greenlet_within_asyncio.py

#!/usr/bin/python3
import sys
import asyncio
import greenlet

class AsyncIoGreenlet(greenlet.greenlet):
    def __init__(self, driver, fn):
        greenlet.greenlet.__init__(self, fn, driver)
        self.driver = driver

async def green_spawn(fn, *args):
    context = AsyncIoGreenlet(greenlet.getcurrent(), fn)

    result = context.switch(*args)

    while context:
        try:
            value = await result
        except:
            result = context.throw(*sys.exc_info())
        else:
            result = context.switch(value)

    return result

def green_await(awaitable):
    current = greenlet.getcurrent()
    if not isinstance(current, AsyncIoGreenlet):
        raise TypeError('Cannot use green_await outside of green_spawn target')
    return current.driver.switch(awaitable)

if __name__ == '__main__':
    import time

    def green_sleeper(delay, count=1):
        while count > 0:
            print(f'Green sleeping for {delay} seconds...')
            now = time.time()
            green_await(asyncio.sleep(delay))
            print(f'Green returned after {time.time()-now:.1f} seconds (expected {delay} seconds).')
            count -= 1

    async def asyncio_sleeper(delay, count=1):
        while count > 0:
            print(f'AsyncIo sleeping for {delay} seconds...')
            now = time.time()
            await asyncio.sleep(delay)
            print(f'AsyncIo returned after {time.time()-now:.1f} seconds (expected {delay} seconds).')
            count -= 1

    async def main():
        tasks = []
        tasks.extend(green_spawn(green_sleeper, i + 1, 3) for i in range(2))
        tasks.extend(asyncio_sleeper(i + 1, 3) for i in range(2))
        await asyncio.gather(*tasks)

    asyncio.run(main())