Stop using asyncio.get_event_loop()

It is deprecated in newer Python versions.
Closes #4013.

readthedocs/concepts/asyncio.rst

@@ -40,22 +40,22 @@ because tasks are smaller than threads, which are smaller than processes.
 What are asyncio basics?
 ========================
 
+The code samples below assume that you have Python 3.7 or greater installed.
+
 .. code-block:: python
 
     # First we need the asyncio library
     import asyncio
 
-    # Then we need a loop to work with
-    loop = asyncio.get_event_loop()
-
     # We also need something to run
     async def main():
         for char in 'Hello, world!\n':
             print(char, end='', flush=True)
             await asyncio.sleep(0.2)
 
-    # Then, we need to run the loop with a task
-    loop.run_until_complete(main())
+    # Then, we can create a new asyncio loop and use it to run our coroutine.
+    # The creation and tear-down of the loop is hidden away from us.
+    asyncio.run(main())
 
 
 What does telethon.sync do?
@@ -101,7 +101,7 @@ Instead of this:
 
     # or, using asyncio's default loop (it's the same)
     import asyncio
-    loop = asyncio.get_event_loop()  # == client.loop
+    loop = asyncio.get_running_loop()  # == client.loop
     me = loop.run_until_complete(client.get_me())
     print(me.username)
 
@@ -158,13 +158,10 @@ loops or use ``async with``:
 
                 print(message.sender.username)
 
-    loop = asyncio.get_event_loop()
-    # ^ this assigns the default event loop from the main thread to a variable
-
-    loop.run_until_complete(main())
-    # ^ this runs the *entire* loop until the main() function finishes.
-    #   While the main() function does not finish, the loop will be running.
-    #   While the loop is running, you can't run it again.
+    asyncio.run(main())
+    # ^ this will create a new asyncio loop behind the scenes and tear it down
+    #   once the function returns. It will run the loop untiil main finishes.
+    #   You should only use this function if there is no other loop running.
 
 
 The ``await`` keyword blocks the *current* task, and the loop can run
@@ -184,14 +181,14 @@ concurrently:
         await asyncio.sleep(delay)  # await tells the loop this task is "busy"
         print('world')  # eventually the loop finishes all tasks
 
-    loop = asyncio.get_event_loop()  # get the default loop for the main thread
-    loop.create_task(world(2))  # create the world task, passing 2 as delay
-    loop.create_task(hello(delay=1))  # another task, but with delay 1
+    async def main():
+        asyncio.create_task(world(2))  # create the world task, passing 2 as delay
+        asyncio.create_task(hello(delay=1))  # another task, but with delay 1
+        await asyncio.sleep(3)  # wait for three seconds before exiting
+
     try:
-        # run the event loop forever; ctrl+c to stop it
-        # we could also run the loop for three seconds:
-        #     loop.run_until_complete(asyncio.sleep(3))
-        loop.run_forever()
+        # create a new temporary asyncio loop and use it to run main
+        asyncio.run(main())
     except KeyboardInterrupt:
         pass
 
@@ -209,10 +206,15 @@ The same example, but without the comment noise:
         await asyncio.sleep(delay)
         print('world')
 
-    loop = asyncio.get_event_loop()
-    loop.create_task(world(2))
-    loop.create_task(hello(1))
-    loop.run_until_complete(asyncio.sleep(3))
+    async def main():
+        asyncio.create_task(world(2))
+        asyncio.create_task(hello(delay=1))
+        await asyncio.sleep(3)
+
+    try:
+        asyncio.run(main())
+    except KeyboardInterrupt:
+        pass
 
 
 Can I use threads?
@@ -250,9 +252,9 @@ You may have seen this error:
 
     RuntimeError: There is no current event loop in thread 'Thread-1'.
 
