Merge pull request #161 from tiqi-group/160-control-of-tasks-in-instances-derived-from-same-class-only-controls-task-of-first-instance

fix: controlling tasks of instances derived from same class

src/pydase/observer_pattern/observable/observable.py

@@ -22,12 +22,9 @@ class Observable(ObservableObject):
             - {"__annotations__"}
         }
         for name, value in class_attrs.items():
-            if isinstance(value, property) or callable(value):
+            if isinstance(value, property) or callable(value) or is_descriptor(value):
-                continue
+                # Properties, methods and descriptors have to be stored as class
-            if is_descriptor(value):
+                # attributes to work properly. So don't make it an instance attribute.
-                # Descriptors have to be stored as a class variable in another class to
-                # work properly. So don't make it an instance attribute.
-                self._initialise_new_objects(name, value)
                 continue
             self.__dict__[name] = self._initialise_new_objects(name, value)
 

src/pydase/observer_pattern/observer/property_observer.py

@@ -5,6 +5,7 @@ from typing import Any
 
 from pydase.observer_pattern.observable.observable import Observable
 from pydase.observer_pattern.observer.observer import Observer
+from pydase.utils.helpers import is_descriptor
 
 logger = logging.getLogger(__name__)
 
@@ -61,17 +62,27 @@ class PropertyObserver(Observer):
         self, obj: Observable, deps: dict[str, Any], prefix: str
     ) -> None:
         for k, value in {**vars(type(obj)), **vars(obj)}.items():
+            actual_value = value
             prefix = (
                 f"{prefix}." if prefix != "" and not prefix.endswith(".") else prefix
             )
             parent_path = f"{prefix}{k}"
-            if isinstance(value, Observable):
+
+            # Get value from descriptor
+            if not isinstance(value, property) and is_descriptor(value):
+                actual_value = getattr(obj, k)
+
+            if isinstance(actual_value, Observable):
                 new_prefix = f"{parent_path}."
                 deps.update(
-                    self._get_properties_and_their_dependencies(value, new_prefix)
+                    self._get_properties_and_their_dependencies(
+                        actual_value, new_prefix
+                    )
                 )
             elif isinstance(value, list | dict):
-                self._process_collection_item_properties(value, deps, parent_path)
+                self._process_collection_item_properties(
+                    actual_value, deps, parent_path
+                )
 
     def _process_collection_item_properties(
         self,

src/pydase/task/decorator.py

@@ -1,7 +1,8 @@
 import logging
 from collections.abc import Callable, Coroutine
-from typing import Any, TypeVar
+from typing import Any, Generic, TypeVar, overload
 
+from pydase.data_service.data_service import DataService
 from pydase.task.task import Task
 
 logger = logging.getLogger(__name__)
@@ -9,6 +10,69 @@ logger = logging.getLogger(__name__)
 R = TypeVar("R")
 
