399 lines
15 KiB
Python
399 lines
15 KiB
Python
# Copyright 2023 The Matrix.org Foundation C.I.C.
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License");
|
|
# you may not use this file except in compliance with the License.
|
|
# You may obtain a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS,
|
|
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
# See the License for the specific language governing permissions and
|
|
# limitations under the License.
|
|
|
|
import logging
|
|
from typing import TYPE_CHECKING, Awaitable, Callable, Dict, List, Optional, Set, Tuple
|
|
|
|
from twisted.python.failure import Failure
|
|
|
|
from synapse.logging.context import nested_logging_context
|
|
from synapse.metrics import LaterGauge
|
|
from synapse.metrics.background_process_metrics import (
|
|
run_as_background_process,
|
|
wrap_as_background_process,
|
|
)
|
|
from synapse.types import JsonMapping, ScheduledTask, TaskStatus
|
|
from synapse.util.stringutils import random_string
|
|
|
|
if TYPE_CHECKING:
|
|
from synapse.server import HomeServer
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
|
|
class TaskScheduler:
|
|
"""
|
|
This is a simple task sheduler aimed at resumable tasks: usually we use `run_in_background`
|
|
to launch a background task, or Twisted `deferLater` if we want to do so later on.
|
|
|
|
The problem with that is that the tasks will just stop and never be resumed if synapse
|
|
is stopped for whatever reason.
|
|
|
|
How this works:
|
|
- A function mapped to a named action should first be registered with `register_action`.
|
|
This function will be called when trying to resuming tasks after a synapse shutdown,
|
|
so this registration should happen when synapse is initialised, NOT right before scheduling
|
|
a task.
|
|
- A task can then be launched using this named action with `schedule_task`. A `params` dict
|
|
can be passed, and it will be available to the registered function when launched. This task
|
|
can be launch either now-ish, or later on by giving a `timestamp` parameter.
|
|
|
|
The function may call `update_task` at any time to update the `result` of the task,
|
|
and this can be used to resume the task at a specific point and/or to convey a result to
|
|
the code launching the task.
|
|
You can also specify the `result` (and/or an `error`) when returning from the function.
|
|
|
|
The reconciliation loop runs every minute, so this is not a precise scheduler.
|
|
There is a limit of 10 concurrent tasks, so tasks may be delayed if the pool is already
|
|
full. In this regard, please take great care that scheduled tasks can actually finished.
|
|
For now there is no mechanism to stop a running task if it is stuck.
|
|
|
|
Tasks will be run on the worker specified with `run_background_tasks_on` config,
|
|
or the main one by default.
|
|
"""
|
|
|
|
# Precision of the scheduler, evaluation of tasks to run will only happen
|
|
# every `SCHEDULE_INTERVAL_MS` ms
|
|
SCHEDULE_INTERVAL_MS = 1 * 60 * 1000 # 1mn
|
|
# How often to clean up old tasks.
|
|
CLEANUP_INTERVAL_MS = 30 * 60 * 1000
|
|
# Time before a complete or failed task is deleted from the DB
|
|
KEEP_TASKS_FOR_MS = 7 * 24 * 60 * 60 * 1000 # 1 week
|
|
# Maximum number of tasks that can run at the same time
|
|
MAX_CONCURRENT_RUNNING_TASKS = 10
|
|
# Time from the last task update after which we will log a warning
|
|
LAST_UPDATE_BEFORE_WARNING_MS = 24 * 60 * 60 * 1000 # 24hrs
|
|
|
|
def __init__(self, hs: "HomeServer"):
|
|
self._hs = hs
|
|
self._store = hs.get_datastores().main
|
|
self._clock = hs.get_clock()
|
|
self._running_tasks: Set[str] = set()
