What should be best mechanism to stop and start same thread again?

Qt embedded developer

I have created one class

Which shared between both

This class have one queue

Using this class I have created 2 queue

In one of that queue frontend will write data using safeguard lock and it will be read by backend

In other queue back end will write data and front will read data

Now to not block GUI I have created 2 thread on front end side where one will do write and other do reading

What should be best mechanism to stop and start same thread again so that when data is not available at that time we can save usage of cpu?

In this queue

I want to push the one command

Which have

Struct {
Int id;
String type;
// here I am confused what I should declare so that there any number of data I can pass
}

So what I should declare 3rd var?

SGaist

Hi,

Isn't QWaitCondition what you are looking for ?
Check the associated producer consumer example.

Qt embedded developer

@SGaist what about
My third variable to declare? Where I mentioned below comment
// here I am confused what I should declare so that there any number of data I can pass

I want to share here information it can be any type of information

SGaist

@Qt-embedded-developer "any number of data" ? What is the type of data ? Once you know that, you can use a QList<TypeOfData>.

Pl45m4

@Qt-embedded-developer said in What should be best mechanism to stop and start same thread again?:

So what I should declare 3rd var?

This says it all... Since it's C++ (and not something like JS, where you can have "variable Varibales") , you need to know what datatype you put there before you compile/run it.
In general one could use <T> templates or void pointers to your "data" but in your case , in a struct it might be difficult.
So there is no way that you know before what kind of data is stored there?! Why you not know? Re-think your design. Or create different structs for different cases

Qt embedded developer

@SGaist @Pl45m4 i know that using json format we can send as many as various types of data. So similar way I want to create structure that replace json format

JonB

@Qt-embedded-developer
One Qt type which approximates JSON's variety of types is QVariant/QVariantList etc. I don't know what your case is where you do not define the type/structure of your data. QList<TypeOfData> might be preferable, but QVariant allows for a number of underlying types in answer to your question.

SGaist

@Qt-embedded-developer JSON is a textual exchange format which C++ is not. You can't create new data structure out of the blue without any prior knowledge like that.

What exactly are you trying to put in that structure ?

Qt embedded developer

@SGaist @JonB

My actually requirement is like

Consider in ui there are several button for different devices

Now when any button get clicked I need to send request through this type of data structure so when response is send by backend

Based on devices properties there could be more or less data in various format comes.

And this type of data I need put to send and receive

JonB

@Qt-embedded-developer said in What should be best mechanism to stop and start same thread again?:

i know that using json format we can send as many as various types of data. So similar way I want to create structure that replace json format

So going back to this. If you really do want to pass a bunch of unknown, arbitrary data structures around JSON is a possibility. Why do you want to "replace" JSON format?

Qt embedded developer

@JonB because there is clear requirement that we should not use json, we need to find alternative like using C++17 and any custom data structure

SGaist

@Qt-embedded-developer what is the justification of that requirement ?

You can make use of Qt's JSON classes to parse and generate from / to the backend.

JonB

@Qt-embedded-developer
If that is your requirement then you can always restrict yourself to the same subset of types as JSON does. From Qt use QList<> for lists/arrays (JSON [...]) and QMap<> for objects with keys (JSON {...}). Or equivalent std:: types if that floats your boat.