Problem with running timer in another thread

[Damian7546]

@Pl45m4 I should change only event_timer_ or whole function CctalkDevice::startTimer() ?
Can you explain me?

[Pl45m4]

@Damian7546 said in Problem with running timer in another thread:

I should change only event_timer_ or whole function CctalkDevice::startTimer() ?

@Pl45m4 said in Problem with running timer in another thread:

Allocate the timer on the heap and make it a child of the class it is in.

This is everything you have to do and the error/warning should be gone.
No need to change the function.

[Damian7546]

@Pl45m4 In cctalk_device.h I changed

QTimer event_timer_;

to

QTimer *event_timer_; ,

next in CctalkDevice() constructor I added

event_timer_ = new QTimer(this);

and enought ?

[Pl45m4]

@Damian7546 said in Problem with running timer in another thread:

and enough ?

When there is no more error, yes.

Does it work now?

[Damian7546]

@Pl45m4 No, it still the same error : QObject::startTimer: Timers cannot be started from another thread

[JoeCFD]

@Pl45m4 Allocating the timer on the heap or stack should not matter.

[JoeCFD]

@Damian7546 Maybe try to add the following code into the func

    if ( QThread::currentThread() != thread() ) {
        metaObject()->invokeMethod( this, "startTimer()", Qt::QueuedConnection );
        return;
    }

Make startTimer() to be a slot.

[Pl45m4]

@JoeCFD

I know :)
Haven't checked the complete repository where and how everything is put together.

But yeah,

event_timer.setParent(this);

might also work.

[SGaist]

@Pl45m4 that's a bad idea: this will trigger a double deletion. One when the parent is deleted and the second when the object goes out of scope.

[jsulm]

@Damian7546 said in Problem with running timer in another thread:

next in CctalkDevice() constructor I added

Don't do this in the constructor, do it in the method which is actually executed in the other thread.

[JonB]

As @jsulm says, reminder: objects created in thread constructor live in parent thread, objects created in thread run live in that thread.

[Pl45m4]

@SGaist said in Problem with running timer in another thread:

that's a bad idea: this will trigger a double deletion

Oh my... that's why I initially thought of heap allocation and then using the parent-child architecture :D

@jsulm said in Problem with running timer in another thread:

Don't do this in the constructor, do it in the method which is actually executed in the other thread.

But when creating the timer on the heap and as child of the containing class in the contructor... if you then move the ccDevice object, the timer (= child of ccDevice) is also moved, right?!

@JoeCFD said in Problem with running timer in another thread:

Allocating the timer on the heap or stack should not matter.

So this doesn't matter in technical terms as the timer can/should be allocated on the stack, however when you want to use the parent-child relation to move the object to another thread, it does matter to avoid double deletion

[Damian7546]

@Pl45m4 It doesn't work, still the same.

[Damian7546]

@JoeCFD said in Problem with running timer in another thread:

@Damian7546 Maybe try to add the following code into the func

    if ( QThread::currentThread() != thread() ) {
        metaObject()->invokeMethod( this, "startTimer()", Qt::QueuedConnection );
        return;
    }

Make startTimer() to be a slot.

This one , still not working
QMetaObject::invokeMethod: No such method qtcc::CctalkDevice::startTimer()()

[hskoglund]

Hi, try without the parentheses, like this:
...
metaObject()->invokeMethod( this, "startTimer", Qt::QueuedConnection );
...

[Damian7546]

@hskoglund

still the same QMetaObject::invokeMethod: No such method qtcc::CctalkDevice::startTimer()

[Damian7546]

I thinking why we are talking about more than one thread? And why the error applies other thread? Since both CctalkDevice and MyCcTalkApp class are the same thread.... Only SerialWorker works in own thread which one is launched by CctalkLinkController .
The polling timer is in CctalkDevice, so what is the problem ?

[JoeCFD]

@Damian7546 print out thread ids on the screen in the constructor and in this function. Check out why they are different.

[hskoglund]

Ah, I see in your cctalk_device.h file, startTimer() is declared under protected:
try moving it under slots: (like your function void timerIteration();)

[Damian7546]

@hskoglund without changes.

@JoeCFD

QML debugging is enabled. Only use this in a safe environment.
ThreadID SerialWorker: 0x7cb34f9b27c0
ThreadID CctalkLinkController: 0x7cb34f9b27c0
ThreadID CctalkDevice: 0x7cb34f9b27c0
ThreadID MyCcTalkApp: 0x7cb34f9b27c0
LogMessgae: "* Coin acceptor configured device: /dev/ttyUSB0"
LogMessgae: "* Opening port "/dev/ttyUSB0"."
LogMessgae: "Requested device state change from ShutDown to: Initialized"
ThreadID in startTimer() 0x71df85200640
LogMessgae: "* Port "/dev/ttyUSB0" opened."
LogMessgae: "> ccTalk request: SimplePoll, address: 2, data: (empty)"
QMetaObject::invokeMethod: No such method qtcc::CctalkDevice::startTimer()
LogMessgae: "> Request: 020001feff"
LogMessgae: "< Full response: 020001feff01000200fd"
LogMessgae: "< ccTalk response from address 2, data: (empty)"
LogMessgae: "* Device is alive (answered to simple poll)"
QObject::startTimer: Timers cannot be started from another thread*

now I don't understand anything, why only the startTimer is on other thread?