How to call async code from sync code in another thread? - python-3.x

Question

I'm making a Discord bot which send PM when it receive a Github hook.
It use Discord.py and BottlePy, the last one run in a dedicated thread.
Because both frameworks have a blocking main loop.
In BottlePy callback, I call some Discord.py async code.
I wasn't knowing what is Python async, this appear to be complicated when mixed with synchronous code...
Here's the full source code :
import discord
import bottle
import threading
import asyncio
client = discord.Client()
server = bottle.Bottle()
async def dm_on_github_async(userid,request):
print("Fire Discord dm to "+str(userid))
global client
user = client.get_user(userid)
if (user==None):
abort(500, "User lookup failed");
dm_channel = user.dm_channel
if (dm_channel==None):
dm_channel = await user.create_dm()
if (dm_channel==None):
abort(500, "Fail to create DM channel");
print("DM channel is "+str(asyncio.wait(dm_channel.id)))
await dm_channel.send("There's a Github shot !")
await dm_channel.send(str(request.body))
return
#server.post("/dm_on_github/<userid:int>")
def dm_on_github(userid):
return asyncio.run(dm_on_github_async(userid,bottle.request))
#client.event
async def on_ready():
print('We have logged in as {0.user} '.format(client))
##client.event
#async def on_message(message):
# if message.author == client.user:
# return
#
# if message.content.startswith('$hello'):
# await message.channel.send('Hello!')
# # This sample was working very well
class HTTPThread(threading.Thread):
def run(self):
global server
server.run(port=8080)
server_thread = HTTPThread()
print("Starting HTTP server")
server_thread.start()
print("Starting Discord client")
client.run('super secret key')
print("Client terminated")
server.close()
print("Asked server to terminate")
server_thread.join()
print("Server thread successful join")
I want that my Python bot send the body of the HTTP request as PM.
I get a RuntimeError: Timeout context manager should be used inside a task at return asyncio.run(dm_on_github_async(userid,bottle.request)).
I think I'm not doing this mix in the right way...

Answer 1

After a night, I found the way.
To call async code from sync code in another thread, we ask the loop (here this one from Discord.py) to run the callback with asyncio.run_coroutine_threadsafe(), this return a Task() and we wait for his result with result().
The callback will be run in the loop thread, in my case I need to copy() the Bottle request.
Here's a working program (as long you don't mind to stop it...) :
import discord
import bottle
import threading
import asyncio
client = discord.Client()
server = bottle.Bottle()
class HTTPThread(threading.Thread):
def run(self):
global server
server.run(port=8080)
async def dm_on_github_async(userid,request):
user = client.get_user(userid)
if (user==None):
abort(500, "User lookup failed");
dm_channel = user.dm_channel
if (dm_channel==None):
dm_channel = await user.create_dm()
if (dm_channel==None):
abort(500, "Fail to create DM channel");
# Handle the request
event = request.get_header("X-GitHub-Event")
await dm_channel.send("Got event "+str(event))
#await dm_channel.send(str(request.body)) # Doesn't work well...
return
#server.post("/dm_on_github/<userid:int>")
def dm_on_github(userid):
request = bottle.request
asyncio.run_coroutine_threadsafe(dm_on_github_async(userid,request.copy()),client.loop).result()
#client.event
async def on_ready():
print('We have logged in as {0.user} '.format(client))
# Wait for the old HTTP server
if hasattr(client,"server_thread"):
server.close()
client.server_thread.join()
client.server_thread = HTTPThread()
client.server_thread.start()
##client.event
#async def on_message(message):
# if message.author == client.user:
# return
#
# if message.content.startswith('$hello'):
# await message.channel.send('Hello!')
print("Starting Discord client")
client.run('super secret key')
print("Client terminated")
server.close()
print("Asked server to terminate")
server_thread.join()
print("Server thread successful join")