alligator 0.5.1

Requirements

• Python 2.6+ or Python 3.3+

• (Optional) redis for the Redis backend

• FUTURE (Optional) beanstalkc for the Beanstalk backend

WHY?!!1!

• Because I have NIH-syndrome.

• Or because I longed for something simple (~375 loc).

• Or because I wanted something with tests (90%+ coverage) & docs.

• Or because I wanted pluggable backends.

• Or because testing some other queuing system was a pain.

• Or because I’m an idiot.

Basic Usage

This example uses Django, but there’s nothing Django-specific about Alligator. You can use it with any Python code.

from alligator import Gator

from django.contrib.auth.models import User
from django.shortcuts import send_email


# Make a Gator instance.
# Under most circumstances, you would configure this in one place &
# import that instance instead.
gator = Gator('redis://localhost:6379/0')


# The task itself.
# Nothing special, just a plain *undecorated* function.
def follow_email(followee_username, follower_username):
    followee = User.objects.get(username=followee_username)
    follower = User.objects.get(username=follower_username)

    subject = 'You got followed!'
    message = 'Hey {}, you just got followed by {}! Whoohoo!'.format(
        followee.username,
        follower.username
    )
    send_email(subject, message, 'server@example.com', [followee.email])


# An simple, previously expensive view.
@login_required
def follow(request, username):
    # You'd import the task function above.
    if request.method == 'POST':
        # Schedule the task.
        # Use args & kwargs as normal.
        gator.task(follow_email, request.user.username, username)
        return redirect('...')

Running Tasks

Rather than trying to do autodiscovery, fanout, etc., you control how your workers are configured & what they consumer. Create a new executable file (bin script, management command, whatever) & drop in the following code.

from alligator import Gator, Worker

# Bonus points if you import that one pre-configured ``Gator`` instead.
gator = Gator('redis://localhost:6379/0')

# Consume & handle all tasks.
worker = Worker(gator)
worker.run_forever()

License

New BSD

Complex Usage (For Future Docs)

# We're re-using the above imports/setup.

def log_func(job):
    # A simple example of logging a failed task.
    if job.result != SUCCESS:
        logging.error("Job {} failed.".format(job.id))

# A context manager for supplying options
with gator.options(retries=3, async=settings.ASYNC_TASKS, on_error=log_func) as task:
    feeds_job = task(sketchy_fetch_feeds, timeout=30)


# Future wishlist items...

# Dependent tasks, will only run if the listed tasks succeed.
with gator.options(depends_on=[feeds_job]) as task:
    task(rebuild_cache)

# Delayed tasks (run in an hour).
with gator.options(run_after=60 * 60) as task:
    task(this_can_wait)

Running Tests

$ virtualenv env2
$ . env2/bin/activate
$ pip install -r requirements.txt
$ python setup.py develop
$ py.test -s -v --cov=alligator --cov-report=html tests

TODO

• Scheduled tasks

• Dependent tasks

• Cancellable tasks