janus

Mixed sync-async queue, supposed to be used for communicating between classic synchronous (threaded) code and asynchronous (in terms of asyncio) one.

Like Janus god the queue object from the library has two faces: synchronous and asynchronous interface.

Synchronous is fully compatible with standard queue, asynchronous one follows asyncio queue design.

Usage example (Python 3.7+)

import asyncio
import janus


def threaded(sync_q: janus.SyncQueue[int]) -> None:
    for i in range(100):
        sync_q.put(i)
    sync_q.join()


async def async_coro(async_q: janus.AsyncQueue[int]) -> None:
    for i in range(100):
        val = await async_q.get()
        assert val == i
        async_q.task_done()


async def main() -> None:
    queue: janus.Queue[int] = janus.Queue()
    loop = asyncio.get_running_loop()
    fut = loop.run_in_executor(None, threaded, queue.sync_q)
    await async_coro(queue.async_q)
    await fut
    queue.close()
    await queue.wait_closed()


asyncio.run(main())

Usage example (Python 3.5 and 3.6)

N.B. For python 3.6 and below you must use janus < 1.0.0

import asyncio
import janus

loop = asyncio.get_event_loop()


def threaded(sync_q):
    for i in range(100):
        sync_q.put(i)
    sync_q.join()


async def async_coro(async_q):
    for i in range(100):
        val = await async_q.get()
        assert val == i
        async_q.task_done()


async def main():
    queue = janus.Queue()
    fut = loop.run_in_executor(None, threaded, queue.sync_q)
    await async_coro(queue.async_q)
    await fut
    queue.close()
    await queue.wait_closed()

try:
    loop.run_until_complete(main())
finally:
    loop.close()

Communication channels

GitHub Discussions: https://github.com/aio-libs/janus/discussions

Feel free to post your questions and ideas here.

gitter chat https://gitter.im/aio-libs/Lobby

License

janus library is offered under Apache 2 license.

Thanks

The library development is sponsored by DataRobot (https://datarobot.com)