Mixing
Defer a function call in Qt
I have a function in Qt 4.8 (windows), which has 3 things to do, like this:
void f()
{
//1. Do initialization
//2. Defer g() for next event (on the same thread) so that it may execute after f() is over
//3. Call h() which is time consuming
}
Now, I am not sure how to implement the 2nd step i.e. how to ensure that g() is called after the call to f() is complete, on the same thread (but on the different stack). I tried using QTimer but if I provide a short time say 10 ms, the function g() is called even when f() has not completed execution. So, relying on timers does not seem to be a reliable idea. Please help, any ideas are much appreciated.
qt qt4
asked Jun 18 '14 at 13:58
AarkanAarkan
1,45342244
add a comment |
I have a function in Qt 4.8 (windows), which has 3 things to do, like this:
void f()
{
//1. Do initialization
//2. Defer g() for next event (on the same thread) so that it may execute after f() is over
//3. Call h() which is time consuming
}
Now, I am not sure how to implement the 2nd step i.e. how to ensure that g() is called after the call to f() is complete, on the same thread (but on the different stack). I tried using QTimer but if I provide a short time say 10 ms, the function g() is called even when f() has not completed execution. So, relying on timers does not seem to be a reliable idea. Please help, any ideas are much appreciated.
qt qt4
asked Jun 18 '14 at 13:58
AarkanAarkan
1,45342244
What does this meanon the same thread (but on the different stack)?
– Alex F
Jun 18 '14 at 14:01
What prevents you to callg()afterf()and notg()fromf()?
– vahancho
Jun 18 '14 at 14:11
So, I want g() to be called from the next event stack of message loop which means that instead of calling g() at this time, I just want to post an event in message loop and call that later when current event processing is complete. I hope it clarifies the things.
– Aarkan
Jun 18 '14 at 14:32
add a comment |
I have a function in Qt 4.8 (windows), which has 3 things to do, like this:
void f()
{
//1. Do initialization
//2. Defer g() for next event (on the same thread) so that it may execute after f() is over
//3. Call h() which is time consuming
}
Now, I am not sure how to implement the 2nd step i.e. how to ensure that g() is called after the call to f() is complete, on the same thread (but on the different stack). I tried using QTimer but if I provide a short time say 10 ms, the function g() is called even when f() has not completed execution. So, relying on timers does not seem to be a reliable idea. Please help, any ideas are much appreciated.
qt qt4
asked Jun 18 '14 at 13:58
AarkanAarkan
1,45342244
I have a function in Qt 4.8 (windows), which has 3 things to do, like this:
void f()
{
//1. Do initialization
//2. Defer g() for next event (on the same thread) so that it may execute after f() is over
//3. Call h() which is time consuming
}
Now, I am not sure how to implement the 2nd step i.e. how to ensure that g() is called after the call to f() is complete, on the same thread (but on the different stack). I tried using QTimer but if I provide a short time say 10 ms, the function g() is called even when f() has not completed execution. So, relying on timers does not seem to be a reliable idea. Please help, any ideas are much appreciated.
qt qt4
qt qt4
asked Jun 18 '14 at 13:58
AarkanAarkan
1,45342244
asked Jun 18 '14 at 13:58
AarkanAarkan
1,45342244
asked Jun 18 '14 at 13:58
AarkanAarkan
1,45342244
asked Jun 18 '14 at 13:58
AarkanAarkan
1,45342244
asked Jun 18 '14 at 13:58
AarkanAarkan
1,45342244
1,45342244
What does this meanon the same thread (but on the different stack)?
– Alex F
Jun 18 '14 at 14:01
What prevents you to callg()afterf()and notg()fromf()?
– vahancho
Jun 18 '14 at 14:11
So, I want g() to be called from the next event stack of message loop which means that instead of calling g() at this time, I just want to post an event in message loop and call that later when current event processing is complete. I hope it clarifies the things.
– Aarkan
Jun 18 '14 at 14:32
add a comment |
What does this meanon the same thread (but on the different stack)?
– Alex F
Jun 18 '14 at 14:01
What prevents you to callg()afterf()and notg()fromf()?
– vahancho
Jun 18 '14 at 14:11
So, I want g() to be called from the next event stack of message loop which means that instead of calling g() at this time, I just want to post an event in message loop and call that later when current event processing is complete. I hope it clarifies the things.
