Am Tuesday 12 January 2010 16:33:31 schrieben Sie:
Am Tuesday 12 January 2010 15:17:05 schrieb Vicente Botet Escriba:
thread_specific_ptr operator*: one branch to make sure the vector is large enough(a new thread_specific_ptr might have been created by another thread), one indirection. constant-time average, linear to vector if reallocation is necessary. but that can only happen when a new thread_specific_ptr was created.
I think the branch also could be avoided with some effort and a second indirection(using pages to avoid reallocating and making sure the page exists in each thread on thread_specific_ptr construction) but to me the branch is acceptable.
For me it is unacceptable to use reallocation of the vector on the operator*. More, any non-constant time operator* don't satisfy my requirements for some specific contexts.
I'd prefer reallocation, but reallocation can be avoided using pages at the cost of a second or third indirection.
plus, as I've said it could be possible to do the work on construction of a thread_specific_ptr for all threads so there is no branch in operator*. however, that depends on if the boost thread API can be used together with other thread APIs, because then the pages must be initialized on start of a new thread. so only boost threads could access thread_specific_ptrs, accessing a thread_specific_ptr from a natively created thread would fail.