回答

通过判断其状态，和push的返回值来判断，代码如下：

<?php

$server = new Swoole\Websocket\Server("0.0.0.0", 9502);
$server->set([
    'open_http_protocol' => true,
]);

$server->on('open', function($server, $req) {
    echo "connection open: {$req->fd}\n";
});
$server->on('request', function($request, $response) {



    $response->header("Content-Type", "text/html; charset=utf-8");
    $response->end("<h1>OK.</h1>");

});
$server->on('message', function($server, $frame) {
    echo "received message: {$frame->data}\n";

    $info = $server->getClientInfo($frame->fd);
    if ($info && $info['websocket_status'] == WEBSOCKET_STATUS_FRAME) {
        //本机推送
        if ($server->isEstablished($frame->fd) && $server->push($frame->fd, "ddd")) {

            echo "发送成功
";
        } else {
            //推送失败，更新用户在线信息，走离线消息

            echo "发送失败
";
        }
    } else {
        echo "不在线 \n";
    }
    // $server->push($frame->fd, json_encode(["hello", "world"]));
});

$server->on('close', function($server, $fd) {
    echo "connection close: {$fd}\n";
});

$server->start();