libWebSockets上的Qt Wrapper类-不从回调方法发出信号

Question

我基于示例编写WebSocket客户端应用程序，其中在与服务器建立连接时，客户端应用程序需要通过WebSocket Protocol 。 由于QtWebSockets不支持Websocket协议，因此我正在编写一个C ++包装器以使用libWebSockets库，并发出类似于QWebSocket的已connected, disconnected, textReceived的信号。

我的客户端应用程序能够连接到服务器并正在接收来自服务器的文本消息，并且我在下面复制了最少的示例代码，在这里我面临一个问题，当我从回调函数发出信号时，该信号实际上并没有发布，并且我连接到该信号的插槽从未执行。 我已验证在会话数据中传递的对象地址正确（已复制程序的日志）。 我在这里做错什么了。

---

WebSocket.h

class WebSocket : public QObject
{
    Q_OBJECT

public:
    WebSocket(QObject *parent = Q_NULLPTR);
    ~WebSocket();

signals:
    void connected();
    void disconnected();
    void textMessageReceived(const QString &message);

private:
    static int callback_dumb_increment(struct lws *wsi, enum lws_callback_reasons reason,
        void *user, void *in, size_t len);

    struct lws_context *context;
    struct lws *client_wsi;
    static const struct lws_protocols protocols[];
};

---

WebSocket.cpp

const struct lws_protocols WebSocket::protocols[] = {
    {
        "dumb_protocol",
        callback_dumb_increment,
        sizeof(per_session_data),
        0,
    },
    { NULL, NULL, 0, 0 }
};

WebSocket::WebSocket(QObject *parent) : QObject(parent)
{
    struct lws_context_creation_info info;
    struct lws_client_connect_info i;
    int n = 0;

    memset(&info, 0, sizeof info); /* otherwise uninitialized garbage */
    info.port = CONTEXT_PORT_NO_LISTEN; /* we do not run any server */
    info.protocols = protocols;

    qDebug() << "[parent] address: " << this;
    info.user = this;

    /*
     * since we know this lws context is only ever going to be used with
     * one client wsis / fds / sockets at a time, let lws know it doesn't
     * have to use the default allocations for fd tables up to ulimit -n.
     * It will just allocate for 1 internal and 1 (+ 1 http2 nwsi) that we
     * will use.
     */
    info.fd_limit_per_thread = 1 + 1 + 1;

    context = lws_create_context(&info);
    if (!context) {
        qDebug() << "lws init failed";
    }

    memset(&i, 0, sizeof i); /* otherwise uninitialized garbage */
    i.context = context;

    i.port = 7070;
    i.address = "localhost";
    i.path = "/";
    i.host = i.address;
    i.origin = i.address;
    i.pwsi = &client_wsi;

    lws_client_connect_via_info(&i);

    while (n >= 0 && client_wsi)
        n = lws_service(context, 0);
}


int WebSocket::callback_dumb_increment( struct lws *wsi, enum lws_callback_reasons reason,
                                        void *user, void *in, size_t len )
{
    /* This will be same for every connected peer */
    void *userdata = lws_context_user(lws_get_context(wsi));
    qDebug() << "userData address: " << userdata;

    QString message = "";

    switch (reason) {

    case LWS_CALLBACK_CLIENT_CONNECTION_ERROR:
        if (in)
            qDebug() << "CLIENT_CONNECTION_ERROR: " << (char *)in;
        else
            qDebug() << "CLIENT_CONNECTION_ERROR: (null)";
        wsi = NULL;
        break;

    case LWS_CALLBACK_CLIENT_ESTABLISHED:
        qDebug() << __func__ << " established";
        emit static_cast<WebSocket*>(userdata)->connected();
        break;

    case LWS_CALLBACK_CLIENT_RECEIVE:
        message = QString::fromUtf8((const char *)in);
        qDebug() << "RX: " << message;
        emit static_cast<WebSocket*>(userdata)->textMessageReceived(message);
        break;

    case LWS_CALLBACK_CLIENT_CLOSED:
        wsi = NULL;
        emit static_cast<WebSocket*>(userdata)->disconnected();
        break;

    default:
        break;

    }

    return lws_callback_http_dummy(wsi, reason, user, in, len);
}

---

SocketClient.h

class SocketClient : public QObject
{
    Q_OBJECT
public:
    explicit SocketClient(QObject *parent = Q_NULLPTR);
    ~SocketClient();

public slots:
    void onConnected();
    void onTextMessageReceived(QString message);

private:
    std::shared_ptr<WebSocket> webSock = nullptr;
};

---

SocketClient.cpp

SocketClient::SocketClient(QObject *parent) :QObject(parent)
{
    webSock = std::make_shared<WebSocket>(this);    

    connect(webSock .get(), &WebSocket::connected, this, &SocketClient::onConnected);
    connect(webSock .get(), &WebSocket::textMessageReceived,
        this, &SocketClient::onTextMessageReceived);
}

日志：

[parent] address:  WebSocket(0x1b2cae32140)
userData address:  0x1b2cae32140
WebSocket::callback_dumb_increment  established
userData address:  0x1b2cae32140
RX:  "Hello World"