How to implement redis distributed lock in python

 1 import time 2 import redis 3 from redis.exceptions import WatchError 4  5  6 class RedisUtil(): 7     def __init__(self): 8         self.redis = redis.Redis(host="redis账户url", 9                                  port=6379,10                                  password="你的redis密码",11                                  decode_responses=True)12         self.online_set_name = "palm_online_devices"13 14     # 获取锁15     def acquire_lock(self, key, val, acquire_time=60, time_out=60):16         start_time = time.time()17         # 阻塞等待，轮询去获取锁，获取不到，轮询等待，直到拿到锁或者超时18         while True:19             if time.time() - start_time > acquire_time:20                 return False21             # 用setnx实现分布式锁，当key存在时候，setnx不做任何动作，如果key不存在，将value值设置为val22             # 如果 SETNX 返回1，说明该进程获得锁，SETNX将键 lock.foo 的值设置为锁的超时时间（当前时间 + 锁的有效时间）。23             # 如果 SETNX 返回0，说明其他进程已经获得了锁，进程不能进入临界区。进程可以在一个循环中不断地尝试 SETNX 操作，以获得锁24             if self.redis.setnx(name=key, value=val):25                 # 设置key的时长为60秒，如果超过60秒，key销毁26                 self.redis.expire(key, time_out)27                 return True28 29     # 释放锁30     def release_lock(self, key, val):31         pip = self.redis.pipeline(True)32         while True:33             try:34                 pip.watch(key)35                 lock_value = self.redis.get(key)36                 if not lock_value:37                     return True38                 if lock_value == val:39                     pip.multi()40                     pip.delete(key)41                     pip.execute()42                     return True43                 pip.unwatch()44                 break45             except WatchError:46                 pass47         return False

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