seahoh / aiogevent

fork of https://bitbucket.org/haypo/aiogevent

aiogevent implements the asyncio API (PEP 3156) on top of gevent. It makes possible to write asyncio code in a project currently written for gevent.

aiogevent allows to use greenlets in asyncio coroutines, and to use asyncio coroutines, tasks and futures in greenlets: see yield_future() and wrap_greenlet() functions.

The main visible difference between aiogevent and trollius is the behaviour of run_forever(): run_forever() blocks with trollius, whereas it runs in a greenlet with aiogevent. It means that aiogevent event loop can run in an greenlet while the Python main thread runs other greenlets in parallel.

• aiogevent on Python Cheeseshop (PyPI) <https://pypi.python.org/pypi/aiogevent>_
• aiogevent at Bitbucket <https://bitbucket.org/haypo/aiogevent>_
• gevent <http://www.gevent.org/>_
• Copyright/license: Open source, Apache 2.0. Enjoy!

See also the aioeventlet project <http://aioeventlet.readthedocs.org/>_.

Hello World

import aiogevent

def hello_world():
    print("Hello World")
    loop.stop()

asyncio.set_event_loop_policy(aiogevent.EventLoopPolicy())
loop = asyncio.get_event_loop()
loop.call_soon(hello_world)
loop.run_forever()
loop.close()

API

aiogevent specific functions:

yield_future

yield_future(future, loop=None):

Wait for a future, a task, or a coroutine object from a greenlet.

Yield control other eligible greenlet until the future is done (finished successfully or failed with an exception).

Return the result or raise the exception of the future.

The function must not be called from the greenlet running the aiogreen event loop.

Example of greenlet waiting for a trollius task. The progress() callback is called regulary to see that the event loop in not blocked.

import aiogevent
import gevent
import asyncio

def progress():
    print("computation in progress...")
    loop.call_later(0.5, progress)

async def coro_slow_sum(x, y):
    await asyncio.sleep(1.0)
    return x + y

def green_sum():
     loop.call_soon(progress)
     task = asyncio.ensure_future(coro_slow_sum(1, 2))
     value = aiogevent.yield_future(task)
     print("1 + 2 = %s" % value)
     loop.stop()

asyncio.set_event_loop_policy(aiogevent.EventLoopPolicy())
gevent.spawn(green_sum)
loop = asyncio.get_event_loop()
loop.run_forever()
loop.close()

Output

computation in progress...
computation in progress...
computation in progress...
1 + 2 = 3

wrap_greenlet

wrap_greenlet(gt):

Wrap a greenlet into a Future object.

The Future object waits for the completion of a greenlet. The result or the exception of the greenlet will be stored in the Future object.

Greenlet of greenlet and gevent modules are supported: gevent.greenlet and greenlet.greenlet objects.

The greenlet must be wrapped before its execution starts. If the greenlet is running or already finished, an exception is raised.

For gevent.Greenlet, the _run attribute must be set. For greenlet.greenlet, the run attribute must be set.

Example of trollius coroutine waiting for a greenlet. The progress() callback is called regulary to see that the event loop in not blocked

import aiogevent
import gevent
import trollius as asyncio
from trollius import From, Return

def progress():
    print("computation in progress...")
    loop.call_later(0.5, progress)

def slow_sum(x, y):
    gevent.sleep(1.0)
    return x + y

@asyncio.coroutine
def coro_sum():
    loop.call_soon(progress)

    gt = gevent.spawn(slow_sum, 1, 2)
    fut = aiogevent.wrap_greenlet(gt, loop=loop)

    result = yield From(fut)
    print("1 + 2 = %s" % result)

asyncio.set_event_loop_policy(aiogevent.EventLoopPolicy())
loop = asyncio.get_event_loop()
loop.run_until_complete(coro_sum())
loop.close()

Output

computation in progress...
computation in progress...
computation in progress...
1 + 2 = 3

Installation

Install aiogevent with pip

pip install aiogevent

Install aiogevent on Windows with pip

Procedure for Python 2.7:

• If pip is not installed yet, install pip <http://www.pip-installer.org/en/latest/installing.html>_: download get-pip.py and type::

  \Python27\python.exe get-pip.py

• Install aiogevent with pip::

  \Python27\python.exe -m pip install aiogevent

• pip also installs dependencies: eventlet and trollius

Manual installation of aiogevent

Requirements:

• Python 2.6 or 2.7
• gevent 0.13 or newer
• trollius 0.3 or newer (pip install trollius), but trollius 1.0 or newer is recommended

python setup.py install

To do

• support gevent versions older than 0.13. With version older than 0.13, import gevent raise "ImportError: .../python2.7/site-packages/gevent/core.so: undefined symbol: current_base"
• support gevent monkey patching: enable py27_patch in tox.ini
• enable py33 environments in tox.ini: gevent 1.0.1 does not support Python 3, need a new release. Tests pass on the development (git) version of gevent.

gevent and Python 3

The development version of gevent has an experimental support of Python 3. See the gevent issue #38: python3 <https://github.com/gevent/gevent/issues/38>_.

Threading

gevent does not support threads: the aiogevent event loop must run in the main thread.

Changelog

2014-12-18: Version 0.2

• Rename the link_future() function to yield_future()
• Add run_aiotest.py
• tox now also runs aiotest test suite

2014-11-25: Version 0.1

• First public release