Unique id inside of thread

Question

Unique id inside of thread

Flaviu_ 1,031

It's the following approach assure me a unique id in every thread ?

class CMyDoc : public CDocument
{
 static size_t m_id;
.....

};

then

size_t CMyDoc::m_id = 1;

And I have a method which is called as:

std::vector<std::thread> v;
for (int x = 0; x < 5; ++x)
{
  v.push_back(std::thread(ExecutionThread, AfxGetMainWnd(), _T("bla bla"));
}

the thread method is:

void CMyDoc::ExecutionThread(HWND hWndPostMessage, const CString& sFile)
{
 const size_t id{ m_id++ };
....
        ::PostMessage(hWndPostMessage, WMU_NOTIFYTHREAD, 0, static_cast<LPARAM>(id));
}

My question is: id from CMyDoc::ExecutionThread is unique across all threads ?

David Lowndes 4,726 Reputation points

2022-04-05T14:58:01.643+00:00

Probably ... for the snippet shown, but why not use the GetCurrentThreadId API?
Flaviu_ 1,031 Reputation points

2022-04-08T15:14:54.01+00:00

Good idea. I used std::atomic<int> type. And goes pretty well.

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David Lowndes 4,726 Reputation points

2022-04-05T14:58:01.643+00:00

Probably ... for the snippet shown, but why not use the GetCurrentThreadId API?
Flaviu_ 1,031 Reputation points

2022-04-08T15:14:54.01+00:00

Good idea. I used std::atomic<int> type. And goes pretty well.

Answer 1

Viorel 122.6K

According to https://www.bing.com/search?q=is+intel+increment+atomic%3F, it is necessary to use the std::atomic_size_t for m_id. (Or use the LONG volatile type, and the InterlockedIncrement function instead of ++; however, it performs ++m_id instead of m_id++).

Answer 2

RLWA32 49,636

This function is specifically designed to return a unique ID for the calling thread nf-combaseapi-cogetcurrentprocess

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Unique id inside of thread

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