class PerformanceDataCollector

class PerformanceDataCollector implements EventSubscriberInterface, DestructableInterface {
    
    /**
     * Database events collected during the request.
     *
     * @var \Drupal\Core\Database\Event\DatabaseEvent[]
     */
    protected array $databaseEvents = [];
    
    /**
     * Cache operations collected during the request.
     */
    protected array $cacheOperations = [];
    
    /**
     * Cache tag operations collected during the request.
     */
    protected array $cacheTagOperations = [];
    
    /**
     * {@inheritdoc}
     */
    public static function getSubscribedEvents() : array {
        return [
            StatementExecutionEndEvent::class => 'onDatabaseEvent',
            StatementExecutionFailureEvent::class => 'onDatabaseEvent',
        ];
    }
    
    /**
     * Logs database statements.
     */
    public function onDatabaseEvent(DatabaseEvent $event) : void {
        // Use the event object as a value object.
        $this->databaseEvents[] = $event;
    }
    
    /**
     * Adds a cache operation.
     */
    public function addCacheOperation(array $operation) {
        $this->cacheOperations[] = $operation;
    }
    
    /**
     * Adds a cache tag operation.
     */
    public function addCacheTagOperation(array $operation) {
        $this->cacheTagOperations[] = $operation;
    }
    
    /**
     * {@inheritdoc}
     */
    public function destruct() : void {
        // Get the events now before issuing any more database queries so that this
        // logging does not become part of the recorded data.
        $database_events = $this->databaseEvents;
        // Deliberately do not use an injected key value or lock service to avoid
        // any overhead up until this point.
        $lock = \Drupal::lock();
        // There are a finite number of requests, so if we don't get the lock just
        // wait for up to ten seconds then record the data anyway.
        if (!$lock->acquire('performance_test')) {
            $lock->wait('performance_test', 10);
        }
        $collection = \Drupal::keyValue('performance_test');
        $existing_data = $collection->get('performance_test_data') ?? [
            'database_events' => [],
            'cache_operations' => [],
            'cache_tag_operations' => [],
        ];
        $existing_data['database_events'] = array_merge($existing_data['database_events'], $database_events);
        $existing_data['cache_operations'] = array_merge($existing_data['cache_operations'], $this->cacheOperations);
        $existing_data['cache_tag_operations'] = array_merge($existing_data['cache_tag_operations'], $this->cacheTagOperations);
        $collection->set('performance_test_data', $existing_data);
        $lock->release('performance_test');
    }

}