Add basic scheduler for plugins

maubot/plugin_base.py

@@ -27,6 +27,8 @@ from mautrix.util.async_db import Database, UpgradeTable
 from mautrix.util.config import BaseProxyConfig
 from mautrix.util.logging import TraceLogger
 
+from .scheduler import BasicScheduler
+
 if TYPE_CHECKING:
     from .client import MaubotMatrixClient
     from .loader import BasePluginLoader
@@ -40,6 +42,7 @@ class Plugin(ABC):
     log: TraceLogger
     loop: AbstractEventLoop
     loader: BasePluginLoader
+    sched: BasicScheduler
     config: BaseProxyConfig | None
     database: Engine | Database | None
     webapp: PluginWebApp | None
@@ -58,6 +61,7 @@ class Plugin(ABC):
         webapp_url: str | None,
         loader: BasePluginLoader,
     ) -> None:
+        self.sched = BasicScheduler(log=log.getChild("scheduler"))
         self.client = client
         self.loop = loop
         self.http = http
@@ -117,6 +121,7 @@ class Plugin(ABC):
             self.client.remove_event_handler(event_type, func)
         if self.webapp is not None:
             self.webapp.clear()
+        self.sched.stop()
         await self.stop()
 
     async def stop(self) -> None:

maubot/scheduler.py

@@ -0,0 +1,159 @@
+# maubot - A plugin-based Matrix bot system.
+# Copyright (C) 2024 Tulir Asokan
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+from __future__ import annotations
+
+from typing import Awaitable, Callable
+import asyncio
+import logging
+
+
+class BasicScheduler:
+    background_loop: asyncio.Task | None
+    tasks: set[asyncio.Task]
+    log: logging.Logger
+
+    def __init__(self, log: logging.Logger) -> None:
+        self.log = log
+        self.tasks = set()
+
+    def _find_caller(self) -> str:
+        try:
+            file_name, line_number, function_name, _ = self.log.findCaller()
+            return f"{function_name} at {file_name}:{line_number}"
+        except ValueError:
+            return "unknown function"
+
+    def run_periodically(
+        self,
+        period: float | int,
+        func: Callable[[], Awaitable],
+        run_task_in_background: bool = False,
+        catch_errors: bool = True,
+    ) -> asyncio.Task:
+        """
+        Run a function periodically in the background.
+
+        Args:
+            period: The period in seconds between each call to the function.
+            func: The function to run. No parameters will be provided,
+                use :meth:`functools.partial` if you need to pass parameters.
+            run_task_in_background: If ``True``, the function will be run in a background task.
+                If ``False`` (the default), the loop will wait for the task to return before
+                sleeping for the next period.
+            catch_errors: Whether the scheduler should catch and log any errors.
+                If ``False``, errors will be raised, and the caller must await the returned task
+                to find errors. This parameter has no effect if ``run_task_in_background``
+                is ``True``.
+
+        Returns:
+            The asyncio task object representing the background loop.
+        """
+        task = asyncio.create_task(
+            self._call_periodically(
+                period,
+                func,
+                caller=self._find_caller(),
+                catch_errors=catch_errors,
+                run_task_in_background=run_task_in_background,
+            )
+        )
+        self._register_task(task)
+        return task
+
+    def run_later(
+        self, delay: float | int, coro: Awaitable, catch_errors: bool = True
+    ) -> asyncio.Task:
+        """
+        Run a coroutine after a delay.
+
+        Examples:
+            >>> self.sched.run_later(5, self.async_task(meow=True))
+
+        Args:
+            delay: The delay in seconds to await the coroutine after.
+            coro: The coroutine to await.
+            catch_errors: Whether the scheduler should catch and log any errors.
+                If ``False``, errors will be raised, and the caller must await the returned task
+                to find errors.
+
+        Returns:
+            The asyncio task object representing the scheduled task.
+        """
+        task = asyncio.create_task(
+            self._call_with_delay(
+                delay, coro, caller=self._find_caller(), catch_errors=catch_errors
+            )
+        )
+        self._register_task(task)
+        return task
+
+    def _register_task(self, task: asyncio.Task) -> None:
+        self.tasks.add(task)
+        task.add_done_callback(self.tasks.discard)
+
+    async def _call_periodically(
+        self,
+        period: float | int,
+        func: Callable[[], Awaitable],
+        caller: str,
+        catch_errors: bool,
+        run_task_in_background: bool,
+    ) -> None:
+        while True:
+            try:
+                await asyncio.sleep(period)
+                if run_task_in_background:
+                    self._register_task(
+                        asyncio.create_task(self._call_periodically_background(func(), caller))
+                    )
+                else:
+                    await func()
+            except asyncio.CancelledError:
+                raise
+            except Exception:
+                if catch_errors:
+                    self.log.exception(f"Uncaught error in background loop (created in {caller})")
+                else:
+                    raise
+
+    async def _call_periodically_background(self, coro: Awaitable, caller: str) -> None:
+        try:
+            await coro
+        except asyncio.CancelledError:
+            raise
+        except Exception:
+            self.log.exception(f"Uncaught error in background loop subtask (created in {caller})")
+
+    async def _call_with_delay(
+        self, delay: float | int, coro: Awaitable, caller: str, catch_errors: bool
+    ) -> None:
+        try:
+            await asyncio.sleep(delay)
+            await coro
+        except asyncio.CancelledError:
+            raise
+        except Exception:
+            if catch_errors:
+                self.log.exception(f"Uncaught error in scheduled task (created in {caller})")
+            else:
+                raise
+
+    def stop(self) -> None:
+        """
+        Stop all scheduled tasks and background loops.
+        """
+        for task in self.tasks:
+            task.cancel(msg="Scheduler stopped")