HHVM async example using curl_multi_exec

async_fetcher.php

<?hh

// Based on https://gist.github.com/chregu/9740519

class Fetcher {
    // async function: http://docs.hhvm.com/manual/en/hack.async.php
    // return type annotation: http://docs.hhvm.com/manual/en/hack.annotations.introexample.php
    // generics: http://docs.hhvm.com/manual/en/hack.generics.php
    public async function fetch(string $url) : Awaitable<array>
    {
        $ch1 = curl_init();
        print "get $url \n";
 
        curl_setopt($ch1, CURLOPT_URL, $url);
        curl_setopt($ch1, CURLOPT_HEADER, 0);
        curl_setopt($ch1, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch1, CURLOPT_FOLLOWLOCATION, true);

        $mh = curl_multi_init();
        curl_multi_add_handle($mh,$ch1);
        
        $active = null;
        do {
            $mrc = curl_multi_exec($mh, $active);
            // reschedule it for async to work properly
            await RescheduleWaitHandle::Create(1, 1);
        } while ($mrc == CURLM_CALL_MULTI_PERFORM);
        
        while ($active && $mrc == CURLM_OK) {
            if (curl_multi_select($mh) != -1) {
                do {
                    $mrc = curl_multi_exec($mh, $active);
                    await RescheduleWaitHandle::Create(1, 1); // simulate blocking I/O
                } while ($mrc == CURLM_CALL_MULTI_PERFORM);
            }
        }
        $content = curl_multi_getcontent($ch1);
        print "finished $url\n";
//        print $content;

        return array(
            'url' => $url,
            'content'=> $content
        );
    }
}
 
 
class Fetch {

protected Fetcher $fetcher;

    //Constructor Argument Promotion http://docs.hhvm.com/manual/en/hack.constructorargumentpromotion.php
    //Vector http://docs.hhvm.com/manual/en/hack.collections.vector.php (instead of array)
    //Annotating Arrays and Collections: http://docs.hhvm.com/manual/en/hack.annotations.arrays.php
    public function __construct(private Vector<string> $urls)
    {
        $this->fetcher = new Fetcher();
    }
    
    public async function run() : Awaitable<array>
    {
        //lambda expressions: http://docs.hhvm.com/manual/en/hack.lambda.php
        $waithandles = $this->urls->map(function($url) {
            return $this->fetcher->fetch($url);
        });

        // works too, but not supported by typechecker yet
        //$waithandles = $this->urls->map((string $url): Awaitable<int> ==> $this->fetcher->fetch($url));
        // same as above, but with closure and annotations, so it catches type errors
        //$waithandles = $this->urls->map(function(string $url): Awaitable<int> {return $this->fetcher->fetch($url);});

        //create wait handle for all and only continue when all have finished
        $x = await GenVectorWaitHandle::Create($waithandles);

//        print_r($x);

        return $x;
    }

    public function start() : array
    {
        $x = $this->run()->join();
//        print_r($x);

        return $x;
    }
}
 
function main() {
    //Vector with Literal Syntax: http://docs.hhvm.com/manual/en/hack.collections.literalsyntax.php
    $urls = Vector{'http://chregu.tv/webinc/sleep.php?s=1', 'http://chregu.tv/webinc/sleep.php?s=1', 'http://chregu.tv/webinc/sleep.php?s=1'};

    $f = new Fetch($urls);
    $dataFetched = $f->start();

    $dataFetched->map(function($urlContent) {
            print $urlContent['url'] . ' => ' . substr($urlContent['content'], 0, 120) . "...\n\n";
        });
//    print_r($dataFetched);
}
main();