Save all AJAX queries performed to track AJAX performance [WordPress]

sz_ajax_logger.php

add_action('shutdown','sz_log_all_ajax_queries');
function sz_log_all_ajax_queries() {
    global $wpdb;

    if ( empty($wpdb->queries) ) {
        return;
    }

    $timestamp = date('Y-m-d H:i:s');

    // Define log files
    $log_full       = WP_CONTENT_DIR . '/ajax-queries-full.log';
    $log_filtered   = WP_CONTENT_DIR . '/ajax-queries-filtered.log';
    $log_options    = WP_CONTENT_DIR . '/ajax-queries-options.log';
    $log_summary    = WP_CONTENT_DIR . '/ajax-queries-summary.log';

    // Define exclusion patterns (extendable)
    $exclude_patterns = [
        $wpdb->prefix . 'options',
        $wpdb->prefix . 'usermeta',
        $wpdb->prefix . 'postmeta',
        $wpdb->prefix . 'comments',
        $wpdb->prefix . 'commentmeta',
        $wpdb->prefix . 'users',
        $wpdb->prefix . 'terms',
        $wpdb->prefix . 'posts',

        // families of tables
        $wpdb->prefix . 'actionscheduler', // Action Scheduler
        $wpdb->prefix . 'rocket',          // WP Rocket
        $wpdb->prefix . 'wpr',             // WPR / Above the fold
        $wpdb->prefix . 'wc_',             // WooCommerce
        $wpdb->prefix . 'woocommerce',     // WooCommerce
    ];

    // Normalize query so matching is easier
    $normalize_query = function($query) {
        $query = strtolower($query);
        $query = str_replace(['\\_', '\_'], '_', $query);
        $query = preg_replace('/\s+/', ' ', $query);
        return $query;
    };

    // Check if query should be excluded
    $is_excluded = function($query) use ($exclude_patterns, $normalize_query) {
        $q = $normalize_query($query);
        foreach ($exclude_patterns as $pattern) {
            if (strpos($q, strtolower($pattern)) !== false) {
                return true;
            }
        }
        return false;
    };

    // Logs
    $full_log     = "=== {$timestamp} ===\n";
    $filtered_log = "=== {$timestamp} ===\n";
    $options_log  = "=== {$timestamp} ===\n";

    foreach ($wpdb->queries as $q) {
        list($query, $time, $caller) = $q;

        // Add to full log
        $full_log .= sprintf(
            "[%.5fs] %s\n-- Caller: %s\n\n",
            $time,
            $query,
            $caller
        );

        // Add to filtered log
        if (!$is_excluded($query)) {
            $filtered_log .= sprintf(
                "[%.5fs] %s\n-- Caller: %s\n\n",
                $time,
                $query,
                $caller
            );
        }

        // Add to options-only log
        if (strpos($normalize_query($query), $wpdb->prefix . 'options') !== false) {
            $options_log .= sprintf(
                "[%.5fs] %s\n-- Caller: %s\n\n",
                $time,
                $query,
                $caller
            );
        }
    }

    // Calculate totals
    $total_queries = count($wpdb->queries);
    $total_time    = array_sum( array_column($wpdb->queries, 1) );
    $avg_time      = $total_queries ? $total_time / $total_queries : 0;

    // Request context
    $request_method = $_SERVER['REQUEST_METHOD'] ?? 'CLI';
    $request_uri    = $_SERVER['REQUEST_URI'] ?? '(no URI)';

    // Summary log
    $summary_log = "=== {$timestamp} ===\n";
    $summary_log .= "Request: {$request_method} {$request_uri}\n";
    $summary_log .= "Total queries: {$total_queries}\n";
    $summary_log .= "Total time: " . number_format($total_time, 5) . "s\n";
    $summary_log .= "Average per query: " . number_format($avg_time, 5) . "s\n\n";

    // Write files
    file_put_contents($log_full,     $full_log . "\n", FILE_APPEND);
    file_put_contents($log_filtered, $filtered_log . "\n", FILE_APPEND);
    file_put_contents($log_options,  $options_log . "\n", FILE_APPEND);
    file_put_contents($log_summary,  $summary_log, FILE_APPEND);
}