为什么我post过来的数据想转发给过去，但是返回值为NUlLL，我看了下表示放入待发送队列，等待异步发送，怎么能立即发送出去呢

<?php
use \Workerman\Worker;
use \Workerman\Connection\AsyncTcpConnection;
require_once './Workerman/Autoloader.php';

//远程CCS地址
$REAL_CCS_ADDRESS = 'tcp://xx.xx.xx.xx:80';

// 监听本地4237端口
$proxy = new Worker('http://0.0.0.0:4237');

$proxy->onConnect = function($connection)
{
    global $REAL_CCS_ADDRESS;
    // 异步建立一个到实际ccs服务器的连接
    $connection_to_css = new AsyncTcpConnection($REAL_CCS_ADDRESS);
    // ccs连接发来数据时，转发给对应客户端的连接
    $connection_to_css->onMessage = function($connection_to_css, $buffer)use($connection)
    {
        var_dump($buffer);
        $connection->send($buffer);
    };
    // ccs连接关闭时，关闭对应的代理到客户端的连接
    $connection_to_css->onClose = function($connection_to_css)use($connection)
    {
        $connection->close();
    };
    // ccs连接上发生错误时，关闭对应的代理到客户端的连接
    $connection_to_css->onError = function($connection_to_css)use($connection)
    {
        $connection->close();
    };

    // 执行异步连接
    $connection_to_css->connect();

    // 客户端发来数据时，转发给对应的ccs连接
    $connection->onMessage = function($connection, $buffer)use($connection_to_css)
    {
        $buffer = $_POST;
        var_dump($connection_to_css->send($buffer));
    };
    // 客户端连接断开时，断开对应的ccs连接
    $connection->onClose = function($connection)use($connection_to_css)
    {
        $connection_to_css->close();
    };
    // 客户端连接发生错误时，断开对应的ccs连接
    $connection->onError = function($connection)use($connection_to_css)
    {
        $connection_to_css->close();
    };

};
// 运行worker
Worker::runAll();