Michael Marcin wrote:

I have a program that protects an object containing a linked with what is essentially a shared_mutex. I'd like to take advantage of the logical constness of traversing a linked list with const iterators and allow concurrent traversal protected by the external shared_mutex. Unfortunately the standard makes no such guarantees on std::list so I've determined I'll have to write my own linked list with a slightly stronger guarantee that concurrent read access is safe.

I remember reading during the review that intrusive could be used to make high quality non-intrusive data structures easily. Can I use intrusive to make a std::list like container that is safe to read concurrently?

Yes. Although the standard does not guarantee it, I think most (all?) implementations offer read-only thread-safety. Intrusive offers similar guarantees. Intrusive documentation says: http://www.boost.org/doc/libs/1_36_0/doc/html/intrusive/thread_safety.html Thread safety guarantees Intrusive containers have thread safety guarantees similar to STL containers. * Several threads having read or write access to different instances is safe as long as inserted objects are different. * Concurrent read-only access to the same container is safe. Some Intrusive hooks (auto-unlink hooks, for example) modify containers without having a reference to them: this is considered a write access to the container. Other functions, like checking if an object is already inserted in a container using the is_linked() member of safe hooks, constitute read access on the container without having a reference to it, so no other thread should have write access (direct or indirect) to that container. Since the same object can be inserted in several containers at the same time using different hooks, the thread safety of Boost.Intrusive is related to the containers and also to the object whose lifetime is manually managed by the user.

Thanks,

Michael Marcin

Regards, Ion