144,7 +144,7 @@ macro_rules! setup_interned_struct {
                         // FIXME(rust-lang/rust#65991): The `db` argument *should* have the type `dyn Database`
                         $Db: ?Sized + $zalsa::Database,
                     {
-                        let fields = $Configuration::ingredient(db).fields(db.as_dyn_database(), self);
+                        let fields = $Configuration::ingredient(db).fields(self);
                         $zalsa::maybe_clone!(
                             $field_option,
                             $field_ty,
@@ -156,7 +156,7 @@ macro_rules! setup_interned_struct {
                 /// Default debug formatting for this struct (may be useful if you define your own `Debug` impl)
                 pub fn default_debug_fmt(this: Self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
                     $zalsa::with_attached_database(|db| {
-                        let fields = $Configuration::ingredient(db).fields(db.as_dyn_database(), this);
+                        let fields = $Configuration::ingredient(db).fields(this);
                         let mut f = f.debug_struct(stringify!($Struct));
                         $(
                             let f = f.field(stringify!($field_id), &fields.$field_index);

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

@@ -96,7 +96,7 @@ macro_rules! setup_tracked_fn {
                 if $needs_interner {
                     #[derive(Copy, Clone)]
                     struct $InternedData<$db_lt>(
-                        salsa::Id,
+                        std::ptr::NonNull<$zalsa::interned::Value<$Configuration>>,
                         std::marker::PhantomData<&$db_lt $zalsa::interned::Value<$Configuration>>,
                     );
 
@@ -114,14 +114,14 @@ macro_rules! setup_tracked_fn {
 
                         type Struct<$db_lt> = $InternedData<$db_lt>;
 
-                        fn struct_from_id<$db_lt>(
-                            id: salsa::Id,
+                        unsafe fn struct_from_raw<$db_lt>(
+                            ptr: std::ptr::NonNull<$zalsa::interned::Value<Self>>,
                         ) -> Self::Struct<$db_lt> {
-                            $InternedData(id, std::marker::PhantomData)
+                            $InternedData(ptr, std::marker::PhantomData)
                         }
 
-                        fn deref_struct(s: Self::Struct<'_>) -> salsa::Id {
-                            s.0
+                        fn deref_struct(s: Self::Struct<'_>) -> &$zalsa::interned::Value<Self> {
+                            unsafe { s.0.as_ref() }
                         }
                     }
                 } else {
@@ -191,7 +191,7 @@ macro_rules! setup_tracked_fn {
                 fn id_to_input<$db_lt>(db: &$db_lt Self::DbView, key: salsa::Id) -> Self::Input<$db_lt> {
                     $zalsa::macro_if! {
                         if $needs_interner {
-                            $Configuration::intern_ingredient(db).data(db, key).clone()
+                            $Configuration::intern_ingredient(db).data(key).clone()
                         } else {
                             $zalsa::LookupId::lookup_id(key, db.as_dyn_database())
                         }

src/interned.rs

@@ -1,7 +1,10 @@
+use crossbeam::atomic::AtomicCell;
 use std::fmt;
 use std::hash::Hash;
 use std::marker::PhantomData;
+use std::ptr::NonNull;
 
+use crate::alloc::Alloc;
 use crate::durability::Durability;
 use crate::id::AsId;
 use crate::ingredient::fmt_index;
@@ -24,16 +27,24 @@ pub trait Configuration: Sized + 'static {
     /// The end user struct
     type Struct<'db>: Copy;
 
-    /// Create an end-user struct from the salsa id
+    /// Create an end-user struct from the underlying raw pointer.
     ///
     /// This call is an "end-step" to the tracked struct lookup/creation
     /// process in a given revision: it occurs only when the struct is newly
     /// created or, if a struct is being reused, after we have updated its
     /// fields (or confirmed it is green and no updates are required).
-    fn struct_from_id<'db>(id: Id) -> Self::Struct<'db>;
-
-    /// Deref the struct to yield the underlying id.
-    fn deref_struct(s: Self::Struct<'_>) -> Id;
+    ///
+    /// # Safety
+    ///
+    /// Requires that `ptr` represents a "confirmed" value in this revision,
+    /// which means that it will remain valid and immutable for the remainder of this
+    /// revision, represented by the lifetime `'db`.
+    unsafe fn struct_from_raw<'db>(ptr: NonNull<Value<Self>>) -> Self::Struct<'db>;
+
+    /// Deref the struct to yield the underlying value struct.
+    /// Since we are still part of the `'db` lifetime in which the struct was created,
+    /// this deref is safe, and the value-struct fields are immutable and verified.
+    fn deref_struct(s: Self::Struct<'_>) -> &Value<Self>;
 }
 
 pub trait InternedData: Sized + Eq + Hash + Clone {}
@@ -55,6 +66,14 @@ pub struct IngredientImpl<C: Configuration> {
     /// Deadlock requirement: We access `value_map` while holding lock on `key_map`, but not vice versa.
     key_map: FxDashMap<C::Data<'static>, Id>,
 