– Aarkan
Jun 18 '14 at 14:32
What does this mean
on the same thread (but on the different stack)?– Alex F
Jun 18 '14 at 14:01
What does this mean
on the same thread (but on the different stack)?– Alex F
Jun 18 '14 at 14:01
What prevents you to call
g() after f() and not g() from f()?– vahancho
Jun 18 '14 at 14:11
What prevents you to call
g() after f() and not g() from f()?– vahancho
Jun 18 '14 at 14:11
So, I want g() to be called from the next event stack of message loop which means that instead of calling g() at this time, I just want to post an event in message loop and call that later when current event processing is complete. I hope it clarifies the things.
– Aarkan
Jun 18 '14 at 14:32
So, I want g() to be called from the next event stack of message loop which means that instead of calling g() at this time, I just want to post an event in message loop and call that later when current event processing is complete. I hope it clarifies the things.
– Aarkan
Jun 18 '14 at 14:32
add a comment |
2 Answers
2
active
oldest
votes
Make g() a slot or a Q_INVOKABLE. Then use QMetaObject::invokeMethod(this, "g", Qt::QueuedConnection).
answered Jun 18 '14 at 18:20
Kuba OberKuba Ober
69.7k982186
add a comment |
If I understand correctly, it's needed simply to call g() after f(), but on the next message loop cycle, after all Qt events issued from f() would be processed. In this case I suggest the following trick:
f();
QApplication::processEvents();
g();
answered Nov 20 '18 at 18:33
RedSoftRedSoft
111111
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Make g() a slot or a Q_INVOKABLE. Then use QMetaObject::invokeMethod(this, "g", Qt::QueuedConnection).
answered Jun 18 '14 at 18:20
Kuba OberKuba Ober
69.7k982186
add a comment |
Make g() a slot or a Q_INVOKABLE. Then use QMetaObject::invokeMethod(this, "g", Qt::QueuedConnection).
answered Jun 18 '14 at 18:20
Kuba OberKuba Ober
69.7k982186
add a comment |
Make g() a slot or a Q_INVOKABLE. Then use QMetaObject::invokeMethod(this, "g", Qt::QueuedConnection).
answered Jun 18 '14 at 18:20
Kuba OberKuba Ober
69.7k982186
Make g() a slot or a Q_INVOKABLE. Then use QMetaObject::invokeMethod(this, "g", Qt::QueuedConnection).
answered Jun 18 '14 at 18:20
Kuba OberKuba Ober
69.7k982186
answered Jun 18 '14 at 18:20
Kuba OberKuba Ober
69.7k982186
answered Jun 18 '14 at 18:20
Kuba OberKuba Ober
69.7k982186
answered Jun 18 '14 at 18:20
Kuba OberKuba Ober
69.7k982186
69.7k982186
add a comment |
add a comment |
If I understand correctly, it's needed simply to call g() after f(), but on the next message loop cycle, after all Qt events issued from f() would be processed. In this case I suggest the following trick:
f();
QApplication::processEvents();
g();
answered Nov 20 '18 at 18:33
RedSoftRedSoft
111111
add a comment |
If I understand correctly, it's needed simply to call g() after f(), but on the next message loop cycle, after all Qt events issued from f() would be processed. In this case I suggest the following trick:
f();
QApplication::processEvents();
g();
answered Nov 20 '18 at 18:33
RedSoftRedSoft
111111
add a comment |
If I understand correctly, it's needed simply to call g() after f(), but on the next message loop cycle, after all Qt events issued from f() would be processed. In this case I suggest the following trick:
f();
QApplication::processEvents();
g();
answered Nov 20 '18 at 18:33
RedSoftRedSoft
111111
If I understand correctly, it's needed simply to call g() after f(), but on the next message loop cycle, after all Qt events issued from f() would be processed. In this case I suggest the following trick:
f();
QApplication::processEvents();
g();
answered Nov 20 '18 at 18:33
RedSoftRedSoft
111111
answered Nov 20 '18 at 18:33
RedSoftRedSoft
111111
answered Nov 20 '18 at 18:33
RedSoftRedSoft
111111
answered Nov 20 '18 at 18:33
RedSoftRedSoft
111111
111111
add a comment |
add a comment |
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What does this mean
on the same thread (but on the different stack)?– Alex F
Jun 18 '14 at 14:01
What prevents you to call
g()afterf()and notg()fromf()?– vahancho
Jun 18 '14 at 14:11
So, I want g() to be called from the next event stack of message loop which means that instead of calling g() at this time, I just want to post an event in message loop and call that later when current event processing is complete. I hope it clarifies the things.
– Aarkan
Jun 18 '14 at 14:32