[Development] Automatic signal-slot statistics

[Taras Kushnir]

Hi Olivier

Thanks for fast response.

Sorry for asking trivial questions but I didn’t quite understand about “redeclaring” things in my project. 

As far as I understand all I need to do is pass an instance of [QSignalSpyCallbackSet] struct with my custom callbacks to [qt_register_signal_spy_callbacks], isn’t it? Can you please clarify “redeclaring”?

Thanks,
Taras


> On Aug 8, 2018, at 08:15, Olivier Goffart <olivier at woboq.com> wrote:
> 
> On 2018-08-08 06:53, Taras Kushnir wrote:
>> Hello
>> I’ve been refactoring giant pieces (like 50-60%) of one project's codebase and I’m concerned about validity/quality of the result. Except different kinds of tests I’m thinking about statistical metrics one of which would be to get a feel how Qt-specific parts of the project have changes.
>> Is there any way to produce statistics which signals got fired and how many times (+ the same for slots) automatically during any application runtime?
>> (“any" way except of patching and recompiling Qt framework itself)
> 
> 
> There is a way:
> There is some exported private API from qobject_p.h that you can trivially re-declare in your project:
> 
> 
> struct QSignalSpyCallbackSet
> {
>    typedef void (*BeginCallback)(QObject *caller, int signal_or_method_index, void **argv);
>    typedef void (*EndCallback)(QObject *caller, int signal_or_method_index);
>    BeginCallback signal_begin_callback,
>                    slot_begin_callback;
>    EndCallback signal_end_callback,
>                slot_end_callback;
> };
> void Q_CORE_EXPORT qt_register_signal_spy_callbacks(const QSignalSpyCallbackSet &callback_set);
> 
> extern QSignalSpyCallbackSet Q_CORE_EXPORT qt_signal_spy_callback_set;
> 
> https://code.woboq.org/qt5/qtbase/src/corelib/kernel/qobject_p.h.html#73
> 
> 
> All you need to do is to call qt_register_signal_spy_callbacks to register the signal_begin_callback, and this will be called everytime a signal is emited. So you can gather some statistics from that.
> 
> 
> -- 
> Olivier
> 
> Woboq - Qt services and support - https://woboq.com - https://code.woboq.org
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