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Stateless Authentication with RedisIn a distributed architecture, relying on Tomcat's local sessions for user state leads to inconsistencies across instances. Redis serves as a centralized session store to solve this. When a user logs in via SMS, a unique token is generated and stored in Redis as the key, with the serialized user DTO as the val ...

Understanding MyBatis Caching Mechanisms MyBatis incorporates an internal caching system designed to enhance application performance by minimizing redundant database interactions. This caching operates at two distinct levels: a local, session-scoped cache and a global, application-scoped cache. First-Level Cache: SqlSession Scope The first-leve ...

In the previous article, we explored Spring Boot integration with Redis. This article focuses on implementing Redis caching in MyBatis operations. We'll examine four key annotations: @CachePut, @Cacheable, @CacheEvict, and @CacheConfig. Fundamentals @Cacheable The @Cacheable annotation configures method-level caching, storing results based on m ...

Introduction to LFU Caching LFU (Least Frequently Used) is a caching algorithm that removes the least frequently accessed items when the cache reaches its capacity. Unlike LRU (Least Recently Used), which considers only recency, LFU prioritizes access frequency. Comparison of LFU and LRU Consider a cache with capacity 3 and the following access ...

Cache Penetration Cache penetration occurs when a large number of requests target data that exists neither in the cache nor in the database. For example, if users repeatedly request non-existent order numbers like -1, these requests bypass the cache entirely and hit the database directly. This scenario can be exploited maliciously to overwhelm ...

Redis Cache and Database Consistency Caching improves performance and reduces database load, but introduces potential inconsistencies between cached data and the database. Inconsistent data leads to stale reads from the cache. Non-Concurrency Scenarios Update Cache First, Then Database If cache udpate succeeds but database update fails, the cac ...

ReentrantReadWriteLock Introduction and Usage Overview ReentrantReadWriteLock is ideal for scenarios with far more read operations than write operations. It allows concurrent read access while ensuring mutual exclusion between reads and writes, or between writes and writes—similar to database shared locks (select ... from ... lock in share mode ...

What is Redis Redis is a high‑performance, in‑memory key‑value database that also supports optional data persistence. It is open‑source and written in C, widely used both as a cache and as a primary datastore for specialised scenarios. Why Redis Is So Fast In‑memory storage – data is served directly from RAM, avoiding disk I/O for most operati ...

Cache Anomalies Cache Penetration: Requested data does not exist in the system. Use a Bloom filter. Cache Breakdown: A hot key expires. Implement mutual exclusion locks. Apply logical expiration (no actual TTL set). Cache Avalanche: Numerous keys expire simultaneously. Assign random expiration times. Deploy a Redis cluster. Cache Pen ...

Building Varnish from Source Begin by preparing the required system libraries. Compile and install PCRE2 from source: tar -xzf pcre2-10.23.tar.gz cd pcre2-10.23 ./configure --prefix=/opt/pcre2 make && make install Update the package configuration environment variable and install remaining dependencies via YUM: export PKG_CONFIG_PATH=/o ...