Workaround for asyncio.get_event_loop() deprecation

aiosmtpd/__init__.py

@@ -1,4 +1,21 @@
 # Copyright 2014-2021 The aiosmtpd Developers
 # SPDX-License-Identifier: Apache-2.0
+import asyncio
+import warnings
 
-__version__ = "1.4.4a0"
+
+__version__ = "1.4.4a1"
+
+
+def _get_or_new_eventloop() -> asyncio.AbstractEventLoop:
+    loop = None
+    with warnings.catch_warnings():
+        warnings.simplefilter("error")
+        try:
+            loop = asyncio.get_event_loop()
+        except (DeprecationWarning, RuntimeError):  # pragma: py-lt-310
+            if loop is None:  # pragma: py-lt-312
+                loop = asyncio.new_event_loop()
+                asyncio.set_event_loop(loop)
+    assert isinstance(loop, asyncio.AbstractEventLoop)
+    return loop

aiosmtpd/docs/NEWS.rst

@@ -16,10 +16,12 @@ Fixed/Improved
 * A whole bunch of annotations
 
 
-1.4.4a0 (ad hoc)
+1.4.4a1 (ad hoc)
 ================
 
-(Stub ``NEWS.rst`` entry as placeholder for ``qa`` test.)
+Fixed/Improved
+--------------
+* No longer expect an implicit creation of the event loop through ``get_event_loop()`` (Closes #353)
 
 
 1.4.3 (2022-12-21)

aiosmtpd/docs/controller.rst

@@ -236,7 +236,8 @@ you'll have to do something similar to this:
 .. doctest:: unthreaded
 
     >>> import asyncio
-    >>> loop = asyncio.get_event_loop()
+    >>> loop = asyncio.new_event_loop()
+    >>> asyncio.set_event_loop(loop)
     >>> from aiosmtpd.controller import UnthreadedController
     >>> from aiosmtpd.handlers import Sink
     >>> controller = UnthreadedController(Sink(), loop=loop)

aiosmtpd/handlers.py

@@ -25,6 +25,7 @@
 
 from public import public
 
+from aiosmtpd import _get_or_new_eventloop
 from aiosmtpd.smtp import SMTP as SMTPServer
 from aiosmtpd.smtp import Envelope as SMTPEnvelope
 from aiosmtpd.smtp import Session as SMTPSession
@@ -218,7 +219,7 @@ def __init__(
         loop: Optional[asyncio.AbstractEventLoop] = None,
     ):
         super().__init__(message_class)
-        self.loop = loop or asyncio.get_event_loop()
+        self.loop = loop or _get_or_new_eventloop()
 
     async def handle_DATA(
         self, server: SMTPServer, session: SMTPSession, envelope: SMTPEnvelope

aiosmtpd/main.py

@@ -1,7 +1,6 @@
 # Copyright 2014-2021 The aiosmtpd Developers
 # SPDX-License-Identifier: Apache-2.0
 
-import asyncio
 import logging
 import os
 import signal
@@ -16,7 +15,7 @@
 
 from public import public
 
-from aiosmtpd import __version__
+from aiosmtpd import __version__, _get_or_new_eventloop
 from aiosmtpd.smtp import DATA_SIZE_DEFAULT, SMTP
 
 try:
@@ -252,7 +251,7 @@ def main(args: Optional[Sequence[str]] = None) -> None:
 
     logging.basicConfig(level=logging.ERROR)
     log = logging.getLogger("mail.log")
-    loop = asyncio.get_event_loop()
+    loop = _get_or_new_eventloop()
 
     if args.debug > 0:
         log.setLevel(logging.INFO)

aiosmtpd/smtp.py

@@ -34,7 +34,7 @@
 import attr
 from public import public
 
-from aiosmtpd import __version__
+from aiosmtpd import __version__, _get_or_new_eventloop
 from aiosmtpd.proxy_protocol import ProxyData, get_proxy
 
 
@@ -208,7 +208,7 @@ def __init__(self) -> None:
 # unit test suite.  In that case, this function is mocked to set the debug
 # level on the loop (as if PYTHONASYNCIODEBUG=1 were set).
 def make_loop() -> asyncio.AbstractEventLoop:
-    return asyncio.get_event_loop()
+    return _get_or_new_eventloop()
 
