Qt5:如何等待线程中的信号? [英] Qt5: How to wait for a signal in a thread?

问题描述

标题问题可能不是很明确.我正在Windows7上使用Qt5.

Probably the title question is not very explicit. I am using Qt5 on Windows7.

在某个线程(QThread)中的某个位置，在"process()"函数/方法中，我必须等待属于我在此线程中使用的QSslSocket的"encrypted()"信号.另外我想我应该使用QTimer并等待"timeout()" SIGNAL，以避免在无限循环中被阻塞...
我现在拥有的是:

In a thread (QThread) at some point, in the "process()" function/method, I must wait for the "encrypted()" SIGNAL belonging to a QSslSocket I am using in this thread. Also I suppose I should use a QTimer and wait for a "timeout()" SIGNAL in order to avoid getting blocked in an infinite loop...
What I have now is:

// start processing data
void Worker::process()
{
    status = 0;
    connect(sslSocket, SIGNAL(encrypted()), this, SLOT(encryptionStarted()));
    QTimer timer;
    connect(&timer, SIGNAL(timeout()), this, SLOT(timerTimeout()));
    timer.start(10000);
    while(status == 0)
    {
        QThread::msleep(5);
    }

    qDebug("Ok, exited loop!");

    // other_things here
    // .................
    // end other_things

    emit finished();
}

// slot (for timer)
void Worker::timerTimeout()
{
    status = 1;
}

// slot (for SSL socket encryption ready)
void Worker::encryptionStarted()
{
    status = 2;
}

好吧，显然这是行不通的.它永远停留在while循环中...
所以，问题是:有没有办法解决这个问题?我怎样才能等待"encrypted()"信号，但不能超过-假设是10秒-以避免卡在该等待循环/线程中?

Well, obviously it doesn't work. It stays in that while-loop forever...
So, the question is: Is there a way to solve this problem? How can I wait for that "encrypted()" SIGNAL but not more than - let's say 10 seconds - in order to avoid getting stuck in that waiting-loop/thread?

推荐答案

您可以使用本地事件循环来等待信号被发出:

You can use a local event loop to wait for the signal to be emitted :

QTimer timer;
timer.setSingleShot(true);
QEventLoop loop;
connect( sslSocket, &QSslSocket::encrypted, &loop, &QEventLoop::quit );
connect( &timer, &QTimer::timeout, &loop, &QEventLoop::quit );
timer.start(msTimeout);
loop.exec();

if(timer.isActive())
    qDebug("encrypted");
else
    qDebug("timeout");

在这里等待，直到发出encrypted或超时.

Here it waits until encrypted is emitted or the the timeout reaches.

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