What are the implementation methods of coroutine technology in PHP7.0?

With the continuous development of Internet applications, the use of PHP language is becoming more and more widespread, and coroutine technology has become one of the important tools to improve system performance. Coroutine technology was introduced in PHP7.0. This article will introduce the implementation of coroutine technology in PHP7.0.

What is a coroutine?

Coroutine is a lightweight user thread that is scheduled by the user. Compared with operating system threads, coroutine switching takes less time, takes up less resources, and can better handle a large number of concurrent requests.

In the traditional multi-threading model, one thread corresponds to a system-level operating system thread. Thread context switching is completed by the operating system, which requires some time-consuming operations, such as saving register states, scheduling, etc. As a result, every time a coroutine switches, a context switch is required, resulting in increased system latency. Coroutines are threads implemented at the user level. Thread context switching is controlled by the user. There is no need for context switching overhead, which can effectively improve system performance.

Coroutine implementation in PHP7.0

In the PHP language, there are many ways to implement coroutines. The following introduces the implementation of coroutines in PHP7.0.

1. Generator coroutine

PHP’s Generator coroutine is a generator that can be used to create a state machine, which is very convenient when implementing coroutines. When using the yield keyword, the program will pause execution and save the current state. When the generator is called next time, the program will continue execution from where it was last paused, thus realizing the function of the coroutine.

In this way, coroutines can be used in the PHP language to achieve concurrent execution of multiple coroutines and improve system performance. The following is a sample code implemented using the Generator coroutine:

function coroutine()  
{  
    echo "coroutine start
";  
    yield;  
    echo "coroutine end
";  
}  

$coroutine = coroutine();  
$coroutine->send();  

In this code, a coroutine is created using the Generator function coroutine(). When $coroutine->send() is called, the program will enter the coroutine, output "coroutine start", and then yield will cause the program to pause execution. Then when $coroutine->send() is called again, the program will start execution from yield and output "coroutine end". This implementation method is how to use Generator coroutine.

2. Co coroutine library

In addition to Generator coroutine, there is also a third-party library Co that can be used to implement coroutine. Co is a coroutine library similar to the NodeJS front-end language. It is written in C language and can quickly create coroutine-related syntax in PHP.

Through the Co coroutine library, non-blocking IO operations can be achieved and the running efficiency of the program can be improved. Co supports TCP, HTTP and other protocols, and can be applied to scenarios such as TCP connection pooling and asynchronous tasks.

The following is an example code for implementing a coroutine using the Co coroutine library:

Coun(function() {
    $result = (yield getUrlData("http://www.baidu.com"));
    var_dump($result);
});

function getUrlData($url) {
    $httpClient = new SwooleCoroutineHttpClient($url);
    $httpClient->setHeaders([
        "User-Agent" => "swoole-http-client",
        "Accept" => "text/html,application/xhtml+xml,application/xml"
    ]);
    
    $httpClient->get("/");
    
    yield $httpClient->getBody();
}

In this code, a coroutine is created through the run() function of the Co coroutine library. Execute the getUrlData() function. The getUrlData() function uses CoroutineHttpClient to access the url, perform non-blocking IO operations, and finally returns the result through yield.

In general, there are many ways to implement coroutine technology in PHP7.0, including Generator coroutine and Co coroutine library. By using coroutines, you can greatly improve the running efficiency of your program and handle a large number of concurrent requests. It is believed that in the near future, coroutine technology will play a more important role in the Internet field and become one of the key technologies to improve system processing capabilities.

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