Problem with running timer in another 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?

JoeCFD

@Damian7546 move startTimer() to public slots:
public slots:
void startTimer();

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

If you have stop func for timer, you may need to do the same thing. The code above works in my app.

Damian7546

@JoeCFD something is starting to work...

JoeCFD

@Damian7546 Have fun.

Damian7546

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

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

Problem is more complicated then can I thought, probably not related with startTimer() function .
I totally remove calling startTimer() from my project and still have the same error :

QML debugging is enabled. Only use this in a safe environment.
ThreadID SerialWorker:   0x79e36d8867c0
ThreadID CctalkLinkController:   0x79e36d8867c0
ThreadID CctalkDevice:   0x79e36d8867c0
Using  "/home/developer/.config/CCtalkProj.ini"  as a user-specific settings file
ThreadID MyCcTalkApp:   0x79e36d8867c0
"* Coin acceptor configured device: /dev/ttyUSB0"
"* Opening port \"/dev/ttyUSB0\"."
"Requested device state change from ShutDown to: Initialized"
test test test
"* Port \"/dev/ttyUSB0\" opened."
"> ccTalk request: SimplePoll, address: 2, data: (empty)"
"> Request: 020001feff"
"< Full response: 020001feff01000200fd"
"< ccTalk response from address 2, data: (empty)"
"* Device is alive (answered to simple poll)"
QObject::startTimer: Timers cannot be started from another thread

Below I publish code wihich I try run:
[https://github.com/ienecode/cctalk.git](link url)

Damian7546

@JoeCFD @JoeCFD code analysis should be do from the creating object - MyCcTalkApp, where are created
Coin acceptor communicator - qtcc::Coin AcceptorDevice coin acceptor _;
Analyzing further do you see any problems ?

J.Hilk

Still the same problem as originally.

your 'serial_port_' is not moved with move ToThread QSerialPort uses internally QTimer thats why you see the message.

Damian7546

@J-Hilk So, how can I fix this code ? Can you give me tips ?

Christian Ehrlicher

Pass the correct parent to your timer.

J.Hilk

@Damian7546

Fix your constructor of your QObject based worker: More of a principal matter in this case

class SerialWorker : public QObject {
	Q_OBJECT
	public:

		/// Constructor
		SerialWorker();
...->...
class SerialWorker : public QObject {
	Q_OBJECT
	public:

		/// Constructor
		explicit SerialWorker(QObbject *parent = nullptr);
.....
SerialWorker::SerialWorker()
{
...->...
SerialWorker::SerialWorker(QObject*parent) : QObject(parent)
{

Drop the scoped pointer, you're trying to be fancy when there's no need for it and it's causing trouble

QScopedPointer<QSerialPort> serial_port_; 
...->
QSerialPort * const serial_port_; //Raw dogging the serial port, hell ya

Init the QSerialport correctly:

SerialWorker::SerialWorker(QObject*parent) : QObject(parent), serial_port_{new QSerialPort(this)}
{

Pl45m4

@J-Hilk said in Problem with running timer in another thread:

Fix your constructor of your QObject based worker: More of a principal matter in this case

Drop the scoped pointer, you're trying to be fancy when there's no need for it and it's causing trouble

Init the QSerialport correctly:

TBH these things are also "weird" / designed badly in the original repository, @Damian7546 just copied/forked this structure.
I'm wondering if any of the original stuff actually works... from looking at it I would say it also has many issues.
Usually just including the class inQObject's parent-child structure and therefore moving the thread affinity with the parent would fix this. That's what I wrote/thought earlier, but it seems that this is not so easy to do due to the way the whole thing is designed.

QSerialPort * const serial_port_; //Raw dogging the serial port, hell ya

LMAO :D