Pyjo-Reactor-Twisted

Low level event reactor with Twisted support for Pyjoyment.

Pyjo.Reactor.Twisted runs the I/O and the timers of Pyjo.IOLoop in the reactor of Twisted, so that a Pyjoyment application and the code of Twisted share one event loop.

Installation

From PyPI, with Pyjoyment and Twisted, which it depends on:

pip install Pyjo-Reactor-Twisted

or, in a project managed with uv:

uv add Pyjo-Reactor-Twisted

The development version is installed from the Git repository:

pip install git+https://github.com/pyjoyment/Pyjo-Reactor-Twisted

Usage

Select the reactor with PYJO_REACTOR before Pyjo.IOLoop is loaded:

PYJO_REACTOR=Pyjo.Reactor.Twisted python myapp.py daemon

The reactor of Twisted is unique in a process, so only one Pyjo.IOLoop uses it at a time; the others get Pyjo.Reactor.Poll. When the reactor of Twisted is running already, as under twistd or Scrapy, Pyjo.IOLoop.start() returns right away and the events are handled by the reactor that runs.

Examples

examples/hello_world_twisted.py runs Pyjo.HelloWorld on the server of Pyjoyment in the event loop that Twisted runs, with reactor.run(), in a with block, which closes the listen sockets of the server at its end:

import os


# The reactor of Pyjoyment on the reactor of Twisted, selected before Pyjo.IOLoop is loaded
os.environ['PYJO_REACTOR'] = 'Pyjo.Reactor.Twisted'

import Pyjo.Reactor.Twisted  # noqa: E402


# The reactor of Twisted of poll or select, before Twisted is imported, which would install its default, epoll on Linux
Pyjo.Reactor.Twisted.install()

import Pyjo.HelloWorld  # noqa: E402
import Pyjo.Server.Daemon  # noqa: E402

from twisted.internet import reactor  # noqa: E402


# The server of Pyjoyment, which closes its listen sockets at the end of the block
with Pyjo.Server.Daemon.new(app=Pyjo.HelloWorld.new(), listen=['http://*:3000']) as daemon:
    daemon.start()

    # Twisted runs the event loop, with the server of Pyjoyment in it
    reactor.run()

$ python examples/hello_world_twisted.py
Web application available at http://127.0.0.1:3000

$ curl http://127.0.0.1:3000/
Your Pyjo is working!

examples/user_agent_twisted.py is an application of Twisted, a server of twisted.web, whose timer requests it every second with the user agent of Pyjoyment, without blocking the reactor of Twisted. The user agent is in a with block, which closes its connections at its end, so the callback shows the error of a request that it interrupts:

import os


# The reactor of Pyjoyment on the reactor of Twisted, selected before Pyjo.IOLoop is loaded
os.environ['PYJO_REACTOR'] = 'Pyjo.Reactor.Twisted'

import Pyjo.Reactor.Twisted  # noqa: E402


# The reactor of Twisted of poll or select, before Twisted is imported, which would install its default, epoll on Linux
Pyjo.Reactor.Twisted.install()

import Pyjo.UserAgent  # noqa: E402

from twisted.internet import reactor, task  # noqa: E402
from twisted.web import resource, server  # noqa: E402


# An application of Twisted
class Hello(resource.Resource):
    isLeaf = True

    def render_GET(self, request):
        return b'Hello from Twisted!'


reactor.listenTCP(3000, server.Site(Hello()))

# The user agent of Pyjoyment, which closes its connections at the end of the block
with Pyjo.UserAgent.new() as ua:
    # A request every second, which does not block the reactor of Twisted; a request that the end of the block
    # interrupts gets an error
    def fetch():
        def done(ua, tx):
            print(tx.error['message'] if tx.error else f'{tx.res.code} {tx.res.text}')

        ua.get('http://127.0.0.1:3000/', done)

    task.LoopingCall(fetch).start(1)
    reactor.run()

$ python examples/user_agent_twisted.py
200 Hello from Twisted!
200 Hello from Twisted!
200 Hello from Twisted!

examples/loopback_twisted.py is a server of Pyjoyment and its user agent on the reactor of Twisted, a blocking request, which runs the event loop until the response, and the class of the reactor, which Build checks with the wheel:

import os


# The reactor of Pyjoyment on the reactor of Twisted, selected before Pyjo.IOLoop is loaded
os.environ['PYJO_REACTOR'] = 'Pyjo.Reactor.Twisted'

import Pyjo.HelloWorld  # noqa: E402
import Pyjo.IOLoop  # noqa: E402
import Pyjo.Server.Daemon  # noqa: E402
import Pyjo.UserAgent  # noqa: E402


# The server, on a port that the system picks, and the user agent, in the same event loop, which close their sockets at
# the end of the block
with (
    Pyjo.Server.Daemon.new(app=Pyjo.HelloWorld.new(), listen=['http://127.0.0.1'], silent=True) as daemon,
    Pyjo.UserAgent.new(ioloop=Pyjo.IOLoop.singleton) as ua,
):
    # A blocking request, which runs the event loop of the server on the reactor of Twisted until the response
    tx = ua.get(f'http://127.0.0.1:{daemon.start().ports()[0]}/')
    print(type(Pyjo.IOLoop.singleton.reactor).__name__)
    print(tx.result.code, tx.result.text)

$ python examples/loopback_twisted.py
Pyjo_Reactor_Twisted
200 Your Pyjo is working!

The first two call Pyjo.Reactor.Twisted.install() before they import Twisted, which would install its default, epoll on Linux, in the place of poll or select; the third does not import Twisted, so the reactor installs it.

Documentation

The API of the module and the examples are on Read the Docs.

Status

An experiment: the first reactor of Pyjoyment in a distribution of its own.

License

The Artistic License 2.0, as Pyjoyment.