Alternative WP Cron

alt-cron.php

<?php

/**
 * Pseudocron via a tag file in wp-content/service
 * It is triggered on every request (init hook), but it is actually triggered no more than once every 10 minutes.
 */
add_action('init', function () {
    $dir = WP_CONTENT_DIR . '/service';
    $file = $dir . '/timestamp.lock'

    if (!is_dir($dir)) {
        // wp_mkdir_p will create the entire hierarchy if necessary
        if (!function_exists('wp_mkdir_p') || !wp_mkdir_p($dir)) {
            return;
        }
    }

    $should_run = false;
    $next_ts = time() + 10 * 60; // current time + 10 minutes

    $fp = @fopen($file, 'c+');
    if (!$fp) {
        return;
    }

    try {
        // ЭWe use exclusive file locking to prevent competitive execution
        if (!flock($fp, LOCK_EX)) {
            fclose($fp);
            return;
        }

        // We read the current value (if available)
        clearstatcache(true, $file);
        $size = filesize($file);
        $current_ts = 0;

        if ($size > 0) {
            rewind($fp);
            $raw = fread($fp, $size);
            if ($raw !== false) {
                $current_ts = (int)trim($raw);
            }
        }

        // If the current time exceeds or is equal to the timestamp, 
        // then we specify the next timestamp and overwrite it to a file,
        // as well as allow tasks to be completed.
        if ($current_ts === 0 || time() >= $current_ts) {
            // Updating timestamp for the next 10 minutes
            ftruncate($fp, 0);
            rewind($fp);
            fwrite($fp, (string)$next_ts);
            fflush($fp);

            // We allow the launch after the lock is released
            $should_run = true;
        }
        flock($fp, LOCK_UN);
        fclose($fp);
    } catch (\Throwable $e) {
        try {
            flock($fp, LOCK_UN);
        } catch (\Throwable $e2) {
        }
        fclose($fp);
        return;
    }

    // We are already completing the task without a file lock (so as not to keep it during execution)
    if ($should_run) {
        if (function_exists('runBackground')) {
            runBackground();
        }
    }
});


/**
 * @param string $prefixText
 * @return string
 */
function get_update_time_message(string $prefixText = 'The data will be updated'): string
{
    $file_path = WP_CONTENT_DIR . '/service/timestamp.lock';

    if (file_exists($file_path)) {
        $timestamp = file_get_contents($file_path);

        if (is_numeric($timestamp)) {
            return sprintf(
                '%s %s',
                $prefixText,
                date('H:i:s d.m.Y', intval($timestamp))
            );
        }
    }

    return '';
}