Refactor shutdown procedure

pyproject.toml

@@ -4,6 +4,19 @@ version = "0.1.1"
 description = "Text User Interface using Rich"
 authors = ["Will McGugan <willmcgugan@gmail.com>"]
 license = "MIT"
+classifiers = [
+    "Development Status :: 1 - Planning",
+    "Environment :: Console",
+    "Intended Audience :: Developers",
+    "Operating System :: Microsoft :: Windows",
+    "Operating System :: MacOS",
+    "Operating System :: POSIX :: Linux",
+    "Programming Language :: Python :: 3.7",
+    "Programming Language :: Python :: 3.8",
+    "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.10",
+]
+
 
 [tool.poetry.dependencies]
 python = "^3.7"

src/textual/_linux_driver.py

@@ -139,15 +139,21 @@ class LinuxDriver(Driver):
             | termios.IGNCR
         )
 
+    def disable_input(self) -> None:
+        try:
+            if not self.exit_event.is_set():
+                signal.signal(signal.SIGWINCH, signal.SIG_DFL)
+                self._disable_mouse_support()
+                self.exit_event.set()
+                if self._key_thread is not None:
+                    self._key_thread.join()
+        except Exception:
+            log.exception("error in disable_input")
+
     def stop_application_mode(self) -> None:
         log.debug("stop_application_mode()")
 
-        signal.signal(signal.SIGWINCH, signal.SIG_DFL)
-
-        self._disable_mouse_support()
-        self.exit_event.set()
-        if self._key_thread is not None:
-            self._key_thread.join()
+        self.disable_input()
 
         if self.attrs_before is not None:
             try:
@@ -190,12 +196,18 @@ class LinuxDriver(Driver):
         read = os.read
 
         log.debug("started key thread")
-        while not self.exit_event.is_set():
-            selector_events = selector.select(0.1)
-            for _selector_key, mask in selector_events:
-                unicode_data = decode(read(fileno, 1024))
-                for event in parser.feed(unicode_data):
-                    send_event(event)
+        try:
+            while not self.exit_event.is_set():
+                selector_events = selector.select(0.1)
+                for _selector_key, mask in selector_events:
+                    if mask | selectors.EVENT_READ:
+                        unicode_data = decode(read(fileno, 1024))
+                        for event in parser.feed(unicode_data):
+                            send_event(event)
+        except Exception:
+            log.exception("error running key thread")
+        finally:
+            selector.close()
 
 
 if __name__ == "__main__":

src/textual/_timer.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import weakref
-from asyncio import Event, TimeoutError, wait_for
+from asyncio import CancelledError, Event, TimeoutError, wait_for
 from time import monotonic
 from typing import Awaitable, Callable
 
@@ -62,18 +62,21 @@ class Timer:
         _interval = self._interval
         _wait = self._stop_event.wait
         start = monotonic()
-        while _repeat is None or count <= _repeat:
-            next_timer = start + (count * _interval)
-            try:
-                if await wait_for(_wait(), max(0, next_timer - monotonic())):
+        try:
+            while _repeat is None or count <= _repeat:
+                next_timer = start + (count * _interval)
+                try:
+                    if await wait_for(_wait(), max(0, next_timer - monotonic())):
+                        break
+                except TimeoutError:
+                    pass
+                event = events.Timer(
+                    self.sender, timer=self, count=count, callback=self._callback
+                )
+                try:
+                    await self.target.post_message(event)
+                except EventTargetGone:
                     break
-            except TimeoutError:
-                pass
-            event = events.Timer(
-                self.sender, timer=self, count=count, callback=self._callback
-            )
-            try:
-                await self.target.post_message(event)
-            except EventTargetGone:
-                break
-            count += 1
+                count += 1
+        except CancelledError:
+            pass

src/textual/_types.py

@@ -16,20 +16,12 @@ Callback = Callable[[], None]
 
 
 class MessageTarget(Protocol):
-    async def post_message(
-        self,
-        message: "Message",
-        priority: Optional[int] = None,
-    ) -> bool:
+    async def post_message(self, message: "Message") -> bool:
         ...
 
 
 class EventTarget(Protocol):
-    async def post_message(
-        self,
-        message: "Message",
-        priority: Optional[int] = None,
-    ) -> bool:
+    async def post_message(self, message: "Message") -> bool:
         ...
 
