Swoole's coroutine and asynchronous programming practice

With the continuous development of Internet applications, high concurrency has become a challenge that every developer must face. In order to cope with high concurrency, front-end students use technologies such as front-end display and asynchronous I/O, while back-end students use coroutines and asynchronous programming technologies. Among them, Swoole is a coroutine framework in the PHP language. It uses coroutines and asynchronous programming ideas to simplify development and debugging under high concurrency and provide developers with a better development experience.

1. The concepts of coroutines and asynchronous programming

The understanding of coroutines can be simply understood as "micro-threads", which are similar concepts to threads, but are different from the thread switching mechanism. Coroutines are not threads of the operating system kernel, but are switched within the user process. Using coroutines can perform non-blocking waiting, while improving CPU utilization and reducing the number of context switches.

Asynchronous programming is an "event-driven" programming method. Its main feature is the use of non-blocking I/O, which avoids the thread waiting time caused by I/O blocking waiting and increases the amount of concurrency. In asynchronous programming, when an event is completed, the program will notify the relevant thread to continue processing, instead of letting the thread block and wait. Asynchronous programming uses callbacks to handle asynchronous operations to handle the alternation between coroutines and improve the concurrent processing capabilities of the program.

2. Swoole’s coroutine and asynchronous programming practice

1. Coroutine

Swoole coroutine simulates and implements processes in the PHP language environment And the coroutine mechanism in threads. In Swoole's coroutine, you can use the coroutine scheduler to hand over the running control of PHP to the coroutine, avoiding thread waiting time caused by I/O blocking waiting, and improving operating efficiency. Coroutines realize switching between coroutines with the help of swoole_coroutine_create() and swoole_coroutine_resume() functions. At the same time, Swoole provides event-driven functions such as swoole_event_add(), swoole_event_set(), etc., which significantly simplifies the coroutine programming model.

Below, we will understand the use of Swoole coroutine step by step through code practice.

1) Install the Swoole extension

First, we need to install the Swoole extension to realize the development of Swoole coroutine. The Swoole extension can be installed through the following command:

$ pecl install swoole

2) Create a coroutine

Next, we need to create a coroutine and use the swoole_coroutine_resume() function to execute the coroutine. The specific code is as follows:

<?php
function test_coroutine(){
    echo "Start coroutine
";
    swoole_coroutine::sleep(1);
    echo "End coroutine
";
}
swoole_coroutine::create("test_coroutine");
echo "Main func end
";

We can see that the swoole_coroutine_create() function is used in the code to create a coroutine and a test_coroutine() function is passed in. At this time, the coroutine has not yet been executed. After calling swoole_coroutine_create(), the system submits the coroutine to the coroutine scheduler and waits for execution. Next, by calling the swoole_coroutine_resume() function, the test_coroutine() function is executed and the relevant results are output.

3) Switching between coroutines

In the coroutine, we can also use the swoole_coroutine_yield() function to manually switch coroutines. The specific implementation code is as follows:

<?php
function test_coroutine(){
    for ($i=0; $i<5; $i++){
        echo "Coroutine $i
";
        swoole_coroutine::yield();
    }
}
$c = swoole_coroutine::create("test_coroutine");
for ($i=0; $i<5; $i++){
    swoole_coroutine::resume($c);
}

Through the above code, we create a coroutine and loop 5 times in the test_coroutine() function to output the coroutine number. Use the swoole_coroutine_yield() function to manually switch coroutines so that multiple coroutines can be processed fairly.

2. Asynchronous Programming

Swoole's asynchronous programming is mainly implemented based on event-driven functions such as woole_event_add(), swoole_event_set() and swoole_event_wait(). Specifically, the woole_event_add() and swoole_event_set() functions are used to add I/O events to the event loop, while the swoole_event_wait() function is used to start the event loop.

Below, we will understand Swoole’s asynchronous programming practice step by step through code.

1) Install the Swoole extension

First, we need to install the Swoole extension to achieve the development of Swoole asynchronous programming. The Swoole extension can be installed through the following command:

$ pecl install swoole

2) Asynchronous TCP communication

In Swoole, asynchronous TCP communication between systems can be supported through swoole_client and swoole_server. In asynchronous TCP communication, we need to use SwooleServer to start a TCP service, and use the swoole_event_add() function on the server side to add an I/O event to the service. The message sender uses swoole_client to implement asynchronous communication. The specific implementation code is as follows:

<?php
//异步TCP服务端
$serv = new swoole_server("127.0.0.1", 9501);
$serv->set(array(
    'worker_num' => 4,
    'daemonize' => false,
));

$serv->on('Receive', function ($serv, $fd, $from_id, $data) {
    $serv->send($fd, 'Server: '.$data);
    $serv->close($fd);
});

$serv->start();

<?php
//异步TCP客户端
$client = new swoole_client(SWOOLE_SOCK_TCP, SWOOLE_SOCK_ASYNC);

$client->on("connect", function($cli) {
    $cli->send("hello world
");
});

$client->on("receive", function($cli, $data){
    echo "Received: ".$data."
";
});

$client->on("error", function($cli){
    echo "Connect failed
";
});

$client->on("close", function($cli){
    echo "Connection closed
";
});

$client->connect('127.0.0.1', 9501);

Through the above code, we have implemented an example of asynchronous TCP communication. When the client sends a message, the server receives the message and returns the processing result.

Summary:

This article mainly explains the practice of Swoole coroutines and asynchronous programming. In the development of highly concurrent Internet applications, the use of asynchronous programming and coroutines can effectively improve system performance and improve development efficiency. The Swoole framework provides good coroutine and asynchronous programming support, allowing programmers to easily implement efficient asynchronous processing and coroutine scheduling, thereby improving the system's concurrent processing capabilities.

The above is the detailed content of Swoole's coroutine and asynchronous programming practice. For more information, please follow other related articles on the PHP Chinese website!