aevent 0.1.1

Support functions

aevent monkey-patches anyio’s TaskGroup.spawn in two ways.

• the child task is instrumented to support greenback.

• spawn returns a cancel scope. You can use it to cancel the new task.

Call aevent.per_task in your child task if you start tasks some other way.

Threading

Threads are translated to tasks. In order for that to work, you must start your program with aevent.run, or run the sync code in question within an aevent.runner async context manager. Runners may be nested.

Not yet supported

• select

  • anything else

• dns

• os

  • read

  • write

• ssl

• subprocess

• signal

Subclassing patched classes

Directly subclassing one of the classes patched by aevent does not work and requires special consideration. Consider this code:

class my_thread(threading.Thread):
   def run(self):
       ...

For use with aevent you can choose the original Thread implementation:

orig_Thread = getattr(threading.Thread, "_aevent_orig", threading.Thread)
class my_thread(orig_Thread):
  ...

or the aevent-ified version:

new_Thread = threading.Thread._aevent_new # fails when aevent is not loaded
class my_thread(new_Thread):
  ...

or you might want to create two separate implementations, and switch based on the aevent context:

class _orig_my_thread(threading.Thread._aevent_orig):
   ...
class _new_my_thread(threading.Thread._aevent_new):
   ...
my_thread = aevent.patch__new_my_thread, name="my_thread", orig=_orig_my_thread)

If you generate local subclasses on the fly, you can simplify this to:

def some_code():
    class my_thread(threading.Thread._aevent_select()):
        def run(self):
            ...
    job = my_tread()
    my_thread.start()

Other affected modules

You need to import any module which requires non-patched code before importing aevent.

Modules which are known to be affected:

• multiprocessing

Testing

The test suite runs with trio as backend. Due to aevent’s monkeypatching, switching backends around is not supported. However, you can set the environment variable AEVENT_BACKEND to asyncio to run the test suite with that.

The test suite pulls in a copy of pyroute2 (no changes, other than fixing bugs unrelated to aevent) and tests against its test suite, thereby (mostly) ensuring that this particular package works with aevent.