Class PythonAsyncioStreams

java.lang.Object

io.micronaut.context.python.PythonAsyncioStreams

@Internal
public final class PythonAsyncioStreams
extends Object

The Java half of Python-native streaming: a Reactive Streams Publisher consumed by a Python async for, and a Python async iterator exposed as a Publisher.

Both directions keep the reactive signals and the Python state on different sides of one rule: Python runs only on the asyncio loop that owns the stream. Reactive signals arriving on arbitrary threads are queued onto the Micronaut event loop, inside an execution frame of the stream's context, before any Python callback runs. Without a Micronaut loop (a plain asyncio loop in a test), the callbacks run on the signalling thread and the Python side hops onto its loop with call_soon_threadsafe. The Python state machines live in the micronaut_asyncio module (as_async_iterable and as_publisher).

Since:

5.2.3

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	PythonAsyncioStreams.GeneratorSubscription	The subscription handed to a Java subscriber of a Python async iterator, and the facade the Python driver signals through.
static final class	PythonAsyncioStreams.PublisherIterator	Subscribes to a publisher one item at a time on behalf of a Python async iterator.

Method Summary

Modifier and Type	Method	Description
static PythonAsyncioStreams.PublisherIterator	iterator(org.graalvm.polyglot.Value publisher, @Nullable PythonEventLoop eventLoop, org.graalvm.polyglot.Value callbacks, @Nullable PythonReactiveContext reactiveContext)	Java entry point of as_async_iterable: a demand-driven subscriber over a publisher that reports its signals to Python callbacks.
static Publisher<Object>	publisher(org.graalvm.polyglot.Value start, @Nullable PythonEventLoop eventLoop)	Java entry point of as_publisher: a cold publisher whose every subscription starts a Python driver over a fresh async iterator.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

iterator

public static PythonAsyncioStreams.PublisherIterator iterator(org.graalvm.polyglot.Value publisher,
 @Nullable PythonEventLoop eventLoop,
 org.graalvm.polyglot.Value callbacks,
 @Nullable PythonReactiveContext reactiveContext)

Java entry point of as_async_iterable: a demand-driven subscriber over a publisher that reports its signals to Python callbacks.

Parameters:

publisher - The publisher, or any value convertible to one

eventLoop - The Micronaut event loop of the consuming coroutine, or null

callbacks - A Python object with on_next, on_error and on_complete

reactiveContext - The reactive context of the consuming coroutine to subscribe within, or null

Returns:

The subscriber; Python calls PythonAsyncioStreams.PublisherIterator.request() and PythonAsyncioStreams.PublisherIterator.cancel()

publisher

public static Publisher<Object> publisher(org.graalvm.polyglot.Value start,
 @Nullable PythonEventLoop eventLoop)

Java entry point of as_publisher: a cold publisher whose every subscription starts a Python driver over a fresh async iterator.

Parameters:

start - A Python callable taking the PythonAsyncioStreams.GeneratorSubscription and returning the driver, a Python object with request(n) and cancel()

eventLoop - The Micronaut event loop the driver runs on, or null for a plain asyncio loop

Returns:

The publisher