How to optimize the cache strategy of tokens in PHP to improve application performance?

Efficient processing of Token cache and Session in PHP

In PHP applications, efficient management and cache tokens are essential. This article discusses the method of cached tokens in Session and proposes an optimization solution.

Problem description: Some developers reported that when using Session to cache the token, the first request token is empty (especially after the token expires), and the second request is normal. This is mainly because there are defects in the code logic, which causes the business logic to fail to execute correctly.

The following code example shows the problem:

 <?php header("Content-type:text/html;charset=utf-8");
session_start();
// ... (The code that receives POST data, omitted here) ...

$conn = mysqli_connect("192.168.0.232", "root", "@jjgw6201", "user_wechat");
$wxresult = mysqli_query($conn,"select * from user_wechat where PHONE_NUM = &#39;$userPhone&#39;");
$result = mysqli_fetch_array($wxresult, MYSQLI_ASSOC);

if(!empty($_SESSION[&#39;access_token&#39;]) && $_SESSION[&#39;expire_time&#39;] > time() ) {
    // ... (Use the code of cached tokens, omitted here) ...
} else {
    // ... (Get the code for the new token, omitted here) ...
}

Problem analysis and optimization suggestions:

1. Limitations of Session Caching: The Session Expiration Time (120 seconds) in the code is much smaller than the Token's validity period (7200 seconds). Frequent updates of Sessions will reduce efficiency. In addition, using Session cache tokens at the same time by a large number of users will increase the server burden.

2. Code logic improvement: The original code only executes business logic when there is a valid token in the Session. The improved code should execute business logic regardless of whether the token exists or not, and update the token if needed. It is recommended to modify the if condition judgment to ensure that the token can be obtained and used when the token expires or does not exist.

3. Better caching strategy: File caching is a feasible alternative for scenarios where distributed caching such as Redis or Memcached is not applicable. You can create a file storage token and expiration time (for example: cache_time access_token ), and all users share this token. Update the file content every once in a while (for example, 7000 seconds). Check the expiration time when reading, and re-get the token when expired. Use flock() function to avoid concurrent read and write conflicts.

4. Timing Task: In order to completely solve the problem of concurrent writes, it is recommended to use timing tasks (such as crontab) to regularly update the Token file. There is no need to consider concurrency when reading operations.

Summarize:

An efficient token caching strategy should be selected based on application size and resource conditions. For high concurrency applications, Redis or Memcached is preferred. For small applications, file caching combined with timing tasks is also a feasible solution. The key is to optimize the code logic, ensure the correct execution of the business logic, and select the appropriate caching mechanism to improve application performance and stability. The improved code should ensure that the token is checked for validity on each request and update the token if necessary without the subsequent request failing due to the failure of the first request.

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