检测到“我正在跑步".在Qt GUI事件线程中 [英] Detect that "I'm running" in Qt GUI event thread

问题描述

我具有此功能来更新一些GUI内容:

I have this function to update some GUI stuff:

void SavedConnections::renderList()
{
  // Do GUI stuff! Must run in Qt thread!!!
    ...
}

我需要确保不从其他线程调用此函数.我计划要做的是将其推迟到事件循环中并发出警告:

I need to ensure that this function isn't called from other threads. What I plan to do is to defer it into event loop and raise a warning:

void SavedConnections::renderList()
{ 
  if(!this_thread_is_Qt_GUI_thread()) {
    qDebug()<< "Warning: GUI operation attempted from non GUI thread!\n";
    QCoreApplication::postEvent(this, new UpdateGUIEvent());
    return;
  }
  // Do GUI stuff! Must run in Qt thread!!!
    ...
}

此模式也非常方便，使方法可以保证在GUI线程中异步运行而无需任何难看的语法. 我已经问过有关Java的ExecutorService的类似问题.

This pattern is also very convenient to make methods that are guaranteed to run asynchronously in GUI thread without any ugly syntax. I already asked similar question about Java's ExecutorService.

推荐答案

您可以检查当前线程是否是对象所在的线程:

You can check if the current thread is the thread your object lives in:

if (QThread::currentThread() != this->thread()) {
   // Called from different thread
}

请注意，这可能不是主GUI线程！它是this所在的线程(请参见 QObject线程相似性).如果不使用QObject::moveToThread进行更改，则该线程是在其中创建对象的线程.

Note that this might not be the main GUI-Thread! It is the thread this lives in (see QObject Thread affinity). If you don't change it using QObject::moveToThread, it is the thread the object was created in.

这也是QCoreApplication::postEvent用于确定将事件发布到哪个线程的方法.目标线程必须运行QEventLoop才能响应事件.

This is also what QCoreApplication::postEvent uses to determine into which thread the event should be posted. The targeted Thread must run a QEventLoop to respond to the event.

因此，如果对象不在主GUI线程中，则检查主GUI线程(qApp->thread())，但将其发布到this的线程可能不起作用.但是，如果在那里进行GUI处理，则无论如何它都应该存在于GUI线程中

So checking for the main-GUI-Thread (qApp->thread()), but posting to this's thread might not work, if your object does not live in the main-GUI-Thread. However, if you do GUI stuff there, it should anyway live in the GUI-Thread

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