我创建了一个演示来研究QObject，QThread和QT Signal / Slot作为下面的链接
这个想法是：
我创建了一个ExtentQThread，其范围来自QThread并实现了run（）函数，该函数将在调用exec（）之前循环 loopTimeoutMsec （在构造函数上设置）（这使得它进入其线程事件循环）。我从main创建了一个ExtentQThread extQThread1 实例， loopTimeoutMsec 设置为 10000 。
然后我从主线程创建了两个ExtentQObject实例。创建 extQObject10 并将其移动到 extQThread1 和 extQObject11 ，但不会移动。
测试期望：
[main.cpp中]
unsigned long long[extentqthread.cpp]
#include <QCoreApplication>
#include <QTimer>
#include "extentqthread.h"
long baseMSecsSinceEpoch;
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
baseMSecsSinceEpoch = QDateTime::currentMSecsSinceEpoch();
qDebug() << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << "Main thread 1" << QThread::currentThreadId();
// === test1
ExtentQThread extQThread1("extQThread1 created from main thread", 10000);
ExtentQObject extQObject10("extQObject10 created from main thread then moved to extQThread1");
extQObject10.moveToThread(&extQThread1);
ExtentQObject extQObject11("extQObject11 created from main thread");
extQThread1.start();
// 1.0 to test signal of extQObject10 which is moved to extQThread1
// and signal of extQObject11 which is not moved
long timeout = 5000;
QTimer::singleShot(timeout, [&extQThread1, &timeout]() {
qDebug() << "\n==" << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << "timeout" << timeout
<< "\n>> To test signal of extQObject10 which is moved to extQThread1 and signal of extQObject11 which is not moved"
<< "\n>> extQThread1.isRunning()" << extQThread1.isRunning();
});
QTimer::singleShot(timeout, &extQObject10, &ExtentQObject::onExtentQObjectFirstSlot);
QTimer::singleShot(timeout, &extQObject11, &ExtentQObject::onExtentQObjectFirstSlot);
qDebug() << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << "Main thread 2" << QThread::currentThreadId();
return a.exec();
}
[extentqobject.cpp]
#include "extentqthread.h"
extern long baseMSecsSinceEpoch;
ExtentQThread::ExtentQThread(QString name_, long loopTimeoutMsec_)
{
name = name_;
loopTimeoutMsec = loopTimeoutMsec_;
qDebug() << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << Q_FUNC_INFO
<< "instance" << name
<< "loopTimeoutMsec" << loopTimeoutMsec
<< "created on thread" << QThread::currentThreadId();
}
void ExtentQThread::run() {
qDebug() << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << Q_FUNC_INFO
<< "instance" << name
<< "STARTED on thread" << QThread::currentThreadId();
ExtentQObject extQObject("extQObject created from (" + name + ")");
connect(this, &ExtentQThread::runFirstSlot, &extQObject, &ExtentQObject::onExtentQObjectFirstSlot);
if (loopTimeoutMsec < 0) {
while(1) {};
} else {
QThread::msleep(loopTimeoutMsec);
}
qDebug() << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << Q_FUNC_INFO
<< "instance" << name
<< "before exec() on thread" << QThread::currentThreadId();
exec();
qDebug() << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << Q_FUNC_INFO
<< "instance" << name
<< "after exec() on thread" << QThread::currentThreadId();
if (loopTimeoutMsec < 0) {
while(1) {};
} else {
QThread::msleep(loopTimeoutMsec);
}
qDebug() << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << Q_FUNC_INFO
<< "instance" << name
<< "STOPPED on thread" << QThread::currentThreadId();
}
void ExtentQThread::onExtentQThreadFirstSlot() {
qDebug() << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << Q_FUNC_INFO
<< "instance" << name
<< "run on thread" << QThread::currentThreadId();
Q_EMIT runFirstSlot();
}
这是输出
#include "extentqobject.h"
extern long baseMSecsSinceEpoch;
ExtentQObject::ExtentQObject(QString name_)
{
name = name_;
qDebug() << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << Q_FUNC_INFO
<< "instance" << name
<< "created on thread" << QThread::currentThreadId();
}
void ExtentQObject::onExtentQObjectFirstSlot() {
qDebug() << QDateTime::currentMSecsSinceEpoch() - baseMSecsSinceEpoch << Q_FUNC_INFO
<< "instance" << name
<< "run on thread" << QThread::currentThreadId();
