Add logs for trace action init and fini

tracetools_launch/tracetools_launch/action.py

@@ -18,6 +18,7 @@ import re
 from typing import List
 from typing import Optional
 
+from launch import logging
 from launch.action import Action
 from launch.event import Event
 from launch.event_handlers import OnShutdown
@@ -75,6 +76,7 @@ class Trace(Action):
         self.__events_kernel = events_kernel
         self.__context_names = context_names
         self.__profile_fast = profile_fast
+        self.__logger = logging.get_logger(__name__)
         self.__ld_preload_actions = []
         # Add LD_PRELOAD actions if corresponding events are enabled
         if self.has_profiling_events(self.__events_ust):
@@ -124,15 +126,17 @@ class Trace(Action):
         return self.__ld_preload_actions
 
     def _setup(self) -> None:
-        lttng.lttng_init(
+        trace_directory = lttng.lttng_init(
             self.__session_name,
             self.__base_path,
             ros_events=self.__events_ust,
             kernel_events=self.__events_kernel,
             context_names=self.__context_names,
         )
+        self.__logger.info(f'Writing tracing session to: {trace_directory}')
 
     def _destroy(self, event: Event, context: LaunchContext) -> None:
+        self.__logger.debug(f'Finalizing tracing session: {self.__session_name}')
         lttng.lttng_fini(self.__session_name)
 
     def __repr__(self):

tracetools_trace/tracetools_trace/tools/lttng.py

@@ -15,6 +15,7 @@
 """Interface for tracing with LTTng."""
 
 from typing import List
+from typing import Optional
 
 try:
     from . import lttng_impl
@@ -38,7 +39,7 @@ def lttng_init(
     ros_events: List[str] = DEFAULT_EVENTS_ROS,
     kernel_events: List[str] = DEFAULT_EVENTS_KERNEL,
     context_names: List[str] = DEFAULT_CONTEXT,
-) -> None:
+) -> Optional[str]:
     """
     Set up and start LTTng session.
 
@@ -47,9 +48,11 @@ def lttng_init(
     :param ros_events: list of ROS events to enable
     :param kernel_events: list of kernel events to enable
     :param context_names: list of context elements to enable
+    :return: the full path to the trace directory
     """
-    _lttng.setup(session_name, base_path, ros_events, kernel_events, context_names)
+    trace_directory = _lttng.setup(session_name, base_path, ros_events, kernel_events, context_names)
     _lttng.start(session_name)
+    return trace_directory
 
 
 def lttng_fini(

tracetools_trace/tracetools_trace/tools/lttng_impl.py

@@ -15,6 +15,7 @@
 """Implementation of the interface for tracing with LTTng."""
 
 from typing import List
+from typing import Optional
 
 import lttng
 
@@ -33,7 +34,7 @@ def setup(
     context_names: List[str] = DEFAULT_CONTEXT,
     channel_name_ust: str = 'ros2',
     channel_name_kernel: str = 'kchan',
-) -> None:
+) -> Optional[str]:
     """
     Set up LTTng session, with events and context.
 
@@ -46,6 +47,7 @@ def setup(
     :param context_names: list of context elements to enable
     :param channel_name_ust: the UST channel name
     :param channel_name_kernel: the kernel channel name
+    :return: the full path to the trace directory
     """
     # Resolve full tracing directory path
     full_path = get_full_session_path(session_name, base_path=base_path)
@@ -113,6 +115,8 @@ def setup(
     enabled_handles = [h for h in [handle_ust, handle_kernel] if h is not None]
     _add_context(enabled_handles, context_list)
 
+    return full_path
+
 
 def start(
     session_name: str,