Ben Hutchings wrote:
John Torjo <john.lists@torjo.com> wrote:
Alexander Terekhov wrote:
John Torjo wrote: [...]
Whenever a thread (other than main) wants to access this window, it will query the weak_pointer. The weak_pointer needs to know the LATEST reference count in order to know if the weak pointer is still valid. Thus, atomic_read that simply returns the value is not enough.
However, the weak_ptr doesn't just use atomic_read. If atomic_read returns 0 that means the use count has dropped to 0 [*] and can never increase again, so it must be the latest version. Otherwise weak_ptr makes a second test that is properly protected. So it can never use an old value.
[*] I think this is right but I'm not certain that it can't return a 0 that the processor read during creation of an object that uses enable_shared_from_this.
Having said all that, I feel the naming of functions may give a false sense of generality and encapsulation when they actually only work in the way they are being used currently.
I'm not sure which functions do you have in mind here.
<snip>
Here's my scenario: (remember - we're talking about: http://www.pdimov.com/cpp/shared_count_x86_exp2.hpp)
This is still unaccessible. why don't you mail the code to Alexander and me (or to the list, in case anyone else is interested)?
http://66.102.9.104/search?q=cache:1ZQ1uXtFUEIJ:www.pdimov.com/cpp/shared_co...