Subj : Re: Can C++ local static objects be made thread safe?
To   : comp.programming.threads
From : Gianni Mariani
Date : Thu Jan 20 2005 09:23 am

Alexander Terekhov wrote:
> Gianni Mariani wrote:
> [...]
> 
>>>[snip busted "DCL"]
>>
>>If it was unbusted, what would it look like ?
> 
> 
> Unbusted, it would look like DCSI-MBR or DCSI-TLS/TSD (DCSI-SEMAS-01 
> and DCSI-SEMAS-11 aside for a moment).
> 
> http://www.google.de/groups?selm=40DFD511.A10D1DA0%40web.de
> 
> regards,
> alexander.

Would this DCL work now ?

#define MTSafeStatic( Type, Name, Initializer )         \
     static Type * volatile x_ ## Name;                   \
                                                          \
     if ( ! x_ ## Name )                                  \
     {                                                    \
         Lock<Mutex>     l_lock( StaticInitializerMutex );\
                                                          \
         if ( ! x_ ## Name )                              \
         {                                                \
             static Type v_ ## Name Initializer;          \
                                                          \
             x_ ## Name = & v_ ## Name ;                  \
         }                                                \
     }                                                    \
                                                          \
     Type & Name = * x_ ## Name;                          \
// End macro
// Note that there must be exactly one StaticInitializerMutex
// otherwise you will be making deadlock posssible when
// you have recursive constructors

The reason I think this may work is that the value of x_Name is 
idempotent and the only thing the lock is doing is to have threads wait 
for the initialization.

.