concurrent renders

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

@@ -88,9 +88,10 @@ class LifeCycleHook:
         "__weakref__",
         "_context_providers",
         "_current_state_index",
-        "_effect_generators",
+        "_pending_effects",
         "_render_access",
         "_rendered_atleast_once",
+        "_running_effects",
         "_schedule_render_callback",
         "_schedule_render_later",
         "_state",
@@ -109,7 +110,8 @@ def __init__(
         self._rendered_atleast_once = False
         self._current_state_index = 0
         self._state: tuple[Any, ...] = ()
-        self._effect_generators: list[AsyncGenerator[None, None]] = []
+        self._pending_effects: list[AsyncGenerator[None, None]] = []
+        self._running_effects: list[AsyncGenerator[None, None]] = []
         self._render_access = Semaphore(1)  # ensure only one render at a time
 
     def schedule_render(self) -> None:
@@ -131,7 +133,7 @@ def use_state(self, function: Callable[[], T]) -> T:
 
     def add_effect(self, effect_func: Callable[[], AsyncGenerator[None, None]]) -> None:
         """Add an effect to this hook"""
-        self._effect_generators.append(effect_func())
+        self._pending_effects.append(effect_func())
 
     def set_context_provider(self, provider: ContextProviderType[Any]) -> None:
         self._context_providers[provider.type] = provider
@@ -150,29 +152,32 @@ async def affect_component_will_render(self, component: ComponentType) -> None:
     async def affect_component_did_render(self) -> None:
         """The component completed a render"""
         self.unset_current()
-        del self.component
         self._rendered_atleast_once = True
         self._current_state_index = 0
         self._render_access.release()
 
     async def affect_layout_did_render(self) -> None:
         """The layout completed a render"""
         try:
-            await gather(*[g.asend(None) for g in self._effect_generators])
+            await gather(*[g.asend(None) for g in self._pending_effects])
+            self._running_effects.extend(self._pending_effects)
         except Exception:
-            logger.exception("Error during effect execution")
+            logger.exception("Error during effect startup")
+        finally:
+            self._pending_effects.clear()
         if self._schedule_render_later:
             self._schedule_render()
         self._schedule_render_later = False
+        del self.component
 
     async def affect_component_will_unmount(self) -> None:
         """The component is about to be removed from the layout"""
         try:
-            await gather(*[g.aclose() for g in self._effect_generators])
+            await gather(*[g.aclose() for g in self._running_effects])
         except Exception:
-            logger.exception("Error during effect cancellation")
+            logger.exception("Error during effect cleanup")
         finally:
-            self._effect_generators.clear()
+            self._running_effects.clear()
 
     def set_current(self) -> None:
         """Set this hook as the active hook in this thread
@@ -192,7 +197,7 @@ def unset_current(self) -> None:
             raise RuntimeError("Hook stack is in an invalid state")  # nocov
 
     def _is_rendering(self) -> bool:
-        return self._render_access.value != 0
+        return self._render_access.value == 0
 
     def _schedule_render(self) -> None:
         try:

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

@@ -160,12 +160,20 @@ async def effect() -> AsyncGenerator[None, None]:
             if last_clean_callback.current is not None:
                 last_clean_callback.current()
 
-            clean = last_clean_callback.current = sync_function()
+            cleaned = False
+            clean = sync_function()
+
+            def callback() -> None:
+                nonlocal cleaned
+                if clean and not cleaned:
+                    cleaned = True
+                    clean()
+
+            last_clean_callback.current = callback
             try:
                 yield
             finally:
-                if clean is not None:
-                    clean()
+                callback()
 
         return memoize(lambda: hook.add_effect(effect))
 
@@ -266,7 +274,7 @@ def render(self) -> VdomDict:
         return {"tagName": "", "children": self.children}
 
     def __repr__(self) -> str:
-        return f"{type(self).__name__}({self.type})"
+        return f"ContextProvider({self.type})"
 