 
+class PerInstanceTaskDescriptor(Generic[R]):
+    """
+    A descriptor class that provides a unique [`Task`][pydase.task.task.Task] object
+    for each instance of a [`DataService`][pydase.data_service.data_service.DataService]
+    class.
+
+    The `PerInstanceTaskDescriptor` is used to transform an asynchronous function into a
+    task that is managed independently for each instance of a `DataService` subclass.
+    This allows tasks to be initialized, started, and stopped on a per-instance basis,
+    providing better control over task execution within the service.
+
+    The `PerInstanceTaskDescriptor` is not intended to be used directly. Instead, it is
+    used internally by the `@task` decorator to manage task objects for each instance of
+    the service class.
+    """
+
+    def __init__(
+        self,
+        func: Callable[[Any], Coroutine[None, None, R]]
+        | Callable[[], Coroutine[None, None, R]],
+        autostart: bool = False,
+    ) -> None:
+        self.__func = func
+        self.__autostart = autostart
+        self.__task_instances: dict[object, Task[R]] = {}
+
+    def __set_name__(self, owner: type[DataService], name: str) -> None:
+        """Stores the name of the task within the owning class. This method is called
+        automatically when the descriptor is assigned to a class attribute.
+        """
+
+        self.__task_name = name
+
+    @overload
+    def __get__(
+        self, instance: None, owner: type[DataService]
+    ) -> "PerInstanceTaskDescriptor[R]":
+        """Returns the descriptor itself when accessed through the class."""
+
+    @overload
+    def __get__(self, instance: DataService, owner: type[DataService]) -> Task[R]:
+        """Returns the `Task` object associated with the specific `DataService`
+        instance.
+        If no task exists for the instance, a new `Task` object is created and stored
+        in the `__task_instances` dictionary.
+        """
+
+    def __get__(
+        self, instance: DataService | None, owner: type[DataService]
+    ) -> "Task[R] | PerInstanceTaskDescriptor[R]":
+        if instance is None:
+            return self
+
+        # Create a new Task object for this instance, using the function's name.
+        if instance not in self.__task_instances:
+            self.__task_instances[instance] = instance._initialise_new_objects(
+                self.__task_name,
+                Task(self.__func.__get__(instance, owner), autostart=self.__autostart),
+            )
+
+        return self.__task_instances[instance]
+
+
 def task(
     *, autostart: bool = False
 ) -> Callable[
@@ -16,18 +80,22 @@ def task(
         Callable[[Any], Coroutine[None, None, R]]
         | Callable[[], Coroutine[None, None, R]]
     ],
-    Task[R],
+    PerInstanceTaskDescriptor[R],
 ]:
     """
-    A decorator to define a function as a task within a
+    A decorator to define an asynchronous function as a per-instance task within a
     [`DataService`][pydase.DataService] class.
 
     This decorator transforms an asynchronous function into a
-    [`Task`][pydase.task.task.Task] object. The `Task` object provides methods like
+    [`Task`][pydase.task.task.Task] object that is unique to each instance of the
-    `start()` and `stop()` to control the execution of the task.
+    `DataService` class. The resulting `Task` object provides methods like `start()`
+    and `stop()` to control the execution of the task, and manages the task's lifecycle
+    independently for each instance of the service.
 
-    Tasks are typically used to perform periodic or recurring jobs, such as reading
+    The decorator is particularly useful for defining tasks that need to run
-    sensor data, updating databases, or other operations that need to be repeated over
+    periodically or perform asynchronous operations, such as polling data sources,
+    updating databases, or any recurring job that should be managed within the context
+    of a `DataService`.
     time.
 
     Args:
@@ -36,8 +104,10 @@ def task(
             initialized. Defaults to False.
 
     Returns:
-        A decorator that converts an asynchronous function into a
+        A decorator that wraps an asynchronous function in a
-          [`Task`][pydase.task.task.Task] object.
+        [`PerInstanceTaskDescriptor`][pydase.task.decorator.PerInstanceTaskDescriptor]
+        object, which, when accessed, provides an instance-specific
+        [`Task`][pydase.task.task.Task] object.
 
     Example:
         ```python
@@ -69,7 +139,7 @@ def task(
     def decorator(
         func: Callable[[Any], Coroutine[None, None, R]]
         | Callable[[], Coroutine[None, None, R]],
-    ) -> Task[R]:
+    ) -> PerInstanceTaskDescriptor[R]:
-        return Task(func, autostart=autostart)
+        return PerInstanceTaskDescriptor(func, autostart=autostart)
 
     return decorator

src/pydase/task/task.py

@@ -4,19 +4,16 @@ import logging
 import sys
 from collections.abc import Callable, Coroutine
 from typing import (
-    Any,
     Generic,
     TypeVar,
 )
 
-from typing_extensions import TypeIs
-
 from pydase.task.task_status import TaskStatus
 
 if sys.version_info < (3, 11):
-    from typing_extensions import Self
+    pass
 else:
-    from typing import Self
+    pass
 
 import pydase.data_service.data_service
 from pydase.utils.helpers import current_event_loop_exists
@@ -27,17 +24,8 @@ logger = logging.getLogger(__name__)
 R = TypeVar("R")
 
 
-def is_bound_method(
-    method: Callable[[], Coroutine[None, None, R | None]]
-    | Callable[[Any], Coroutine[None, None, R | None]],
-) -> TypeIs[Callable[[], Coroutine[None, None, R | None]]]:
-    """Check if instance method is bound to an object."""
-    return inspect.ismethod(method)
-
-
 class Task(pydase.data_service.data_service.DataService, Generic[R]):
-    """
+    """A class representing a task within the `pydase` framework.
-    A class representing a task within the `pydase` framework.
 
