38e
Subj : Re: stl & threads
To   : comp.programming.threads
From : David Schwartz
Date : Tue May 24 2005 08:11 pm


"Uenal Mutlu" <520001085531-0001@t-online.de> wrote in message 
news:d70ha8$69s$05$1@news.t-online.com...

[snip]

>      bool   IsLockedByAny() const { return cLocked > 0; }
>      bool   IsLockedByMe()  const { return cLocked > 0 && dwThrId == 
> GetCurrentThreadId(); }

[snip]

>    private:
>      CRITICAL_SECTION cs;
>      size_t           cLocked;
>      DWORD            dwThrId;
>      const bool       fRecursiveMutex;
>  };

[snip]

    Suppose I write code like this:

 while(IsLockedByAny() && !IsLockedByMe()) i++;

    What guarantees that the compiler doesn't optimize away the repeated 
reads of 'cLocked' and spin forever? I admit that it's dumb to do something 
like that, but it's also bad for a mutex class to contain errors.

    DS

.

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