We write online chat on Websockets using Swoole

/**
     * @return Message[]
     */publicfunctiongetAll(){
        $stmt = $this->pdo->query('SELECT * from messages');
        $messages = [];
        foreach ($stmt->fetchAll() as $row) {
            $messages[] = new Message( $row['username'], $row['message'], new \DateTime($row['date_time']) );
        }
        return $messages;
    }

publicfunction__construct(){
        $this->ws = new swoole_websocket_server('0.0.0.0', 9502);
        $this->ws->on('open', function($ws, $request){
            $this->onConnection($request);
        });
        $this->ws->on('message', function($ws, $frame){
            $this->onMessage($frame);
        });
        $this->ws->on('close', function($ws, $id){
            $this->onClose($id);
        });
        $this->ws->on('workerStart', function(swoole_websocket_server $ws){
            $this->onWorkerStart($ws);
        });
        $this->ws->start();
    }

privatefunctiononWorkerStart(swoole_websocket_server $ws){
        $this->messagesRepository = new MessagesRepository();
        $ws->tick(self::PING_DELAY_MS, function()use($ws){
            foreach ($ws->connections as $id) {
                $ws->push($id, 'ping', WEBSOCKET_OPCODE_PING);
            }
        });
    }

/**
     * Init new Connection, and ping DB timer function
     */privatestaticfunctioninitPdo(){
        if (self::$timerId === null || (!Timer::exists(self::$timerId))) {
            self::$timerId = Timer::tick(self::MySQL_PING_INTERVAL, function(){
                self::ping();
            });
        }
        self::$pdo = new PDO(self::DSN, DBConfig::USER, DBConfig::PASSWORD, self::OPT);
    }
    /**
     * Ping database to maintain the connection
     */privatestaticfunctionping(){
        try {
            self::$pdo->query('SELECT 1');
        } catch (PDOException $e) {
            self::initPdo();
        }
    }

/**
     * @param string $username
     * @return bool
     */privatefunctionisUsernameCurrentlyTaken(string $username){
        foreach ($this->usersRepository->getByIds($this->ws->connection_list()) as $user) {
            if ($user->getUsername() == $username) {
                returntrue;
            }
        }
        returnfalse;
    }

<?phpnamespaceApp\Helpers;
useSwoole\Channel;
classRequestLimiter{
    /**
     * @var Channel
     */private $userIds;
    const MAX_RECORDS_COUNT = 10;
    const MAX_REQUESTS_BY_USER = 4;
    publicfunction__construct(){
        $this->userIds = new Channel(1024 * 64);
    }
    /**
     * Check if there are too many requests from user
     *  and make a record of request from that user
     *
     * @param int $userId
     * @return bool
     */publicfunctioncheckIsRequestAllowed(int $userId){
        $requestsCount = $this->getRequestsCountByUser($userId);
        $this->addRecord($userId);
        if ($requestsCount >= self::MAX_REQUESTS_BY_USER) returnfalse;
        returntrue;
    }
    /**
     * @param int $userId
     * @return int
     */privatefunctiongetRequestsCountByUser(int $userId){
        $channelRecordsCount = $this->userIds->stats()['queue_num'];
        $requestsCount = 0;
        for ($i = 0; $i < $channelRecordsCount; $i++) {
            $userIdFromChannel = $this->userIds->pop();
            $this->userIds->push($userIdFromChannel);
            if ($userIdFromChannel === $userId) {
                $requestsCount++;
            }
        }
        return $requestsCount;
    }
    /**
     * @param int $userId
     */privatefunctionaddRecord(int $userId){
        $recordsCount = $this->userIds->stats()['queue_num'];
        if ($recordsCount >= self::MAX_RECORDS_COUNT) {
            $this->userIds->pop();
        }
        $this->userIds->push($userId);
    }
}

<?phpnamespaceApp\Helpers;
classSpamFilter{
    /**
     * @var string[] errors
     */private $errors = [];
    /**
     * @param string $text
     * @return bool
     */publicfunctioncheckIsMessageTextCorrect(string $text){
        $isCorrect = true;
        if (empty(trim($text))) {
            $this->errors[] = 'Empty message text';
            $isCorrect = false;
        }
        return $isCorrect;
    }
    /**
     * @return string[] errors
     */publicfunctiongetErrors(): array{
        return$this->errors;
    }
}