How to get the return of multi Curl (curl_multi_add_handle)?

Question

I wanted to know how to get the return via multi Curl why by normal Curl just use the function curl_exec to get the result of the page but in the multi Curl I can’t get anything with the curl_exec.

Answer 1

First, the curl_multi is not "compatible" with the functions of curl_*. That is, first you create Curl normally (using the curl_init() and the curl_setopt()), then add this Curl to Handle in curl_multi_add_handle.

Once you have the curl_multi_init, you should use only functions curl_multi_*.

---

To execute:

curl_multi_exec()

But, it has a "mystery", because the documentation itself will make the CPU go to 100%, or even enter an infinite loop.

There are two ways to contain this, using:

$executando = 1;
while($executando > 0){
    curl_multi_exec($mh, $executando);
    curl_multi_select($mh);
}

Another option would be to use the usleep:

$executando = 1;
while($running > 0){
    curl_multi_exec($mh, $executando);
    usleep(10);
}

---

Now how do I get the return, since everyone is inside the curl_multi_exec? There are other functions in comparison:

CURL                                   CURL MULTI 

curl_exec()                            curl_multi_exec()
                                       curl_multi_getcontent()

curl_close()                           curl_multi_remove_handle()
                                       curl_multi_close()

To obtain the curl_getinfo can directly use own curl_getinfo($ch), now if you want to get Curl Multi information, use curl_multi_info_read($mh) in his stead.

---

In an example of use, obtaining the content of multiple pages:

// Cria o primeiro cURL
$ch1 = curl_init('https://jsonplaceholder.typicode.com/posts/1');
curl_setopt_array($ch1, [
    CURLOPT_SSLVERSION => CURL_SSLVERSION_TLSv1_2,
    CURLOPT_SSL_VERIFYHOST => 2,
    CURLOPT_SSL_VERIFYPEER => 0,  // Isto é inseguro, não use isto em produção, altere para `1`.
    CURLOPT_PROTOCOLS => CURLPROTO_HTTPS,
    CURLOPT_FOLLOWLOCATION => 1,
    CURLOPT_RETURNTRANSFER => 1
]);

// Copia o primeiro cURL e muda a URL, criando um segundo cURL
$ch2 = curl_copy_handle($ch1);
curl_setopt($ch2, CURLOPT_URL, 'https://api.fixer.io/latest');

// Cria o cURL Multi
$mh = curl_multi_init();

// Importa os cURL criados
curl_multi_add_handle($mh,$ch1);
curl_multi_add_handle($mh,$ch2);

// Executa o cURL Multi
$running = 1;

while($running > 0){
    curl_multi_exec($mh, $running);
    curl_multi_select($mh);
}

// Exibe primeiro cURL:
echo curl_multi_getcontent($ch1);

// Exibe segundo cURL:
echo curl_multi_getcontent($ch2);

// Fecha o cURL Multi:
curl_multi_close($mh);

// Fecha o cURL:
curl_close($ch1);
curl_close($ch2);

This will return two distinct JSON, one is from this page and the other of this.