How to execute PHP asynchronously without waiting for return and execute code directly

In PHP programming, sometimes you need to perform some time-consuming operations, such as making network requests, reading and writing files, etc. If traditional synchronization is used, the program will wait until the operation is completed and the result is returned. This will cause the program to be unable to do other things while waiting, thus reducing the efficiency of the program.

If you use the asynchronous method, you can let the program continue to perform other tasks while waiting for the operation to complete. To put it simply, it means to directly execute other code without waiting for the return result of the operation, and then come back to process the return result after the operation is completed. This approach greatly improves the efficiency and concurrency of the program.

In PHP, asynchronous methods are generally implemented using multi-process or multi-thread. However, this method is complex, error-prone, and usually requires the use of third-party libraries or extensions. After PHP 7.2, a new asynchronous programming framework-Swoole was introduced, which provides a complete set of asynchronous programming solutions and can be used well with PHP native code and third-party libraries.

Swoole provides a variety of asynchronous programming methods, including coroutines, asynchronous non-blocking IO, asynchronous multi-process, etc. The most commonly used method is coroutine, which can implement asynchronous programming within a single thread and has the advantages of lightweight and high efficiency.

Below we use a simple example to introduce how to use Swoole to implement PHP asynchronous execution.

First, we need to install the Swoole extension. You can use the following command to install:

pecl install swoole

After the installation is complete, you need to add the following configuration to the php.ini file:

extension=swoole

Next, let’s take a look at a simple example. We need to perform a very time-consuming operation - sleep for 5 seconds and then return to the current time. This operation takes 5 seconds in traditional synchronization mode. In the asynchronous mode using Swoole, we can submit this operation to Swoole's asynchronous task pool and then return immediately. After the operation is completed, Swoole will automatically call the callback function we specified and return the operation result.

<?php

/* 创建Swoole的异步任务池 */
$pool = new Swoole\Process\Pool(4);

/* 添加异步任务 */
$pool->on("WorkerStart", function($pool, $workerId) {
    /* 启动5个不同的异步任务 */
    for ($i = 0; $i < 5; $i++) {
        /* 异步执行一个耗时5秒的任务 */
        $pool->add(function() {
            sleep(5);
            return date("Y-m-d H:i:s");
        });
    }
});

/* 处理异步任务完成的回调函数 */
$pool->on("WorkerStop", function($pool, $workerId) {
    /* 获取执行结果，并输出到控制台 */
    $results = $pool->getResults();
    foreach ($results as $result) {
        echo "{$result}\n";
    }
});

$pool->start();

In the above code, we create an asynchronous task pool containing 4 sub-processes. Then in the WorkerStart event callback function, we submitted 5 different asynchronous tasks and specified an anonymous callback function as the callback function after the task is completed. This callback function receives a list of result objects and prints the value of each result object to the console.

Finally call Swoole's start method to start the asynchronous task pool. When all asynchronous tasks are completed, Swoole will automatically call the callback function we specified and return the operation results. The execution results are as follows:

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In summary, using Swoole's asynchronous programming method can greatly improve the efficiency and concurrency of PHP programs. Using Swoole to write asynchronous programs allows us to focus more on the processing of business logic without paying too much attention to the details of the underlying implementation.

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