-It just means you didn't create a loop for that thread, and if you don't
-pass a loop when creating the client, it uses ``asyncio.get_event_loop()``,
-which only works in the main thread.
+It just means you didn't create a loop for that thread. Please refer to
+the ``asyncio`` documentation to correctly learn how to set the event loop
+for non-main threads.
 
 
 client.run_until_disconnected() blocks!

readthedocs/concepts/updates.rst

@@ -191,8 +191,7 @@ so the code above and the following are equivalent:
     async def main():
         await client.disconnected
 
-    loop = asyncio.get_event_loop()
-    loop.run_until_complete(main())
+    asyncio.run(main())
 
 
 You could also run `client.disconnected

readthedocs/misc/changelog.rst

@@ -2088,7 +2088,7 @@ the scenes! This means you're now able to do both of the following:
     async def main():
       await client.send_message('me', 'Hello!')
 
-    asyncio.get_event_loop().run_until_complete(main())
+    asyncio.run(main())
 
     # ...can be rewritten as:
 

readthedocs/misc/compatibility-and-convenience.rst

@@ -161,19 +161,17 @@ just get rid of ``telethon.sync`` and work inside an ``async def``:
 
             await client.run_until_disconnected()
 
-    loop = asyncio.get_event_loop()
-    loop.run_until_complete(main())
+    asyncio.run(main())
 
 
-The ``telethon.sync`` magic module simply wraps every method behind:
+The ``telethon.sync`` magic module essentially wraps every method behind:
 
 .. code-block:: python
 
-    loop = asyncio.get_event_loop()
-    loop.run_until_complete(main())
+    asyncio.run(main())
 
-So that you don't have to write it yourself every time. That's the
-overhead you pay if you import it, and what you save if you don't.
+With some other tricks, so that you don't have to write it yourself every time.
+That's the overhead you pay if you import it, and what you save if you don't.
 
 Learning
 ========

telethon/client/telegrambaseclient.py

@@ -192,7 +192,7 @@ class TelegramBaseClient(abc.ABC):
             Defaults to `lang_code`.
 
         loop (`asyncio.AbstractEventLoop`, optional):
-            Asyncio event loop to use. Defaults to `asyncio.get_event_loop()`.
+            Asyncio event loop to use. Defaults to `asyncio.get_running_loop()`.
             This argument is ignored.
 
         base_logger (`str` | `logging.Logger`, optional):
@@ -470,7 +470,7 @@ def loop(self: 'TelegramClient') -> asyncio.AbstractEventLoop:
                 # Join the task (wait for it to complete)
                 await task
         """
-        return asyncio.get_event_loop()
+        return helpers.get_running_loop()
 
     @property
     def disconnected(self: 'TelegramClient') -> asyncio.Future:

telethon/events/inlinequery.py

@@ -4,7 +4,7 @@
 import asyncio
 
 from .common import EventBuilder, EventCommon, name_inner_event
-from .. import utils
+from .. import utils, helpers
 from ..tl import types, functions, custom
 from ..tl.custom.sendergetter import SenderGetter
 
@@ -242,6 +242,6 @@ def _as_future(obj):
             if inspect.isawaitable(obj):
                 return asyncio.ensure_future(obj)
 
-            f = asyncio.get_event_loop().create_future()
+            f = helpers.get_running_loop().create_future()
             f.set_result(obj)
             return f

telethon/helpers.py

@@ -153,7 +153,7 @@ def retry_range(retries, force_retry=True):
     while attempt != retries:
         attempt += 1
         yield attempt
-        
+
 
 
 async def _maybe_await(value):
@@ -426,7 +426,10 @@ def close(self, *args, **kwargs):
 # endregion
 
 def get_running_loop():
-    if sys.version_info[:2] <= (3, 6):
-        return asyncio._get_running_loop()
-
-    return asyncio.get_running_loop()
+    if sys.version_info >= (3, 7):
+        try:
+            return asyncio.get_running_loop()
+        except RuntimeError:
+            return asyncio.get_event_loop_policy().get_event_loop()
+    else:
+        return asyncio.get_event_loop()

telethon/network/connection/connection.py

@@ -155,7 +155,7 @@ async def _proxy_connect(self, timeout=None, local_addr=None):
 
