php 协程 generator中的yield实现协程

ゝ一纸荒年。 2022-06-13 09:45 204阅读 0赞

简单讲述一下php里面的协程支持。

<?php
    
    //yield是干什么的?
    //当程序运行到yield的时候，当前程序就唤起协程记录上下文。
    function num()
    {
    	for ($i=1;$i<10;$i++)
    	{
    		yield $i;
    	}
    }
    
    foreach(num() as $n){
    
    	echo $n."\n";
    }
    //当然还可以这样
    function printer() {
    
    	while (true) {
    
    		$string = yield;
    		echo $string;
    
    	}
    }
    $printer = printer();
    $printer->send("Hello world! \n");
    
    //Generator 是干什么的，Generator 是迭代器,实现了Iterator 接口
    /*
        //官方的代码
        <?php
            class Generator implements Iterator {
                public function rewind();          // Rewinds the iterator. If
                                                   // iteration has already begun,
                                                   // this will throw an exception.
    
                public function valid();           // Returns false if the
                                                   // iterator has been closed.
                                                   // Otherwise returns true.
    
                public function current();         // Returns the yielded value.
    
                public function key();             // Returns the yielded key.
    
                public function next();            // Resumes execution of the
                                                   // generator.
                
                public function send($value);      // Sends the given value to the
                                                   // generator as the result of
                                                   // the yield expression and
                                                   // resumes execution of the
                                                   // generator.
            }
            ?> 
    */
    //利用Generator写一个中间件,类似于laravel框架的中间件
    function MyMiddleware($middleware = [])
    {
    	$stack = [];
    
    	foreach ($middleware  as $mid)
    	{
    
    		$handle = call_user_func_array($mid,[]);
    		$stack[] = $handle;
    		$handle->current();
    
    	}
    
    	while($handle = array_pop($stack)){
    
    		$handle->send("ok! \n");
    		$handle->next();
    
    	}
    }
    
    function one(){
    
    	echo "this is one start \n";
    	$a = yield;
    	echo $a;
    	echo "this is one end \n";
    
    }
    function two(){
    
    	echo "this is two start \n";
    	$a = yield;
    	echo $a;
    	echo "this is two end \n";
    }
    MyMiddleware(['one','two']);
    //再列举一个生产 和 消费者直接的例子 加以说明
    function consumer()
    {
    	while (true)
    	{
    		$n = yield;
    		if(!$n){
    
    			return;
    		}
    		echo '[CONSUMER] Consuming'.$n.'...'."\n";
    		sleep(1);
    		$msg = '200,ok!';
    		yield $msg;
    	}
    }
    
    function produce(Generator $generator)
    {
    
    	$n = 0;
    	while ($n < 5)
    	{
    		$n ++;
    		echo '[PRODUCER] Producing '.$n.'...'."\n";
    		$generator->send($n);
    		$msg = $generator->current();
    		$generator->next();
    		echo '[PRODUCER] Consumer return: '.$msg.'...'."\n";
    	}
    }
    
    $c = consumer();
    produce($c);
    /**
     * 解释
     * 启动生成器
     * 然后，一旦生产了东西，通过$generator.send($n)切换到consumer执行
     * consumer通过yield拿到消息，处理，又通过yield把结果传回
     * produce拿到consumer处理的结果，继续生产下一条消息
     * 直到produce结束
     */

以上代码可以直接拷贝到本地使用php 命令运行。

输出结果：

D:\\myapache\\www\\demo\\middleware>php demo.php  
1  
2  
3  
4  
5  
6  
7  
8  
9  
Hello world!  
this is one start  
this is two start  
ok!  
this is two end  
ok!  
this is one end  
\[PRODUCER\] Producing 1...  
\[CONSUMER\] Consuming1...  
\[PRODUCER\] Consumer return: 200,ok!...  
\[PRODUCER\] Producing 2...  
\[CONSUMER\] Consuming2...  
\[PRODUCER\] Consumer return: 200,ok!...  
\[PRODUCER\] Producing 3...  
\[CONSUMER\] Consuming3...  
\[PRODUCER\] Consumer return: 200,ok!...  
\[PRODUCER\] Producing 4...  
\[CONSUMER\] Consuming4...  
\[PRODUCER\] Consumer return: 200,ok!...  
\[PRODUCER\] Producing 5...  
\[CONSUMER\] Consuming5...  
\[PRODUCER\] Consumer return: 200,ok!...