Apache DirectMemory :: Cache framework technical principles detailed explanation

Apache DirectMemory (also known as DirectMemory) is an open source cache framework, which aims to provide high -performance and low -delay memory data access solutions.This article will explain the technical principles of the DirectMemory framework in detail and provide a related Java code example. The main goal of the DirectMemory framework is to store data in RAM (random access to stores) to speed up data access.The cache data is usually loaded from other data sources (such as database or file system), and is then stored in memory for fast access and operation.Below is a detailed explanation of the technical principle of the DirectMemory framework: 1. Data structure: DirectMemory uses a core component called `MemoryManagerservice`, which is responsible for managing the distribution, release and management of memory.It uses the `ORG.APACHE.DirectMemory.Memory.poIinter` class to track the status of the memory block. Each memory block is assigned a unique identifier as a pointer. 2. Second -level cache: The DirectMemory framework uses a secondary cache: a pile of outer memory cache (OFF-Heap Cache) and an on-heap cache. -Staters and memory cavities are implemented with DirectBytebuffer, and the memory is directly operated by using the `UNSAFE` class.DirectMemory uses the pile of memory to avoid the effect of Java garbage recycling on cache performance. -ConcurrenThashMap is used to store data, and Java's memory management mechanism is used for recycling the cache object. 3. Memory allocation and release: DirectMemory uses a adaptive memory allocation strategy that dynamically adjusts the distribution and release of memory according to the requirements of the application.When the cache needs to store new data objects, it will first try to obtain available memory blocks from the pile of memory cache. If there is no available memory block, it will be allocated through the `MemoryManagerService`.When the data object in the cache is removed, the memory will be released and marked as reusable. 4. Data storage and retrieval: DirectMemory uses a data structure similar to HashMap to quickly store and retrieve data storage and retrieval in cache.It is stored by mapping data objects into key value pairs.Using keys as a unique identifier, it can quickly locate and retrieve data objects in cache. Here are some examples of Java code using the DirectMemory framework: 1. Initialization and configuration DirectMemory cache: int MaxSize = 100; // Set the maximum capacity of the cache int Office = 10; // Set the size of the pile of external memory cache MemoryManagerService memoryManager = new UnpooledMemoryManagerService(offHeapSize); CacheService cache = CacheServiceImpl.createNewProvider(maxSize, memoryManager); 2. Store the data object into the cache: String key = "user_1"; User user = new User("John Doe", 25); cache.put(key, user); 3. Get the data object from the cache: User cachedUser = cache.get(key); System.out.println (cacheduser.getName ()); // Output: John Doe 4. Remove the data object from the cache: cache.free(key); The technical principle of the DirectMemory framework covers key aspects such as memory management, data storage and retrieval, making it a powerful tool for processing large -scale memory data.By understanding these principles and using the corresponding Java code examples, you can better use the DirectMemory framework to improve the performance and response speed of the application.