What are the high-end technologies of Java?

Commonly used data types in Redis

The five commonly used data types in Redis are: String, Hash, List, Set and Sorted set

Redis usage scenarios

1.Counting
2.Display the top list of the latest, hottest, highest click rate, highest activity, etc.
3.The user’s recent access records are also Very good application scenarios of redis list
4. Write and consume the queue through the lpop and lpush interfaces of the list
5. The functional expansion of Redis's Lua actually brings more application scenarios to Redis. You You can write several command combinations as a small non-blocking transaction or update logic
6. The master-slave data synchronization function provided by Redis is actually a powerful functional extension of the cache

Summary

So many applications are inseparable from all the features of Redis

Uncover the mystery of Redis

Redis is an open source (KEY-VALUE key-value pair) , an in-memory data structure server that can be used as a database, cache, and message queue agent. It adopts a single-process single-thread model and has strong concurrency capabilities. It is the mainstream distributed caching tool in the current Internet architecture.

Redis high-performance cache architecture design

1. Architecture design

Since redis is a single point, the project If you need to use it, you must implement distribution yourself. The basic architecture diagram is as follows:

2. Distributed implementation

Do consistent hashing through key to achieve key correspondence The distribution of redis nodes.

Implementation of consistent hashing:

Hash value calculation: By supporting two calculation methods, MD5 and MurmurHash, MurmurHash is used by default for efficient hash calculation.

Achievement of consistency: simulate the ring structure through java's TreeMap to achieve uniform distribution

3.Client selection

For jedis modification The main thing is the modification of the partition module, so that it supports partitioning based on BufferKey. Different ShardInfo can be initialized based on different redis node information. At the same time, the underlying implementation of JedisPool is also modified so that the connection pool pool supports following data. The construction method of key and value creates different jedis connection clients according to different ShardInfos to achieve the effect of partitioning and is called by the application layer

4. Module description

Dirty data processing module, handles failed cache operations.

Shield monitoring module, for abnormal monitoring of jedis operations, when an abnormality occurs in a node, it can control the removal of redis nodes and other operations.

The entire distributed module uses hornetq to remove abnormal redis nodes. The addition of new nodes can also be achieved through the reload method. (This module can also be easily implemented for adding new nodes)

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