mirror of
https://github.com/LonamiWebs/Telethon.git
synced 2024-12-02 14:23:45 +03:00
322 lines
10 KiB
ReStructuredText
322 lines
10 KiB
ReStructuredText
.. _asyncio-magic:
|
|
|
|
==================
|
|
Magic with asyncio
|
|
==================
|
|
|
|
.. important::
|
|
|
|
TL; DR; If you've upgraded to Telethon 1.0 from a previous version
|
|
**and you're not using events or updates**, add this line:
|
|
|
|
.. code-block:: python
|
|
|
|
import telethon.sync
|
|
|
|
At the beginning of your main script and you will be good. If you
|
|
do use updates or events, keep reading, or use `a simpler version
|
|
<https://github.com/LonamiWebs/Telethon/tree/sync>`_ (discouraged).
|
|
|
|
You might also want to check the :ref:`changelog`.
|
|
|
|
|
|
The sync module
|
|
***************
|
|
|
|
It's time to tell you the truth. The library has been doing magic behind
|
|
the scenes. We're sorry to tell you this, but at least it wasn't dark magic!
|
|
|
|
You may have noticed one of these lines across the documentation:
|
|
|
|
.. code-block:: python
|
|
|
|
from telethon import sync
|
|
# or
|
|
import telethon.sync
|
|
|
|
Either of these lines will import the *magic* ``sync`` module. When you
|
|
import this module, you can suddenly use all the methods defined in the
|
|
:ref:`TelegramClient <telethon-client>` like so:
|
|
|
|
.. code-block:: python
|
|
|
|
client.send_message('me', 'Hello!')
|
|
|
|
for dialog in client.iter_dialogs():
|
|
print(dialog.title)
|
|
|
|
|
|
What happened behind the scenes is that all those methods, called *coroutines*,
|
|
were rewritten to be normal methods that will block (with some exceptions).
|
|
This means you can use the library without worrying about ``asyncio`` and
|
|
event loops.
|
|
|
|
However, this only works until you run the event loop yourself explicitly:
|
|
|
|
.. code-block:: python
|
|
|
|
import asyncio
|
|
|
|
async def coro():
|
|
client.send_message('me', 'Hello!') # <- no longer works!
|
|
|
|
loop = asyncio.get_event_loop()
|
|
loop.run_until_complete(coro())
|
|
|
|
|
|
What things will work and when?
|
|
*******************************
|
|
|
|
You can use all the methods in the :ref:`TelegramClient <telethon-client>`
|
|
in a synchronous, blocking way without trouble, as long as you're not running
|
|
the loop as we saw above (the ``loop.run_until_complete(...)`` line runs "the
|
|
loop"). If you're running the loop, then *you* are the one responsible to
|
|
``await`` everything. So to fix the code above:
|
|
|
|
.. code-block:: python
|
|
|
|
import asyncio
|
|
|
|
async def coro():
|
|
await client.send_message('me', 'Hello!')
|
|
# ^ notice this new await
|
|
|
|
loop = asyncio.get_event_loop()
|
|
loop.run_until_complete(coro())
|
|
|
|
The library can only run the loop until the method completes if the loop
|
|
isn't already running, which is why the magic can't work if you run the
|
|
loop yourself.
|
|
|
|
**When you work with updates or events**, the loop needs to be
|
|
running one way or another (using `client.run_until_disconnected()
|
|
<telethon.client.updates.UpdateMethods.run_until_disconnected>` runs the loop),
|
|
so your event handlers must be ``async def``.
|
|
|
|
.. important::
|
|
|
|
Turning your event handlers into ``async def`` is the biggest change
|
|
between Telethon pre-1.0 and 1.0, but updating will likely cause a
|
|
noticeable speed-up in your programs. Keep reading!
|
|
|
|
|
|
So in short, you can use **all** methods in the client with ``await`` or
|
|
without it if the loop isn't running:
|
|
|
|
.. code-block:: python
|
|
|
|
client.send_message('me', 'Hello!') # works
|
|
|
|
async def main():
|
|
await client.send_message('me', 'Hello!') # also works
|
|
|
|
loop.run_until_complete(main())
|
|
|
|
|
|
When you work with updates, you should stick using the ``async def main``
|
|
way, since your event handlers will be ``async def`` too.
