tornado.platform.asyncio — Bridge between asyncio and Tornado

Bridges between the asyncio module and Tornado IOLoop.

New in version 3.2.

This module integrates Tornado with the asyncio module introduced in Python 3.4. This makes it possible to combine the two libraries on the same event loop.

Deprecated since version 5.0: While the code in this module is still used, it is now enabled automatically when asyncio is available, so applications should no longer need to refer to this module directly.

Note

Tornado requires the add_reader family of methods, so it is not compatible with the ProactorEventLoop on Windows. Use the SelectorEventLoop instead.

class tornado.platform.asyncio.AsyncIOMainLoop(*args: Any, **kwargs: Any)

AsyncIOMainLoop creates an IOLoop that corresponds to the current asyncio event loop (i.e. the one returned by asyncio.get_event_loop()).

Deprecated since version 5.0: Now used automatically when appropriate; it is no longer necessary to refer to this class directly.

Changed in version 5.0: Closing an AsyncIOMainLoop now closes the underlying asyncio loop.

class tornado.platform.asyncio.AsyncIOLoop(*args: Any, **kwargs: Any)

AsyncIOLoop is an IOLoop that runs on an asyncio event loop. This class follows the usual Tornado semantics for creating new IOLoops; these loops are not necessarily related to the asyncio default event loop.

Each AsyncIOLoop creates a new asyncio.EventLoop; this object can be accessed with the asyncio_loop attribute.

Changed in version 5.0: When an AsyncIOLoop becomes the current IOLoop, it also sets the current asyncio event loop.

Deprecated since version 5.0: Now used automatically when appropriate; it is no longer necessary to refer to this class directly.

tornado.platform.asyncio.to_tornado_future(asyncio_future: _asyncio.Future) → _asyncio.Future

Convert an asyncio.Future to a tornado.concurrent.Future.

New in version 4.1.

Deprecated since version 5.0: Tornado Futures have been merged with asyncio.Future, so this method is now a no-op.

tornado.platform.asyncio.to_asyncio_future(tornado_future: _asyncio.Future) → _asyncio.Future

Convert a Tornado yieldable object to an asyncio.Future.

New in version 4.1.

Changed in version 4.3: Now accepts any yieldable object, not just tornado.concurrent.Future.

Deprecated since version 5.0: Tornado Futures have been merged with asyncio.Future, so this method is now equivalent to tornado.gen.convert_yielded.

class tornado.platform.asyncio.AnyThreadEventLoopPolicy

Event loop policy that allows loop creation on any thread.

The default asyncio event loop policy only automatically creates event loops in the main threads. Other threads must create event loops explicitly or asyncio.get_event_loop (and therefore IOLoop.current) will fail. Installing this policy allows event loops to be created automatically on any thread, matching the behavior of Tornado versions prior to 5.0 (or 5.0 on Python 2).

Usage:

asyncio.set_event_loop_policy(AnyThreadEventLoopPolicy())

New in version 5.0.