disnake.ext.tasks
– asyncio.Task helpers¶
New in version 1.1.0.
One of the most common operations when making a bot is having a loop run in the background at a specified interval. This pattern is very common but has a lot of things you need to look out for:
How do I handle
asyncio.CancelledError
?What do I do if the internet goes out?
What is the maximum number of seconds I can sleep anyway?
The goal of this disnake extension is to abstract all these worries away from you.
Recipes¶
A simple background task in a Cog
:
from disnake.ext import tasks, commands
class MyCog(commands.Cog):
def __init__(self):
self.index = 0
self.printer.start()
def cog_unload(self):
self.printer.cancel()
@tasks.loop(seconds=5.0)
async def printer(self):
print(self.index)
self.index += 1
Adding an exception to handle during reconnect:
import asyncpg
from disnake.ext import tasks, commands
class MyCog(commands.Cog):
def __init__(self, bot):
self.bot = bot
self.data = []
self.batch_update.add_exception_type(asyncpg.PostgresConnectionError)
self.batch_update.start()
def cog_unload(self):
self.batch_update.cancel()
@tasks.loop(minutes=5.0)
async def batch_update(self):
async with self.bot.pool.acquire() as con:
# batch update here...
pass
Looping a certain amount of times before exiting:
from disnake.ext import tasks
@tasks.loop(seconds=5.0, count=5)
async def slow_count():
print(slow_count.current_loop)
@slow_count.after_loop
async def after_slow_count():
print('done!')
slow_count.start()
Waiting until the bot is ready before the loop starts:
from disnake.ext import tasks, commands
class MyCog(commands.Cog):
def __init__(self, bot):
self.index = 0
self.bot = bot
self.printer.start()
def cog_unload(self):
self.printer.cancel()
@tasks.loop(seconds=5.0)
async def printer(self):
print(self.index)
self.index += 1
@printer.before_loop
async def before_printer(self):
print('waiting...')
await self.bot.wait_until_ready()
Doing something during cancellation:
from disnake.ext import tasks, commands
import asyncio
class MyCog(commands.Cog):
def __init__(self, bot):
self.bot= bot
self._batch = []
self.lock = asyncio.Lock()
self.bulker.start()
async def do_bulk(self):
# bulk insert data here
...
@tasks.loop(seconds=10.0)
async def bulker(self):
async with self.lock:
await self.do_bulk()
@bulker.after_loop
async def on_bulker_cancel(self):
if self.bulker.is_being_cancelled() and len(self._batch) != 0:
# if we're cancelled and we have some data left...
# let's insert it to our database
await self.do_bulk()
API Reference¶
- async__call__
- defadd_exception_type
- @after_loop
- @before_loop
- defcancel
- defchange_interval
- defclear_exception_types
- @error
- deffailed
- defget_task
- defis_being_cancelled
- defis_running
- defremove_exception_type
- defrestart
- defstart
- defstop
- class disnake.ext.tasks.Loop[source]¶
A background task helper that abstracts the loop and reconnection logic for you.
The main interface to create this is through
loop()
.- @after_loop[source]¶
A decorator that register a coroutine to be called after the loop finished running.
The coroutine must take no arguments (except
self
in a class context).Note
This coroutine is called even during cancellation. If it is desirable to tell apart whether something was cancelled or not, check to see whether
is_being_cancelled()
isTrue
or not.
- @before_loop[source]¶
A decorator that registers a coroutine to be called before the loop starts running.
This is useful if you want to wait for some bot state before the loop starts, such as
disnake.Client.wait_until_ready()
.The coroutine must take no arguments (except
self
in a class context).
- @error[source]¶
A decorator that registers a coroutine to be called if the task encounters an unhandled exception.
The coroutine must take only one argument the exception raised (except
self
in a class context).By default this prints to
sys.stderr
however it could be overridden to have a different implementation.New in version 1.4.
- property seconds[source]¶
Read-only value for the number of seconds between each iteration.
None
if an explicittime
value was passed instead.New in version 2.0.
- Type:
Optional[
float
]
- property minutes[source]¶
Read-only value for the number of minutes between each iteration.
None
if an explicittime
value was passed instead.New in version 2.0.
- Type:
Optional[
float
]
- property hours[source]¶
Read-only value for the number of hours between each iteration.
None
if an explicittime
value was passed instead.New in version 2.0.
- Type:
Optional[
float
]
- property time[source]¶
Read-only list for the exact times this loop runs at.
None
if relative times were passed instead.New in version 2.0.