 

src/textual/app.py

@@ -56,17 +56,18 @@ class App(MessagePump):
         self,
         console: Console = None,
         screen: bool = True,
-        driver: Type[Driver] = None,
+        driver_class: Type[Driver] = None,
         view: View = None,
         title: str = "Megasoma Application",
     ):
         super().__init__()
         self.console = console or get_console()
         self._screen = screen
-        self.driver = driver or LinuxDriver
+        self.driver_class = driver_class or LinuxDriver
         self.title = title
         self.view = view or LayoutView()
         self.children: set[MessagePump] = set()
+        self._driver: Driver | None = None
 
         self._action_targets = {"app": self, "view": self.view}
 
@@ -78,7 +79,7 @@ class App(MessagePump):
         cls, console: Console = None, screen: bool = True, driver: Type[Driver] = None
     ):
         async def run_app() -> None:
-            app = cls(console=console, screen=screen, driver=driver)
+            app = cls(console=console, screen=screen, driver_class=driver)
             await app.process_messages()
 
         asyncio.run(run_app())
@@ -95,11 +96,11 @@ class App(MessagePump):
             self.console.print_exception(show_locals=True)
 
     async def _process_messages(self) -> None:
-        log.debug("driver=%r", self.driver)
+        log.debug("driver=%r", self.driver_class)
         loop = asyncio.get_event_loop()
 
         loop.add_signal_handler(signal.SIGINT, self.on_keyboard_interupt)
-        driver = self.driver(self.console, self)
+        driver = self._driver = self.driver_class(self.console, self)
 
         active_app.set(self)
 
@@ -116,32 +117,53 @@ class App(MessagePump):
             await super().process_messages()
         finally:
             try:
-                if self.children:
-
-                    async def close_all() -> None:
-                        for child in self.children:
-                            await child.close_messages()
-                        await asyncio.gather(*(child.task for child in self.children))
-
-                    try:
-                        await asyncio.wait_for(close_all(), timeout=5)
-                    except asyncio.TimeoutError as error:
-                        raise ShutdownError(
-                            "Timeout closing messages pump(s)"
-                        ) from None
-
-                self.children.clear()
+                driver.stop_application_mode()
             finally:
-                try:
-                    driver.stop_application_mode()
-                finally:
-                    loop.remove_signal_handler(signal.SIGINT)
+                loop.remove_signal_handler(signal.SIGINT)
 
     async def add(self, child: MessagePump) -> None:
         self.children.add(child)
         child.start_messages()
         await child.post_message(events.Created(sender=self))
 
+    async def remove(self, child: MessagePump) -> None:
+        self.children.remove(child)
+
+    async def shutdown(self):
+        driver = self._driver
+        driver.disable_input()
+
+        async def shutdown_procedure() -> None:
+            log.debug("1")
+            await self.stop_messages()
+            log.debug("2")
+            await self.view.stop_messages()
+            log.debug("3")
+            log.debug("4")
+            await self.remove(self.view)
+            if self.children:
+                log.debug("5")
+
+                async def close_all() -> None:
+                    for child in self.children:
+                        await child.close_messages(wait=False)
+                    await asyncio.gather(*(child.task for child in self.children))
+
+                try:
+                    await asyncio.wait_for(close_all(), timeout=5)
+                    log.debug("6")
+                except asyncio.TimeoutError as error:
+                    raise ShutdownError("Timeout closing messages pump(s)") from None
+                log.debug("7")
+
+            log.debug("8")
+            await self.view.close_messages()
+            log.debug("9")
+            await self.close_messages()
+            log.debug("10")
+
+        await asyncio.create_task(shutdown_procedure())
+
     def refresh(self) -> None:
         console = self.console
         try:
@@ -150,7 +172,7 @@ class App(MessagePump):
         except Exception:
             log.exception("refresh failed")
 