                 # Actual TCP connection is performed here.
                 await asyncio.wait_for(
-                    asyncio.get_event_loop().sock_connect(sock=sock, address=address),
+                    helpers.get_running_loop().sock_connect(sock=sock, address=address),
                     timeout=timeout
                 )
 
@@ -190,7 +190,7 @@ async def _proxy_connect(self, timeout=None, local_addr=None):
 
             # Actual TCP connection and negotiation performed here.
             await asyncio.wait_for(
-                asyncio.get_event_loop().sock_connect(sock=sock, address=address),
+                helpers.get_running_loop().sock_connect(sock=sock, address=address),
                 timeout=timeout
             )
 
@@ -244,7 +244,7 @@ async def connect(self, timeout=None, ssl=None):
         await self._connect(timeout=timeout, ssl=ssl)
         self._connected = True
 
-        loop = asyncio.get_event_loop()
+        loop = helpers.get_running_loop()
         self._send_task = loop.create_task(self._send_loop())
         self._recv_task = loop.create_task(self._recv_loop())
 

telethon/network/mtprotosender.py

@@ -68,7 +68,7 @@ def __init__(self, auth_key, *, loggers,
         # pending futures should be cancelled.
         self._user_connected = False
         self._reconnecting = False
-        self._disconnected = asyncio.get_event_loop().create_future()
+        self._disconnected = helpers.get_running_loop().create_future()
         self._disconnected.set_result(None)
 
         # We need to join the loops upon disconnection
@@ -261,7 +261,7 @@ async def _connect(self):
             await self._disconnect(error=e)
             raise e
 
-        loop = asyncio.get_event_loop()
+        loop = helpers.get_running_loop()
         self._log.debug('Starting send loop')
         self._send_loop_handle = loop.create_task(self._send_loop())
 
@@ -400,7 +400,7 @@ async def _reconnect(self, last_error):
                 self._pending_state.clear()
 
                 if self._auto_reconnect_callback:
-                    asyncio.get_event_loop().create_task(self._auto_reconnect_callback())
+                    helpers.get_running_loop().create_task(self._auto_reconnect_callback())
 
                 break
         else:
@@ -425,7 +425,7 @@ def _start_reconnect(self, error):
             # gets stuck.
             # TODO It still gets stuck? Investigate where and why.
             self._reconnecting = True
-            asyncio.get_event_loop().create_task(self._reconnect(error))
+            helpers.get_running_loop().create_task(self._reconnect(error))
 
     def _keepalive_ping(self, rnd_id):
         """

telethon/sync.py

@@ -14,7 +14,7 @@
 import functools
 import inspect
 
-from . import events, errors, utils, connection
+from . import events, errors, utils, connection, helpers
 from .client.account import _TakeoutClient
 from .client.telegramclient import TelegramClient
 from .tl import types, functions, custom
@@ -32,7 +32,7 @@ def _syncify_wrap(t, method_name):
     @functools.wraps(method)
     def syncified(*args, **kwargs):
         coro = method(*args, **kwargs)
-        loop = asyncio.get_event_loop()
+        loop = helpers.get_running_loop()
         if loop.is_running():
             return coro
         else:

telethon_examples/gui.py

@@ -53,7 +53,7 @@ def callback(func):
     def wrapped(*args, **kwargs):
         result = func(*args, **kwargs)
         if inspect.iscoroutine(result):
-            aio_loop.create_task(result)
+            asyncio.create_task(result)
 
     return wrapped
 
@@ -369,10 +369,4 @@ async def main(interval=0.05):
 
 
 if __name__ == "__main__":
-    # Some boilerplate code to set up the main method
-    aio_loop = asyncio.get_event_loop()
-    try:
-        aio_loop.run_until_complete(main())
-    finally:
-        if not aio_loop.is_closed():
-            aio_loop.close()
+    asyncio.run(main())