On Sunday, 13 October 2013 at 07:03:39 UTC, Rainer Schuetze wrote:
According to the "Handbook of Garbage Collection" by Richard
Jones eager lock-free reference counting can only be done with
a cas2 operation modifying two seperate locations atomically
(algorithm 18.2 "Eager reference counting with CompareAndSwap
is broken"). This might be the quoted paper:
http://scholr.ly/paper/2199608/lock-free-reference-counting
Unfortunately the CAS2 operation does not exist in most
processors.
I suppose it's worth noting that Boost (and now standard C++) has
a shared_ptr that works across threads and the implementation
I've seen doesn't use a mutex. In fact, I think the Boost one
doesn't even use CAS on x86, though it's been quite a few years
so my memory could be wrong on that last detail.
