Re: MT Design Question
"Chris M. Thomasson" <cristom@charter.net>
"Balog Pal" <pasa@lib.hu> wrote in message
news:i5f5a0$2n8a$1@news.ett.com.ua...
Oops. On must platforms, and definitely with a C++0x std::mutex, it is
undefined behaviour to unlock a mutex from a thread other than that
which locked it. This is the use for a semaphore (which we don't have in
C++0x).
Wow. That's something good to know.
While we're at it, is that requirement specific to C++0x or also present
in common APIs? I don't recall it for either pthread or Win32 manuals.
The MSDN documentation mentions this:
http://msdn.microsoft.com/en-us/library/ms684169(VS.85).aspx
I will quote the relevant section:
"If a thread calls LeaveCriticalSection when it does not have ownership of
the specified critical section object, an error occurs that may cause
another thread using EnterCriticalSection to wait indefinitely."
Oh yeah, I refreshed my readings in the meantime. In the earlier idea I was
thinking in W32 mutex, not CS, but that also is in fact recursive, and would
not work even if allowed the foreign unlocking...
I feel pissed, because before posting the previous question I actually
fetched the man page gor pthread_mutex_unlock, and read the part. And the
text stating UB is actually there, just little earlier. DOH. :-/ I need
an upgrade for my reading module.
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