How to Optimize Remote Image Existence Checking with PHP?

Verifying Remote Image Existence with PHP

Determining the existence of an image at a remote URL is crucial when generating dynamic image URLs for databases. PHP libraries like curl can facilitate this task, but their performance can vary significantly. Given the substantial number of images to be checked, optimizing this process is paramount.

The most efficient solution involves leveraging the curl library with the following parameters:

function checkRemoteFile($url)
{
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL,$url);
    // don't download content
    curl_setopt($ch, CURLOPT_NOBODY, 1);
    curl_setopt($ch, CURLOPT_FAILONERROR, 1);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

    $result = curl_exec($ch);
    curl_close($ch);
    if($result !== FALSE)
    {
        return true;
    }
    else
    {
        return false;
    }
}

This approach prioritizes speed by setting CURLOPT_NOBODY to 1, which instructs curl to retrieve only the HTTP header without actually downloading the image content. Additionally, CURLOPT_FAILONERROR is set to 1 to return FALSE if the remote file does not exist. The function then evaluates the return value of curl_exec to determine if the image exists remotely.

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