- Type:
Optional[List[
datetime.time
]]
- property next_iteration[source]¶
When the next iteration of the loop will occur.
New in version 1.3.
- Type:
Optional[
datetime.datetime
]
- await __call__(*args, **kwargs)[source]¶
This function is a coroutine.
Calls the internal callback that the task holds.
New in version 1.6.
- Parameters:
*args – The arguments to use.
**kwargs – The keyword arguments to use.
- start(*args, **kwargs)[source]¶
Starts the internal task in the event loop.
- Parameters:
*args – The arguments to use.
**kwargs – The keyword arguments to use.
- Raises:
RuntimeError – A task has already been launched and is running.
- Returns:
The task that has been created.
- Return type:
- stop()[source]¶
Gracefully stops the task from running.
Unlike
cancel()
, this allows the task to finish its current iteration before gracefully exiting.Note
If the internal function raises an error that can be handled before finishing then it will retry until it succeeds.
If this is undesirable, either remove the error handling before stopping via
clear_exception_types()
or usecancel()
instead.New in version 1.2.
- restart(*args, **kwargs)[source]¶
A convenience method to restart the internal task.
Note
Due to the way this function works, the task is not returned like
start()
.- Parameters:
*args – The arguments to use.
**kwargs – The keyword arguments to use.
- add_exception_type(*exceptions)[source]¶
Adds exception types to be handled during the reconnect logic.
By default the exception types handled are those handled by
disnake.Client.connect()
, which includes a lot of internet disconnection errors.This function is useful if you’re interacting with a 3rd party library that raises its own set of exceptions.
- Parameters:
*exceptions (Type[
BaseException
]) – An argument list of exception classes to handle.- Raises:
TypeError – An exception passed is either not a class or not inherited from
BaseException
.
- clear_exception_types()[source]¶
Removes all exception types that are handled.
Note
This operation obviously cannot be undone!
- remove_exception_type(*exceptions)[source]¶
Removes exception types from being handled during the reconnect logic.
- Parameters:
*exceptions (Type[
BaseException
]) – An argument list of exception classes to handle.- Returns:
Whether all exceptions were successfully removed.
- Return type:
- get_task()[source]¶
Fetches the internal task or
None
if there isn’t one running.- Return type:
Optional[
asyncio.Task
]
- change_interval(*, seconds=0, minutes=0, hours=0, time=...)[source]¶
Changes the interval for the sleep time.
New in version 1.2.
- Parameters:
seconds (
float
) – The number of seconds between every iteration.minutes (
float
) – The number of minutes between every iteration.hours (
float
) – The number of hours between every iteration.time (Union[
datetime.time
, Sequence[datetime.time
]]) –The exact times to run this loop at. Either a non-empty list or a single value of
datetime.time
should be passed. This cannot be used in conjunction with the relative time parameters.New in version 2.0.
Note
Duplicate times will be ignored, and only run once.
- Raises:
ValueError – An invalid value was given.
TypeError – An invalid value for the
time
parameter was passed, or thetime
parameter was passed in conjunction with relative time parameters.
- @disnake.ext.tasks.loop(cls=disnake.ext.tasks.Loop[typing.Any], **kwargs)[source]¶
A decorator that schedules a task in the background for you with optional reconnect logic. The decorator returns a
Loop
.- Parameters:
cls (Type[
Loop
]) –The loop subclass to create an instance of. If provided, the following parameters described below do not apply. Instead, this decorator will accept the same keywords as the passed cls does.
New in version 2.6.
seconds (
float
) – The number of seconds between every iteration.minutes (
float
) – The number of minutes between every iteration.hours (
float
) – The number of hours between every iteration.time (Union[
datetime.time
, Sequence[datetime.time
]]) –The exact times to run this loop at. Either a non-empty list or a single value of
datetime.time
should be passed. Timezones are supported. If no timezone is given for the times, it is assumed to represent UTC time.This cannot be used in conjunction with the relative time parameters.
Note
Duplicate times will be ignored, and only run once.
New in version 2.0.
count (Optional[
int
]) – The number of loops to do,None
if it should be an infinite loop.reconnect (
bool
) – Whether to handle errors and restart the task using an exponential back-off algorithm similar to the one used indisnake.Client.connect()
.loop (
asyncio.AbstractEventLoop
) – The loop to use to register the task, if not given defaults toasyncio.get_event_loop()
.
- Raises:
ValueError – An invalid value was given.
TypeError – The function was not a coroutine, the
cls
parameter was not a subclass ofLoop
, an invalid value for thetime
parameter was passed, ortime
parameter was passed in conjunction with relative time parameters.