-    async def on_event(self, event: events.Event, priority: int) -> None:
+    async def on_event(self, event: events.Event) -> None:
         if isinstance(event, events.Key):
             key_action = self.KEYS.get(event.key, None)
             if key_action is not None:
@@ -160,7 +182,7 @@ class App(MessagePump):
         if isinstance(event, events.InputEvent):
             await self.view.forward_input_event(event)
         else:
-            await super().on_event(event, priority)
+            await super().on_event(event)
 
     async def on_idle(self, event: events.Idle) -> None:
         await self.view.post_message(event)
@@ -215,7 +237,7 @@ class App(MessagePump):
         await self.view.post_message(event)
 
     async def action_quit(self) -> None:
-        await self.close_messages()
+        await self.shutdown()
 
     async def action_bang(self) -> None:
         1 / 0

src/textual/driver.py

@@ -1,18 +1,10 @@
 from __future__ import annotations
 
-from abc import ABC, abstractmethod
-import asyncio
 import logging
-import os
-import signal
-import curses
 import platform
-import sys
-import shutil
-from threading import Event, Thread
+from abc import ABC, abstractmethod
 from typing import TYPE_CHECKING
 
-from . import events
 from ._types import MessageTarget
 
 if TYPE_CHECKING:
@@ -34,159 +26,9 @@ class Driver(ABC):
         ...
 
     @abstractmethod
-    def stop_application_mode(self) -> None:
+    def disable_input(self) -> None:
         ...
 
-
-# class CursesDriver(Driver):
-
-#     _MOUSE_PRESSED = [
-#         curses.BUTTON1_PRESSED,
-#         curses.BUTTON2_PRESSED,
-#         curses.BUTTON3_PRESSED,
-#         curses.BUTTON4_PRESSED,
-#     ]
-
-#     _MOUSE_RELEASED = [
-#         curses.BUTTON1_RELEASED,
-#         curses.BUTTON2_RELEASED,
-#         curses.BUTTON3_RELEASED,
-#         curses.BUTTON4_RELEASED,
-#     ]
-
-#     _MOUSE_CLICKED = [
-#         curses.BUTTON1_CLICKED,
-#         curses.BUTTON2_CLICKED,
-#         curses.BUTTON3_CLICKED,
-#         curses.BUTTON4_CLICKED,
-#     ]
-
-#     _MOUSE_DOUBLE_CLICKED = [
-#         curses.BUTTON1_DOUBLE_CLICKED,
-#         curses.BUTTON2_DOUBLE_CLICKED,
-#         curses.BUTTON3_DOUBLE_CLICKED,
-#         curses.BUTTON4_DOUBLE_CLICKED,
-#     ]
-
-#     _MOUSE = [
-#         (events.MouseDown, _MOUSE_PRESSED),
-#         (events.MouseUp, _MOUSE_RELEASED),
-#         (events.Click, _MOUSE_CLICKED),
-#         (events.DoubleClick, _MOUSE_DOUBLE_CLICKED),
-#     ]
-
-#     def __init__(self, console: "Console", target: "MessageTarget") -> None:
-#         super().__init__(console, target)
-#         self._stdscr = None
-#         self._exit_event = Event()
-#         self._key_thread: Thread | None = None
-
-#     def _get_terminal_size(self) -> tuple[int, int]:
-#         width: int | None = 80
-#         height: int | None = 25
-#         if WINDOWS:  # pragma: no cover
-#             width, height = shutil.get_terminal_size()
-#         else:
-#             try:
-#                 width, height = os.get_terminal_size(sys.stdin.fileno())
-#             except (AttributeError, ValueError, OSError):
-#                 try:
-#                     width, height = os.get_terminal_size(sys.stdout.fileno())
-#                 except (AttributeError, ValueError, OSError):
-#                     pass
-#         width = width or 80
-#         height = height or 25
-#         return width, height
-
-#     def start_application_mode(self):
-#         loop = asyncio.get_event_loop()
-
-#         def on_terminal_resize(signum, stack) -> None:
-#             terminal_size = self._get_terminal_size()
-#             width, height = terminal_size
-#             event = events.Resize(self._target, width, height)
-#             self.console.size = terminal_size
-#             asyncio.run_coroutine_threadsafe(
-#                 self._target.post_message(event),
-#                 loop=loop,
-#             )
-
-#         signal.signal(signal.SIGWINCH, on_terminal_resize)
-#         self._stdscr = curses.initscr()
-#         curses.noecho()
-#         curses.cbreak()
-#         curses.halfdelay(1)
-#         curses.mousemask(curses.REPORT_MOUSE_POSITION | curses.ALL_MOUSE_EVENTS)
-#         # curses.mousemask(-1)
-
-#         self._stdscr.keypad(True)
-#         self.console.show_cursor(False)
-#         self.console.file.write("\033[?1003h\n")
-#         self._key_thread = Thread(
-#             target=self.run_key_thread, args=(asyncio.get_event_loop(),)
-#         )
-
-#         width, height = self.console.size = self._get_terminal_size()
-#         asyncio.run_coroutine_threadsafe(
-#             self._target.post_message(events.Resize(self._target, width, height)),
-#             loop=loop,
-#         )
-
-#         self._key_thread.start()
-
-#     def stop_application_mode(self):
-
-#         signal.signal(signal.SIGWINCH, signal.SIG_DFL)
-
-#         self._exit_event.set()
-#         self._key_thread.join()
-#         curses.nocbreak()
-#         self._stdscr.keypad(False)
-#         curses.echo()
-#         curses.endwin()
-#         self.console.show_cursor(True)
-
-#     def run_key_thread(self, loop) -> None:
-#         stdscr = self._stdscr
-#         assert stdscr is not None
-#         exit_event = self._exit_event
-
-#         def send_event(event: events.Event) -> None:
-#             asyncio.run_coroutine_threadsafe(
-#                 self._target.post_message(event),
-#                 loop=loop,
-#             )
-
-#         while not exit_event.is_set():
-#             code = stdscr.getch()
-#             if code == -1:
-#                 continue
-
-#             if code == curses.KEY_MOUSE:
-
-#                 try:
-#                     _id, x, y, _z, button_state = curses.getmouse()
-#                 except Exception:
-#                     log.exception("error in curses.getmouse")
-#                 else:
-#                     if button_state & curses.REPORT_MOUSE_POSITION:
-#                         send_event(events.MouseMove(self._target, x, y))
-#                     alt = bool(button_state & curses.BUTTON_ALT)
-#                     ctrl = bool(button_state & curses.BUTTON_CTRL)
-#                     shift = bool(button_state & curses.BUTTON_SHIFT)
-#                     for event_type, masks in self._MOUSE:
-#                         for button, mask in enumerate(masks, 1):
-#                             if button_state & mask:
-#                                 send_event(
-#                                     event_type(
-#                                         self._target,
-#                                         x,
-#                                         y,
-#                                         button,
-#                                         alt=alt,
-#                                         ctrl=ctrl,
-#                                         shift=shift,
-#                                     )
-#                                 )
-#             else:
-#                 send_event(events.Key(self._target, code=code))
+    @abstractmethod
+    def stop_application_mode(self) -> None:
+        ...