 
 @public

aiosmtpd/tests/conftest.py

@@ -5,6 +5,7 @@
 import inspect
 import socket
 import ssl
+import warnings
 from contextlib import suppress
 from functools import wraps
 from smtplib import SMTP as SMTPClient
@@ -200,14 +201,20 @@ def getter(*args, **kwargs) -> Any:
 
 @pytest.fixture
 def temp_event_loop() -> Generator[asyncio.AbstractEventLoop, None, None]:
-    default_loop = asyncio.get_event_loop()
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore")
+        try:
+            default_loop = asyncio.get_event_loop()
+        except (DeprecationWarning, RuntimeError):
+            default_loop = None
     new_loop = asyncio.new_event_loop()
     asyncio.set_event_loop(new_loop)
     #
     yield new_loop
     #
     new_loop.close()
-    asyncio.set_event_loop(default_loop)
+    if default_loop is not None:
+        asyncio.set_event_loop(default_loop)
 
 
 @pytest.fixture

aiosmtpd/tests/test_misc.py

@@ -0,0 +1,52 @@
+# Copyright 2014-2021 The aiosmtpd Developers
+# SPDX-License-Identifier: Apache-2.0
+
+"""Test other aspects of the server implementation."""
+
+import asyncio
+import warnings
+from typing import Generator, Optional
+
+import pytest
+
+from aiosmtpd import _get_or_new_eventloop
+
+
+@pytest.fixture(scope="module")
+def close_existing_loop() -> Generator[Optional[asyncio.AbstractEventLoop], None, None]:
+    loop: Optional[asyncio.AbstractEventLoop]
+    with warnings.catch_warnings():
+        warnings.filterwarnings("error")
+        try:
+            loop = asyncio.get_event_loop()
+        except (DeprecationWarning, RuntimeError):
+            loop = None
+    if loop:
+        loop.stop()
+        loop.close()
+        asyncio.set_event_loop(None)
+        yield loop
+    else:
+        yield None
+
+
+class TestInit:
+
+    def test_create_new_if_none(self, close_existing_loop):
+        old_loop = close_existing_loop
+        loop: Optional[asyncio.AbstractEventLoop]
+        loop = _get_or_new_eventloop()
+        assert loop is not None
+        assert loop is not old_loop
+        assert isinstance(loop, asyncio.AbstractEventLoop)
+
+    def test_not_create_new_if_exist(self, close_existing_loop):
+        old_loop = close_existing_loop
+        loop: Optional[asyncio.AbstractEventLoop]
+        loop = asyncio.new_event_loop()
+        assert loop is not old_loop
+        asyncio.set_event_loop(loop)
+        ret_loop = _get_or_new_eventloop()
+        assert ret_loop is not old_loop
+        assert ret_loop == loop
+        assert ret_loop is loop

examples/authenticated_relayer/server.py

@@ -94,7 +94,8 @@ async def amain():
         print(f"Please create {DB_AUTH} first using make_user_db.py")
         sys.exit(1)
     logging.basicConfig(level=logging.DEBUG)
-    loop = asyncio.get_event_loop()
+    loop = asyncio.new_event_loop()
+    asyncio.set_event_loop(loop)
     loop.create_task(amain())
     try:
         loop.run_forever()

examples/basic/server.py

@@ -15,7 +15,8 @@ async def amain(loop):
 
 if __name__ == '__main__':
     logging.basicConfig(level=logging.DEBUG)
-    loop = asyncio.get_event_loop()
+    loop = asyncio.new_event_loop()
+    asyncio.set_event_loop(loop)
     loop.create_task(amain(loop=loop))
     try:
         loop.run_forever()

pyproject.toml

@@ -35,6 +35,8 @@ source = [
 
 [tool.coverage.coverage_conditional_plugin.rules]
 # Here we specify our pragma rules:
+py-lt-312 = "sys_version_info < (3, 12)"
+py-lt-310 = "sys_version_info < (3, 10)"
 py-ge-38 = "sys_version_info >= (3, 8)"
 py-lt-38 = "sys_version_info < (3, 8)"
 py-gt-36 = "sys_version_info > (3, 6)"