PHPDaemon\SockJS\Methods\Generic::poll PHP Method

    protected function poll($cb = null)
    {
        $this->appInstance->subscribe('s2c:' . $this->sessId, [$this, 's2c'], function ($redis) use($cb) {
            $this->appInstance->publish('poll:' . $this->sessId, json_encode($this->pollMode), function ($redis) use($cb) {
                if (!$redis) {
                    $cb === null || $cb();
                    return;
                }
                if ($redis->result > 0) {
                    $cb === null || $cb();
                    return;
                }
                $this->appInstance->setnx('sess:' . $this->sessId, $this->attrs->server['REQUEST_URI'], function ($redis) use($cb) {
                    if (!$redis || $redis->result === 0) {
                        $this->error(3000);
                        $cb === null || $cb();
                        return;
                    }
                    $this->appInstance->expire('sess:' . $this->sessId, $this->appInstance->config->deadsessiontimeout->value, function ($redis) use($cb) {
                        if (!$redis || $redis->result === 0) {
                            $this->error(3000);
                            $cb === null || $cb();
                            return;
                        }
                        $this->appInstance->subscribe('state:' . $this->sessId, function ($redis) use($cb) {
                            if (!$redis) {
                                return;
                            }
                            list(, $chan, $state) = $redis->result;
                            if ($state === 'started') {
                                $this->sendFrame('o');
                                if (!in_array('stream', $this->pollMode)) {
                                    $this->finish();
                                    return;
                                }
                            }
                            $this->appInstance->publish('poll:' . $this->sessId, json_encode($this->pollMode), function ($redis) use($cb) {
                                if (!$redis || $redis->result === 0) {
                                    $this->error(3000);
                                    $cb === null || $cb();
                                    return;
                                }
                                $cb === null || $cb();
                            });
                        }, function ($redis) use($cb) {
                            if (!$this->appInstance->beginSession($this->path, $this->sessId, $this->attrs->server)) {
                                $this->header('404 Not Found');
                                $this->finish();
                                $this->unsubscribeReal('state:' . $this->sessId);
                            }
                            $cb === null || $cb();
                        });
                    });
                });
            });
        });
    }