A brief discussion on asynchronous programming of PHP functions

In PHP, asynchronous programming allows time-consuming tasks to be performed without blocking the execution flow. Techniques for implementing asynchronous programming include: Callback functions: Function pointers that execute code after another function has completed execution. Coroutines: lightweight multitasking mechanism that allows switching multiple function executions in the same thread. Parallelization: Using different threads or processes to perform multiple tasks simultaneously. Practical example: By processing HTTP requests in parallel, you can significantly reduce processing time while maintaining responsiveness.

A brief discussion on asynchronous programming of PHP functions

Introduction

In PHP , the asynchronous programming pattern allows us to perform time-consuming tasks without blocking the current execution flow. This article will explore how to use callback functions, coroutines, and parallelization techniques to implement asynchronous programming in PHP, and illustrate how to apply these techniques through a practical case.

Callback function

A callback function is a function pointer that allows code to be executed after another function has completed execution. They are very useful when handling asynchronous operations. The following example shows a simple asynchronous operation using a callback function:

function long_task($seconds, callable $callback)
{
    // 模拟耗时任务
    sleep($seconds);

    // 执行回调函数
    $callback();
}

long_task(5, function () {
    echo "任务已完成！\n";
});

Coroutine

Coroutine is a lightweight multitasking mechanism that allows us to Switch the execution of multiple functions in a thread. By using coroutines, we can handle multiple time-consuming tasks simultaneously without blocking the current execution flow.

The following is an example of asynchronous programming using the coroutine library in PHP 7.2:

$coroutine = function () {
    $data = yield long_task(5);
    echo "Data received: $data\n";
};

go($coroutine);

Parallelization

Similar to asynchronous programming, parallelization Allows us to perform multiple tasks at the same time. However, parallelization is done in different threads or processes, not in the same thread. Parallelization can be achieved using PHP's Process and Thread classes.

The following example shows the use of the Process class to process two time-consuming tasks in parallel:

$process1 = new Process(function () {
    long_task(5, function () {
        echo "任务 1 完成！\n";
    });
});

$process2 = new Process(function () {
    long_task(3, function () {
        echo "任务 2 完成！\n";
    });
});

$process1->start();
$process2->start();

$process1->wait();
$process2->wait();

Practical case: Asynchronous HTTP request

As a practical example case, we can use the above techniques to process multiple HTTP requests in parallel without blocking the current execution flow.

use GuzzleHttp\Client;
use GuzzleHttp\Psr7\Request;
use GuzzleHttp\Pool;
use GuzzleHttp\Promise\EachPromise;

// 创建 Guzzle 客户端
$client = new Client();

// 初始化请求队列
$queue = [];
$urls = ['https://example.com', 'https://example2.com', 'https://example3.com'];
foreach ($urls as $url) {
    $queue[] = new Request('GET', $url);
}

// 创建请求池并指定并发限制
$pool = new Pool($client, $queue, [
    'concurrency' => 5,
    'fulfilled' => function (Response $response) {
        echo $response->getBody() . "\n";
    }
]);

// 开始并行处理请求
$pool->promise()->wait();

By processing HTTP requests in parallel, we can significantly reduce processing time while still maintaining responsiveness because the current execution flow is not blocked.

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