How does php use caching?

As a popular server-side programming language, PHP often needs to handle large amounts of data and requests, so efficient cache management is crucial to improving website performance. This article will introduce how PHP uses caching, including the basic principles of caching, PHP's own caching methods and other popular caching libraries.

1. Basic principles of caching

In web development, caching refers to saving frequently read data in a fast-access medium to reduce the need for data to be retrieved from the database or other sources during each request. The time the resource reads data. When using cache, you first need to determine whether the data already exists in the cache. If so, read the data directly from the cache. Otherwise, read it from the database or other resources, and add the read data to the cache.

The advantage of caching is that it can greatly reduce the cost of system resources and improve the performance and response speed of the website. However, caching also has some disadvantages. For example, for dynamically changing data, caching may cause the data to not be updated in time, resulting in errors.

2. PHP’s own caching method

Php provides a variety of caching methods, the most commonly used of which are memory cache (Memory Cache) and file cache (File Cache).

1. Memory cache

Php provides three memory cache methods, namely Memcached, APC and XCache. These caching libraries are very effective when handling large amounts of data and can make PHP programs run faster.

(1)Memcached

Memcached is a commonly used distributed memory object caching system. It is based on the libevent network library and can share data between multiple servers. Php can easily call Memcached by extending the class library Memcache.

Sample code:

$mem = new Memcache;
$mem->connect("localhost", 11211);
$result = $mem->get("product_123");

if(!$result) {
  $result = '...'; // 从数据库或其他资源中读取数据
  $mem->set("product_123", $result, 3600);
}

echo $result;

(2) APC

APC is a memory object caching system called "Alternative PHP Cache", which can help PHP achieve fast Data reading and processing, and reducing server load. Php can easily call APC by extending the class library APC.

Sample code:

$value = apc_fetch('variable_key');
if($value === false) {
    $value = '...'; // 从数据库或其他资源中读取数据
    apc_store('variable_key', $value, $ttl);
}
echo $value;

(3) XCache

XCache is a high-speed memory object caching system that can cache compiled PHP scripts, thereby improving PHP Execution speed. Php can be easily called by extending the class library XCache.

Sample code:

$value = xcache_get('variable_key');
if(!$value) {
    $value = '...'; // 从数据库或其他资源中读取数据
    xcache_set('variable_key', $value, $ttl);
}
echo $value;

2. File cache

In addition to memory cache, Php also provides file cache, which can save data to the local hard disk. The advantage of file caching is that data can be saved for a long time and will not become invalid due to server restarts. However, under high concurrency conditions, file caching may become a bottleneck.

Sample code:

$cache_file = 'cache/product_123.cache';
if(file_exists($cache_file) && (time() - filemtime($cache_file) < 3600)) {
    $result = file_get_contents($cache_file);
} else {
    $result = '...'; // 从数据库或其他资源中读取数据
    file_put_contents($cache_file, $result);
}
echo $result;

3. Other popular caching libraries

In addition to the caching method that comes with PHP, there are also many third-party caching libraries that can be used, such as Redis, MongoDB and Couchbase, etc. These caching libraries usually provide client libraries that can be easily integrated with Php.

1.Redis

Redis is a high-speed storage system and a high-speed cache system that supports a variety of data structures, including strings, lists, sets, and ordered sets. and hash etc.

Sample code:

$redis = new Redis();
$redis->connect('127.0.0.1', 6379);
$result = $redis->get('product_123');
if(!$result) {
  $result = '...'; // 从数据库或其他资源中读取数据
  $redis->setex('product_123', 3600, $result);
}
echo $result;

2.MongoDB

MongoDB is a document database that supports multiple storage formats, including JSON and BSON. Php can easily call MongoDB through MongoDB's official extension class library.

Sample code:

$m = new MongoClient();
$db = $m->test;
$collection = $db->products;
$result = $collection->findOne(array('id' => '123'));
if(!$result) {
  $result = '...'; // 从数据库或其他资源中读取数据
  $collection->insert(array('id' => '123', 'data' => $result));
} else {
  $result = $result['data'];
}
echo $result;

3.Couchbase

Couchbase is a memory-based distributed key-value storage system that supports automatic sharding and load balancing, and has High performance and high availability.

Sample code:

$cluster = new CouchbaseCluster('http://localhost:8091');
$bucket = $cluster->openBucket('default');
$result = $bucket->get('product_123')->value;
if(!$result) {
  $result = '...'; // 从数据库或其他资源中读取数据
  $bucket->upsert('product_123', $result);
}
echo $result;

4. Summary

Caching is a very important means of performance optimization. Php provides a variety of caching methods, including memory caching and file caching. , you can also use third-party caching libraries, such as Redis, MongoDB and Couchbase. When choosing a cache method, you need to choose the most suitable solution based on your own business needs and system architecture, and adjust parameters such as cache time, cache size, and cache algorithm according to the actual situation to achieve the best performance optimization effect.

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