|
|
|
|
.. note::
|
|
|
|
There are two exceptions. Both `client.run_until_disconnected()
|
|
<telethon.client.updates.UpdateMethods.run_until_disconnected>` and
|
|
`client.start() <telethon.client.updates.UpdateMethods.start>` work in
|
|
and outside of ``async def`` for convenience without importing the
|
|
magic module. The rest of methods remain ``async`` unless you import it.
|
|
|
|
You can skip the rest if you already know how ``asyncio`` works and you
|
|
already understand what the magic does and how it works. Just remember
|
|
to ``await`` all your methods if you're inside an ``async def`` or are
|
|
using updates and you will be good.
|
|
|
|
|
|
Why asyncio?
|
|
************
|
|
|
|
Python's `asyncio <https://docs.python.org/3/library/asyncio.html>`_ is the
|
|
standard way to run asynchronous code from within Python. Since Python 3.5,
|
|
using ``async def`` and ``await`` became possible, and Python 3.6 further
|
|
improves what you can do with asynchronous code, although it's not the only
|
|
way (other projects like `Trio <https://github.com/python-trio>`_ also exist).
|
|
|
|
Telegram is a service where all API calls are executed in an asynchronous
|
|
way. You send your request, and eventually, Telegram will process it and
|
|
respond to it. It feels natural to make a library that also behaves this
|
|
way: you send a request, and you can ``await`` for its result.
|
|
|
|
Now that we know that Telegram's API follows an asynchronous model, you
|
|
should understand the benefits of developing a library that does the same,
|
|
it greatly simplifies the internal code and eases working with the API.
|
|
|
|
Using ``asyncio`` keeps a cleaner library that will be easier to understand,
|
|
develop, and that will be faster than using threads, which are harder to get
|
|
right and can cause issues. It also enables to use the powerful ``asyncio``
|
|
system such as futures, timeouts, cancellation, etc. in a natural way.
|
|
|
|
If you're still not convinced or you're just not ready for using ``asyncio``,
|
|
the library offers a synchronous interface without the need for all the
|
|
``async`` and ``await`` you would otherwise see. `Follow this link
|
|
<https://github.com/LonamiWebs/Telethon/tree/sync>`_ to find out more.
|
|
|
|
|
|
How do I get started?
|
|
*********************
|
|
|
|
To get started with ``asyncio``, all you need is to setup your main
|
|
``async def`` like so:
|
|
|
|
.. code-block:: python
|
|
|
|
import asyncio
|
|
|
|
async def main():
|
|
pass # Your code goes here
|
|
|
|
if __name__ == '__main__':
|
|
loop = asyncio.get_event_loop()
|
|
loop.run_until_complete(main())
|
|
|
|
You don't need to ``import telethon.sync`` if you're going to work this
|
|
way. This is the best way to work in real programs since the loop won't
|
|
be starting and ending all the time, but is a bit more annoying to setup.
|
|
|
|
Inside ``async def main()``, you can use the ``await`` keyword. Most
|
|
methods in the :ref:`TelegramClient <telethon-client>` are ``async def``.
|
|
You must ``await`` all ``async def``, also known as a *coroutines*:
|
|
|
|
.. code-block:: python
|
|
|
|
async def main():
|
|
client = TelegramClient(...)
|
|
|
|
# client.start() is a coroutine (async def), it needs an await
|
|
await client.start()
|
|
|
|
# Sending a message also interacts with the API, and needs an await
|
|
await client.send_message('me', 'Hello myself!')
|
|
|
|
|
|
If you don't know anything else about ``asyncio``, this will be enough
|
|
to get you started. Once you're ready to learn more about it, you will
|
|
be able to use that power and everything you've learnt with Telethon.
|
|
Just remember that if you use ``await``, you need to be inside of an
|
|
``async def``.
|
|
|
|
Another way to use ``async def`` is to use ``loop.run_until_complete(f())``,
|
|
but the loop must not be running before.
