feat(pointcloud_preprocessor): add pipeline latency time debug inform…

…ation for pointcloud pipeline (autowarefoundation#6056)

sensing/pointcloud_preprocessor/README.md

@@ -56,7 +56,45 @@ Detail description of each filter's algorithm is in the following links.
 
 ## Assumptions / Known limits
 
-`pointcloud_preprocessor::Filter` is implemented based on pcl_perception [1] because of [this issue](https://github.com/ros-perception/perception_pcl/issues/9).
+`pointcloud_preprocessor::Filter` is implemented based on pcl_perception [1] because
+of [this issue](https://github.com/ros-perception/perception_pcl/issues/9).
+
+## Measuring the performance
+
+In Autoware, point cloud data from each LiDAR sensor undergoes preprocessing in the sensing pipeline before being input
+into the perception pipeline. The preprocessing stages are illustrated in the diagram below:
+
+![pointcloud_preprocess_pipeline.drawio.png](docs%2Fimage%2Fpointcloud_preprocess_pipeline.drawio.png)
+
+Each stage in the pipeline incurs a processing delay. Mostly, we've used `ros2 topic delay /topic_name` to measure
+the time between the message header and the current time. This approach works well for small-sized messages. However,
+when dealing with large point cloud messages, this method introduces an additional delay. This is primarily because
+accessing these large point cloud messages externally impacts the pipeline's performance.
+
+Our sensing/perception nodes are designed to run within composable node containers, leveraging intra-process
+communication. External subscriptions to these messages (like using ros2 topic delay or rviz2) impose extra delays and
+can even slow down the pipeline by subscribing externally. Therefore, these measurements will not be accurate.
+
+To mitigate this issue, we've adopted a method where each node in the pipeline reports its pipeline latency time.
+This approach ensures the integrity of intra-process communication and provides a more accurate measure of delays in the
+pipeline.
+
+### Benchmarking The Pipeline
+
+The nodes within the pipeline report the pipeline latency time, indicating the duration from the sensor driver's pointcloud
+output to the node's output. This data is crucial for assessing the pipeline's health and efficiency.
+
+When running Autoware, you can monitor the pipeline latency times for each node in the pipeline by subscribing to the
+following ROS 2 topics:
+
+- `/sensing/lidar/LidarX/crop_box_filter_self/debug/pipeline_latency_ms`
+- `/sensing/lidar/LidarX/crop_box_filter_mirror/debug/pipeline_latency_ms`
+- `/sensing/lidar/LidarX/distortion_corrector/debug/pipeline_latency_ms`
+- `/sensing/lidar/LidarX/ring_outlier_filter/debug/pipeline_latency_ms`
+- `/sensing/lidar/concatenate_data_synchronizer/debug/sensing/lidar/LidarX/pointcloud/pipeline_latency_ms`
+
+These topics provide the pipeline latency times, giving insights into the delays at various stages of the pipeline
+from the sensor output of LidarX to each subsequent node.
 
 ## (Optional) Error detection and handling
 

sensing/pointcloud_preprocessor/src/concatenate_data/concatenate_and_time_sync_nodelet.cpp

@@ -380,6 +380,20 @@ void PointCloudConcatenateDataSynchronizerComponent::publish()
   const auto & transformed_raw_points =
     PointCloudConcatenateDataSynchronizerComponent::combineClouds(concat_cloud_ptr);
 
+  for (const auto & e : cloud_stdmap_) {
+    if (e.second != nullptr) {
+      if (debug_publisher_) {
+        const auto pipeline_latency_ms =
+          std::chrono::duration<double, std::milli>(
+            std::chrono::nanoseconds(
+              (this->get_clock()->now() - e.second->header.stamp).nanoseconds()))
+            .count();
+        debug_publisher_->publish<tier4_debug_msgs::msg::Float64Stamped>(
+          "debug" + e.first + "/pipeline_latency_ms", pipeline_latency_ms);
+      }
+    }
+  }
+
   // publish concatenated pointcloud
   if (concat_cloud_ptr) {
     auto output = std::make_unique<sensor_msgs::msg::PointCloud2>(*concat_cloud_ptr);

sensing/pointcloud_preprocessor/src/crop_box_filter/crop_box_filter_nodelet.cpp

@@ -65,7 +65,7 @@ CropBoxFilterComponent::CropBoxFilterComponent(const rclcpp::NodeOptions & optio
     using tier4_autoware_utils::DebugPublisher;
     using tier4_autoware_utils::StopWatch;
     stop_watch_ptr_ = std::make_unique<StopWatch<std::chrono::milliseconds>>();
-    debug_publisher_ = std::make_unique<DebugPublisher>(this, "crop_box_filter");
+    debug_publisher_ = std::make_unique<DebugPublisher>(this, this->get_name());
     stop_watch_ptr_->tic("cyclic_time");
     stop_watch_ptr_->tic("processing_time");
   }
@@ -195,6 +195,14 @@ void CropBoxFilterComponent::faster_filter(
       "debug/cyclic_time_ms", cyclic_time_ms);
     debug_publisher_->publish<tier4_debug_msgs::msg::Float64Stamped>(
       "debug/processing_time_ms", processing_time_ms);
+
+    auto pipeline_latency_ms =
+      std::chrono::duration<double, std::milli>(
+        std::chrono::nanoseconds((this->get_clock()->now() - input->header.stamp).nanoseconds()))
+        .count();
+
+    debug_publisher_->publish<tier4_debug_msgs::msg::Float64Stamped>(
+      "debug/pipeline_latency_ms", pipeline_latency_ms);
   }
 }
 

sensing/pointcloud_preprocessor/src/distortion_corrector/distortion_corrector.cpp

@@ -128,6 +128,16 @@ void DistortionCorrectorComponent::onPointCloud(PointCloud2::UniquePtr points_ms
 
   undistortPointCloud(tf2_base_link_to_sensor, *points_msg);
 
+  if (debug_publisher_) {
+    auto pipeline_latency_ms =
+      std::chrono::duration<double, std::milli>(
+        std::chrono::nanoseconds(
+          (this->get_clock()->now() - points_msg->header.stamp).nanoseconds()))
+        .count();
+    debug_publisher_->publish<tier4_debug_msgs::msg::Float64Stamped>(
+      "debug/pipeline_latency_ms", pipeline_latency_ms);
+  }
+
   undistorted_points_pub_->publish(std::move(points_msg));
 
   // add processing time for debug

sensing/pointcloud_preprocessor/src/outlier_filter/ring_outlier_filter_nodelet.cpp

@@ -204,6 +204,14 @@ void RingOutlierFilterComponent::faster_filter(
       "debug/cyclic_time_ms", cyclic_time_ms);
     debug_publisher_->publish<tier4_debug_msgs::msg::Float64Stamped>(
       "debug/processing_time_ms", processing_time_ms);
+
+    auto pipeline_latency_ms =
+      std::chrono::duration<double, std::milli>(
+        std::chrono::nanoseconds((this->get_clock()->now() - input->header.stamp).nanoseconds()))
+        .count();
+
+    debug_publisher_->publish<tier4_debug_msgs::msg::Float64Stamped>(
+      "debug/pipeline_latency_ms", pipeline_latency_ms);
   }
 }