     The `Task` class wraps an asynchronous function and provides methods to manage its
     lifecycle, such as `start()` and `stop()`. It is typically used to perform periodic
@@ -85,25 +73,24 @@ class Task(pydase.data_service.data_service.DataService, Generic[R]):
 
     def __init__(
         self,
-        func: Callable[[Any], Coroutine[None, None, R | None]]
+        func: Callable[[], Coroutine[None, None, R | None]],
-        | Callable[[], Coroutine[None, None, R | None]],
         *,
         autostart: bool = False,
     ) -> None:
         super().__init__()
         self._autostart = autostart
         self._func_name = func.__name__
-        self._bound_func: Callable[[], Coroutine[None, None, R | None]] | None = None
+        self._func = func
-        self._set_up = False
-        if is_bound_method(func):
-            self._func = func
-            self._bound_func = func
-        else:
-            self._func = func
         self._task: asyncio.Task[R | None] | None = None
         self._status = TaskStatus.NOT_RUNNING
         self._result: R | None = None
 
+        if not current_event_loop_exists():
+            self._loop = asyncio.new_event_loop()
+            asyncio.set_event_loop(self._loop)
+        else:
+            self._loop = asyncio.get_event_loop()
+
     @property
     def autostart(self) -> bool:
         """Defines if the task should be started automatically when the
@@ -144,10 +131,10 @@ class Task(pydase.data_service.data_service.DataService, Generic[R]):
             self._result = task.result()
 
         async def run_task() -> R | None:
-            if inspect.iscoroutinefunction(self._bound_func):
+            if inspect.iscoroutinefunction(self._func):
                 logger.info("Starting task %r", self._func_name)
                 self._status = TaskStatus.RUNNING
-                res: Coroutine[None, None, R] = self._bound_func()
+                res: Coroutine[None, None, R | None] = self._func()
                 try:
                     return await res
                 except asyncio.CancelledError:
@@ -167,24 +154,3 @@ class Task(pydase.data_service.data_service.DataService, Generic[R]):
 
         if self._task:
             self._task.cancel()
-
-    def __get__(self, instance: Any, owner: Any) -> Self:
-        """Descriptor method used to correctly set up the task.
-
-        This descriptor method is called by the class instance containing the task.
-        It binds the task function to that class instance.
-
-        Since the `__init__` function is called when a function is decorated with
-        [`@task`][pydase.task.decorator.task], some setup is delayed until this
-        descriptor function is called.
-        """
-
-        if instance and not self._set_up:
-            if not current_event_loop_exists():
-                self._loop = asyncio.new_event_loop()
-                asyncio.set_event_loop(self._loop)
-            else:
-                self._loop = asyncio.get_event_loop()
-            self._bound_func = self._func.__get__(instance, owner)
-            self._set_up = True
-        return self

src/pydase/utils/helpers.py

@@ -204,6 +204,17 @@ def function_has_arguments(func: Callable[..., Any]) -> bool:
 
 def is_descriptor(obj: object) -> bool:
     """Check if an object is a descriptor."""
+
+    # Exclude functions, methods, builtins and properties
+    if (
+        inspect.isfunction(obj)
+        or inspect.ismethod(obj)
+        or inspect.isbuiltin(obj)
+        or isinstance(obj, property)
+    ):
+        return False
+
+    # Check if it has any descriptor methods
     return any(hasattr(obj, method) for method in ("__get__", "__set__", "__delete__"))
 
