上篇在学习$mem->set();的时候少写了一个参数,第三个参数,MEMCACHE_COMPRESSED,这个参数的作用在于压缩。
memcache是独立机构,是C/S结构。如果memcache满了,LRU算法删除,把最早没有访问过的拿掉。
memcache的分布式 这里是重点
在第二部中将connect这个方法改成addserver(),在链接池中添加了一个memcache服务器。
例如 :
$mem -> new Memcache();$mem -> addServer('127.0.0.1',11211); //增加链接池$mem -> addServer('127.0.0.1',9999); //增加链接池 $mem -> get($key);
memcached尽管是‘分布式’缓存服务器,但服务器端并没有分布式功能。
各个memcache不会互相通信以便信息共享。每个memcache服务的数据不是同步的。
而且把什么样的数据放入到哪一个memcached是由客户端的mem对象来决定的。
当执行addServer的时候,并不是立即去连接mem服务,而是通过计算,hash后才去决定链接哪一台mem服务,所以当大量加入服务到连接池,不会有多余的开销。
memcache细节的研究
生命周期。从放入开始计时,时间到就自动销毁。memcache被销毁有以下几种情况。一,时间到。二、重启memcache。三,重启服务器。
如何将session放入到memcache中保存
修改php.ini配置文件
session.save_handler=user 它有三个选项 user 表示自定义 files入库保存到文件 memcache保存在内存
修改如下 将session.save_handler 改为 memcache
将 session.save_path=“tcp://127.0.0.1,11211”
2. 重启apache
注意:如果session数据存入memcache,那它一定是以session_id为key值进行添加的。
如果以后做大型门户网站,一定要把session写入到memcache。(强烈建议)
如果无法修改php.ini文件,可以通过函数修改php.ini任何配置。可以把以下两句写到脚本的前端
ini_set("session.sava_handler","memcache");ini_set("session.save_path","tcp://127.0.0.1:9999"); //函数的参数都是以减值对的形式存入
ini_set()功能很强大,可以修改php.ini中的任何值。
safe_mode模式的谈论
他们的最大区别就在于,安全模式一旦打开,对服务器上文件的操作几乎失效。
ini_set()只会在很脚本起作用,不对其他文件起作用。

Setting session cookie parameters in PHP can be achieved through the session_set_cookie_params() function. 1) Use this function to set parameters, such as expiration time, path, domain name, security flag, etc.; 2) Call session_start() to make the parameters take effect; 3) Dynamically adjust parameters according to needs, such as user login status; 4) Pay attention to setting secure and httponly flags to improve security.

The main purpose of using sessions in PHP is to maintain the status of the user between different pages. 1) The session is started through the session_start() function, creating a unique session ID and storing it in the user cookie. 2) Session data is saved on the server, allowing data to be passed between different requests, such as login status and shopping cart content.

How to share a session between subdomains? Implemented by setting session cookies for common domain names. 1. Set the domain of the session cookie to .example.com on the server side. 2. Choose the appropriate session storage method, such as memory, database or distributed cache. 3. Pass the session ID through cookies, and the server retrieves and updates the session data based on the ID.

HTTPS significantly improves the security of sessions by encrypting data transmission, preventing man-in-the-middle attacks and providing authentication. 1) Encrypted data transmission: HTTPS uses SSL/TLS protocol to encrypt data to ensure that the data is not stolen or tampered during transmission. 2) Prevent man-in-the-middle attacks: Through the SSL/TLS handshake process, the client verifies the server certificate to ensure the connection legitimacy. 3) Provide authentication: HTTPS ensures that the connection is a legitimate server and protects data integrity and confidentiality.

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.


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