RACHE

.. image:: https://travis-ci.org/brutasse/rache.png?branch=master :alt: Build Status :target: https://travis-ci.org/brutasse/rache

A scheduler backed by Redis_ with a very simple interface.

.. _Redis: http://redis.io/

RACHE doesn't handle job execution. It only maintains a list of jobs and their theoretical execution time. It's up to you to monitor pending jobs and send them to an actual task queue.

Installation

RACHE works with any Python version from 2.6 to 3.3. You only need a working Redis server.

::

pip install rache

Configuration

By default RACHE connects to Redis on localhost, port 6379, database 0. To override this, set a REDIS_URL environment variable::

REDIS_URL=redis://redis.example.com:6379/2

RACHE prefixes all its Redis keys with rache:. You can override this by setting the RACHE_REDIS_PREFIX environment variable.

Usage

::

import rq

from rache import schedule_job, pending_jobs

# Schedule a job now
schedule_job('http://github.com/brutasse/rache', schedule_in=0, timeout=10)

# Get pending jobs
jobs = pending_jobs()

# Send them to the task queue for immediate execution
for job in jobs:
    rq.enqueue_job(...)

schedule_job

::

    schedule_job('job id', schedule_in=<seconds>, connection=None, **kwargs)

A given job ID is unique from the scheduler perspective. Scheduling it twice
results in it being scheduled at the time decided in the last call.

``**kwargs`` can be used to attach data to your jobs. For instance, if you
have jobs to fetch URLs and want to attach a timeout to these jobs::

    schedule_job('http://example.com/test', schedule_in=3600, timeout=10)

The job data is persistent. To remove a key from the data, call
``schedule_job()`` with that key set to None::

    schedule_job('http://example.com/test', schedule_in=3600, timeout=None)

``schedule_in`` is mandatory. This means you can't update an existing job
without rescheduling it.

``connection`` allows you to pass a custom Redis connection object. This is
useful if you have your own connection pooling and want to manage connections
yourself.

``pending_jobs``

::

jobs = pending_jobs(reschedule_in=None, limit=None, connection=None)

(the returned value is a generator)

Fetches the pending jobs and returns a list of jobs. Each job is a dictionnary with an id key and its additional data.

reschedule_in controls whether to auto-reschedule jobs in a given time. This is useful if you have periodic jobs but also want to special-case some jobs according to their results (enqueue is rq_-style syntax)::

jobs = pending_jobs(reschedule_in=3600)

for job in jobs:
    enqueue(do_something, kwargs=job)

def do_something(**kwargs):
    # … do some work

    if some_condition:
        # re-schedule in 30 days
        schedule_job(kwargs['id'], schedule_in=3600 * 24 * 30)

.. _rq: http://python-rq.org/

limit allows you to limit the number of jobs returned. Remaining jobs are left on schedule, even if they should have been scheduled right now.

connection allows you to pass a custom Redis connection object.

delete_job

::

    delete_job('<job id>', connection=None)

Removes a job completely from the scheduler.

``connection`` allows you to pass a custom Redis connection object.

``job_details``

::

job_details('<job id>', connection=None)

Returns a dictionnary with the job data. The job ID and scheduled time are set in the id and schedule_at keys of the returned value.

connection allows you to pass a custom Redis connection object.

scheduled_jobs

::

    scheduled_jobs(with_times=False, connection=None)

(the returned value is a generator)

Fetches all the job IDs stored in the scheduler. This returns a list of IDs or
a list of ``(job_id, timestamp)`` tuples if ``with_times`` is set to ``True``.

This is useful for syncing jobs between the scheduler and a database, for
instance.

``connection`` allows you to pass a custom Redis connection object.

Contributing
------------

Create a local environment::

    virtualen env
    source env/bin/activate
    pip install -e .

Run the tests::

    python setup.py test

Or for all supported python versions::

    tox

Hack, fix bugs and submit pull requests!

Changelog
---------

* **0.3.1** (2013-08-31):

  * Made ``pending_jobs`` work correctly with both ``Redis`` and
    ``StrictRedis`` clients.

* **0.3** (2013-08-31):

  * Allow passing custom Redis connection objects for fine control on open
    connections.

* **0.2.2** (2013-07-10):

  * Fixed a typo that lead to ``AttributeError`` when retrieving some jobs.

* **0.2.1** (2013-07-03):

  * Allowed ``pending_jobs()`` to return non-unicode data if undecodable bytes
    are passed to ``schedule_job()``.

* **0.2** (2013-06-02):

  * Added ``limit`` kwarg to ``pending_jobs()``.
  * Allowed ``schedule_in`` to be a timedelta alternatively to a number of
    seconds.
  * Added ``job_details()``.
  * Numerical data attached to jobs is cast to ``int()`` when returned.

* **0.1** (2013-06-01):

  * Initial release