generalize list of "entities created" to "outputs"

We will record each thing that gets *output* by the query.
Use a btree-set so that we can get a sorted list.
That will allow us to easily compare what is output between revisions.
We will use that to clear stale values.

components/salsa-2022/src/function/specify.rs

@@ -27,7 +27,7 @@ where
         };
 
         let entity_index = key.database_key_index(db);
-        if !runtime.was_entity_created(entity_index) {
+        if !runtime.is_output_of_active_query(entity_index) {
             panic!("can only use `set` on entities created during current query");
         }
 

components/salsa-2022/src/runtime.rs

@@ -144,15 +144,15 @@ impl Runtime {
         }
     }
 
-    /// Adds `entity` to the lits of entities created by the current query.
-    /// Panics if `entity` was already added.
-    pub(crate) fn add_entity_created(&self, entity: DatabaseKeyIndex) {
-        self.local_state.add_entity_created(entity);
+    /// Adds `key` to the list of output created by the current query
+    /// (if not already present).
+    pub(crate) fn add_output(&self, key: DatabaseKeyIndex) {
+        self.local_state.add_output(key);
     }
 
-    /// Check whether `entity` is contained the list of entities created by the current query.
-    pub(super) fn was_entity_created(&self, entity: DatabaseKeyIndex) -> bool {
-        self.local_state.was_entity_created(entity)
+    /// Check whether `entity` is contained the list of outputs written by the current query.
+    pub(super) fn is_output_of_active_query(&self, entity: DatabaseKeyIndex) -> bool {
+        self.local_state.is_output(entity)
     }
 
     /// Called when the active queries creates an index from the

components/salsa-2022/src/runtime/active_query.rs

@@ -86,8 +86,7 @@ impl ActiveQuery {
 
     /// Adds a key to our list of outputs.
     pub(super) fn add_output(&mut self, key: DatabaseKeyIndex) {
-        let is_new = self.outputs.insert(key);
-        assert!(is_new);
+        self.outputs.insert(key);
     }
 
     /// True if the given key was output by this query.

components/salsa-2022/src/runtime/local_state.rs

@@ -115,7 +115,7 @@ impl LocalState {
         })
     }
 
-    pub(super) fn add_entity_created(&self, entity: DatabaseKeyIndex) {
+    pub(super) fn add_output(&self, entity: DatabaseKeyIndex) {
         self.with_query_stack(|stack| {
             if let Some(top_query) = stack.last_mut() {
                 top_query.add_output(entity)
@@ -123,7 +123,7 @@ impl LocalState {
         })
     }
 
-    pub(super) fn was_entity_created(&self, entity: DatabaseKeyIndex) -> bool {
+    pub(super) fn is_output(&self, entity: DatabaseKeyIndex) -> bool {
         self.with_query_stack(|stack| {
             if let Some(top_query) = stack.last_mut() {
                 top_query.is_output(entity)

components/salsa-2022/src/tracked_struct.rs

@@ -76,7 +76,7 @@ where
             data,
         };
         let result = self.interned.intern(runtime, entity_key);
-        runtime.add_entity_created(self.database_key_index(result));
+        runtime.add_output(self.database_key_index(result));
         result
     }