rq-retry-scheduler 0.2.1
RQ Retry and Scheduler
License: MIT

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RQ Retry Scheduler
==================

`RQ Retry Scheduler <https://github.com/mikemill/rq_retry_scheduler>`__
extends the RQ worker class to provide functionality to enqueue jobs
based on time.

Additionally, it provides a worker that will automatically retry failed
jobs using a backoff scheme.

Usage
=====

Queues
------

The ``rq_retry_scheduler.Queue`` class can be used as a drop in
replacement for ``rq.Queue``. It provides two additional enqueuing
methods:

-  ``enqueue_at`` - Enqueue the job at the specified time. The time
   should be a ``datetime.datetime`` object with the UTC timezone.
-  ``enqueue_in`` - Enqueue the job after the specified amount of time.
   The time should be a ``datetime.timedelta`` object.

Additionally, two other methods are available ``enqueue_job_at`` and
``enqueue_job_in`` which work like the above methods but take a
``rq.Job`` object as the paramter.

Getting list of jobs
~~~~~~~~~~~~~~~~~~~~

| ``Queue.scheduled_jobs`` is a generator that produces the jobs that
  are currently scheduled for a particular queue.
| ``Scheduler.schedule`` returns a list of job ids and scheduled time.

Checking if a job is scheduled
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can check if a job or job id is currently scheduled. Example:
``job in queue``

Unscheduling jobs
~~~~~~~~~~~~~~~~~

You can unschedule jobs with ``Queue.remove_job``. This removes the job
from the scheduler queue but does not remove it from RQ.

Repeating jobs
~~~~~~~~~~~~~~

Once a job has been enqueued you can set it to repeat with
``Queue.repeat`` which takes the job and a ``datetime.timedelta``
object. Additionally you can pass a ``max_runs`` value to limit the
number of times it will repeat.

If the job is not already in the queue it will be enqueued at the given
interval.

In order to ensure that job results cleanup doesn’t remove the job (thus
breaking the repetition) the job is copied into a new job. The parent
job can be accessed via ``Job.parent`` for the repeated jobs.

Due to how the jobs are put into the work queues the maximum frequency
is controlled by the scheduler’s interval.

Scheduler
---------

In order to move jobs from the schedule queue into the proper RQ queue a
scheduler needs to be ran. This can be accomplished via the
``rqscheduler`` script. Additionally, you can extend from
``rq_retry_scheduler.Scheduler`` to customize the functonality.

Worker
------

A worker is provided that will requeue jobs that fail using a defiend
backoff strategy. The worker is designed to use the functionality from
the ``Queue`` class to control the backoff.

The worker can be used by using the ``-w`` option to ``rq worker``:
``rq worker -w 'rq_rety_scheduler.Worker``.

The backoff times and total attempts is controlled by
``Worker.retry_delays``.

Installation
============

Install via pip

::

   pip install rq-retry-scheduler

Acknowledgements
================

This package was based heavily on the work of `RQ
Scheduler <https://github.com/ui/rq-scheduler>`__.

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