promocodes.php

<?php

$startTime = time();

$finalResults = array();
for ($j = 0; $j < 1000000; $j++) {
    
    do {
        $candidate = getToken();
    } while (array_key_exists($candidate, $finalResults));

    $finalResults[$candidate] = 1;
}

$endTime = time();

print 'done' . PHP_EOL;
print 'Time Elapsed: ' . gmdate("H:i:s", $endTime - $startTime) . PHP_EOL;

function getToken($length = 8)
{
    $firstChar = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    $chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    $result = $firstChar[mt_rand(0, strlen($firstChar)-1)];
    $remainingLength = $length - 1;
    for ($i = 0; $i < $remainingLength; $i++) {
        $result .= $chars[mt_rand(0, strlen($chars)-1)];
    }
    return $result;
}