Re: [Boost-users] thread safety of the mutex ctor

From: Christopher Hunt (huntc_at_[hidden])
Date: 2005-08-17 15:22:20

On 18/08/2005, at 1:19 AM, boost-users-request_at_[hidden] wrote:

> I envisage two threads accessing a function like this concurrently:
>
> template<typename T>
> boost::shared_ptr<T>
> my_func()
> {
>     static boost::mutex m;
>     boost::mutex::scoped_lock l(m);
>
>     static boost::shared_ptr<T> p(new T);
>     return p;
> }
>
> and my worry is that both threads could attempt to do the static 
> initialisation of m concurrently.  Is there protection against this?  
> Is it even possible to protect against this?
The scope of m is actually outside of your function given that it is 
static. Thus it will be initialised outside of your function generally 
before any other threads get to start up.

Cheers,
-C