The implementation of redis affairs and optimism in the Java library

Redis is a high -performance key value storage system. In Redis, transaction and Optimistic Locking are two commonly used concurrent control mechanisms.This article will introduce the implementation of Redis affairs and optimism in the Java class library, and provide relevant Java code examples. ## redis transaction Redis transactions are the atomic execution operation of a set of commands, that is, this set of commands either succeeded in execution or all execution failed, ensuring the consistency of multiple commands.In Redis, the execution of transactions follow four steps: Multi, Exec, Discard, and Watch.The MULTI instruction is used to start transactions, the EXEC instruction is used to perform transactions, the Discard instruction is used to cancel transactions, and the Watch instruction is used to monitor the specified keys.Code examples are as follows: Jedis jedis = new Jedis("localhost", 6379); jedis.watch("key1", "key2"); Transaction transaction = jedis.multi(); transaction.set("key1", "value1"); transaction.set("key2", "value2"); Response<String> response1 = transaction.get("key1"); Response<String> response2 = transaction.get("key2"); transaction.exec(); String value1 = response1.get(); String value2 = response2.get(); In this code, first use the Watch instruction to monitor Key1 and Key2, and then use the Multi instruction to turn on the transaction, perform multiple command operations through the Transaction object, and finally use EXEC instructions to perform transactions, and use the Response object to obtain results. It should be noted that when the monitoring key changes, the transaction will be canceled. You can use the Watch instruction to continue to monitor in the cycle until the transaction is successfully executed. ## optimism lock Optimistic lock is a concurrent control mechanism. It assumes that multiple threads or transactions can be read at the same time, but you need to check whether the data changes when writing operations.In Redis, optimistic locks can be achieved by using the version number or timestamp.Code examples are as follows: Jedis jedis = new Jedis("localhost", 6379); String key = "counter"; Long version = jedis.incr(key + ":version"); Transaction transaction = jedis.multi(); transaction.set(key, "value"); transaction.set(key + ":version", version.toString()); Response<List<Object>> response = transaction.exec(); if (response != null) { // Successful transaction execution } else { // The execution of the transaction fails, and the conflict needs to be dealt with } In this code, a counter is used to simulate the operation of optimistic locks.First, use the INCR instruction to add the version number and save it in the variable version.Then, start the transaction and set up a new value and a new version number in the transaction.Finally, use the Exec instruction to perform transactions and check the return results. If the return result is not empty, it means that the transaction is successful, otherwise the conflict is required. The implementation of optimistic locks is relatively simple, but there may be problems with updated conflicts.When multiple threads or transactions update the same record at the same time, conflicts may occur. At this time, it is necessary to deal with according to the specific business logic. In summary, this article introduces the implementation of Redis affairs and optimistic locks in the Java library, and provides related Java code examples.Through the application of transactions and optimism, it can efficiently implement concurrent control and data consistency.