make LifeCycleHook private + add timeout to async effects

Author: rmorshea

src/py/reactpy/reactpy/backend/hooks.py

@@ -4,7 +4,8 @@
 from typing import Any
 
 from reactpy.backend.types import Connection, Location
-from reactpy.core.hooks import Context, create_context, use_context
+from reactpy.core.hooks import create_context, use_context
+from reactpy.core.types import Context
 
 # backend implementations should establish this context at the root of an app
 ConnectionContext: Context[Connection[Any] | None] = create_context(None)

src/py/reactpy/reactpy/config.py

@@ -80,3 +80,11 @@ def boolean(value: str | bool | int) -> bool:
     validator=float,
 )
 """A default timeout for testing utilities in ReactPy"""
+
+REACTPY_EFFECT_DEFAULT_STOP_TIMEOUT = Option(
+    "REACTPY_EFFECT_DEFAULT_STOP_TIMEOUT",
+    30.0,
+    mutable=False,
+    validator=float,
+)
+"""The default amount of time to wait for an effect to complete"""

src/py/reactpy/reactpy/core/_life_cycle_hook.py

@@ -4,16 +4,15 @@
 import logging
 from collections.abc import Coroutine
 from dataclasses import dataclass
-from typing import Any, Callable, Generic, Protocol, TypeVar
+from typing import Any, Callable, TypeVar
 from weakref import WeakSet
 
 from typing_extensions import TypeAlias
 
 from reactpy.core._thread_local import ThreadLocal
-from reactpy.core.types import ComponentType, Key, VdomDict
+from reactpy.core.types import ComponentType, Context, ContextProviderType
 
 T = TypeVar("T")
-
 logger = logging.getLogger(__name__)
 
 
@@ -29,44 +28,24 @@ def current_hook() -> LifeCycleHook:
 _hook_stack: ThreadLocal[list[LifeCycleHook]] = ThreadLocal(list)
 
 
-class Context(Protocol[T]):
-    """Returns a :class:`ContextProvider` component"""
-
-    def __call__(
-        self,
-        *children: Any,
-        value: T = ...,
-        key: Key | None = ...,
-    ) -> ContextProvider[T]:
-        ...
-
-
-class ContextProvider(Generic[T]):
-    def __init__(
-        self,
-        *children: Any,
-        value: T,
-        key: Key | None,
-        type: Context[T],
-    ) -> None:
-        self.children = children
-        self.key = key
-        self.type = type
-        self._value = value
-
-    def render(self) -> VdomDict:
-        current_hook().set_context_provider(self)
-        return {"tagName": "", "children": self.children}
-
-    def __repr__(self) -> str:
-        return f"{type(self).__name__}({self.type})"
-
-
 @dataclass(frozen=True)
 class EffectInfo:
     task: asyncio.Task[None]
     stop: asyncio.Event
 
+    async def signal_stop(self, timeout: float) -> None:
+        """Signal the effect to stop and wait for it to complete."""
+        self.stop.set()
+        try:
+            await asyncio.wait_for(self.task, timeout=timeout)
+        finally:
+            # a no-op if the task has already completed
+            if self.task.cancel():
+                try:
+                    await self.task
+                except asyncio.CancelledError:
+                    logger.exception("Effect failed to stop after %s seconds", timeout)
+
 
 class LifeCycleHook:
     """Defines the life cycle of a layout component.
@@ -150,7 +129,7 @@ def __init__(
         self,
         schedule_render: Callable[[], None],
     ) -> None:
-        self._context_providers: dict[Context[Any], ContextProvider[Any]] = {}
+        self._context_providers: dict[Context[Any], ContextProviderType[Any]] = {}
         self._schedule_render_callback = schedule_render
         self._schedule_render_later = False
         self._is_rendering = False
@@ -181,10 +160,12 @@ def add_effect(self, start_effect: _EffectStarter) -> None:
         """Trigger a function on the occurrence of the given effect type"""
         self._effect_funcs.append(start_effect)
 