 
 _ActionType = TypeVar("_ActionType")

src/py/reactpy/tests/test_client.py

@@ -30,6 +30,11 @@ def SomeComponent():
             ),
         )
 
+    async def get_count():
+        # need to refetch element because may unmount on reconnect
+        count = await page.wait_for_selector("#count")
+        return await count.get_attribute("data-count")
+
     async with AsyncExitStack() as exit_stack:
         server = await exit_stack.enter_async_context(BackendFixture(port=port))
         display = await exit_stack.enter_async_context(
@@ -38,11 +43,10 @@ def SomeComponent():
 
         await display.show(SomeComponent)
 
-        count = await page.wait_for_selector("#count")
         incr = await page.wait_for_selector("#incr")
 
         for i in range(3):
-            assert (await count.get_attribute("data-count")) == str(i)
+            await poll(get_count).until_equals(str(i))
             await incr.click()
 
     # the server is disconnected but the last view state is still shown
@@ -57,13 +61,7 @@ def SomeComponent():
         # use mount instead of show to avoid a page refresh
         display.backend.mount(SomeComponent)
 
-        async def get_count():
-            # need to refetch element because may unmount on reconnect
-            count = await page.wait_for_selector("#count")
-            return await count.get_attribute("data-count")
-
         for i in range(3):
-            # it may take a moment for the websocket to reconnect so need to poll
             await poll(get_count).until_equals(str(i))
 
             # need to refetch element because may unmount on reconnect
@@ -98,11 +96,15 @@ def ButtonWithChangingColor():
 
     button = await display.page.wait_for_selector("#my-button")
 
-    assert (await _get_style(button))["background-color"] == "red"
+    await poll(_get_style, button).until(
+        lambda style: style["background-color"] == "red"
+    )
 
     for color in ["blue", "red"] * 2:
         await button.click()
-        assert (await _get_style(button))["background-color"] == color
+        await poll(_get_style, button).until(
+            lambda style, c=color: style["background-color"] == c
+        )
 
 
 async def _get_style(element):

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

@@ -274,18 +274,18 @@ def double_set_state(event):
     first = await display.page.wait_for_selector("#first")
     second = await display.page.wait_for_selector("#second")
 
-    assert (await first.get_attribute("data-value")) == "0"
-    assert (await second.get_attribute("data-value")) == "0"
+    await poll(first.get_attribute, "data-value").until_equals("0")
+    await poll(second.get_attribute, "data-value").until_equals("0")
 
     await button.click()
 
-    assert (await first.get_attribute("data-value")) == "1"
-    assert (await second.get_attribute("data-value")) == "1"
+    await poll(first.get_attribute, "data-value").until_equals("1")
+    await poll(second.get_attribute, "data-value").until_equals("1")
 
     await button.click()
 
-    assert (await first.get_attribute("data-value")) == "2"
-    assert (await second.get_attribute("data-value")) == "2"
+    await poll(first.get_attribute, "data-value").until_equals("2")
+    await poll(second.get_attribute, "data-value").until_equals("2")
 
 
 async def test_use_effect_callback_occurs_after_full_render_is_complete():
@@ -558,7 +558,7 @@ def bad_effect():
 
         return reactpy.html.div()
 
-    with assert_reactpy_did_log(match_message=r"Layout post-render effect .* failed"):
+    with assert_reactpy_did_log(match_message=r"Error during effect startup"):
         async with reactpy.Layout(ComponentWithEffect()) as layout:
             await layout.render()  # no error
 
