How to use PHP caching technology to improve code running efficiency?

As a commonly used back-end language, the operating efficiency and performance of PHP have always been issues we have to consider. Caching technology is an essential part of PHP to improve code running efficiency. In this article, we will discuss how to use PHP caching technology to improve code running efficiency.

1. What is cache?

Before we start discussing how to use caching technology to improve code running efficiency, we need to understand what caching is. In computing, caching is a temporary storage technique that stores data in faster storage devices so that they can be accessed quickly when needed. In PHP, we can use caching to store calculation results so that the data can be obtained faster the next time we access it.

2. Types of PHP caching technology

PHP provides many caching technologies to improve the running efficiency of the code. The following are some common PHP caching techniques:

(1) File caching: Store data in files and read data from the files when needed.

(2) Memcached: It is a memory-based cache system that can store any type of data.

(3) APCu: It is a PHP extension used to provide a local cache for each process, which basically stores data in variable form in the process memory.

(4) Redis: It is an in-memory data storage system that can be used as a cache, database and messaging agent.

(5) OpCache: It is the built-in PHP caching technology after PHP5.5 version, used to cache compiled PHP scripts.

3. How to use PHP caching technology to improve code running efficiency

The following are some caching technology implementation methods to improve code running efficiency:

(1) File Cache

Implementation process:

First, we need to determine the directory where the data is stored. For security reasons, it is recommended to place this directory outside the web server root directory. Next, we create a directory to store the data and set read and write permissions. (Example: /tmp/cache)

Then we can store the data in the file by following these steps:

1. Check if the file exists.
2. If the file exists, check whether the cache has expired. If the cache expires, delete the file.
3. Calculate the result if the file does not exist or has expired.
4. Write data to the file.

Finally, when the next request is made, we can check if the file exists and check if the cache has expired. If the cache expires, we need to recalculate the results and update the file.

(2) Memcached

Cache data can be easily stored in memory using Memcached. First, we need to install and configure the memcached service. Then use the memcached extension in PHP. In the following example, we use add() and get() methods to store data in memory:

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

$key = 'myKey';
$data = 'my data';

if(!$memcached->get($key)){
  $memcached->add($key, $data, 3600);
}

$result = $memcached->get($key);

(3) APCu

Using APCu caching technology, we can cache data Stored in local process memory. First, we need to install and configure the APCu extension. The data can then be stored in local process memory as follows:

$key = 'myKey';
$data = 'my data';

if(!apcu_exists($key)){
  apcu_add($key, $data, 3600);
}

$result = apcu_fetch($key);

(4) Redis

Redis can be used as a key-value store and cache system. First, we need to install and configure the Redis server. Then, the data can be stored in the Redis cache as follows:

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

$key = 'myKey';
$data = 'my data';

if(!$redis->exists($key)){
  $redis->setex($key, 3600, $data);
}

$result = $redis->get($key);

(5) OpCache

OpCache can cache the compiled code of the PHP script to improve the code running efficiency. By default, OpCache is enabled. We can configure OpCache by modifying the php.ini file. For example, the following is the php.ini file that configures OpCache:

[opcache]
opcache.enable=1
opcache.memory_consumption=128
opcache.max_accelerated_files=4000
opcache.revalidate_freq=60

4. Notes on using caching technology

Using caching technology to improve code running efficiency may have some side effects . The following are some issues that need to be paid attention to when using caching technology:

(1) Selection of cache expiration time: The purpose of setting the cache expiration time is to re-obtain data after the specified time. The expiration time should be chosen appropriately: too long will cause the data to expire and become invalid, while too short a time will cause frequent cache access.

(2) Issues with cache space management: When memory or disk space is insufficient, we need to decide how to manage cache space. One workaround is to use the LRU (Least Recently Used) algorithm, but this may result in insufficient cache.

(3) Problem with data update: When the data changes, we need to update the cache, otherwise we will get old data. We use listeners or scheduled tasks to update the cache.

5. Conclusion

Caching is an important technology to improve the efficiency of PHP code operation. When using caching technology, we need to choose the appropriate caching technology according to the specific situation, and pay attention to issues such as cache expiration time, cache space management and data update during implementation. If we use caching technology correctly, we can significantly improve the efficiency of back-end code.

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