Architectural design and implementation of Memcache cache in PHP

1. Introduction and role of Memcache cache

Memcache is a high-performance distributed caching system, originally developed by the LiveJournal team to cache database query results, page data, etc. In web applications, due to the large amount of access and data processing, it is often necessary to interact with the database, which will occupy a lot of resources and affect performance. At this time, adding a caching function to the application can reduce the load on the server and improve website performance.

2. Architectural design of Memcache cache

1. Usage scenarios

• Caching of database query results
• Caching of page data
• Cache of frequently accessed data
• Cache of business public data

2. Environment settings

Memcache can run on Linux, Windows and other systems. You need to install the PHP extension and Memcache software package, which can be installed through source code compilation or directly using the software package. For specific steps, please refer to the official documentation.

3. Code implementation

For PHP programmers, using Memcache cache is a very convenient thing, and can be called directly using the Memcache class. The following is sample code for operations such as connection, value retrieval, value storage, and deletion of Memcache.

//连接服务器
$mem = new Memcache;
$mem->connect("127.0.0.1", 11211);

//存值
$mem->set('key', 'value', 0, 60);

//取值
$value = $mem->get('key');

//删除
$mem->delete('key');

In practical applications, the Memcache cache can be combined with the original program code to add corresponding cache operations.

3. Implementation of Memcache cache

1. Server selection

In order to achieve high availability, multiple servers can be used for caching. At this time, server selection is required. When choosing a server, you need to consider the following aspects:

• Ease of use: The installation and use of the server should be as simple as possible, without requiring too much configuration and management effort.
• Performance: The server needs to have high performance and be able to handle a large number of requests quickly, and the response time should be as short as possible.
• High reliability and scalability: The server should be able to support high concurrency, have good scalability, and be able to achieve high availability.

2. Data sharding

Since the Memcache server has capacity limitations, in order to improve caching efficiency, data needs to be distributed to multiple servers through data sharding. Data fragmentation can be performed based on the Key value. The Key value can be converted into a Hash value, and then the corresponding server number can be obtained by taking the modulo operation of the number of servers.

3. Cache update

When updating the cache, you need to pay attention to the following points:

• The data update must be done after the database update is completed, otherwise May cause data inconsistency.
• For some very important data, you can use the Write-through strategy, that is, every time the database is updated, the cache is also updated.
• For less frequently used data, you can use the Write-behind strategy, which updates the cache first and then asynchronously updates the database at the appropriate time.

4. Optimization of Memcache cache

1. Reasonable selection of Key value

The selection of Key value has a great impact on the effect of Memcache cache and should be selected A unique and readable Key value to avoid duplication and confusion. At the same time, you also need to be careful not to use too long Key values, otherwise it will affect the caching effect.

2. Set the expiration time reasonably

The expiration time should be set neither too long nor too short, and should be set according to the frequency and importance of data use. For frequently used data, you can set a longer expiration time; for less frequently used data, you can set a shorter expiration time.

3. Control the cache size

In order to avoid excessive use of cached data on server resources, it is necessary to regularly clean up expired or unused data for a long time. At the same time, you can set a cache size limit to a certain extent. After the limit is reached, part of the cached data will be automatically cleared.

5. Summary

Memcache is a very easy-to-use caching system that can greatly improve the performance and stability of web applications. When designing and implementing the architecture of Memcache, you need to select an appropriate server and set up reasonable data sharding and cache update strategies based on actual business needs. At the same time, you also need to pay attention to optimizing the cache Key value, expiration time, cache size, etc. Only when the Memcache cache is used properly can it really play its role.

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