Re: Mutex/Lock
James Kanze schrieb:
On May 31, 10:39 am, Chris Forone <4...@gmx.at> wrote:
Errata:
bool Exit()
{
mutex.Acquire();
if (active)
{
active = false;
mutex.Release();
// wait for thread termination :-)))
}
mutex.Release();
}
if i write:
active = false, mutex.Release()
i think, the mutex is first released -> error
is this right?
No. There's a sequence point at the comma, so all side effects
of the preceding expression must be finished before any side
effects of the following occur.
I do wonder about your code, however. You really need to
recover the mutex before the end of the if---otherwise, you'll
release it twice. And how do you wait for thread termination:
with a join, or with some sort of global thread counter? In the
latter case, you'll need the mutex to read it as well.
Thanx for the example. The wait is done with the win32 function
WaitForSingleObject() with no timeout. Excuse me for the incomplete example:
bool Exit()
{
mutex.Acquire();
if (active)
{
active = false;
mutex.Release();
return WaitForSingleObject(thread, INFINITE) == WAIT_OBJECT_0;
}
mutex.Release();
}
The sideeffect-thing i dont understand...
What about:
return someVar1 == 10 &&
someVar2 != 20 &&
(someVar3 = someFunc()) == true;
and
return (someVar1 == 10) &&
(someVar2 != 20) &&
(someVar3 = someFunc()) == true;
thanx & hand, chris