Add 'tracetools_launch/' from commit 'f673331bd1'

git-subtree-dir: tracetools_launch
git-subtree-mainline: a507bbce6e
git-subtree-split: f673331bd1

tracetools_launch/tracetools_launch/trace.py

@@ -0,0 +1,63 @@
+"""Module for the Trace action."""
+
+import os
+from typing import List
+from typing import Optional
+
+from launch.action import Action
+from launch.event import Event
+from launch.event_handlers import OnShutdown
+from launch.launch_context import LaunchContext
+from tracetools_trace.tools import lttng
+from tracetools_trace.tools import names
+
+
+class Trace(Action):
+    """
+    Tracing action for launch.
+
+    Sets up and enables tracing through a launch file description.
+    """
+
+    def __init__(
+        self,
+        *,
+        session_name: str,
+        base_path: str = '/tmp',
+        events_ust: List[str] = names.DEFAULT_EVENTS_ROS,
+        events_kernel: List[str] = names.DEFAULT_EVENTS_KERNEL,
+        **kwargs,
+    ) -> None:
+        """Constructor."""
+        super().__init__(**kwargs)
+        self.__session_name = session_name
+        self.__path = os.path.join(base_path, session_name)
+        self.__events_ust = events_ust
+        self.__events_kernel = events_kernel
+
+    def execute(self, context: LaunchContext) -> Optional[List[Action]]:
+        # TODO make sure this is done as late as possible
+        context.register_event_handler(OnShutdown(on_shutdown=self._destroy))
+        # TODO make sure this is done as early as possible
+        self._setup()
+
+    def _setup(self) -> None:
+        print('setting up tracing!')
+        lttng.lttng_init(
+            self.__session_name,
+            self.__path,
+            ros_events=self.__events_ust,
+            kernel_events=self.__events_kernel)
+
+    def _destroy(self, event: Event, context: LaunchContext) -> None:
+        print('destroying tracing session!')
+        lttng.lttng_fini(self.__session_name)
+
+    def __repr__(self):
+        return (
+            "Trace("
+            f"session_name='{self.__session_name}', "
+            f"path='{self.__path}', "
+            f"num_events_ust={len(self.__events_ust)}, "
+            f"num_events_kernel={len(self.__events_kernel)})"
+        )