How to use PHP cache development to improve website performance

With the continuous development of Internet technology, the number of various websites is also increasing, and network traffic is also increasing. For developers, how to improve website performance has become an important issue. Among them, the use of caching technology can effectively improve the performance of the website, reduce the pressure on the server, and increase the access speed of the website.

As a commonly used Web programming language, PHP itself supports caching technology. We can implement caching through the built-in functions and extensions provided by PHP. This article will use specific code examples to introduce how to use PHP to develop cache and improve website performance.

1. File caching
File caching refers to the process of storing frequently accessed data in files, thereby avoiding the process of reading data from the database or other storage devices for each request, in order to improve access speed. .

The way to implement file caching is very simple. We only need to use the PHP built-in function file_put_contents() to write data to the file, and use the file_get_contents() function to read the data. The following is a sample code:

function get_data($key) {
    $filename = './cache/' . md5($key); // 缓存在cache目录下，以$key的md5值作为文件名
    if (file_exists($filename)) { // 如果缓存文件存在，读取缓存
        $data = file_get_contents($filename);
        return unserialize($data);
    } else { // 缓存文件不存在，查询数据库并缓存查询结果
        $data = query_from_db($key); // 从数据库中获取数据
        file_put_contents($filename, serialize($data)); // 将查询结果缓存到文件中
        return $data;
    }
}

In the above code, the function of get_data() function is to obtain the cache data. If the cache exists, the data is read directly from the cache file and returned; if the cache does not exist, Then get the data from the database and cache the query results to the file. It should be noted that we need to serialize the query results first when caching, and then deserialize them when reading, in order to obtain the data correctly.

2. Memcached Cache
Memcached is a high-performance cache server that can cache data into memory to improve data access speed. In PHP, Memcached caching can be conveniently used using the Memcached extension.

The following is a sample code:

$memcached = new Memcached();
$memcached->addServer('localhost', 11211); // 连接到本地的11211端口

function get_data($key) {
    global $memcached;
    $data = $memcached->get($key); // 从缓存中获取数据
    if ($data) { // 如果缓存存在，直接返回数据
        return $data;
    } else { // 缓存不存在，从数据库中获取并添加到缓存中
        $data = query_from_db($key); // 从数据库中获取数据
        $memcached->set($key, $data, 3600); // 将数据添加到缓存，有效期为3600秒
        return $data;
    }
}

In the above code, we first create a Memcached object and connect to the local 11211 port, and then define a method named get_data() function. In the function, we get the data from the cache through the get() method of the Memcached object. If the data exists, return it. Otherwise, get the data from the database and add the data to the cache. The validity period is 3600 seconds.

3. Redis Cache
Redis is a high-performance non-relational database that provides a variety of data structures and can be used in a wide range of application scenarios. In PHP, Redis caching can be conveniently used using the Redis extension.

The following is a sample code:

$redis = new Redis();
$redis->connect('localhost', 6379); // 连接到本地的6379端口

function get_data($key) {
    global $redis;
    $data = $redis->get($key); // 从缓存中获取数据
    if ($data) { // 如果缓存存在，直接返回数据
        return $data;
    } else { // 缓存不存在，从数据库中获取并添加到缓存中
        $data = query_from_db($key); // 从数据库中获取数据
        $redis->set($key, $data, 3600); // 将数据添加到缓存，有效期为3600秒
        return $data;
    }
}

In the above code, we first create a Redis object and connect to the local 6379 port, and then define a named get_data() function. In the function, we get the data from the cache through the get() method of the Redis object. If the data exists, return it. Otherwise, get the data from the database and add the data to the cache. The validity period is 3600 seconds.

4. Best Practices
In the process of using cache, we need to pay attention to the following issues:

1. The validity period of the cache
   The validity period of the cache depends on the specific For application scenarios, set an appropriate cache cycle in advance to avoid errors caused by outdated cache data.
2. Cache update
   When the data changes, the cache needs to be updated in time to ensure that the cached data is consistent with the data in the database.
3. Cache Cleaning
   The cached data will occupy memory space. When the cache space is insufficient or the data expires, the cache needs to be cleared in time.

In practical applications, we can combine the above three caching methods and choose an appropriate caching solution according to actual needs to improve website performance and user experience.

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