Add maximum times for a process to respawn (#696)

* Add support to set respawn process amount

Signed-off-by: Santti4go <[email protected]>

Author: Santti4go

launch/launch/actions/execute_local.py

@@ -100,6 +100,7 @@ def __init__(
         ]] = None,
         respawn: Union[bool, SomeSubstitutionsType] = False,
         respawn_delay: Optional[float] = None,
+        respawn_max_retries: int = -1,
         **kwargs
     ) -> None:
         """
@@ -202,6 +203,8 @@ def __init__(
         :param: respawn if 'True', relaunch the process that abnormally died.
             Either a boolean or a Substitution to be resolved at runtime. Defaults to 'False'.
         :param: respawn_delay a delay time to relaunch the died process if respawn is 'True'.
+        :param: respawn_max_retries number of times to respawn the process if respawn is 'True'.
+                A negative value will respawn an infinite number of times (default behavior).
         """
         super().__init__(**kwargs)
         self.__process_description = process_description
@@ -228,6 +231,9 @@ def __init__(
         self.__respawn = normalize_typed_substitution(respawn, bool)
         self.__respawn_delay = respawn_delay
 
+        self.__respawn_max_retries = respawn_max_retries
+        self.__respawn_retries = 0
+
         self.__process_event_args = None  # type: Optional[Dict[Text, Any]]
         self._subprocess_protocol = None  # type: Optional[Any]
         self._subprocess_transport = None
@@ -637,7 +643,11 @@ async def __execute_process(self, context: LaunchContext) -> None:
         if not context.is_shutdown\
                 and self.__shutdown_future is not None\
                 and not self.__shutdown_future.done()\
-                and self.__respawn:
+                and self.__respawn and \
+                (self.__respawn_max_retries < 0 or
+                 self.__respawn_retries < self.__respawn_max_retries):
+            # Increase the respawn_retries counter
+            self.__respawn_retries += 1
             if self.__respawn_delay is not None and self.__respawn_delay > 0.0:
                 # wait for a timeout(`self.__respawn_delay`) to respawn the process
                 # and handle shutdown event with future(`self.__shutdown_future`)

launch/launch/actions/execute_process.py

@@ -232,6 +232,8 @@ def __init__(
         :param: respawn if 'True', relaunch the process that abnormally died.
             Defaults to 'False'.
         :param: respawn_delay a delay time to relaunch the died process if respawn is 'True'.
+        :param: respawn_max_retries number of times to respawn the process if respawn is 'True'.
+                A negative value will respawn an infinite number of times (default behavior).
         """
         executable = Executable(
             cmd=cmd,
@@ -350,6 +352,12 @@ def parse(
             if respawn is not None:
                 kwargs['respawn'] = parser.parse_substitution(respawn)
 
+        if 'respawn_max_retries' not in ignore:
+            respawn_max_retries = entity.get_attr('respawn_max_retries', data_type=int,
+                                                  optional=True)
+            if respawn_max_retries is not None:
+                kwargs['respawn_max_retries'] = respawn_max_retries
+
         if 'respawn_delay' not in ignore:
             respawn_delay = entity.get_attr('respawn_delay', data_type=float, optional=True)
             if respawn_delay is not None:

launch/test/launch/test_execute_local.py

@@ -129,6 +129,46 @@ def generate_launch_description():
     assert expected_called_count == on_exit_callback.called_count
 
 
+def test_execute_process_with_respawn_max_retries():
+    """Test launching a process with respawn_max_retries attribute."""
+    def on_exit_callback(event, context):
+        on_exit_callback.called_count += 1
+        if on_exit_callback.called_count == expected_called_count:
+            timer = TimerAction(
+                period=2.,   # wait to verify if the process continues to respawn itself
+                actions=[
+                    Shutdown(reason='Timer expired')
+                ]
+            )
+            timer.execute(context)
+    on_exit_callback.called_count = 0
+
+    respawn_max_retries = 2   # we want the process to respawn this amount of times
+    expected_called_count = 3   # normal exit + respawn_max_retries exits
+    shutdown_time = 10.0   # security timer to kill the process
+
+    def generate_launch_description():
+        return LaunchDescription([
+
+            ExecuteLocal(
+                process_description=Executable(cmd=[sys.executable, '-c', "print('action')"]),
+                respawn=True, respawn_max_retries=respawn_max_retries, on_exit=on_exit_callback
+            ),
+
+            TimerAction(
+                period=shutdown_time,
+                actions=[
+                    Shutdown(reason='Timer expired')
+                ]
+            )
+        ])
+
+    ls = LaunchService()
+    ls.include_launch_description(generate_launch_description())
+    assert 0 == ls.run()
+    assert expected_called_count == on_exit_callback.called_count
+
+
 def test_execute_process_with_output_dictionary():
     """Test launching a process works when output is specified as a dictionary."""
     executable = ExecuteLocal(

launch/test/launch/test_execute_process.py

@@ -220,6 +220,47 @@ def generate_launch_description():
     assert expected_called_count == on_exit_callback.called_count
 
 
+def test_execute_process_with_respawn_max_retries():
+    """Test launching a process with respawn_max_retries attribute."""
+    def on_exit_callback(event, context):
+        on_exit_callback.called_count += 1
+        if on_exit_callback.called_count == expected_called_count:
+            timer = TimerAction(
+                period=2.,   # wait to verify if the process continues to respawn itself
+                actions=[
+                    Shutdown(reason='Timer expired')
+                ]
+            )
+            timer.execute(context)
+    on_exit_callback.called_count = 0
+
+    respawn_max_retries = 2   # we want the process to respawn this amount of times
+    expected_called_count = 3   # normal exit + respawn_max_retries exits
+    shutdown_time = 10.0   # security timer to kill the process
+
+    def generate_launch_description():
+        return LaunchDescription([
+
+            ExecuteProcess(
+                cmd=[sys.executable, '-c', "print('action')"],
+                respawn=True, respawn_max_retries=respawn_max_retries,
+                on_exit=on_exit_callback
+            ),
+
+            TimerAction(
+                period=shutdown_time,
+                actions=[
+                    Shutdown(reason='Timer expired')
+                ]
+            )
+        ])
+
+    ls = LaunchService()
+    ls.include_launch_description(generate_launch_description())
+    assert 0 == ls.run()
+    assert expected_called_count == on_exit_callback.called_count
+
+
 def test_execute_process_prefix_filter_match():
     lc = LaunchContext()
     lc._set_asyncio_loop(osrf_pycommon.process_utils.get_loop())