src/textual/events.py

@@ -50,7 +50,6 @@ class EventType(Enum):
     CUSTOM = 1000
 
 
-@rich_repr
 class Event(Message):
     type: ClassVar[EventType]
 
@@ -58,30 +57,28 @@ class Event(Message):
         return
         yield
 
-    def __init_subclass__(
-        cls, type: EventType, priority: int = 0, bubble: bool = False
-    ) -> None:
+    def __init_subclass__(cls, type: EventType, bubble: bool = False) -> None:
         cls.type = type
-        super().__init_subclass__(priority=priority, bubble=bubble)
+        super().__init_subclass__(bubble=bubble)
 
-    # def __enter__(self) -> "Event":
-    #     return self
 
-    # def __exit__(self, exc_type, exc_value, exc_tb) -> bool | None:
-    #     if exc_type is not None:
-    #         # Log and suppress exception
-    #         return True
+class NoneEvent(Event, type=EventType.NONE):
+    pass
 
 
 class ShutdownRequest(Event, type=EventType.SHUTDOWN_REQUEST):
     pass
 
 
-class Load(Event, type=EventType.SHUTDOWN_REQUEST):
+class Shutdown(Event, type=EventType.SHUTDOWN):
     pass
 
 
-class Startup(Event, type=EventType.SHUTDOWN_REQUEST):
+class Load(Event, type=EventType.LOAD):
+    pass
+
+
+class Startup(Event, type=EventType.STARTUP):
     pass
 
 
@@ -120,10 +117,6 @@ class Unmount(Event, type=EventType.UNMOUNT):
     pass
 
 
-class Shutdown(Event, type=EventType.SHUTDOWN):
-    pass
-
-
 class InputEvent(Event, type=EventType.NONE, bubble=True):
     pass
 
