[boost] concurrent_hash_map, RFC

From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-10-15 10:03:55

A preliminary documentation for a concurrent_hash_map is available:

http://www.pdimov.com/cpp/concurrent_hash_map.html

There exists a prototype implementation for that :-) and I'll post it online 
after a bit of cleanup.

I have a question on the interface that hopefully may be of interest to 
someone. concurrent_hash_map implements the following member function:

template<class F> bool find_and_visit( K const & k, F f );

that looks up the element with a key k in the map and, if found, invokes f 
on its associated value. This can be useful in a number of situations, but 
it poses the following problem: what if two threads call find_and_visit at 
the same time with the same k and f modifies its argument? Should the map 
serialize the two calls to f, or should it leave the responsibility of 
ensuring proper synchronization (or atomic update, if the mapped_type allows 
it) to the user?

Thanks in advance for any comments/opinions on the interface.

--
Peter Dimov
http://www.pdimov.com