README.rst

pymongo-job-queue

This package (pymjq) is a simple MongoDB based job queue for Python. By using capped collections and tailable cursors, you can queue up data to be consumed by a service worker in order to process your long running tasks asynchronously.

This is currently used to send notifications on the Meta sites (a.k.a. Vinylhub, Bibliogs, Filmogs, Gearogs, Comicogs and the Reference Wiki).

Dependencies

• pymongo 2.7.2

Install

$ pip install pymjq

Examples

>>> from pymongo import MongoClient
>>> from pymjq import JobQueue
>>> client = MongoClient("localhost", 27017)
>>> db = client.job_queue
>>> jobqueue = JobQueue(db)
Creating jobqueue collection.
>>> jobqueue.valid():
True
>>> jobqueue.pub({"message": "hello world!"}) # add a job to queue
True
>>> for j in jobqueue:
...     print (j)
...     print (j["data"]["message"])
...
---
Working on job:
{u'status': u'waiting', u'_id': ObjectId('568d963d2c69a1e3ef34da84'),
  u'data': {u'message': u'hello world!'}...
hello world!
waiting!
waiting!
waiting!
waiting!
waiting!
waiting!
...
^C Keyboard Interrupt
>>> jobqueue.pub({"message": "hello again!"}) # add another job to queue
True
>>>  j = jobqueue.next()
True
>>> print (j["data"]["message"])
hello again!
print (j)
{u'status': u'waiting', u'_id': ObjectId('568d963d2c69a1e3ef34da84'),
  u'data': {u'message': u'hello again!'}...
>>>

How It Works

• Capped collections ensure that documents are accessed in the natural order they are inserted into the collection.
• Tailable cursors give us a cursor which will stay open and wait for new documents to process if the job queue is empty.
• The JobQueue class has an iterator that yields a document from our queue. The iterator will update a doc's status to 'working' and then 'done' once the worker has completed it's task.

Jobs

Job document, when added to the queue, has the following structure:

{
    'ts': {
        'created': datetime,
        'started': datetime,
        'done': datetime
    },
    'status': 'string',
    'site': 'string',
    'data': 'Your job data goes here! Define whatever structure you want. ''
}

In the data field, the JobQueue.pub() method will add whatever data you pass as a parameter. The ts attributes will be updated as the document is worked on.

License

MIT Copyright (c) 2016 Discogs