PHP development APP interface video tutorial

Uses PHP object-oriented thinking to explain how to develop APP server-side interfaces. The course is step-by-step and easy to understand. Key and difficult technologies are explained in detail. By studying this course, you can Learn how to open the APP interface and you will benefit a lot.

Course playback address: http://www.php.cn/course/404.html

The teacher’s teaching style:

The teacher’s lectures are vivid, witty, witty, and touching. A vivid metaphor is like the finishing touch, opening the door to wisdom for students; a well-placed humor brings a knowing smile to students, like drinking a glass of mellow wine, giving people aftertaste and nostalgia; a philosopher's aphorisms, cultural references Proverbs are interspersed from time to time in the narration, giving people thinking and warning.

The more difficult point in this video is Memcache and Redis caching technology:

Memcache

Memcache is a high-performance, distributed memory object caching system , by maintaining a unified huge hash table in memory, it can be used to store data in various formats, including images, videos, files, and database retrieval results. Simply put, the data is called into the memory and then read from the memory, thus greatly improving the reading speed.

Memcache features:

(1) Use physical memory as a cache area and can run independently on the server. Each process has a maximum of 2G. If you want to cache more data, you can open more memcache processes (different ports) or use distributed memcache for caching to cache data on different physical machines or virtual machines.

(2) Use the key-value method to store data, which is a single-index structured data organization form that can make the query time complexity of data items O(1).

(3) The protocol is simple: Based on the text line protocol, data access operations can be performed directly on the memcached server through telnet. It is simple and convenient for various caches to refer to this protocol;

(4 ) High-performance communication based on libevent: Libevent is a set of program libraries developed in C. It encapsulates event processing functions such as kqueue of the BSD system and epoll of the Linux system into an interface, which improves performance compared with the traditional select.

(5) Built-in memory management method: All data is stored in the memory, and accessing data is faster than the hard disk. When the memory is full, unused caches are automatically deleted through the LRU algorithm, but the data is not considered. Disaster recovery issues, restart the service, all data will be lost.

(6) Distributed: Each memcached server does not communicate with each other, each accesses data independently, and does not share any information. The server does not have distributed capabilities, and distributed deployment depends on the memcache client.

(7) Cache strategy: Memcached’s cache strategy is the LRU (least recently used) expiration strategy. When storing data items in memcached, you can specify its cache expiration time, which defaults to permanent. When the memcached server runs out of allocated memory, expired data is replaced first, then data that has not been used recently. In LRU, memcached uses a Lazy Expiration strategy. It does not monitor whether the stored key/vlue pair has expired. Instead, it checks the recorded timestamp when obtaining the key value and checks whether the key/value pair space has expired. This reduces the load on the server.

Redis

Redis is an open source (BSD licensed), memory-based, multi-data structure storage system. Can be used as database, cache and messaging middleware. Supports multiple types of data structures such as strings, hashes, lists, sets, sorted sets and range queries, bitmaps, hyperloglogs and geospatial ) Index radius query.

Built-in replication, LUA scripting, LRU eviction, transactions and different levels of disk persistence, and through redis Sentinel and automatic partitioning (Cluster) provide high availability (high availability).

Commonly used data types in Redis

The most commonly used data types in Redis are as follows:

• String

• Hash

• List

• Set

• Sorted set

• pub/sub

• Transactions

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