Windows Support

[heri16]

Crashes on Windows

PS C:\Windows\system32> D:\aws-ses-proxy\venv\Scripts\python.exe -m aiosmtpd -n
Traceback (most recent call last):
  File "C:\Python36\lib\runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "C:\Python36\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "D:\aws-ses-proxy\venv\lib\site-packages\aiosmtpd\__main__.py", line 5, in <module>
    main()
  File "D:\aws-ses-proxy\venv\lib\site-packages\aiosmtpd\main.py", line 137, in main
    loop.add_signal_handler(signal.SIGINT, loop.stop)
  File "C:\Python36\lib\asyncio\events.py", line 481, in add_signal_handler
    raise NotImplementedError
NotImplementedError

[Mortal]

On some platforms loop.add_signal_handler(signal.SIGINT, loop.stop) is an easy way of handling Ctrl-C. Unfortunately this is currently not supported on Windows. There is a patch python/asyncio#191 that seemingly was never merged into asyncio. Apparently the best workaround is to wake up the event loop often so that Ctrl-C can be handled quickly, since Ctrl-C is not handled when the event loop is sleeping, cf. python/asyncio#407. Signal handling on Windows is (apparently) complicated.

In short, we can fix this particular exception by catching the NotImplementedError on Windows.

--- a/aiosmtpd/main.py
+++ b/aiosmtpd/main.py
@@ -134,7 +134,11 @@ def main(args=None):
 
     server = loop.run_until_complete(
         loop.create_server(factory, host=args.host, port=args.port))
-    loop.add_signal_handler(signal.SIGINT, loop.stop)
+    try:
+        loop.add_signal_handler(signal.SIGINT, loop.stop)
+    except NotImplementedError:
+        if sys.platform != 'win32':
+            raise
 
     log.info('Starting asyncio loop')
     try:

[warsaw]

I definitely want to support Windows officially. I would love it if we could include Windows in the CI, perhaps with AppVeyor. Do you have any experience integrating that with GitHub CI? If we don't do automated testing on Windows, then it's highly likely we'll break compatibility again in the future.

[Mortal]

I'm affiliated with a C++ project on GitHub that uses AppVeyor but I haven't tried setting it up myself for a project, so I don't have any experience. I agree that this is important to set up.

[Mortal]

I'm working on this. Hopefully I'll have a PR for you soon with an Appveyor config.

[warsaw]

#81 and #82