How PHP uses Memcached to cache data

With the continuous development of web applications, caching technology has become one of the important means to optimize website performance. Memcached, as a high-performance distributed memory object caching system, has become the preferred data caching solution for many websites. One of the options. This article will introduce how to use Memcached to cache data in PHP to improve website performance.

1. Installing Memcached

Before starting to use Memcached to cache data, we need to install and start the Memcached service. For specific installation methods, please refer to Memcached official documentation. Generally speaking, the Memcached service listens on port 11211 of 127.0.0.1 by default. You can also specify the port and listening address by modifying the configuration file.

2. PHP extension installation

PHP itself does not include the Memcached extension, so we need to install and enable the Memcached extension first. For specific installation methods, you can refer to the Memcached official documentation, or use the software package management tool that comes with the operating system to install it. After the installation is complete, you need to add the following configuration to the php.ini file to enable the Memcached extension:

extension=memcached.so

3. Data cache operation

In PHP, use Memcached For data caching operations, you need to use the API provided by the Memcached extension. The following are some commonly used API examples:

• Connect to Memcached server

$memcached = new Memcached();
$memcached->addServer('localhost', 11211);

• Cache data

// 缓存字符串
$memcached->set('key', 'value', 3600);

// 缓存数组
$array = array('foo' => 'bar');
$memcached->set('key', $array, 3600);

• Get Cached data

$data = $memcached->get('key');

// 如果缓存不存在，则会返回false
if ($data === false) {
    // 从其他数据源获取数据
}

• Delete cached data

$memcached->delete('key');

• Atomic operation

In Memcached, use CAS (Compare -and-swap) operations can achieve atomic operations. For example, we can extend the cache expiration time through CAS operations:

$key = 'key';
$expires = 3600;
$retries = 5;

// 获取当前值和CAS token
$cas = null;
$value = $memcached->get($key, null, $cas);

// 如果值存在并且CAS token不为空，则进行CAS操作
while ($retries-- > 0 && $value !== false) {
    $memcached->cas($cas, $key, $value, $expires);
    $value = $memcached->get($key, null, $cas);
}

4. Summary

Using Memcached to cache data is an effective means to improve website performance, through PHP By extending the provided API, we can easily implement the operation of caching data. Of course, when using Memcached to cache data, you need to pay attention to issues such as caching strategies and cache update strategies to give full play to the advantages of caching and improve website performance and user experience.

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