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")