Re: [Boost-users] Boost-users Digest, Vol 637, Issue 1

From: James E Taylor (james_at_[hidden])
Date: 2005-08-18 05:27:19

Thanks, Pablo,

I'll have a look at it.

James

> FYI Matthew Wilson gave a technique (in "Imperfect C++&quot for handling
> this, 
> by turning the mutex initialization into an integer initialization (that 
> doesn't have a problem with [multiple] simultaneous threads entering the 
> function)
> 
> It uses STLSoft's spin_mutex, and looks pretty much like what you have 
> already:
> 
> <code>
> #include <platformstl/spin_mutex.hpp>
> #include <stlsoft/lock_scope.hpp>
> using platformstl::spin_mutex;
> using stlsoft::lock_scope;
> 
> template<typename T>
> boost::shared_ptr<T>
> my_func()
> {
> //   static boost::mutex m;
> //   boost::mutex::scoped_lock l(m);
>    static int spin_count = 0;        // No race condition initializing an 
> int
>    spin_mutex mutex(&spin_count);    // Build the mutex on top of the
> static 
> int
>    lock_scope lock(mutex);
> 
>    static boost::shared_ptr<T> p(new T);
>    return p;
> }
> </code>
> 
> This assumes, of course, you can (and are willing to) use STLSoft...
> 
> 
> HTH,
> Pablo

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