Re: [Boost-users] shared_ptr questions

Subject: Re: [Boost-users] shared_ptr questions
From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2009-08-18 11:43:34

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On Tuesday 18 August 2009, John Dlugosz wrote:
> But I was specifically wondering about the mix of weak_ptr's.  I guess mine
> is more complicated because it can do lazy copy on write, but still the
> effect of making the unowned pointer getting ownership at the same time as
> other threads are releasing all the existing owners was an issue of
> specific importance.  I implemented a "sticky zero" non-blocking counter
> for the purpose.
>
> I want to make sure that the Boost implementation can do this robustly and
> efficiently, too.  And perhaps point out that weak_ptr's need thread issue
> documentation too.

shared_ptr/weak_ptr does modify its reference count atomically.  You can't 
resurrect an expired shared_ptr through a weak_ptr, it will throw or return 
an empty shared_ptr depending on whether you are using the shared_ptr 
constructor or weak_ptr::lock.

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