This is a pre-production deployment of Warehouse, however changes made here WILL affect the production instance of PyPI.
Latest Version Dependencies status unknown Test status unknown Test coverage unknown
Project Description
RING REDIS
===

What for:
---

I want a lightweight, High Available & Extensible cache solution using redis, but nutcracker is too heavy for a system with only 2 or 3 application servers and 2 or 3 redis instances. and there isnt a good enough implementation of consistant hash using pure python. so I wrote this. I used it in 2 project and they are running well till now when half a year passed. so I shared it for people who have the same requirement.

Features:
---

- lightweight & pure python solution
- auto eject & rediscover redis nodes
- O(log(slice_number)) time complexity for a consistant hash calculation. (slice_number = max(2000, 200 * node_number))
- O(slice_number * log(slice_number)) time complexity for hash ring rebuilding.
- use O(slice_number) memory space always.

API list:
---

- `redis_dict(redis_confs, prefix='', key=str, expire=None, on_fail=None, on_node_ejected=None, on_node_rediscovered=None, retry_ratio=1e-2, hash_function=crc32)`: construct a redis_dict instance, which can be used as a normal python dict
- `some_redis_dict_instance.visit_redis(cmd, k, args)`: visit lower level redis apis
- `some_redis_dict_instance.get_entry(k)`: return the really redis entry of k
- `some_redis_dict_instance.alive_hash(redis_entry)`: return the node name for redis_entry via alive_hash
- `some_redis_dict_instance.total_hash(redis_entry)`: return the node name for redis_entry via total_hash
- `len(some_redis_dict_instance.alive_hash)`: return the alive nodes number

Install
---

### via pip
```shell
pip install ring_redis
```

### via source code
```shell
cd path/to/ring_redis
python setup.py install
```

How to use:
---

```python
################### your redis configuration #####################

REDIS_CONF = {
'group0' : {
'node0': {
'capacity': 50 * 1024 ** 2,
'connection': {
'host' : '192.168.230.45',
'port' : 15061,
'db': 0,
'socket_timeout': 5e-3,
},
},
'node1': {
'capacity': 50 * 1024 ** 2,
'connection': {
'host' : '192.168.230.46',
'port' : 15061,
'db': 0,
'socket_timeout': 5e-3,
},
},
},
}

############################ useage ##############################

from ring_redis import redis_dict

test = redis_dict(REDIS_CONF['group0'], prefix='test.', expire=20)

test['a'] = 'abc'
print("test['a'] : %s" % (test['a']))

print("len(test) : %s" % (len(test)))
print("test.keys() : %s" % (test.keys()[:100]))
print("'a' in test? : %s" % ('a' in test))
print("'b' in test? : %s" % ('b' in test))

print("test.visit_redis('incr', 'x', 1) : %s" % (test.visit_redis('incr', 'x', 1)))
print("test.get_entry('x') : %s" % (test.get_entry('x')))
print("test.total_hash(test.get_entry('x')) : %s" % (test.total_hash(test.get_entry('x'))))
print("test.alive_hash(test.get_entry('x')) : %s" % (test.alive_hash(test.get_entry('x'))))
```

Notice:
---

- The really redis entry equals to the dict key **only if** `prefix + key(dict_key) == redis_entry`
- The configuration field 'socket_timeout' in REDIS_CONF **should be choosed carefully**, do some test yourself to findout the expected time(in seconds, depending on your network delay & bandwidth) needed for your biggest data case.
- Python built-in function hash is neither consistant nor equally distributed, so **don't use it** as hash_function.
- If non instance of the redis cluster available, exception `RedisClusterUnavailable` will be raised, you should pass `on_fail` as argument of redis_dict constructor or catch this exception to **handler this situation yourself**.
Release History

Release History

0.9.0

This version

History Node

TODO: Figure out how to actually get changelog content.

Changelog content for this version goes here.

Donec et mollis dolor. Praesent et diam eget libero egestas mattis sit amet vitae augue. Nam tincidunt congue enim, ut porta lorem lacinia consectetur. Donec ut libero sed arcu vehicula ultricies a non tortor. Lorem ipsum dolor sit amet, consectetur adipiscing elit.

Show More

0.8.0

History Node

TODO: Figure out how to actually get changelog content.

Changelog content for this version goes here.

Donec et mollis dolor. Praesent et diam eget libero egestas mattis sit amet vitae augue. Nam tincidunt congue enim, ut porta lorem lacinia consectetur. Donec ut libero sed arcu vehicula ultricies a non tortor. Lorem ipsum dolor sit amet, consectetur adipiscing elit.

Show More

Download Files

Download Files

TODO: Brief introduction on what you do with files - including link to relevant help section.

File Name & Checksum SHA256 Checksum Help Version File Type Upload Date
ring_redis-0.9.0.zip (15.0 kB) Copy SHA256 Checksum SHA256 Source Sep 4, 2014

Supported By

WebFaction WebFaction Technical Writing Elastic Elastic Search Pingdom Pingdom Monitoring Dyn Dyn DNS Sentry Sentry Error Logging CloudAMQP CloudAMQP RabbitMQ Heroku Heroku PaaS Kabu Creative Kabu Creative UX & Design Fastly Fastly CDN DigiCert DigiCert EV Certificate Rackspace Rackspace Cloud Servers DreamHost DreamHost Log Hosting