Fixes in the rosbag2_performance_benchmarking message data generator (#2078)

* Fixes in performance benchmarking msg_utils::helpers::generate_data

 - Clear data before generating a new data
 - Correctly calculate the size need for the payload

Signed-off-by: Michael Orlov <[email protected]>

* Bugfix: Don't override process env variable with 'PYTHONUNBUFFERED=1'

- In previous implementation the process environment variable was
 override with the 'PYTHONUNBUFFERED=1' value.

Signed-off-by: Michael Orlov <[email protected]>

---------

Signed-off-by: Michael Orlov <[email protected]>

Author: MichaelOrlov

rosbag2_performance/rosbag2_performance_benchmarking/src/msg_utils/helpers.cpp

@@ -22,6 +22,7 @@ namespace helpers
 {
 void generate_data(rosbag2_performance_benchmarking_msgs::msg::ByteArray & array, size_t size)
 {
+  array.data.clear();
   array.data.reserve(size);
   for (auto i = 0u; i < size; ++i) {
     array.data.emplace_back(std::rand() % 255);
@@ -30,18 +31,22 @@ void generate_data(rosbag2_performance_benchmarking_msgs::msg::ByteArray & array
 
 void generate_data(sensor_msgs::msg::Image & msg, size_t size)
 {
-  // TODO(carlossvg): calculate message base size to set total size
-  msg.data.reserve(size);
-  for (auto i = 0u; i < size; ++i) {
+  msg.data.clear();
+  auto msg_type_size = sizeof(msg);
+  auto data_size = (size > msg_type_size) ? size - msg_type_size : 0;
+  msg.data.reserve(data_size);
+  for (auto i = 0u; i < data_size; ++i) {
     msg.data.emplace_back(std::rand() % 255);
   }
 }
 
 void generate_data(sensor_msgs::msg::PointCloud2 & msg, size_t size)
 {
-  // TODO(carlossvg): calculate message base size to set total size
-  msg.data.reserve(size);
-  for (auto i = 0u; i < size; ++i) {
+  msg.data.clear();
+  auto msg_type_size = sizeof(msg);
+  auto data_size = (size > msg_type_size) ? size - msg_type_size : 0;
+  msg.data.reserve(data_size);
+  for (auto i = 0u; i < data_size; ++i) {
     msg.data.emplace_back(std::rand() % 255);
   }
 }

rosbag2_performance/rosbag2_performance_benchmarking/test/benchmark_test.py

@@ -332,9 +332,6 @@ def set_expectations(self, benchmark, producer, expectation):
 
 
 def generate_test_description():
-    proc_env = os.environ.copy()
-    proc_env['PYTHONUNBUFFERED'] = '1'
-
     config_path = os.path.join(
         ament_index_python.get_package_share_directory('rosbag2_performance_benchmarking'),
         'config'
@@ -375,7 +372,7 @@ def generate_test_description():
             process = launch.actions.ExecuteProcess(
                 cmd=['ros2', 'launch', 'rosbag2_performance_benchmarking',
                      'benchmark_launch.py'] + args,
-                env=proc_env,
+                additional_env={'PYTHONUNBUFFERED': '1'},
                 output='screen'
             )
             benchmark_processes.append(process)