@@ -205,7 +198,7 @@ class DoubleClick(MouseEvent, type=EventType.DOUBLE_CLICK):
 
 
 @rich_repr
-class Timer(Event, type=EventType.TIMER, priority=10):
+class Timer(Event, type=EventType.TIMER):
     __slots__ = ["time", "count", "callback"]
 
     def __init__(

src/textual/message.py

@@ -7,7 +7,6 @@ from .case import camel_to_snake
 from ._types import MessageTarget
 
 
-@rich_repr
 class Message:
     """Base class for a message."""
 
@@ -21,7 +20,6 @@ class Message:
 
     sender: MessageTarget
     bubble: ClassVar[bool] = False
-    default_priority: ClassVar[int] = 0
 
     def __init__(self, sender: MessageTarget) -> None:
         self.sender = sender
@@ -35,10 +33,9 @@ class Message:
         return
         yield
 
-    def __init_subclass__(cls, bubble: bool = False, priority: int = 0) -> None:
+    def __init_subclass__(cls, bubble: bool = False) -> None:
         super().__init_subclass__()
         cls.bubble = bubble
-        cls.default_priority = priority
 
     def can_batch(self, message: "Message") -> bool:
         """Check if another message may supersede this one.

src/textual/message_pump.py

@@ -2,7 +2,7 @@ from __future__ import annotations
 
 from typing import Any, Coroutine, Awaitable, NamedTuple
 import asyncio
-from asyncio import Event, PriorityQueue, Task, QueueEmpty
+from asyncio import Event, Queue, Task, QueueEmpty
 
 import logging
 
@@ -14,50 +14,21 @@ from ._types import MessageHandler
 log = logging.getLogger("rich")
 
 
-class MessageQueueItem(NamedTuple):
-    priority: int
-    message: Message
-
-    def __lt__(self, other: object) -> bool:
-        other_priority = other.priority if isinstance(other, MessageQueueItem) else 0
-        return self.priority < other_priority
-
-    def __le__(self, other: object) -> bool:
-        other_priority = other.priority if isinstance(other, MessageQueueItem) else 0
-        return self.priority <= other_priority
-
-    def __gt__(self, other: object) -> bool:
-        other_priority = other.priority if isinstance(other, MessageQueueItem) else 0
-        return self.priority > other_priority
-
-    def __ge__(self, other: object) -> bool:
-        other_priority = other.priority if isinstance(other, MessageQueueItem) else 0
-        return self.priority >= other_priority
-
-    def __eq__(self, other: object) -> bool:
-        other_priority = other.priority if isinstance(other, MessageQueueItem) else 0
-        return self.priority == other_priority
-
-    def __ne__(self, other: object) -> bool:
-        other_priority = other.priority if isinstance(other, MessageQueueItem) else 0
-        return self.priority != other_priority
-
-
 class MessagePumpClosed(Exception):
     pass
 
 
 class MessagePump:
     def __init__(self, queue_size: int = 10, parent: MessagePump | None = None) -> None:
-        self._message_queue: PriorityQueue[MessageQueueItem | None] = PriorityQueue(
-            queue_size
-        )
+        self._message_queue: Queue[Message | None] = Queue()
         self._parent = parent
         self._closing: bool = False
         self._closed: bool = False
         self._disabled_messages: set[type[Message]] = set()
-        self._pending_message: MessageQueueItem | None = None
+        self._pending_message: Message | None = None
         self._task: Task | None = None
+        self._child_tasks: set[Task] = set()
+        self._queue_empty_event = Event()
 
     @property
     def task(self) -> Task:
@@ -78,26 +49,26 @@ class MessagePump:
         """Enable processing of messages types."""
         self._disabled_messages.difference_update(messages)
 
-    async def get_message(self) -> MessageQueueItem:
+    async def get_message(self) -> Message:
         """Get the next event on the queue, or None if queue is closed.
 
