======= janus

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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 <https://en.wikipedia.org/wiki/Janus>_ the queue object from the library has two faces: synchronous and asynchronous interface.

Synchronous is fully compatible with standard queue <https://docs.python.org/3/library/queue.html>, asynchronous one follows asyncio queue design <https://docs.python.org/3/library/asyncio-queue.html>.

Usage example (Python 3.7+)

.. code:: python

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

.. code:: python

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)

.. _asyncio: https://docs.python.org/3/library/asyncio.html