curl_multi_init - PHP code example

The php Function Curl_Multi_Init

The php function curl_multi_init is used to create multiple cURL handle objects and process them asynchronously. This is a more efficient way to process a large number of requests than calling each request one by one.

cURL is a powerful library in PHP that lets developers transfer data between different servers and protocols. It is widely used in web services and RESTful APIs to communicate with external services and integrate them into web applications. cURL also helps in gathering data imparted by other websites through its various features including SSL support, authentication, and proxy use.

If you see the error “Call to undefined function curl_init()” on your site, it is usually because the cURL library is not installed or enabled in your system. The good news is that this is an easy issue to fix. This article will walk you through the steps of installing and enabling the cURL library in PHP so that you can run your code without errors.

Before PHP 8, cURL functions like curl_init(), curl_setopt(), and curl_exec() returned a resource of type Curl. Starting with PHP 8 these functions return an instance of the CurlHandle class. This change does not introduce backwards-incompatibilities but may break your existing code that checks if a resource is created with is_resource().

After a cURL session is initialized, you can set various options using the curl_setopt() function. Once you have all the parameters set, you can execute the cURL request by calling curl_exec(). The response will be returned as a string which you can then process in your script, such as parsing it into JSON or XML.

curl_multi_init example

    public function __get($name)
    {
        if ($name !== '_mh') {
            throw new \BadMethodCallException("Can not get other property as '_mh'.");
        }

        $multiHandle = \curl_multi_init();

        if (false === $multiHandle) {
            throw new \RuntimeException('Can not initialize curl multi handle.');
        }

        $this->_mh = $multiHandle;

        foreach ($this->options as $option => $value) {
            // A warning is raised in case of a wrong option.             curl_multi_setopt($this->_mh, $option, $value);
        }

return [];
        }

        if (InputValidator::has_array_access($requests) === false || InputValidator::is_iterable($requests) === false) {
            throw InvalidArgument::create(1, '$requests', 'array|ArrayAccess&Traversable', gettype($requests));
        }

        if (is_array($options) === false) {
            throw InvalidArgument::create(2, '$options', 'array', gettype($options));
        }

        $multihandle = curl_multi_init();
        $subrequests = [];
        $subhandles  = [];

        $class = get_class($this);
        foreach ($requests as $id => $request) {
            $subrequests[$id] = new $class();
            $subhandles[$id]  = $subrequests[$id]->get_subrequest_handle($request['url'], $request['headers'], $request['data'], $request['options']);
            $request['options']['hooks']->dispatch('curl.before_multi_add', [&$subhandles[$id]]);
            curl_multi_add_handle($multihandle, $subhandles[$id]);
        }

/** @var float[] */
    public array $pauseExpiries = [];
    public int $execCounter = \PHP_INT_MIN;
    public ?LoggerInterface $logger = null;

    public static array $curlVersion;

    public function __construct(int $maxHostConnections, int $maxPendingPushes)
    {
        self::$curlVersion ??= curl_version();

        $this->handle = curl_multi_init();
        $this->dnsCache = new DnsCache();
        $this->reset();

        // Don't enable HTTP/1.1 pipelining: it forces responses to be sent in order         if (\defined('CURLPIPE_MULTIPLEX')) {
            curl_multi_setopt($this->handle, \CURLMOPT_PIPELINING, \CURLPIPE_MULTIPLEX);
        }
        if (\defined('CURLMOPT_MAX_HOST_CONNECTIONS')) {
            $maxHostConnections = curl_multi_setopt($this->handle, \CURLMOPT_MAX_HOST_CONNECTIONS, 0 < $maxHostConnections ? $maxHostConnections : \PHP_INT_MAX) ? 0 : $maxHostConnections;
        }
        if (\defined('CURLMOPT_MAXCONNECTS') && 0 < $maxHostConnections) {