Add comment on error

Author: LiaCastaneda

datafusion/physical-expr/src/expressions/dynamic_filters.rs

@@ -276,6 +276,12 @@ impl DynamicFilterPhysicalExpr {
     ///
     /// This method will return when [`Self::update`] is called and the generation increases.
     /// It does not guarantee that the filter is complete.
+    ///
+    /// # Note
+    ///
+    /// In the unlikely scenario where this method waits indefinitely, it indicates
+    /// a programming error where `wait_update()` is being called without any consumers
+    /// holding a reference to the filter.
     pub async fn wait_update(&self) {
         let mut rx = self.state_watch.subscribe();
         // Get the current generation
@@ -292,6 +298,12 @@ impl DynamicFilterPhysicalExpr {
     ///
     /// Unlike [`Self::wait_update`], this method guarantees that when it returns,
     /// the filter is fully complete with no more updates expected.
+    ///
+    /// # Note
+    ///
+    /// In the unlikely scenario where this method waits indefinitely, it indicates
+    /// a programming error where `wait_complete()` is being called without any consumers
+    /// holding a reference to the filter.
     pub async fn wait_complete(&self) {
         if self.inner.read().is_complete {
             return;