mongoqueue 0.5.0

mongoqueue
----------

Properties
==========

- Isolation

Do not let different consumers process the same message.

- Reliablity

Do not let a failed consumer disappear an item.

- Atomic

Operations on the queue are atomic.

Usage
=====

A queue can be instantiated with a mongo collection and a consumer
identifier. The consumer identifier helps distinguish multiple queue
consumers that are taking jobs from the queue.

>> from pymongo import Connection
>> from mongoqueue import MongoQueue
>> queue = MongoQueue(
... Connection(TEST_DB).doctest_queue,
... consumer_id="consumer-1",
... timeout=300,
... max_attempts=3)

The ``MongoQueue`` class ``timeout`` parameters specifies how long in a
seconds a how long a job may be held by a consumer before its
considered failed.

A job which timeouts or errors more than the ``max_attempts``
parameter is considered permanently failed, and will no longer be
processed.

New jobs/items can be placed in the queue by passing a dictionary.

>> queue.put({"foobar": 1})

A job ``priority`` key and integer value can be specified in the
dictionary which will cause the job to be processed before lower
priority items.

>> queue.put({"foobar": 0, "priority": 1})

An item can be fetched out by calling the ``next`` method on a queue.
This returns a Job object.

>> job = queue.next()
>> job.data
{"foobar": 1}

The job class exposes some control methods on the job, for marking progress,
completion, errors, or releasing the job back into the queue.

- ``complete`` Marks a job as complete and removes it from the queue.

- ``error`` Optionally specified with a message, releases the job back to the
queue, and increments its attempts, and stores the error message on the job.

- ``progress`` Optionally takes a progress count integer, notes progress on the job
and resets the lock timeout.

- ``release`` Release a job back to the pool. The attempts counter is not modified.

As a convience the job supports the context manager protocol.

>> with job as data:
... print data

{"foobar: 0}

If the context closure is exited without the job is marked complete,
if there's an exception the error is stored on the job.


Inspired By
===========

[0] https://github.com/skiz/mongo_queue/blob/master/lib/mongo_queue.rb
[1] http://blog.boxedice.com/2011/09/28/replacing-rabbitmq-with-mongodb/
[2] http://blog.boxedice.com/2011/04/13/queueing-mongodb-using-mongodb/
[3] https://github.com/lunaru/mongoqueue
[4] http://www.captaincodeman.com/2011/05/28/simple-service-bus-message-queue-mongodb/


Running

Fully Configurable

Distributed

Atomic Locking

Thread Safe

Priority Support

Worker Timeout Support

Fully Tested

Production Ready

Simple API


--------------------------



Per Queue error queues

Max attempts per item


Identity in queue.

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