Move the RefCellExt trait in a dedicated module

crates/milli/src/update/new/ref_cell_ext.rs

@@ -0,0 +1,52 @@
+use std::cell::{Ref, RefCell, RefMut};
+
+pub trait RefCellExt<T: ?Sized> {
+    fn try_borrow_or_yield(&self) -> std::result::Result<Ref<'_, T>, std::cell::BorrowError>;
+    fn try_borrow_mut_or_yield(
+        &self,
+    ) -> std::result::Result<RefMut<'_, T>, std::cell::BorrowMutError>;
+
+    fn borrow_or_yield(&self) -> Ref<'_, T> {
+        self.try_borrow_or_yield().unwrap()
+    }
+
+    fn borrow_mut_or_yield(&self) -> RefMut<'_, T> {
+        self.try_borrow_mut_or_yield().unwrap()
+    }
+}
+
+impl<T: ?Sized> RefCellExt<T> for RefCell<T> {
+    fn try_borrow_or_yield(&self) -> std::result::Result<Ref<'_, T>, std::cell::BorrowError> {
+        /// TODO: move this trait and impl elsewhere
+        loop {
+            match self.try_borrow() {
+                Ok(borrow) => break Ok(borrow),
+                Err(error) => {
+                    tracing::warn!("dynamic borrow failed, yielding to local tasks");
+                    match rayon::yield_local() {
+                        Some(rayon::Yield::Executed) => continue,
+                        _ => return Err(error),
+                    }
+                }
+            }
+        }
+    }
+
+    fn try_borrow_mut_or_yield(
+        &self,
+    ) -> std::result::Result<RefMut<'_, T>, std::cell::BorrowMutError> {
+        loop {
+            match self.try_borrow_mut() {
+                Ok(borrow) => break Ok(borrow),
+                Err(error) => {
+                    tracing::warn!("dynamic borrow failed, yielding to local tasks");
+
+                    match rayon::yield_local() {
+                        Some(rayon::Yield::Executed) => continue,
+                        _ => return Err(error),
+                    }
+                }
+            }
+        }
+    }
+}