|
|
# A map between action names and their registered function
|
|
self._actions: Dict[
|
|
str,
|
|
Callable[
|
|
[ScheduledTask],
|
|
Awaitable[Tuple[TaskStatus, Optional[JsonMapping], Optional[str]]],
|
|
],
|
|
] = {}
|
|
self._run_background_tasks = hs.config.worker.run_background_tasks
|
|
|
|
# Flag to make sure we only try and launch new tasks once at a time.
|
|
self._launching_new_tasks = False
|
|
|
|
if self._run_background_tasks:
|
|
self._clock.looping_call(
|
|
self._launch_scheduled_tasks,
|
|
TaskScheduler.SCHEDULE_INTERVAL_MS,
|
|
)
|
|
self._clock.looping_call(
|
|
self._clean_scheduled_tasks,
|
|
TaskScheduler.SCHEDULE_INTERVAL_MS,
|
|
)
|
|
|
|
LaterGauge(
|
|
"synapse_scheduler_running_tasks",
|
|
"The number of concurrent running tasks handled by the TaskScheduler",
|
|
labels=None,
|
|
caller=lambda: len(self._running_tasks),
|
|
)
|
|
|
|
def register_action(
|
|
self,
|
|
function: Callable[
|
|
[ScheduledTask],
|
|
Awaitable[Tuple[TaskStatus, Optional[JsonMapping], Optional[str]]],
|
|
],
|
|
action_name: str,
|
|
) -> None:
|
|
"""Register a function to be executed when an action is scheduled with
|
|
the specified action name.
|
|
|
|
Actions need to be registered as early as possible so that a resumed action
|
|
can find its matching function. It's usually better to NOT do that right before
|
|
calling `schedule_task` but rather in an `__init__` method.
|
|
|
|
Args:
|
|
function: The function to be executed for this action. The parameter
|
|
passed to the function when launched is the `ScheduledTask` being run.
|
|
The function should return a tuple of new `status`, `result`
|
|
and `error` as specified in `ScheduledTask`.
|
|
action_name: The name of the action to be associated with the function
|
|
"""
|
|
self._actions[action_name] = function
|
|
|
|
async def schedule_task(
|
|
self,
|
|
action: str,
|
|
*,
|
|
resource_id: Optional[str] = None,
|
|
timestamp: Optional[int] = None,
|
|
params: Optional[JsonMapping] = None,
|
|
) -> str:
|
|
"""Schedule a new potentially resumable task. A function matching the specified
|
|
`action` should have be registered with `register_action` before the task is run.
|
|
|
|
Args:
|
|
action: the name of a previously registered action
|
|
resource_id: a task can be associated with a resource id to facilitate
|
|
getting all tasks associated with a specific resource
|
|
timestamp: if `None`, the task will be launched as soon as possible, otherwise it
|
|
will be launch as soon as possible after the `timestamp` value.
|
|
Note that this scheduler is not meant to be precise, and the scheduling
|
|
could be delayed if too many tasks are already running
|
|
params: a set of parameters that can be easily accessed from inside the
|
|
executed function
|
|
|
|
Returns:
|
|
The id of the scheduled task
|
|
"""
|
|
status = TaskStatus.SCHEDULED
|
|
if timestamp is None or timestamp < self._clock.time_msec():
|
|
timestamp = self._clock.time_msec()
|
|
status = TaskStatus.ACTIVE
|
|
|
|
task = ScheduledTask(
|
|
random_string(16),
|
|
action,
|
|
status,
|
|
timestamp,
|
|
resource_id,
|
|
params,
|
|
result=None,
|
|
error=None,
|
|
)
|
|
await self._store.insert_scheduled_task(task)
|
|
|
|
if status == TaskStatus.ACTIVE:
|
|
if self._run_background_tasks:
|
|
await self._launch_task(task)
|
|
else:
|
|
self._hs.get_replication_command_handler().send_new_active_task(task.id)
|
|
|
|
return task.id
|
|
|
|
async def update_task(
|
|
self,
|
|
id: str,
|
|
*,
|
|
timestamp: Optional[int] = None,
|
|
status: Optional[TaskStatus] = None,
|
|
result: Optional[JsonMapping] = None,
|
|
error: Optional[str] = None,
|
|
) -> bool:
|
|
"""Update some task associated values. This is exposed publically so it can
|
|
be used inside task functions, mainly to update the result and be able to
|
|
resume a task at a specific step after a restart of synapse.