         Returns:
             Optional[Event]: Event object or None.
         """
+        if self._closed:
+            raise MessagePumpClosed("The message pump is closed")
         if self._pending_message is not None:
             try:
                 return self._pending_message
             finally:
                 self._pending_message = None
-        if self._closed:
-            raise MessagePumpClosed("The message pump is closed")
-        queue_item = await self._message_queue.get()
-        if queue_item is None:
+        message = await self._message_queue.get()
+        if message is None:
             self._closed = True
             raise MessagePumpClosed("The message pump is now closed")
-        return queue_item
+        return message
 
-    def peek_message(self) -> MessageQueueItem | None:
+    def peek_message(self) -> Message | None:
         """Peek the message at the head of the queue (does not remove it from the queue),
         or return None if the queue is empty.
 
@@ -122,7 +93,8 @@ class MessagePump:
         callback: TimerCallback = None,
     ) -> Timer:
         timer = Timer(self, delay, self, name=name, callback=callback, repeat=0)
-        asyncio.get_event_loop().create_task(timer.run())
+        timer_task = asyncio.get_event_loop().create_task(timer.run())
+        self._child_tasks.add(timer_task)
         return timer
 
     def set_interval(
@@ -139,91 +111,131 @@ class MessagePump:
         asyncio.get_event_loop().create_task(timer.run())
         return timer
 
-    async def close_messages(self, wait: bool = False) -> None:
+    async def stop_messages(self) -> None:
+        if not self._closing:
+            await self.post_message(events.NoneEvent(self))
+            self._closing = True
+        return
+        if not (self._closing or self._closed):
+            self._queue_empty_event.clear()
+            await self.post_message(events.NoneEvent(self))
+            self._closing = True
+            await self._queue_empty_event.wait()
+            self._queue_empty_event.clear()
+
+    async def close_messages(self, wait: bool = True) -> None:
         """Close message queue, and optionally wait for queue to finish processing."""
+        if self._closed:
+            return
+        log.debug("close_messages %r wait=%r", self, wait)
         self._closing = True
+        log.debug("close 1 %r", self)
+        for task in self._child_tasks:
+            task.cancel()
+        log.debug("close 2 %r", self)
         await self._message_queue.put(None)
+        log.debug("close 3 %r", self)
         if wait and self._task is not None:
             await self._task
+            self._task = None
+        log.debug("close 4 %r", self)
 
     def start_messages(self) -> None:
-        task = asyncio.create_task(self.process_messages())
-        self._task = task
+        self._task = asyncio.create_task(self.process_messages())
 
     async def process_messages(self) -> None:
         """Process messages until the queue is closed."""
         while not self._closed:
             try:
-                priority, message = await self.get_message()
+                message = await self.get_message()
             except MessagePumpClosed:
+                log.debug("CLOSED %r", self)
                 break
             except Exception as error:
+                log.exception("error in get_message()")
                 raise error from None
 
             log.debug("%r -> %r", message, self)
             # Combine any pending messages that may supersede this one
             while True:
                 pending = self.peek_message()
-                if pending is None or not message.can_batch(pending.message):
+                if pending is None or not message.can_batch(pending):
+                    break
+                try:
+                    message = await self.get_message()
+                except MessagePumpClosed:
                     break
-                priority, message = await self.get_message()
 
             try:
-                await self.dispatch_message(message, priority)
+                await self.dispatch_message(message)
             except Exception as error:
+                log.exception("error in dispatch_message")
                 raise
-
             finally:
+                log.debug("a")
                 if self._message_queue.empty():
-                    idle_handler = getattr(self, "on_idle", None)
-                    if idle_handler is not None:
-                        await idle_handler(events.Idle(self))
+                    log.debug("b")
+                    self._queue_empty_event.set()
+                    if not self._closed:
+                        idle_handler = getattr(self, "on_idle", None)
+                        log.debug("c %r", idle_handler)
+                        if idle_handler is not None and not self._closed:
+                            log.debug("d")
+                            await idle_handler(events.Idle(self))
+                            log.debug("e")
+        self._queue_empty_event.set()
 
-    async def dispatch_message(
-        self, message: Message, priority: int = 0
-    ) -> bool | None:
+    async def dispatch_message(self, message: Message) -> bool | None:
+        log.debug("dispatch_message %r", message)
         if isinstance(message, events.Event):
-            await self.on_event(message, priority)
+            await self.on_event(message)
         else:
             return await self.on_message(message)
         return False
 
