wxThread and wxString::FromUTF8

[Marcus Frenkel]

Hi,

In my secondary thread I have a function like this:

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void Function(std::string & result ) {
  wxString Result = wxString::FromUTF8( result.c_str() );
  wxCommandEvent *event = new wxCommandEvent(wxEVT_COMMAND_MENU_SELECTED,ID_function1);
  event->SetString(Result);
  wxQueueEvent(frame, event);

}

Is it safe to use the wxString::FromUTF8 function in multiple threads at the same time?

Or it's safer to use wxString Result(result.c_str(), wxConvUTF8);?

Thx, Marcus

[jfouche]

wxString is not thread safe.
I suggest you to send a wxChar* buffer, and delete it in the handler :

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wxChar* buffer = new wxChar[Result.Length() + 1];
wxStrcpy(buffer, Result.c_str());
buffer[Result.Length()] = 0;
event.SetClientData(buffer);
...


// In the handler
wxChar* buffer = (wxChar*) event.GetClientData();
wxString Result(buffer);
delete[] buffer;

[doublemax]

Please read:
http://docs.wxwidgets.org/trunk/classwx ... ef0318b59a

While wxString is not thread-safe, the way you're using wxString::FromUTF8 is ok.

However, if you use wxCommandEvent, you should use

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event->SetString( Result.c_str() );

Alternatively, use wxThreadEvent instead (like shown in above link).

[Marcus Frenkel]

While wxString is not thread-safe, the way you're using wxString::FromUTF8 is ok.

I thought that multiple threads cannot call the same global function. Since wxString::FromUTF8 is a static function it actually acts as a global function, am I missing something?

However, if you use wxCommandEvent, you should use

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event->SetString( Result.c_str() );

Is it neceserry to make deep copy twice? Since it is already done once in the conversion from string to wxString as shown below:

Code: Select all

wxString Result = wxString::FromUTF8( result.c_str() );

[doublemax]

I thought that multiple threads cannot call the same global function.

That depends on whether the called function is thread safe or not.

Since wxString::FromUTF8 is a static function it actually acts as a global function, am I missing something?

Now that you mention it, i may have read somewhere that the CSConv classes are not thread safe, i don't know if this is (still) true. So, if you want to be safe, you will have to implement your all small helper class with a mutex to ensure thread safety.

Is it neceserry to make deep copy twice? Since it is already done once in the conversion from string to wxString as shown below:

In this particular case you're right, because the string object goes out of scope immediately. But i'd always enforce deep copy at the latest possible stage and not rely on the fact that it's ensured somewhere earlier in the code.