-    def set_context_provider(self, provider: ContextProvider[Any]) -> None:
+    def set_context_provider(self, provider: ContextProviderType[Any]) -> None:
         self._context_providers[provider.type] = provider
 
-    def get_context_provider(self, context: Context[T]) -> ContextProvider[T] | None:
+    def get_context_provider(
+        self, context: Context[T]
+    ) -> ContextProviderType[T] | None:
         return self._context_providers.get(context)
 
     async def affect_component_will_render(self, component: ComponentType) -> None:

src/py/reactpy/reactpy/core/hooks.py

@@ -19,14 +19,9 @@
 
 from typing_extensions import TypeAlias
 
-from reactpy.config import REACTPY_DEBUG_MODE
-from reactpy.core._life_cycle_hook import (
-    Context,
-    ContextProvider,
-    EffectInfo,
-    current_hook,
-)
-from reactpy.core.types import Key, State
+from reactpy.config import REACTPY_DEBUG_MODE, REACTPY_EFFECT_DEFAULT_STOP_TIMEOUT
+from reactpy.core._life_cycle_hook import EffectInfo, current_hook
+from reactpy.core.types import Context, Key, State, VdomDict
 from reactpy.utils import Ref
 
 if not TYPE_CHECKING:
@@ -109,6 +104,7 @@ def dispatch(new: _Type | Callable[[_Type], _Type]) -> None:
 def use_effect(
     function: None = None,
     dependencies: Sequence[Any] | ellipsis | None = ...,
+    stop_timeout: float = ...,
 ) -> Callable[[_EffectFunc], None]:
     ...
 
@@ -117,13 +113,15 @@ def use_effect(
 def use_effect(
     function: _EffectFunc,
     dependencies: Sequence[Any] | ellipsis | None = ...,
+    stop_timeout: float = ...,
 ) -> None:
     ...
 
 
 def use_effect(
     function: _EffectFunc | None = None,
     dependencies: Sequence[Any] | ellipsis | None = ...,
+    stop_timeout: float = REACTPY_EFFECT_DEFAULT_STOP_TIMEOUT.current,
 ) -> Callable[[_EffectFunc], None] | None:
     """See the full :ref:`Use Effect` docs for details
 
@@ -135,6 +133,11 @@ def use_effect(
             of any value in the given sequence changes (i.e. their :func:`id` is
             different). By default these are inferred based on local variables that are
             referenced by the given function.
+        stop_timeout:
+            The maximum amount of time to wait for the effect to cleanup after it has
+            been signaled to stop. If the timeout is reached, an exception will be
+            logged and the effect will be cancelled. This does not apply to synchronous
+            effects.
 
     Returns:
         If not function is provided, a decorator. Otherwise ``None``.
@@ -150,8 +153,7 @@ def add_effect(function: _EffectFunc) -> None:
         async def create_effect_task() -> EffectInfo:
             if effect_info.current is not None:
                 last_effect_info = effect_info.current
-                last_effect_info.stop.set()
-                await last_effect_info.task
+                await last_effect_info.signal_stop(stop_timeout)
 
             stop = asyncio.Event()
             info = EffectInfo(asyncio.create_task(effect(stop)), stop)
@@ -173,7 +175,8 @@ def _cast_async_effect(function: Callable[..., Any]) -> _AsyncEffectFunc:
             return function
 
         warnings.warn(
-            'Async effect functions should accept a "stop" asyncio.Event as their first argument',
+            'Async effect functions should accept a "stop" asyncio.Event as their '
+            "first argument. This will be required in a future version of ReactPy.",
             stacklevel=3,
         )
 
@@ -249,8 +252,8 @@ def context(
         *children: Any,
         value: _Type = default_value,
         key: Key | None = None,
-    ) -> ContextProvider[_Type]:
-        return ContextProvider(
+    ) -> _ContextProvider[_Type]:
+        return _ContextProvider(
             *children,
             value=value,
             key=key,
@@ -280,7 +283,28 @@ def use_context(context: Context[_Type]) -> _Type:
             raise TypeError(f"{context} has no 'value' kwarg")  # nocov
         return cast(_Type, context.__kwdefaults__["value"])
 