|
|
|
|
It can also be used to stage a task, by setting the `status` to `SCHEDULED` with
|
|
a new timestamp.
|
|
|
|
The `status` can only be set to `ACTIVE` or `SCHEDULED`, `COMPLETE` and `FAILED`
|
|
are terminal status and can only be set by returning it in the function.
|
|
|
|
Args:
|
|
id: the id of the task to update
|
|
timestamp: useful to schedule a new stage of the task at a later date
|
|
status: the new `TaskStatus` of the task
|
|
result: the new result of the task
|
|
error: the new error of the task
|
|
"""
|
|
if status == TaskStatus.COMPLETE or status == TaskStatus.FAILED:
|
|
raise Exception(
|
|
"update_task can't be called with a FAILED or COMPLETE status"
|
|
)
|
|
|
|
if timestamp is None:
|
|
timestamp = self._clock.time_msec()
|
|
return await self._store.update_scheduled_task(
|
|
id,
|
|
timestamp,
|
|
status=status,
|
|
result=result,
|
|
error=error,
|
|
)
|
|
|
|
async def get_task(self, id: str) -> Optional[ScheduledTask]:
|
|
"""Get a specific task description by id.
|
|
|
|
Args:
|
|
id: the id of the task to retrieve
|
|
|
|
Returns:
|
|
The task information or `None` if it doesn't exist or it has
|
|
already been removed because it's too old.
|
|
"""
|
|
return await self._store.get_scheduled_task(id)
|
|
|
|
async def get_tasks(
|
|
self,
|
|
*,
|
|
actions: Optional[List[str]] = None,
|
|
resource_id: Optional[str] = None,
|
|
statuses: Optional[List[TaskStatus]] = None,
|
|
max_timestamp: Optional[int] = None,
|
|
limit: Optional[int] = None,
|
|
) -> List[ScheduledTask]:
|
|
"""Get a list of tasks. Returns all the tasks if no args is provided.
|
|
|
|
If an arg is `None` all tasks matching the other args will be selected.
|
|
If an arg is an empty list, the corresponding value of the task needs
|
|
to be `None` to be selected.
|
|
|
|
Args:
|
|
actions: Limit the returned tasks to those specific action names
|
|
resource_id: Limit the returned tasks to the specific resource id, if specified
|
|
statuses: Limit the returned tasks to the specific statuses
|
|
max_timestamp: Limit the returned tasks to the ones that have
|
|
a timestamp inferior to the specified one
|
|
limit: Only return `limit` number of rows if set.
|
|
|
|
Returns
|
|
A list of `ScheduledTask`, ordered by increasing timestamps
|
|
"""
|
|
return await self._store.get_scheduled_tasks(
|
|
actions=actions,
|
|
resource_id=resource_id,
|
|
statuses=statuses,
|
|
max_timestamp=max_timestamp,
|
|
limit=limit,
|
|
)
|
|
|
|
async def delete_task(self, id: str) -> None:
|
|
"""Delete a task. Running tasks can't be deleted.
|
|
|
|
Can only be called from the worker handling the task scheduling.
|
|
|
|
Args:
|
|
id: id of the task to delete
|
|
"""
|
|
task = await self.get_task(id)
|
|
if task is None:
|
|
raise Exception(f"Task {id} does not exist")
|
|
if task.status == TaskStatus.ACTIVE:
|
|
raise Exception(f"Task {id} is currently ACTIVE and can't be deleted")
|
|
await self._store.delete_scheduled_task(id)
|
|
|
|
def launch_task_by_id(self, id: str) -> None:
|
|
"""Try launching the task with the given ID."""
|
|
# Don't bother trying to launch new tasks if we're already at capacity.
|
|
if len(self._running_tasks) >= TaskScheduler.MAX_CONCURRENT_RUNNING_TASKS:
|
|
return
|
|
|
|
run_as_background_process("launch_task_by_id", self._launch_task_by_id, id)
|
|
|
|
async def _launch_task_by_id(self, id: str) -> None:
|
|
"""Helper async function for `launch_task_by_id`."""
