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Re: [Mingw-w64-public] Fwd: [patch] Reimplement GNU threads library on native Windows

On 02/07/19 12:15 +0200, Jacek Caban wrote:

On 02/07/2019 12:12, Jacek Caban wrote:
On 02/07/2019 11:57, Liu Hao wrote:

在 2019/7/2 下午5:19, Eric Botcazou 写道:
It seems inappropriate to use handles as thread identifiers (as handles imply resource ownership and are not unique identifiers); thread IDs (as
`DWORD` or `unsigned long`) would be a better alternative.
This was considered but ultimately rejected, as you can do nothing with a thread Id, i.e. you need a handle for everything.  But the __gthread_equal
routine does compare the Ids and not the handles.

The `OpenThread()` function can obtain a handle by thread ID. It returns
a real handle that has to be closed when it is out of use. Using the
pseudo handle returned by `GetCurrentThread()` may be more efficient if
the target thread ID is equal to `GetCurrentThreadId()`.

The problem with thread id is that it's not valid nor guaranteed to be identical after the thread is terminated. A handle needs to be used for that.

I meant unique, not identical.

The C++ standard says:

"The library may reuse the value of a thread::id of a terminated
thread that can no longer be joined."

So that's not a reason to use a handle.

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