Tornado celery integration hacks

Question

Since nobody provided a solution to this post plus the fact that I desperately need a workaround, here is my situation and some abstract solutions/ideas for debate.

Answer 1

Here is our solution to the problem. Since we look for result in several handlers in our application we made the celery lookup a mixin class.

This also makes code more readable with the tornado.gen pattern.

from functools import partial

class CeleryResultMixin(object):
    """
    Adds a callback function which could wait for the result asynchronously
    """
    def wait_for_result(self, task, callback):
        if task.ready():
            callback(task.result)
        else:
            # TODO: Is this going to be too demanding on the result backend ?
            # Probably there should be a timeout before each add_callback
            tornado.ioloop.IOLoop.instance().add_callback(
                partial(self.wait_for_result, task, callback)
            )


class ARemoteTaskHandler(CeleryResultMixin, tornado.web.RequestHandler):
    """Execute a task asynchronously over a celery worker.
    Wait for the result without blocking
    When the result is available send it back
    """
    @tornado.web.asynchronous
    @tornado.web.authenticated
    @tornado.gen.engine
    def post(self):
        """Test the provided Magento connection
        """
        task = expensive_task.delay(
            self.get_argument('somearg'),
        )

        result = yield tornado.gen.Task(self.wait_for_result, task)

        self.write({
            'success': True,
            'result': result.some_value
        })
        self.finish()