Frank Mori Hess <frank.hess@nist.gov> writes:
On Friday 30 May 2008 06:40 am, Anthony Williams wrote:
It would also be possible, I think, to make an adapter that actually creates a shared mutex from a normal one. I've never had to write a read/write mutex but I guess that this is how they are implemented internally.
It's a bit more complicated than that. boost::shared_mutex is implemented on top of boost::mutex and boost::condition_variable for pthreads: take a look.
Hmm, so it looks like it would be straightforward to convert the pthread implementation of shared_mutex into an adapter that can convert an arbitrary mutex type (conforming to the boost.thread Lockable concept) into a shared mutex, by turning its boost::mutex into a template type?
No, I don't think so. The internal mutex within shared_mutex is only locked within the member functions, and it is required to be exclusive in order to protect the internal data. When you call shared_lock, the only sense in which this thread holds a mutex is that the internal state of the shared_mutex reflects that. Anthony -- Anthony Williams | Just Software Solutions Ltd Custom Software Development | http://www.justsoftwaresolutions.co.uk Registered in England, Company Number 5478976. Registered Office: 15 Carrallack Mews, St Just, Cornwall, TR19 7UL