采用Redis实现分布式锁的简单实现（在redis中加分布式锁）
Distributed locks are the key to ensuring consistency of the shared data in distributed systems. It allows us to limit only one process for a specific resource at any given time, so that multiple threads or multiple processes can’t access the same resource at the same time and lead to data conflict.
Redis is one of the most popular ways to achieve distributed locks in distributed systems because of its high performance, scalability and fault tolerance. The core idea is to set a key-value pr in the Redis service and implement the locking mechanism with SET command.
Let’s walk through how a distributed lock works.
1. A process that needs to obtn a lock contacts Redis service to set a key-value pr using SET command. The key is the name of the resource that needs to be locked, and the value can include the process ID and other information.
2. After the locking is successful, the process can continue to process the data related to the resource.
3. When the process finishes the operation, it uses DEL to delete the key-value pr in Redis service.
Thus, the process has released a lock on the specified resource.
Below is the example of distributed locking with Redis:
1.String lockKey=”LOCK”;
2.String lockValue=System.currentTimeMillis()+1000;
3.SetParams params=SetParams.setParams().nx().px(1000);
4.string result=jedis.set(lockKey,lockValue,params);
5.if(“OK”.equals(result)){
6. //Successfully locked
7. //Perform operations
8. String oldValue = jedis.get(lockKey);
9. if(oldValue!=null && oldValue.equals(lockValue)){
10. jedis.del(lockKey);
11. }
12.}
Line 1 is the resource that we want to lock, which can be more complex in a real-world scenario. Line 2 is the value of the key, which can be used to distinguish between different locking processes. Line 3 is the parameter for the SET command, indicating that the SET operation is executed only if the key does not exist. Line 4 is where the actual SET command is executed agnst Redis. Finally, when the process is finished, the oldValue is obtned from Redis (Line 8) to get the value that was actually set, and if the values are matched, the key-value pr is removed from Redis service (Line 10).
In conclusion, leveraging Redis is an easy and effective way to implement distributed locks. Redis’ high performance, scalability and fault tolerance make it an ideal tool for distributed systems.
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