Anthony Williams wrote:
"vicente.botet" <vicente.botet@wanadoo.fr> writes:
So which is the complexity of boost::thread_specific_ptr<T>::get()? Looking at the code we see that is O(N). IMHO, the constant complexity is one the major requirements of such a feature. I supose you had some good raison to not use an index key instead of the address.
The set of thread_specific_ptr values accessed by a given thread cannot be known when the thread is launched. Consequently you cannot know which set of indices will be used. Use of indices would require a sparse vector. I intend to upgrade the data structure to a map at some point, which would therefore have faster lookup.
Why not using the sparse vector then? I understand that POSIX gives no guarantees, but as I read TlsGetValue documentation on MSDN I get a strong impression that the lookup is O(1) there. I would expect the same on most POSIX platforms, regardless that the paper does not require that. And I would really like the Boost solution to provide the similar performance, at least where such is provided by OS.