redis_netlock 1.6

一个用redis做的分布式锁，含有超时及重试机制.

###一个用redis实现的分布式锁，含有retry和timetout的功能。

* 用with做锁的逻辑语句
* timeout避免了避免了任务出现异常，没有做delete操作
* 对于长时间的业务，增加retry重试锁的次数

更新:
1. 增加了ask_lock接口

```
#coding:utf-8
#my blog: http://xiaorui.cc
from __future__ import with_statement
import redis
import time
from redis_netlock import dist_lock

client = redis.Redis(connection_pool=redis.BlockingConnectionPool(max_connections=15, host='localhost', port=6379))
with dist_lock('test', client):
time.sleep(10)
print 'welcome to my blog, http://xiaorui.cc'

```
#####同时运行test.py and test2.py
python test.py
```
root@li568-252 redis_netlock]# python test.py
welcome to my blog, http://xiaorui.cc
```

python test2.py
```
[root@li568-252 redis_netlock]# python test2.py
Sleeipng for 0.404031367603
Sleeipng for 1.19347232007
Sleeipng for 2.47668271021
Sleeipng for 4.55280708824
hello
```