Multi Curl, error handling - php

Question

I'm working with multi Curl and was wondering how to handle the errors. I want to check which error occured and if it is an error like, rate limit exceeded I want to crawl that link again after some delay (sleep()). My question: "Is there a build in function which can do this for me or do I need to collect all Urls in an array and just run those again?"
This is what I've got now:
<?php
$urls = array( "https://API-URL.com",
"https://API-URL.com",
"https://API-URL.com",
"https://API-URL.com",
...);
//create the multiple cURL handle
$mh = curl_multi_init();
//Number of elements in $urls
$nbr = count($urls);
// set URL and options
for($x = 0; $x < $nbr; $x++){
// create both cURL resources
$ch[$x] = curl_init();
// set URL and other appropriate options
curl_setopt($ch[$x], CURLOPT_URL, $urls[$x]);
curl_setopt($ch[$x], CURLOPT_RETURNTRANSFER, true );
curl_setopt($ch[$x], CURLOPT_SSL_VERIFYPEER, false);
//add the two handles
curl_multi_add_handle($mh,$ch[$x]);
}
//execute the handles
do {
curl_multi_exec($mh, $running);
} while ($running);
for($x = 0; $x < $nbr; $x++){
$result = curl_multi_getcontent($ch[$x]);
$decoded = json_decode($result, true);
//get info about the request
$error = curl_getinfo($ch[$x], CURLINFO_HTTP_CODE);
//error handling
if($error != 200){
$again[] = array("Url" => $urls[$x], "errornbr" => $error);
} else {
// Here I do what ever I want with the data
}
curl_multi_remove_handle($mh, $ch[$x]);
curl_close($ch[1]);
}
curl_multi_close($mh);
?>

Answer 1

For multiple handles there is
https://www.php.net/manual/en/function.curl-multi-info-read.php
so error check (assuming http connection) should look like:
while ($a = curl_multi_info_read($mh))
{
if ($b = $a['result'])
{
echo curl_strerror($b);# CURLE_* error
}
elseif (!($b = curl_getinfo($a['handle'], CURLINFO_RESPONSE_CODE)))
{
echo 'connection failed';
}
elseif ($b !== 200)
{
echo 'HTTP status is not 200 OK';
}
}
Consider this code as pseudo-code for modern PHPs (i didn't test this exact variant, but scheme will work). Calling curl_errno() on "easy" handles added to "multi" handle will return 0 which is not an error.

Answer 2

In the second for-loop, when you are cycling through the curl handlers to examine what did each curl handler return, I hope, this approach will answer you question
foreach ($ch as $key => $h) {
//This code is actually checking for any error that may occur, whatever that
//error is you can handle it in the if-part of the condition. and save those
//urls to the array $again to call them on a later stage.
if (curl_errno($h)) {
//this is how you will get complete information what did happened to the
//curl handler. And why did it fail. All the inforation will be stored in //error_info.
$again[] = array("Url" =>curl_getinfo($h, CURLINFO_EFFECTIVE_URL), "error_info" => curl_getinfo($h));
}
else{
//here you will handle the success scenario for each curl handler.
$responses[$key] = ['data' => curl_multi_getcontent($h)];
}
//remove curl handler as you are doing in the loop
}