feat: recorder graceful drop (#2327)

lib/llm/src/recorder.rs

 // SPDX-FileCopyrightText: Copyright (c) 2024-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
 
 use serde::{Deserialize, Serialize};
 use std::io;
@@ -386,6 +374,12 @@ where
     }
 }
 
+impl<T> Drop for Recorder<T> {
+    fn drop(&mut self) {
+        self.cancel.cancel();
+    }
+}
+
 /// Helper function to create a rotated file path with an index suffix
 fn create_rotated_path(base_path: &Path, index: usize) -> PathBuf {
     let path_str = base_path.to_string_lossy();
@@ -471,11 +465,11 @@ mod tests {
         // Check that both events were recorded
         assert_eq!(recorder.event_count().await, 2);
 
-        // Check that the elapsed time is between 9 and 11 milliseconds
+        // Check that the elapsed time is between 7 and 13 milliseconds
         let elapsed_ms = recorder.elapsed_time().await.unwrap().as_millis();
-        if !(9..=11).contains(&elapsed_ms) {
+        if !(7..=13).contains(&elapsed_ms) {
             println!("Actual elapsed time: {} ms", elapsed_ms);
-            assert!((9..=11).contains(&elapsed_ms));
+            assert!((7..=13).contains(&elapsed_ms));
         }
 
         // Force shutdown to flush file