-    async def on_event(self, event: events.Event, priority: int) -> None:
+    async def on_event(self, event: events.Event) -> None:
         method_name = f"on_{event.name}"
         dispatch_function: MessageHandler = getattr(self, method_name, None)
+        log.debug("dispatching to %r", dispatch_function)
         if dispatch_function is not None:
             await dispatch_function(event)
         if event.bubble and self._parent and not event._stop_propagaton:
             if event.sender == self._parent:
                 log.debug("bubbled event abandoned; %r", event)
-            else:
-                await self._parent.post_message(event, priority)
+            elif not self._parent._closed and not self._parent._closing:
+                await self._parent.post_message(event)
 
     async def on_message(self, message: Message) -> None:
         pass
 
-    async def post_message(
-        self,
-        message: Message,
-        priority: int | None = None,
-    ) -> bool:
+    def post_message_no_wait(self, message: Message) -> bool:
         if self._closing or self._closed:
             return False
         if not self.check_message_enabled(message):
             return True
-        event_priority = priority if priority is not None else message.default_priority
-        item = MessageQueueItem(event_priority, message)
-        await self._message_queue.put(item)
+        self._message_queue.put_nowait(message)
         return True
 
-    async def post_message_from_child(
-        self, message: Message, priority: int | None = None
-    ) -> None:
-        await self.post_message(message, priority=priority)
+    async def post_message(self, message: Message) -> bool:
+        log.debug("%r post_message 1", self)
+        if self._closing or self._closed:
+            return False
+        log.debug("%r post_message 2", self)
+        if not self.check_message_enabled(message):
+            return True
+        log.debug("%r post_message 3", self)
+        await self._message_queue.put(message)
+        log.debug("%r post_message 4", self)
+        return True
 
-    async def emit(self, message: Message, priority: int | None = None) -> bool:
+    async def post_message_from_child(self, message: Message) -> bool:
+        if self._closing or self._closed:
+            return False
+        return await self.post_message(message)
+
+    async def emit(self, message: Message) -> bool:
         if self._parent:
-            await self._parent.post_message_from_child(message, priority=priority)
+            await self._parent.post_message_from_child(message)
             return True
         else:
             return False

src/textual/view.py

@@ -108,6 +108,7 @@ class LayoutView(View):
         raise NoWidget(f"No widget at ${x}, ${y}")
 
     async def on_message(self, message: Message) -> None:
+        log.debug("on_message %r", repr(message))
         if isinstance(message, UpdateMessage):
             widget = message.sender
             if widget in self._widgets:

src/textual/widget.py

@@ -37,8 +37,6 @@ T = TypeVar("T")
 
 
 class UpdateMessage(Message):
-    default_priority = 10
-
     def can_batch(self, message: Message) -> bool:
         return isinstance(message, UpdateMessage) and message.sender == self.sender
 
@@ -139,7 +137,6 @@ class Widget(MessagePump):
 
     def render_update(self, x: int, y: int) -> Iterable[Segment]:
         width, height = self.size
-        log.debug("widget size = %r", self.size)
         yield from self.line_cache.render(x, y, width, height)
 
     def render(self, console: Console, options: ConsoleOptions) -> RenderableType:
@@ -147,19 +144,19 @@ class Widget(MessagePump):
             Align.center(Pretty(self), vertical="middle"), title=self.__class__.__name__
         )
 
-    async def post_message(self, message: Message, priority: int | None = None) -> bool:
+    async def post_message(self, message: Message) -> bool:
         if not self.check_message_enabled(message):
             return True
 
-        return await super().post_message(message, priority)
+        return await super().post_message(message)
 
-    async def on_event(self, event: events.Event, priority: int) -> None:
+    async def on_event(self, event: events.Event) -> None:
         if isinstance(event, events.Resize):
             new_size = Dimensions(event.width, event.height)
             if self.size != new_size:
                 self.size = new_size
                 self.require_repaint()
-        await super().on_event(event, priority)
+        await super().on_event(event)
 
     async def on_idle(self, event: events.Idle) -> None:
         if self.line_cache is None or self.line_cache.dirty:

src/textual/widgets/header.py

@@ -51,4 +51,5 @@ class Header(Widget):
         return header
 
     async def on_mount(self, event: events.Mount) -> None:
+        return
         self.set_interval(1.0, callback=self.refresh)