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Coroutines example with python's asyncio module
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| import asyncio | |
| @asyncio.coroutine | |
| def open_file(name): | |
| print("opening {}".format(name)) | |
| return open(name) | |
| @asyncio.coroutine | |
| def close_file(file): | |
| print("closing {}".format(file.name)) | |
| file.close() | |
| @asyncio.coroutine | |
| def read_data(file): | |
| print("reading {}".format(file.name)) | |
| return file.read() | |
| @asyncio.coroutine | |
| def process_data(filename): | |
| # I want the result from open_file(filename) | |
| # untill it's done don't bother calling me | |
| file = yield from asyncio.async(open_file(filename)) | |
| print('opened {}'.format(filename)) | |
| # I want the result from read_data(file) | |
| # untill it's done don't bother calling me | |
| data = yield from asyncio.async(read_data(file)) | |
| print('read {}'.format(filename)) | |
| yield from close_file(file) | |
| @asyncio.coroutine | |
| def main_coro(loop): | |
| # start our tasks asynchronously in futures | |
| tasks = [ | |
| asyncio.async(process_data('/etc/passwd')), | |
| asyncio.async(process_data('/etc/group')), | |
| asyncio.async(process_data('/var/log/Xorg.0.log')), | |
| ] | |
| # untill all futures are done | |
| while not all(task.done() for task in tasks): | |
| # take a short nap | |
| yield from asyncio.sleep(0.01) | |
| # we're done, so stop the event loop | |
| loop.stop() | |
| # get event loop | |
| loop = asyncio.get_event_loop() | |
| # schedule the main coroutine to start as soon as possible | |
| loop.call_soon(asyncio.async, main_coro(loop)) | |
| # run untill explicitly stopped | |
| loop.run_forever() | |
| # instead of the above two lines we can also run | |
| # loop.run_until_complete(main_coro()) and remove | |
| # the loop parameter for main_coro and the call | |
| # to loop.stop() at the end of it | |
| loop.close() |
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