refactor(11523): enable TrackConsumersPool to be used in runtime metrics

datafusion/execution/src/memory_pool/pool.rs

@@ -289,7 +289,7 @@ impl<I: MemoryPool> TrackConsumersPool<I> {
     }
 
     /// The top consumers in a report string.
-    fn report_top(&self) -> String {
+    pub fn report_top(&self, top: usize) -> String {
         let mut consumers = self
             .tracked_consumers
             .lock()
@@ -303,7 +303,7 @@ impl<I: MemoryPool> TrackConsumersPool<I> {
             .collect::<Vec<_>>();
         consumers.sort_by(|a, b| b.1.cmp(&a.1)); // inverse ordering
 
-        consumers[0..std::cmp::min(self.top.into(), consumers.len())]
+        consumers[0..std::cmp::min(top, consumers.len())]
             .iter()
             .map(|((name, can_spill), size)| {
                 if self.has_multiple_consumers(name) {
@@ -367,7 +367,7 @@ impl<I: MemoryPool> MemoryPool for TrackConsumersPool<I> {
                     DataFusionError::ResourcesExhausted(
                         provide_top_memory_consumers_to_error_msg(
                             e.to_owned(),
-                            self.report_top(),
+                            self.report_top(self.top.into()),
                         ),
                     )
                 }
@@ -652,4 +652,38 @@ mod tests {
         ));
         test_per_pool_type(tracked_greedy_pool);
     }
+
+    #[test]
+    fn test_tracked_consumers_pool_use_beyond_errors() {
+        let upcasted: Arc<dyn std::any::Any + Send + Sync> =
+            Arc::new(TrackConsumersPool::new(
+                GreedyMemoryPool::new(100),
+                NonZeroUsize::new(3).unwrap(),
+            ));
+        let pool: Arc<dyn MemoryPool> = Arc::clone(&upcasted)
+            .downcast::<TrackConsumersPool<GreedyMemoryPool>>()
+            .unwrap();
+        // set r1=20
+        let mut r1 = MemoryConsumer::new("r1").register(&pool);
+        r1.grow(20);
+        // set r2=15
+        let mut r2 = MemoryConsumer::new("r2").register(&pool);
+        r2.grow(15);
+        // set r3=45
+        let mut r3 = MemoryConsumer::new("r3").register(&pool);
+        r3.grow(45);
+
+        let downcasted = upcasted
+            .downcast::<TrackConsumersPool<GreedyMemoryPool>>()
+            .unwrap();
+
+        // Test: can get runtime metrics, even without an error thrown
+        let expected = "r3 consumed 45 bytes, r1 consumed 20 bytes";
+        let res = downcasted.report_top(2);
+        assert_eq!(
+            res, expected,
+            "should provide list of top memory consumers, instead found {:?}",
+            res
+        );
+    }
 }