@@ -584,7 +584,7 @@ def bad_cleanup():
         return reactpy.html.div()
 
     with assert_reactpy_did_log(
-        match_message=r"Pre-unmount effect .*? failed",
+        match_message=r"Error during effect cleanup",
         error_type=ValueError,
     ):
         async with reactpy.Layout(OuterComponent()) as layout:
@@ -1003,7 +1003,7 @@ def bad_effect():
         return reactpy.html.div()
 
     with assert_reactpy_did_log(
-        match_message=r"post-render effect .*? failed",
+        match_message=r"Error during effect startup",
         error_type=ValueError,
         match_error="The error message",
     ):
@@ -1246,7 +1246,7 @@ def bad_cleanup():
         return reactpy.html.div()
 
     with assert_reactpy_did_log(
-        match_message="Component post-render effect .*? failed",
+        match_message="Error during effect cleanup",
         error_type=ValueError,
         match_error="The error message",
     ):

src/py/reactpy/tests/test_core/test_layout.py

@@ -164,7 +164,7 @@ def make_child_model(state):
 async def test_layout_render_error_has_partial_update_with_error_message():
     @reactpy.component
     def Main():
-        return reactpy.html.div([OkChild(), BadChild(), OkChild()])
+        return reactpy.html.div(OkChild(), BadChild(), OkChild())
 
     @reactpy.component
     def OkChild():
@@ -622,7 +622,7 @@ async def test_hooks_for_keyed_components_get_garbage_collected():
     def Outer():
         items, set_items = reactpy.hooks.use_state([1, 2, 3])
         pop_item.current = lambda: set_items(items[:-1])
-        return reactpy.html.div(Inner(key=k, finalizer_id=k) for k in items)
+        return reactpy.html.div([Inner(key=k, finalizer_id=k) for k in items])
 
     @reactpy.component
     def Inner(finalizer_id):

src/py/reactpy/tests/test_core/test_serve.py

@@ -5,10 +5,12 @@
 from jsonpointer import set_pointer
 
 import reactpy
+from reactpy.core.hooks import use_effect
 from reactpy.core.layout import Layout
 from reactpy.core.serve import serve_layout
 from reactpy.core.types import LayoutUpdateMessage
 from reactpy.testing import StaticEventHandler
+from tests.tooling.aio import Event
 from tests.tooling.common import event_message
 
 EVENT_NAME = "on_event"
@@ -96,9 +98,10 @@ async def test_dispatch():
 
 
 async def test_dispatcher_handles_more_than_one_event_at_a_time():
-    block_and_never_set = asyncio.Event()
-    will_block = asyncio.Event()
-    second_event_did_execute = asyncio.Event()
+    did_render = Event()
+    block_and_never_set = Event()
+    will_block = Event()
+    second_event_did_execute = Event()
 
     blocked_handler = StaticEventHandler()
     non_blocked_handler = StaticEventHandler()
@@ -114,6 +117,10 @@ async def block_forever():
         async def handle_event():
             second_event_did_execute.set()
 
+        @use_effect
+        def set_did_render():
+            did_render.set()
+
         return reactpy.html.div(
             reactpy.html.button({"on_click": block_forever}),
             reactpy.html.button({"on_click": handle_event}),
@@ -129,11 +136,12 @@ async def handle_event():
             recv_queue.get,
         )
     )
-
-    await recv_queue.put(event_message(blocked_handler.target))
-    await will_block.wait()
-
-    await recv_queue.put(event_message(non_blocked_handler.target))
-    await second_event_did_execute.wait()
-
-    task.cancel()
+    try:
+        await did_render.wait()
+        await recv_queue.put(event_message(blocked_handler.target))
+        await will_block.wait()
+
+        await recv_queue.put(event_message(non_blocked_handler.target))
+        await second_event_did_execute.wait()
+    finally:
+        task.cancel()

src/py/reactpy/tests/tooling/aio.py

@@ -0,0 +1,14 @@
+from asyncio import Event as _Event
+from asyncio import wait_for
+
+from reactpy.config import REACTPY_TESTING_DEFAULT_TIMEOUT
+
+
+class Event(_Event):
+    """An event with a ``wait_for`` method."""
+
+    async def wait(self, timeout: float | None = None):
+        return await wait_for(
+            super().wait(),
+            timeout=timeout or REACTPY_TESTING_DEFAULT_TIMEOUT.current,
+        )