How does PHP use Lua to achieve read and write consistency issues?

With the gradual development of Web applications, the technologies used in Web interfaces are becoming more and more diversified. Of course, PHP continues to play an important role as a classic server-side scripting language. In PHP applications, sometimes you need to perform a complex business operation, which may include multiple database read and write operations. In order to improve performance and efficiency, technologies such as caching need to be used for optimization.

Currently in PHP applications, the most common read and write optimization solution is to use Memcache. Using Memcache in PHP applications can effectively avoid frequent reading and writing of the database, but it will cause cache consistency problems. If it needs to be used in a multi-process load balancing environment, a more complex caching strategy needs to be designed, and Memcache is not a lightweight component and needs to occupy more memory.

This article introduces a lightweight alternative: using Lua scripts in PHP applications and using Redis to solve the read-write consistency problem.

What is Lua

Lua is a lightweight scripting language that can be used as an embedded extension language for existing programs. Lua was developed by a research group at the Catholic University of Rio de Janeiro in Brazil, and the first version was released in 1993. Lua is highly praised for its small size, fastness, and embeddability. It is an excellent scripting language.

Lua has powerful dynamic language features, is easy to read and write code, and supports procedural programming, object-oriented programming, functional programming, and data-driven programming. Lua is a highly customizable language that is widely used in some game engines, such as CryEngine, World of Warcraft, etc.

Lua and Redis

Redis is a fast, lightweight NoSQL database, usually used in cache, message queue and other scenarios. Redis is an in-memory database and uses a disk persistence mechanism to meet the needs of high concurrency and high throughput scenarios.

Lua can interact with Redis through Redis's strategy mode to solve data consistency problems. Lua scripts can hand over both read and write operations to Redis, thereby avoiding cache consistency issues caused by applications directly reading and writing to the database.

Using PHP with Lua

PHP installs the LuaJIT extension through Composer to interact with Lua.

Install LuaJIT extension

LuaJIT is an open source implementation of Lua. The bottom layer is written in C, which can provide higher execution efficiency. Using the LuaJIT extension in PHP requires LuaJIT to be installed first. Taking CentOS as an example, the installation command is as follows:

yum install -y luajit-devel

After the installation is completed, you can check whether LuaJIT is successfully installed by the following method:

$ php -r "var_dump(extension_loaded('luajit'));"
bool(true)

Write Lua script

Use it in PHP applications Lua script, you need to write some Lua programs. The following is an example Lua script that saves and obtains data through Redis, specifically implementing a read-and-write operation.

local read_val = redis.call("get", KEYS[1])
if read_val ~= false then
    redis.call("set", KEYS[1], read_val)
    return read_val
end

redis.call("set", KEYS[1], ARGV[1])
return ARGV[1]

In this Lua script, we use Redis to store data and implement read-and-write operations. First, the script reads the value with the key KEYS[1] through the get command of Redis. If the read data is not empty, the read value is directly returned; otherwise, the key is KEYS[1] is written to Redis. , the value is ARGV[1], and ARGV[1] is returned.

Using Lua scripts in PHP

Using Lua scripts in PHP requires the phpredis extension to be installed. The installation command is as follows:

composer require "phpredis/phpredis"

To call Lua scripts in PHP, you can use the pEval() method provided by the phpredis extension. The first parameter of this method is a Lua script string, and the second parameter is a one-dimensional array containing the key name of Redis and the value that needs to be written to Redis.

$options = [
    'host' => '127.0.0.1', 
    'port' => 6379
];

$redis = new \Redis();
$redis->connect($options['host'], $options['port']);

// 导入 Lua 脚本到 Redis 中
$script = <<<EOF
local read_val = redis.call("get", KEYS[1])
if read_val ~= false then
    redis.call("set", KEYS[1], read_val)
    return read_val
end

redis.call("set", KEYS[1], ARGV[1])
return ARGV[1]
EOF;

// 使用 Redis 执行 Lua 脚本
$key = "mykey";
$value = "myvalue";
$result = $redis->pEval($script, [ $key ], [ $value ]);

print_r($result); // output: myvalue

In PHP, we need to use Redis to execute the Lua program to complete the read-and-write operation. In the above example, we import the Lua program into Redis and execute the Lua program through the pEval() method of Redis.

Summary

By using Lua scripts in PHP applications, combined with Redis, the read and write consistency problem can be solved, and the read and write pressure of MySQL can also be reduced. The cooperation between Lua and Redis can easily implement very complex business logic.

However, it should be noted that although using Lua scripts can alleviate read and write consistency problems in applications, it will also reduce the maintainability of the system. In actual use, it is recommended to choose technical solutions reasonably to avoid making the system too complex.

The above is the detailed content of How does PHP use Lua to achieve read and write consistency issues?. For more information, please follow other related articles on the PHP Chinese website!