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https://github.com/percolate/redset

A Redis-backed sorted set useful for coordinating distributed work.
https://github.com/percolate/redset

Last synced: 13 days ago
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A Redis-backed sorted set useful for coordinating distributed work.

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README 

        
redset

======



|PyPI version| |build status| |Coverage Status|



You may not need heavyweights like Celery or RQ. Maintaing an AMQP server 

might be overkill. There's a simpler, easier way to distribute work.



Redset provides simple, generic sorted sets backed by Redis that can be used to

coordinate distributed systems and parcel out work. Unlike more common

distribution libraries like Celery or RQ, redset avoids duplicate work for

certain use-cases by maintaining a set of tasks instead of a list or queue.

And it does so with a dead-simple interface that feels natural for Python.



Redset is currently used in the wild to do things like



- maintain a high-throughput work queue of streaming updates to be processed

- power a multi-producer, multi-consumer scraping architecture that won't do

  the same work twice

- maintain a simple, cross-process set of "seen" items that each have a 

  TTL

- schedule non-duplicate, periodic polling of analytics on social services



Features

--------



-  No worker daemons to run, no heavy AMQP service to monitor

-  Safe for multiple producers and consumers

-  Seamless, simple use with Python objects using serializers

-  Zero dependencies: you provide an object that implements the 

   ``redis.client.Redis`` interface, we don't ask any questions.

-  Simple, easy-to-read implementation

-  Mimics Python's native ``set`` interface

-  Battle-tested

-  Python 3 compatible



Simple example

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



.. code:: python



    import json

    import redis



    from redset import TimeSortedSet



    r = redis.Redis()

    ss = TimeSortedSet(r, 'important_json_biz', serializer=json)



    ss.add({'foo': 'bar1'})

    ss.add({'foo': 'bar2'})

     

    ss.add({'foo': 'bar3'})

    ss.add({'foo': 'bar3'})



    len(ss)

    # 3



    # ...some other process A



    ss.peek()

    # {'foo': 'bar1'}



    ss.pop()

    # {'foo': 'bar1'}



    # ...meanwhile in process B (at exactly same time as A's pop)



    ss.take(2)

    # [{'foo': 'bar2'}, {'foo': 'bar3'}]



Docs

----



`Here `__



About

-----



This software was developed at `Percolate `__,

where we use it for all sorts of things that involve maintaining

synchronized sets of things across process boundaries. A common use-case

is to use redset for coordinating time-sensitive tasks where duplicate

requests may be generated.



Redset is unopinionated about how consumers look or behave. Want to have

a plain 'ol Python consumer managed by supervisor? Fine. Want to be able

to pop off items from within a celery job? Great. Redset has no say in

where or how it is used: mechanism, not policy.



Usage concepts

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



``redset.SortedSet`` and its subclasses can be instantiated with a few

paramters that are notable.



Specifying a serializer

~~~~~~~~~~~~~~~~~~~~~~~



Since Redis only stores primitive numbers and strings, handling

serialization and deserialization is a key part of making redset set

usage simple in Python.



A ``serializer`` instance can be passed (which adheres to the

``redset.interfaces.Serializer`` interface, though it need not subclass

it) to automatically handle packing and unpacking items managed with

redset.



Specifying a scorer

~~~~~~~~~~~~~~~~~~~



A callable that specifies how to generate a score for items being added

can also be passed to SortedSet's constructor as ``scorer``. This

callable takes one argument, which is the item *object* (i.e. the item

before serialization) to be "scored."



Related projects

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



-  `redis-py `__

-  `celery `__

-  `RQ `__



.. |PyPI version| image:: https://badge.fury.io/py/redset.png

   :target: http://badge.fury.io/py/redset

.. |build status| image:: https://travis-ci.org/percolate/redset.png?branch=master

   :target: https://travis-ci.org/percolate/redset

.. |Coverage Status| image:: https://coveralls.io/repos/percolate/redset/badge.png?branch=master

   :target: https://coveralls.io/r/percolate/redset?branch=master