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import asyncio
import functools
import os
from django.core.exceptions import SynchronousOnlyOperation
from django.utils.version import PY37
if PY37:
get_running_loop = asyncio.get_running_loop
else:
get_running_loop = asyncio.get_event_loop
def async_unsafe(message):
"""
Decorator to mark functions as async-unsafe. Someone trying to access
the function while in an async context will get an error message.
"""
def decorator(func):
@functools.wraps(func)
def inner(*args, **kwargs):
if not os.environ.get('DJANGO_ALLOW_ASYNC_UNSAFE'):
# Detect a running event loop in this thread.
try:
event_loop = get_running_loop()
except RuntimeError:
pass
else:
if PY37 or event_loop.is_running():
raise SynchronousOnlyOperation(message)
# Pass onwards.
return func(*args, **kwargs)
return inner
# If the message is actually a function, then be a no-arguments decorator.
if callable(message):
func = message
message = 'You cannot call this from an async context - use a thread or sync_to_async.'
return decorator(func)
else:
return decorator
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