[failure handling] A subclass of FailureHandling

src/pycram/failure_handling.py

@@ -1,8 +1,12 @@
+from .datastructures.enums import State
 from .designator import DesignatorDescription
 from .plan_failures import PlanFailure
+from threading import Lock
+from typing_extensions import Union, Tuple, Any, List
+from .language import Language, Monitor
 
 
-class FailureHandling:
+class FailureHandling(Language):
     """
     Base class for failure handling mechanisms in automated systems or workflows.
 
@@ -11,11 +15,12 @@ class FailureHandling:
     to be extended by subclasses that implement specific failure handling behaviors.
     """
 
-    def __init__(self, designator_description: DesignatorDescription):
+    def __init__(self, designator_description: Union[DesignatorDescription, Monitor]):
         """
         Initializes a new instance of the FailureHandling class.
 
-        :param designator_description: The description or context of the task or process for which the failure handling is being set up.
+        :param Union[DesignatorDescription, Monitor] designator_description: The description or context of the task
+        or process for which the failure handling is being set up.
         """
         self.designator_description = designator_description
 
@@ -37,15 +42,10 @@ class Retry(FailureHandling):
 
     This class represents a specific failure handling strategy where the system
     attempts to retry a failed action a certain number of times before giving up.
-
-    Attributes:
-        max_tries (int): The maximum number of attempts to retry the action.
-
-    Inherits:
-        All attributes and methods from the FailureHandling class.
-
-    Overrides:
-        perform(): Implements the retry logic.
+    """
+    max_tries: int
+    """
+    The maximum number of attempts to retry the action.
     """
 
     def __init__(self, designator_description: DesignatorDescription, max_tries: int = 3):
@@ -58,7 +58,7 @@ def __init__(self, designator_description: DesignatorDescription, max_tries: int
         super().__init__(designator_description)
         self.max_tries = max_tries
 
-    def perform(self):
+    def perform(self) -> Tuple[State, List[Any]]:
         """
         Implementation of the retry mechanism.
 
@@ -79,5 +79,93 @@ def perform(self):
                     raise e
 
 
+class RetryMonitor(FailureHandling):
+    """
+    A subclass of FailureHandling that implements a retry mechanism that works with a Monitor.
 
+    This class represents a specific failure handling strategy that allows us to retry a demo that is
+    being monitored, in case that monitoring condition is triggered.
+    """
+    max_tries: int
+    """
+    The maximum number of attempts to retry the action.
+    """
+    recovery: dict
+    """
+    A dictionary that maps exception types to recovery actions
+    """
 
+    def __init__(self, designator_description: Monitor, max_tries: int = 3, recovery: dict = None):
+        """
+        Initializes a new instance of the RetryMonitor class.
+        :param Monitor designator_description: The Monitor instance to be used.
+        :param int max_tries: The maximum number of attempts to retry. Defaults to 3.
+        :param dict recovery: A dictionary that maps exception types to recovery actions. Defaults to None.
+        """
+        super().__init__(designator_description)
+        self.max_tries = max_tries
+        self.lock = Lock()
+        if recovery is None:
+            self.recovery = {}
+        else:
+            if not isinstance(recovery, dict):
+                raise ValueError(
+                    "Recovery must be a dictionary with exception types as keys and Language instances as values.")
+            for key, value in recovery.items():
+                if not issubclass(key, BaseException):
+                    raise TypeError("Keys in the recovery dictionary must be exception types.")
+                if not isinstance(value, Language):
+                    raise TypeError("Values in the recovery dictionary must be instances of the Language class.")
+            self.recovery = recovery
+
+    def perform(self) -> Tuple[State, List[Any]]:
+        """
+        This method attempts to perform the Monitor + plan specified in the designator_description. If the action
+        fails, it is retried up to max_tries times. If all attempts fail, the last exception is raised. In every
+        loop, we need to clear the kill_event, and set all relevant 'interrupted' variables to False, to make sure
+        the Monitor and plan are executed properly again.
+
+        :raises PlanFailure: If all retry attempts fail.
+
+        :return: The state of the execution performed, as well as a flattened list of the
+        results, in the correct order
+        """
+
+        def reset_interrupted(child):
+            child.interrupted = False
+            try:
+                for sub_child in child.children:
+                    reset_interrupted(sub_child)
+            except AttributeError:
+                pass
+
+        def flatten(result):
+            flattened_list = []
+            if result:
+                for item in result:
+                    if isinstance(item, list):
+                        flattened_list.extend(item)
+                    else:
+                        flattened_list.append(item)
+                return flattened_list
+            return None
+
+        status, res = None, None
+        with self.lock:
+            tries = 0
+            while True:
+                self.designator_description.kill_event.clear()
+                self.designator_description.interrupted = False
+                for child in self.designator_description.children:
+                    reset_interrupted(child)
+                try:
+                    status, res = self.designator_description.perform()
+                    break
+                except PlanFailure as e:
+                    tries += 1
+                    if tries >= self.max_tries:
+                        raise e
+                    exception_type = type(e)
+                    if exception_type in self.recovery:
+                        self.recovery[exception_type].perform()
+        return status, flatten(res)