-    return provider._value
+    return provider.value
+
+
+class _ContextProvider(Generic[_Type]):
+    def __init__(
+        self,
+        *children: Any,
+        value: _Type,
+        key: Key | None,
+        type: Context[_Type],
+    ) -> None:
+        self.children = children
+        self.key = key
+        self.type = type
+        self.value = value
+
+    def render(self) -> VdomDict:
+        current_hook().set_context_provider(self)
+        return {"tagName": "", "children": self.children}
+
+    def __repr__(self) -> str:
+        return f"{type(self).__name__}({self.type})"
 
 
 _ActionType = TypeVar("_ActionType")

src/py/reactpy/reactpy/core/layout.py

@@ -19,7 +19,7 @@
 from weakref import ref as weakref
 
 from reactpy.config import REACTPY_CHECK_VDOM_SPEC, REACTPY_DEBUG_MODE
-from reactpy.core.hooks import LifeCycleHook
+from reactpy.core._life_cycle_hook import LifeCycleHook
 from reactpy.core.types import (
     ComponentType,
     EventHandlerDict,

src/py/reactpy/reactpy/core/types.py

@@ -20,6 +20,7 @@
 from typing_extensions import TypeAlias, TypedDict
 
 _Type = TypeVar("_Type")
+_Type_invariant = TypeVar("_Type_invariant", covariant=False)
 
 
 if TYPE_CHECKING or sys.version_info < (3, 9) or sys.version_info >= (3, 11):
@@ -233,3 +234,26 @@ class LayoutEventMessage(TypedDict):
     """The ID of the event handler."""
     data: Sequence[Any]
     """A list of event data passed to the event handler."""
+
+
+class Context(Protocol[_Type_invariant]):
+    """Returns a :class:`ContextProvider` component"""
+
+    def __call__(
+        self,
+        *children: Any,
+        value: _Type_invariant = ...,
+        key: Key | None = ...,
+    ) -> ContextProviderType[_Type_invariant]:
+        ...
+
+
+class ContextProviderType(ComponentType, Protocol[_Type]):
+    """A component which provides a context value to its children"""
+
+    type: Context[_Type]
+    """The context type"""
+
+    @property
+    def value(self) -> _Type:
+        "Current context value"

src/py/reactpy/reactpy/testing/common.py

@@ -13,8 +13,8 @@
 from typing_extensions import ParamSpec
 
 from reactpy.config import REACTPY_TESTING_DEFAULT_TIMEOUT, REACTPY_WEB_MODULES_DIR
+from reactpy.core._life_cycle_hook import LifeCycleHook, current_hook
 from reactpy.core.events import EventHandler, to_event_handler_function
-from reactpy.core.hooks import LifeCycleHook, current_hook
 
 
 def clear_reactpy_web_modules_dir() -> None:

src/py/reactpy/reactpy/types.py

@@ -6,10 +6,10 @@
 
 from reactpy.backend.types import BackendImplementation, Connection, Location
 from reactpy.core.component import Component
-from reactpy.core.hooks import Context
 from reactpy.core.types import (
     ComponentConstructor,
     ComponentType,
+    Context,
     EventHandlerDict,
     EventHandlerFunc,
     EventHandlerMapping,

src/py/reactpy/tests/test_core/test_hooks.py

@@ -5,7 +5,8 @@
 import reactpy
 from reactpy import html
 from reactpy.config import REACTPY_DEBUG_MODE
-from reactpy.core.hooks import LifeCycleHook, strictly_equal
+from reactpy.core._life_cycle_hook import LifeCycleHook
+from reactpy.core.hooks import strictly_equal
 from reactpy.core.layout import Layout
 from reactpy.testing import DisplayFixture, HookCatcher, assert_reactpy_did_log, poll
 from reactpy.testing.logs import assert_reactpy_did_not_log