写了websocket个聊天室，然后终于弄懂了php的socket

var wsServer = ‘ws://127.0.0.1:8080‘; 
var ws = new WebSocket(wsServer);
ws.onmessage = function (evt) { 
    do sth
};

public function start_server() {
    $this->socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
    //允许使用本地地址
    socket_set_option($this->socket, SOL_SOCKET, SO_REUSEADDR, TRUE); 
    socket_bind($this->socket, $this->host, $this->port);
    //最多10个人连接，超过的客户端连接会返回WSAECONNREFUSED错误
    socket_listen($this->socket, $this->maxuser); 
    while(TRUE) {
        $this->cycle = $this->accept;
        $this->cycle[] = $this->socket;
        //阻塞用，有新连接时才会结束
        socket_select($this->cycle, $write, $except, null);
        foreach ($this->cycle as $k => $v) {
            if($v === $this->socket) {
                if (($accept = socket_accept($v)) < 0) {
                    continue;
                }
                //如果请求来自监听端口那个套接字，则创建一个新的套接字用于通信
                $this->add_accept($accept);
                continue;
            }
            $index = array_search($v, $this->accept);
            if ($index === NULL) {
                continue;
            }
            if (!@socket_recv($v, $data, 1024, 0) || !$data) {//没消息的socket就跳过
                $this->close($v);
                continue;
            }
            if (!$this->isHand[$index]) {
                $this->upgrade($v, $data, $index);
                if(!empty($this->function[‘add‘])) {
                    call_user_func_array($this->function[‘add‘], array($this));
                }
                continue;
            }
            $data = $this->decode($data);
            if(!empty($this->function[‘send‘])) {
                call_user_func_array($this->function[‘send‘], array($data, $index, $this));
            }
        }
        sleep(1);
    }
}
//增加一个初次连接的用户
private function add_accept($accept) {
    $this->accept[] = $accept;
    $index = array_keys($this->accept);
    $index = end($index);
    $this->isHand[$index] = FALSE;
}
//关闭一个连接
private function close($accept) {
    $index = array_search($accept, $this->accept);
    socket_close($accept);
    unset($this->accept[$index]);
    unset($this->isHand[$index]);
    if(!empty($this->function[‘close‘])) {
        call_user_func_array($this->function[‘close‘], array($this));
    }
}
//响应升级协议
private function upgrade($accept, $data, $index) {
    if (preg_match("/Sec-WebSocket-Key: (.*)\r\n/",$data,$match)) {
        $key = base64_encode(sha1($match[1] . ‘258EAFA5-E914-47DA-95CA-C5AB0DC85B11‘, true));
        $upgrade  = "HTTP/1.1 101 Switching Protocol\r\n" .
                "Upgrade: websocket\r\n" .
                "Connection: Upgrade\r\n" .
                "Sec-WebSocket-Accept: " . $key . "\r\n\r\n";  //必须以两个回车结尾
        socket_write($accept, $upgrade, strlen($upgrade));
        $this->isHand[$index] = TRUE;
    }
}

$this->cycle = $this->accept;
$this->cycle[] = $this->socket;
var_dump($this->cycle);//array(n),n>=1
socket_select($this->cycle, $write, $except, null);//有活动后继续往下
var_dump($this->cycle);//array(0),n==0