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From: Peter Dimov (pdimov_at_[hidden])
Date: 2004-01-07 09:32:25

Jason House wrote:
> Peter Dimov wrote:
>> When multiple threads are involved there is a race condition between
>> the unique() test and the actual release, and I'm not sure how such
>> a feature would interact with a lock-free implementation.
> I think this statement might be incorrect. If nothing else, I think
> some careful thought about it might yield an easy solution to the
> problem. If I understand right, a shared_ptr will be unique if and only if
> is the only shared_ptr to that object. In that scenario, there will be
> no other shared_ptr's in any other threads that could cause the
> reference count to change from 1 at any instant in time...

You're almost right, except for one small detail; weak pointers do not
affect unique(), and can generate other shared_ptr copies.

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