Automatically clear the cancellation flag when cancellation completes

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

@@ -138,7 +138,6 @@ macro_rules! setup_tracked_fn {
 
                 pub fn fn_ingredient_mut(db: &mut dyn $Db) -> &mut $zalsa::function::IngredientImpl<Self> {
                     let zalsa_mut = db.zalsa_mut();
-                    zalsa_mut.reset_cancellation_flag();
                     let index = zalsa_mut.add_or_lookup_jar_by_type(&$Configuration);
                     let (ingredient, _) = zalsa_mut.lookup_ingredient_mut(index);
                     ingredient.assert_type_mut::<$zalsa::function::IngredientImpl<Self>>()

src/runtime.rs

@@ -152,7 +152,6 @@ impl Runtime {
         let r_old = self.current_revision();
         let r_new = r_old.next();
         self.revisions[0] = r_new;
-        self.reset_cancellation_flag();
         r_new
     }
 

src/storage.rs

@@ -117,6 +117,8 @@ impl<Db: Database> Storage<Db> {
     ///
     /// This could deadlock if there is a single worker with two handles to the
     /// same database!
+    ///
+    /// Needs to be paired with a call to `reset_cancellation_flag`.
     fn cancel_others(&self, db: &Db) {
         self.handle.zalsa_impl.set_cancellation_flag();
 
@@ -140,9 +142,10 @@ unsafe impl<T: HasStorage> ZalsaDatabase for T {
 
         let storage = self.storage_mut();
         // The ref count on the `Arc` should now be 1
-        let zalsa_mut = Arc::get_mut(&mut storage.handle.zalsa_impl).unwrap();
-        zalsa_mut.new_revision();
-        zalsa_mut
+        let zalsa = Arc::get_mut(&mut storage.handle.zalsa_impl).unwrap();
+        // cancellation is done, so reset the flag
+        zalsa.reset_cancellation_flag();
+        zalsa
     }
 
     fn zalsa_local(&self) -> &ZalsaLocal {

src/zalsa.rs

@@ -45,8 +45,6 @@ pub unsafe trait ZalsaDatabase: Any {
     ///
     /// **WARNING:** Triggers cancellation to other database handles.
     /// This can lead to deadlock!
-    ///
-    /// Note that this needs to be paired with a call to `Zalsa::new_revision` or `Zalsa::clear_cancellation_flag`.
     #[doc(hidden)]
     fn zalsa_mut(&mut self) -> &mut Zalsa;
 
@@ -266,9 +264,7 @@ impl Zalsa {
         self.runtime.load_cancellation_flag()
     }
 
-    /// **NOT SEMVER STABLE**
-    #[doc(hidden)]
-    pub fn reset_cancellation_flag(&mut self) {
+    pub(crate) fn reset_cancellation_flag(&mut self) {
         self.runtime.reset_cancellation_flag();
     }