Re: Thread safe, thread-local variable

From:
"Ivan Brugiolo [MSFT]" <ivanbrug@online.microsoft.com>
Newsgroups:
microsoft.public.vc.language
Date:
Thu, 3 May 2007 00:50:26 -0700
Message-ID:
<eMjU3eVjHHA.3472@TK2MSFTNGP04.phx.gbl>
TlsAlloc/TlsSetValue/TslGetValue ?

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"Bart Simpson" <123evergreen@terrace.com> wrote in message
news:vOOdndpXGKhSEqTbRVnyuAA@bt.com...

(please ignore previous post).

I am writing a class which is an analytic engine that traverses a MxN
matrix space and makes calculations at each point in the matrix. The
calculations involve calling "exposed" functions via callbacks.

In a nutshell, I need to be able to pass the current position in the grid
to the callback function, so I have somehing like this:

//'global' vars
namespace
{
    Point mypoint ;
}

class MyEngine
{
public:
    void WriteCurrentPointValue();
    //...
};

//"registered" functions
int foo()
{
   Point point = ReadCurrentPointValue();
   return DoSomething(point);
}

However, this soln is not thread safe in that if I have multiple instances
of the engine running in different threads, all bets are off. My question
is this:

How can I provide threadsafe, threadlocal 'global' variable for use as
discussed above?

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