|
|
|
|
If you want to handle updates (and don't let the script die), you must
|
|
`await client.run_until_disconnected()
|
|
<telethon.client.updates.UpdateMethods.run_until_disconnected>`
|
|
which is a property that you can wait on until you call
|
|
`await client.disconnect()
|
|
<telethon.client.telegrambaseclient.TelegramBaseClient.disconnect>`:
|
|
|
|
|
|
.. code-block:: python
|
|
|
|
client = TelegramClient(...)
|
|
|
|
@client.on(events.NewMessage)
|
|
async def handler(event):
|
|
print(event)
|
|
|
|
async def main():
|
|
await client.start()
|
|
await client.run_until_disconnected()
|
|
|
|
if __name__ == '__main__':
|
|
loop = asyncio.get_event_loop()
|
|
loop.run_until_complete(main())
|
|
|
|
`client.run_until_disconnected()
|
|
<telethon.client.updates.UpdateMethods.run_until_disconnected>` and
|
|
`client.start()
|
|
<telethon.client.auth.AuthMethods.start>` are special-cased and work
|
|
inside or outside ``async def`` for convenience, even without importing
|
|
the ``sync`` module, so you can also do this:
|
|
|
|
.. code-block:: python
|
|
|
|
client = TelegramClient(...)
|
|
|
|
@client.on(events.NewMessage)
|
|
async def handler(event):
|
|
print(event)
|
|
|
|
if __name__ == '__main__':
|
|
client.start()
|
|
client.run_until_disconnected()
|
|
|
|
|
|
Which methods should I use and when?
|
|
************************************
|
|
|
|
Something to note is that you must always get an event loop if you
|
|
want to be able to make any API calls. This is done as follows:
|
|
|
|
.. code-block:: python
|
|
|
|
import asyncio
|
|
loop = asyncio.get_event_loop()
|
|
|
|
The loop must be running, or things will never get sent.
|
|
Normally, you use ``run_until_complete``:
|
|
|
|
.. code-block:: python
|
|
|
|
async def coroutine():
|
|
await asyncio.sleep(1)
|
|
|
|
loop.run_until_complete(coroutine())
|
|
|
|
Note that ``asyncio.sleep`` is in itself a coroutine, so this will
|
|
work too:
|
|
|
|
.. code-block:: python
|
|
|
|
loop.run_until_complete(asyncio.sleep(1))
|
|
|
|
Generally, you make an ``async def main()`` if you need to ``await``
|
|
a lot of things, instead of typing ``run_until_complete`` all the time:
|
|
|
|
.. code-block:: python
|
|
|
|
async def main():
|
|
message = await client.send_message('me', 'Hi')
|
|
await asyncio.sleep(1)
|
|
await message.delete()
|
|
|
|
loop.run_until_complete(main())
|
|
|
|
# vs
|
|
|
|
message = loop.run_until_complete(client.send_message('me', 'Hi'))
|
|
loop.run_until_complete(asyncio.sleep(1))
|
|
loop.run_until_complete(message.delete())
|
|
|
|
You can see that the first version has more lines, but you had to type
|
|
a lot less. You can also rename the run method to something shorter:
|
|
|
|
.. code-block:: python
|
|
|
|
# Note no parenthesis (), we're not running it, just copying the method
|
|
rc = loop.run_until_complete
|
|
message = rc(client.send_message('me', 'Hi'))
|
|
rc(asyncio.sleep(1))
|
|
rc(message.delete())
|
|
|
|
The documentation generally runs the loop until complete behind the
|
|
scenes if you've imported the magic ``sync`` module, but if you haven't,
|
|
you need to run the loop yourself. We recommend that you use the
|
|
``async def main()`` method to do all your work with ``await``.
|
|
It's the easiest and most performant thing to do.
|
|
|
|
|
|
More resources to learn asyncio
|
|
*******************************
|
|
|
|
If you would like to learn a bit more about why ``asyncio`` is something
|
|
you should learn, `check out my blog post
|
|
<https://lonamiwebs.github.io/blog/asyncio/>`_ that goes into more detail.
|