|
|
task = await self.get_task(id)
|
|
if task:
|
|
await self._launch_task(task)
|
|
|
|
@wrap_as_background_process("launch_scheduled_tasks")
|
|
async def _launch_scheduled_tasks(self) -> None:
|
|
"""Retrieve and launch scheduled tasks that should be running at that time."""
|
|
# Don't bother trying to launch new tasks if we're already at capacity.
|
|
if len(self._running_tasks) >= TaskScheduler.MAX_CONCURRENT_RUNNING_TASKS:
|
|
return
|
|
|
|
if self._launching_new_tasks:
|
|
return
|
|
|
|
self._launching_new_tasks = True
|
|
|
|
try:
|
|
for task in await self.get_tasks(
|
|
statuses=[TaskStatus.ACTIVE], limit=self.MAX_CONCURRENT_RUNNING_TASKS
|
|
):
|
|
await self._launch_task(task)
|
|
for task in await self.get_tasks(
|
|
statuses=[TaskStatus.SCHEDULED],
|
|
max_timestamp=self._clock.time_msec(),
|
|
limit=self.MAX_CONCURRENT_RUNNING_TASKS,
|
|
):
|
|
await self._launch_task(task)
|
|
|
|
finally:
|
|
self._launching_new_tasks = False
|
|
|
|
@wrap_as_background_process("clean_scheduled_tasks")
|
|
async def _clean_scheduled_tasks(self) -> None:
|
|
"""Clean old complete or failed jobs to avoid clutter the DB."""
|
|
now = self._clock.time_msec()
|
|
for task in await self._store.get_scheduled_tasks(
|
|
statuses=[TaskStatus.FAILED, TaskStatus.COMPLETE],
|
|
max_timestamp=now - TaskScheduler.KEEP_TASKS_FOR_MS,
|
|
):
|
|
# FAILED and COMPLETE tasks should never be running
|
|
assert task.id not in self._running_tasks
|
|
await self._store.delete_scheduled_task(task.id)
|
|
|
|
async def _launch_task(self, task: ScheduledTask) -> None:
|
|
"""Launch a scheduled task now.
|
|
|
|
Args:
|
|
task: the task to launch
|
|
"""
|
|
assert self._run_background_tasks
|
|
|
|
if task.action not in self._actions:
|
|
raise Exception(
|
|
f"No function associated with action {task.action} of the scheduled task {task.id}"
|
|
)
|
|
function = self._actions[task.action]
|
|
|
|
async def wrapper() -> None:
|
|
with nested_logging_context(task.id):
|
|
try:
|
|
(status, result, error) = await function(task)
|
|
except Exception:
|
|
f = Failure()
|
|
logger.error(
|
|
f"scheduled task {task.id} failed",
|
|
exc_info=(f.type, f.value, f.getTracebackObject()),
|
|
)
|
|
status = TaskStatus.FAILED
|
|
result = None
|
|
error = f.getErrorMessage()
|
|
|
|
await self._store.update_scheduled_task(
|
|
task.id,
|
|
self._clock.time_msec(),
|
|
status=status,
|
|
result=result,
|
|
error=error,
|
|
)
|
|
self._running_tasks.remove(task.id)
|
|
|
|
# Try launch a new task since we've finished with this one.
|
|
self._clock.call_later(1, self._launch_scheduled_tasks)
|
|
|
|
if len(self._running_tasks) >= TaskScheduler.MAX_CONCURRENT_RUNNING_TASKS:
|
|
return
|
|
|
|
if (
|
|
self._clock.time_msec()
|
|
> task.timestamp + TaskScheduler.LAST_UPDATE_BEFORE_WARNING_MS
|
|
):
|
|
logger.warn(
|
|
f"Task {task.id} (action {task.action}) has seen no update for more than 24h and may be stuck"
|
|
)
|
|
|
|
if task.id in self._running_tasks:
|
|
return
|
|
|
|
self._running_tasks.add(task.id)
|
|
await self.update_task(task.id, status=TaskStatus.ACTIVE)
|
|
run_as_background_process(f"task-{task.action}", wrapper)
|