}
根据我的理解，我希望： ExtentQObject :: onExtentQObjectFirstSlot（）实例“从主线程创建的extQObject10然后移动到extQThread1”在线程0x7fdc8aa03700上运行以10000（msec）而不是14756（msec）运行。因为信号以5000（毫秒）发出，进入ExtentQthread的exec（）在10000（毫秒）之后运行，然后它应该处理 onExtentQObjectFirstSlot 。
有人可以解释一下吗？
////
diff --git a / main.cpp b / main.cpp index ed45d23..0ebabf3 100644 --- a / main.cpp +++ b / main.cpp @@ -25,14 +25,17 @@ int main（int argc，char * argv []）
0 Main thread 1 0x7fdc8f3f3740
1 ExtentQThread::ExtentQThread(QString, long int) instance "extQThread1 created from main thread" loopTimeoutMsec 10000 created on thread 0x7fdc8f3f3740
1 ExtentQObject::ExtentQObject(QString) instance "extQObject10 created from main thread then moved to extQThread1" created on thread 0x7fdc8f3f3740
1 ExtentQObject::ExtentQObject(QString) instance "extQObject11 created from main thread" created on thread 0x7fdc8f3f3740
1 Main thread 2 0x7fdc8f3f3740
1 virtual void ExtentQThread::run() instance "extQThread1 created from main thread" STARTED on thread 0x7fdc8aa03700
1 ExtentQObject::ExtentQObject(QString) instance "extQObject created from (extQThread1 created from main thread)" created on thread 0x7fdc8aa03700
== 4754 timeout 5000
>> To test signal of extQObject10 which is moved to extQThread1 and signal of extQObject11 which is not moved
>> extQThread1.isRunning() true
4754 void ExtentQObject::onExtentQObjectFirstSlot() instance "extQObject11 created from main thread" run on thread 0x7fdc8f3f3740
10001 virtual void ExtentQThread::run() instance "extQThread1 created from main thread" before exec() on thread 0x7fdc8aa03700
14756 void ExtentQObject::onExtentQObjectFirstSlot() instance "extQObject10 created from main thread then moved to extQThread1" run on thread 0x7fdc8aa03700
答案 0 :(得分：0)
我不确定你要做什么，但有一些建议：
run方法，除非您需要非常密切地控制线程活动。只需创建一个QThread，使用moveToThread并启动线程，就是这样。然后，您可以使用线程started信号或其他信号/插槽连接来确保它在您的线程中执行exec将有效地运行线程事件循环，并仅在线程存在时返回。exec和quit方法sleep，或者更常见的是，当事件循环未运行时，将不会处理任何事件或执行插槽。因此，要执行使用Invoke调用的槽或来自另一个线程的信号，必须在消息在QThread事件循环中排队后调用exec。更一般地说，总是使用信号/插槽（你做了什么）在适当的线程中执行代码，并且当你可以使用QtConcurrent等更高级别的类时依赖它。
有关详细信息，您可以查看Qt documentation以及此更新（{3}}
答案 1 :(得分：0)
我找到了原因，可能这对某人有帮助
QTimer::singleShot(timeout, &extQObject10, &ExtentQObject::onExtentQObjectFirstSlot);
在这种情况下，QTimer :: singleShot调用此重载函数
QSingleShotTimer::QSingleShotTimer(int msec, Qt::TimerType timerType, const QObject *r, QtPrivate::QSlotObjectBase *slotObj)
: QObject(QAbstractEventDispatcher::instance()), hasValidReceiver(r), receiver(r), slotObj(slotObj)
{
timerId = startTimer(msec, timerType);
if (r && thread() != r->thread()) {
// Avoid leaking the QSingleShotTimer instance in case the application exits before the timer fires
connect(QCoreApplication::instance(), &QCoreApplication::aboutToQuit, this, &QObject::deleteLater);
setParent(0);
moveToThread(r->thread());
}
}
这创建了一个计时器实例（让我们调用timerA），因为 extQObject10 ，它是为QTimer :: singleShot设置的接收器，被移动到 extThread1 ，所以timerA被移动到那里太
因为QTimer扩展了QObject所以它从QObject继承了 bool QObject :: event（QEvent * e），它处理如下的线程更改
case QEvent::ThreadChange: {
Q_D(QObject);
QThreadData *threadData = d->threadData;
QAbstractEventDispatcher *eventDispatcher = threadData->eventDispatcher.load();
if (eventDispatcher) {
QList<QAbstractEventDispatcher::TimerInfo> timers = eventDispatcher->registeredTimers(this);
if (!timers.isEmpty()) {
// do not to release our timer ids back to the pool (since the timer ids are moving to a new thread).
eventDispatcher->unregisterTimers(this);
QMetaObject::invokeMethod(this, "_q_reregisterTimers", Qt::QueuedConnection,
Q_ARG(void*, (new QList<QAbstractEventDispatcher::TimerInfo>(timers))));
}
}
break;
这里， QMetaObject :: invokeMethod 通过 extQThread1 生成一个槽句柄，因此它将在 loopTimeoutMsec 之后处理，它被设置为< EM> extQThread1 。之后，timerA开始运行并在为其设置 timeout 之后触发，此时 onExtentQObjectFirstSlot 将在 extObject10 上调用。
总之，在 loopTimeoutMsec （为extQThread1设置）+ timeout 之后，将在 extObject10 上调用 onExtentQObjectFirstSlot （为QTimer :: singleShot设置