Programmer Think

What is a bloom filter Bloom Filter was proposed by a young man named bloom in 1970. It has been 50 years since then. It is actually a very long binary vector and a series of random mapping functions. Everyone should know that the stored data is either 0 or 1, and the default is 0. It is mainly used to judge whether an element is in a set. 0 ...

1.caffeine features Caffeine uses ConcurrentHashMap internally, provides a variety of cache elimination mechanisms (according to time, weight, quantity, etc.), and supports elimination notification. Moreover, caffeine has high cache performance on the premise of ensuring thread safety, which is known as the king of cache 1.1 official performa ...

1, Common commands for keys keys * View all current key exists key Judge a key Does it exist type key View your key What type is it del key Delete the specified key data unlink key according to value Select non blocking delete to delete only keys from keyspace If the metadata is deleted, the real deletion will be carried out in subsequent asyn ...

Redis official website: https://redis.io Redis Chinese official website: http://www.redis.cn The following is an overview of Redis data types, which can be read intuitively by using code blocks. 1, Base point 1. There are 16 Redis databases by default, and the first one is used by default. Use select to switch databases. 2. The default port ...

Three characteristics of concurrent programming 1. Visibility: the visibility of shared variables among threads, that is, when one thread changes the value of shared variables, other threads can also see and update the value in their own threads. Shared resources are generally placed in the heap space (main memory). Each thread will copy a cop ...

In the era of WebServer, Jedis direct connection is mostly used in the code to operate Redis server, so people will package a tool class in the project for Jedis. However, in the era of microservice integration SpringBoot, letstructure (underlying Netty, NIO mode) is used. We only need to pay attention to the use of RedisTemplate, but there are ...

catalogue 1 what is AOP 2 appendonly.aof file 3 Rewrite 3.1 what is rewrite  3.2 rewriting principle 3.3 trigger mechanism 4 advantages and disadvantages of AOF 5 Summary 5.1 comparison between RDB and aof 5.2 enable two persistence methods at the same time 1 what is AOP Record every write operation in the form of log, and rec ...

1. Use of springboot cache a.pom introduce jar spring-boot-starter-cache b.Add annotation to startup class@EnableCaching c.Add annotations to the methods that need to be cached @Cacheable(cacheNames = "com:xxx",key = "''+#id") Figure 1 2. Implementation principle of cacheable What is the implementation principle? The first reaction ...

preface In this chapter, learn about the Spring defined annotation @ Cacheable @CachePut @CacheEvict @Caching @CacheConfig and related properties @Cacheable /** * Cacheable Indicates that the caching behavior is enabled. If it is on the annotation class, it means that all methods are cached * Cache keys are generated based on parameter ...

Redis distributed lock Redis is a single process and single thread mode. The queue mode is adopted to change concurrent access into serial access, and there is no competition between multiple clients for redis connection. In redis, SETNX command can be used to realize distributed locking. If and only if the key does not exist, set the val ...