Selection and Advantages and Disadvantages of apcu_entry and Redis Cache

In PHP application development, the choice of caching technology directly affects the performance and scalability of the system. Common caching schemes include local cache and distributed cache, among which APCu and Redis are two very popular caching tools. This article will focus on the usage scenarios, advantages and disadvantages of the apcu_entry function and Redis cache in PHP, and give selection suggestions in actual applications.

1. What is the apcu_entry function?

apcu_entry is an efficient cache function in the APCu extension. APCu is a User Cache extension of PHP, providing memory-level local caching functions. apcu_entry allows developers to specify a key and a callback function:

• If there is a corresponding key in the cache, the cache result will be returned directly;

• Otherwise, execute the callback function, write the result to the cache, and return the result.

This method is particularly suitable for caching data that requires delayed calculations, while ensuring the atomicity of the cache and avoiding cache penetration.

 <?php
$key = 'user_data_123';

// use apcu_entry Cache user data
$data = apcu_entry($key, function() {
    // Simulate getting data from the database
    $userData = file_get_contents('https://gitbox.net/api/user/123');
    return json_decode($userData, true);
});

print_r($data);

2. What is Redis cache?

Redis is an open source, high-performance distributed memory database that supports rich data structures such as strings, hashes, lists, etc. It is usually deployed on a standalone server and is suitable for multiple application instances to share cached data.

Using Redis in PHP is usually operated through phpredis or predis clients:

 <?php
$redis = new Redis();
$redis->connect('127.0.0.1', 6379);

$key = 'user_data_123';
$data = $redis->get($key);

if ($data === false) {
    // Cache miss，Execute a callback to get data
    $userData = file_get_contents('https://gitbox.net/api/user/123');
    $redis->set($key, $userData, 3600); // Cache for one hour
    $data = $userData;
}

print_r(json_decode($data, true));

3. Comparison of advantages and disadvantages of apcu_entry and Redis

4. Selection suggestions in practical applications

• Standalone environment or small project <br> If the application is deployed on a single server and the cached content only needs to be accessed by the current process, apcu_entry is a lightweight and efficient choice. It avoids network overhead, and the apcu_entry function can ensure atomicity and is suitable for cache dynamically generated data.

• Distributed environment or multi-server scenarios <br> Redis is a more reasonable choice when an application needs to share cache across multiple servers. It supports persistence, data sharing and complex data structures, and is suitable for high concurrency and high availability scenarios.

• Mixed use <br> In large systems, APCu can be used as local hotspot cache and Redis as distributed cache. Get data from local APCu first, miss it and then access Redis to further reduce access latency and Redis pressure.

5. Summary

The choice of a caching plan should be based on multiple aspects such as project requirements, system architecture, and maintenance costs. A rational combination of APCu and Redis can improve performance while ensuring the flexibility and scalability of the system.