+    /// Maps from an interned id to its data.
+    ///
+    /// Deadlock requirement: We access `value_map` while holding lock on `key_map`, but not vice versa.
+    value_map: FxDashMap<Id, Alloc<Value<C>>>,
+
+    /// counter for the next id.
+    counter: AtomicCell<u32>,
+
     /// Stores the revision when this interned ingredient was last cleared.
     /// You can clear an interned table at any point, deleting all its entries,
     /// but that will make anything dependent on those entries dirty and in need
@@ -93,6 +112,8 @@ where
         Self {
             ingredient_index,
             key_map: Default::default(),
+            value_map: Default::default(),
+            counter: AtomicCell::default(),
             reset_at: Revision::start(),
         }
     }
@@ -101,10 +122,6 @@ where
         unsafe { std::mem::transmute(data) }
     }
 
-    unsafe fn from_internal_data<'db>(&'db self, data: &C::Data<'static>) -> &C::Data<'db> {
-        unsafe { std::mem::transmute(data) }
-    }
-
     pub fn intern_id<'db>(
         &'db self,
         db: &'db dyn crate::Database,
@@ -132,46 +149,66 @@ where
         if let Some(guard) = self.key_map.get(&internal_data) {
             let id = *guard;
             drop(guard);
-            return C::struct_from_id(id);
+            return self.interned_value(id);
         }
 
         match self.key_map.entry(internal_data.clone()) {
             // Data has been interned by a racing call, use that ID instead
             dashmap::mapref::entry::Entry::Occupied(entry) => {
                 let id = *entry.get();
                 drop(entry);
-                C::struct_from_id(id)
+                self.interned_value(id)
             }
 
             // We won any races so should intern the data
             dashmap::mapref::entry::Entry::Vacant(entry) => {
-                let zalsa = db.zalsa();
-                let table = zalsa.table();
-                let next_id = zalsa_local.allocate(table, self.ingredient_index, internal_data);
+                let next_id = self.counter.fetch_add(1);
+                let next_id = crate::id::Id::from_u32(next_id);
+                let value = self.value_map.entry(next_id).or_insert(Alloc::new(Value {
+                    id: next_id,
+                    fields: internal_data,
+                }));
+                let value_raw = value.as_raw();
+                drop(value);
                 entry.insert(next_id);
-                C::struct_from_id(next_id)
+                // SAFETY: Items are only removed from the `value_map` with an `&mut self` reference.
+                unsafe { C::struct_from_raw(value_raw) }
             }
         }
     }
 
+    pub fn interned_value(&self, id: Id) -> C::Struct<'_> {
+        let r = self.value_map.get(&id).unwrap();
+
+        // SAFETY: Items are only removed from the `value_map` with an `&mut self` reference.
+        unsafe { C::struct_from_raw(r.as_raw()) }
+    }
+
     /// Lookup the data for an interned value based on its id.
     /// Rarely used since end-users generally carry a struct with a pointer directly
     /// to the interned item.
-    pub fn data<'db>(&'db self, db: &'db dyn Database, id: Id) -> &'db C::Data<'db> {
-        let internal_data = db.zalsa().table().get::<C::Data<'static>>(id);
-        unsafe { self.from_internal_data(internal_data) }
+    pub fn data(&self, id: Id) -> &C::Data<'_> {
+        C::deref_struct(self.interned_value(id)).data()
     }
 
     /// Lookup the fields from an interned struct.
     /// Note that this is not "leaking" since no dependency edge is required.
-    pub fn fields<'db>(&'db self, db: &'db dyn Database, s: C::Struct<'db>) -> &'db C::Data<'db> {
-        self.data(db, C::deref_struct(s))
+    pub fn fields<'db>(&'db self, s: C::Struct<'db>) -> &'db C::Data<'db> {
+        C::deref_struct(s).data()
+    }
+
+    /// Variant of `data` that takes a (unnecessary) database argument.
+    /// This exists because tracked functions sometimes use true interning and sometimes use
+    /// [`IdentityInterner`][], which requires the database argument.
+    pub fn data_with_db<'db, DB: ?Sized>(&'db self, id: Id, _db: &'db DB) -> &'db C::Data<'db> {
+        self.data(id)
     }
 
     pub fn reset(&mut self, revision: Revision) {
         assert!(revision > self.reset_at);
         self.reset_at = revision;
         self.key_map.clear();
+        self.value_map.clear();
     }
 }
 

src/lib.rs

@@ -22,7 +22,6 @@ mod revision;
 mod runtime;
 mod salsa_struct;
 mod storage;
-mod table;
 mod tracked_struct;
 mod update;
 mod views;