Redis multi-instance distributed lock: Python implements redlock distributed lock algorithm code example

Redlock is a distributed lock algorithm that coordinates locks across multiple Redis instances. The basic idea of ​​the Redlock algorithm is to use multiple Redis instances to coordinate locks to ensure that no deadlocks or race conditions occur under any circumstances. The implementation of the Redlock algorithm is relatively complicated, and multiple factors need to be considered, such as clock drift and network delay. If you want to know more about the Redlock algorithm, you can refer to the following links:

The following is a Python code example that uses the Redlock algorithm to implement distributed locks:

import redis
import time

class Redlock(object):
    def __init__(self, connection_list, retry_times=3, retry_delay=200):
        self.servers = []
        for connection in connection_list:
            self.servers.append(redis.StrictRedis(host=connection["host"], port=connection["port"], db=connection["db"]))
        self.quorum = len(self.servers) // 2 + 1
        self.retry_times = retry_times
        self.retry_delay = retry_delay

    def lock(self, resource, ttl):
        retry = self.retry_times
        while retry > 0:
            n = 0
            start_time = time.time() * 1000
            for server in self.servers:
                if server.set(resource, 1, nx=True, px=ttl):
                    n += 1
            elapsed_time = time.time() * 1000 - start_time
            validity = ttl - elapsed_time - 2
            if n >= self.quorum and validity > 0:
                return validity
            else:
                for server in self.servers:
                    server.delete(resource)
                retry -= 1
                time.sleep(self.retry_delay / 1000)
        return False

    def unlock(self, resource):
        for server in self.servers:
            server.delete(resource)

# Example usage:
redlock = Redlock([{
    
    "host": "localhost", "port": 6379, "db": 0}], retry_times=3, retry_delay=200)
validity = redlock.lock("my_resource", 10000)
if validity:
    print("Lock acquired")
    # Do something here...
    redlock.unlock("my_resource")
else:
    print("Failed to acquire lock")