 

tests/task/test_task.py

@@ -138,3 +138,154 @@ async def test_nested_dict_autostart_task(
         "'sub_services_dict[\"second\"].my_task.status' changed to 'TaskStatus.RUNNING'"
         in caplog.text
     )
+
+
+@pytest.mark.asyncio(scope="function")
+async def test_manual_start_with_multiple_service_instances(
+    caplog: LogCaptureFixture,
+) -> None:
+    class MySubService(pydase.DataService):
+        @task()
+        async def my_task(self) -> None:
+            logger.info("Triggered task.")
+            while True:
+                await asyncio.sleep(1)
+
+    class MyService(pydase.DataService):
+        sub_services_list = [MySubService() for i in range(2)]
+        sub_services_dict = {"first": MySubService(), "second": MySubService()}
+
+    service_instance = MyService()
+    state_manager = StateManager(service_instance)
+    DataServiceObserver(state_manager)
+
+    autostart_service_tasks(service_instance)
+
+    await asyncio.sleep(0.1)
+
+    assert (
+        service_instance.sub_services_list[0].my_task.status == TaskStatus.NOT_RUNNING
+    )
+    assert (
+        service_instance.sub_services_list[1].my_task.status == TaskStatus.NOT_RUNNING
+    )
+    assert (
+        service_instance.sub_services_dict["first"].my_task.status
+        == TaskStatus.NOT_RUNNING
+    )
+    assert (
+        service_instance.sub_services_dict["second"].my_task.status
+        == TaskStatus.NOT_RUNNING
+    )
+
+    service_instance.sub_services_list[0].my_task.start()
+    await asyncio.sleep(0.01)
+
+    assert service_instance.sub_services_list[0].my_task.status == TaskStatus.RUNNING
+    assert (
+        "'sub_services_list[0].my_task.status' changed to 'TaskStatus.RUNNING'"
+        in caplog.text
+    )
+    assert (
+        "'sub_services_list[1].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+    assert (
+        "'sub_services_dict[\"first\"].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+    assert (
+        "'sub_services_dict[\"second\"].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+
+    service_instance.sub_services_list[0].my_task.stop()
+    await asyncio.sleep(0.01)
+
+    assert "Task 'my_task' was cancelled" in caplog.text
+    caplog.clear()
+
+    service_instance.sub_services_list[1].my_task.start()
+    await asyncio.sleep(0.01)
+
+    assert service_instance.sub_services_list[1].my_task.status == TaskStatus.RUNNING
+    assert (
+        "'sub_services_list[0].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+    assert (
+        "'sub_services_list[1].my_task.status' changed to 'TaskStatus.RUNNING'"
+        in caplog.text
+    )
+    assert (
+        "'sub_services_dict[\"first\"].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+    assert (
+        "'sub_services_dict[\"second\"].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+
+    service_instance.sub_services_list[1].my_task.stop()
+    await asyncio.sleep(0.01)
+
+    assert "Task 'my_task' was cancelled" in caplog.text
+    caplog.clear()
+
+    service_instance.sub_services_dict["first"].my_task.start()
+    await asyncio.sleep(0.01)
+
+    assert (
+        service_instance.sub_services_dict["first"].my_task.status == TaskStatus.RUNNING
+    )
+    assert (
+        "'sub_services_list[0].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+    assert (
+        "'sub_services_list[1].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+    assert (
+        "'sub_services_dict[\"first\"].my_task.status' changed to 'TaskStatus.RUNNING'"
+        in caplog.text
+    )
+    assert (
+        "'sub_services_dict[\"second\"].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+
+    service_instance.sub_services_dict["first"].my_task.stop()
+    await asyncio.sleep(0.01)
+
+    assert "Task 'my_task' was cancelled" in caplog.text
+    caplog.clear()
+
+    service_instance.sub_services_dict["second"].my_task.start()
+    await asyncio.sleep(0.01)
+
+    assert (
+        service_instance.sub_services_dict["second"].my_task.status
+        == TaskStatus.RUNNING
+    )
+    assert (
+        "'sub_services_list[0].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+    assert (
+        "'sub_services_list[1].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+    assert (
+        "'sub_services_dict[\"first\"].my_task.status' changed to 'TaskStatus.RUNNING'"
+        not in caplog.text
+    )
+    assert (
+        "'sub_services_dict[\"second\"].my_task.status' changed to 'TaskStatus.RUNNING'"
+        in caplog.text
+    )
+
+    service_instance.sub_services_dict["second"].my_task.stop()
+    await asyncio.sleep(0.01)
+
+    assert "Task 'my_task' was cancelled" in caplog.text