Workerman\Connection\TcpConnection::baseWrite PHP Method

    public function baseWrite()
    {
        $len = @fwrite($this->_socket, $this->_sendBuffer);
        if ($len === strlen($this->_sendBuffer)) {
            Worker::$globalEvent->del($this->_socket, EventInterface::EV_WRITE);
            $this->_sendBuffer = '';
            // Try to emit onBufferDrain callback when the send buffer becomes empty.
            if ($this->onBufferDrain) {
                try {
                    call_user_func($this->onBufferDrain, $this);
                } catch (\Exception $e) {
                    Worker::log($e);
                    exit(250);
                } catch (\Error $e) {
                    Worker::log($e);
                    exit(250);
                }
            }
            if ($this->_status === self::STATUS_CLOSING) {
                $this->destroy();
            }
            return true;
        }
        if ($len > 0) {
            $this->_sendBuffer = substr($this->_sendBuffer, $len);
        } else {
            self::$statistics['send_fail']++;
            $this->destroy();
        }
    }