Re: [boost] boost::shared_ptr<>::compare_and_swap()--AmIinsaneforwanting this?

From: Chris Thomasson (cristom_at_[hidden])
Date: 2006-11-10 23:20:55

Okay. I will go ahead and post the CAS operations for my "'mostly' lock-free 
refcount library alternative for Boost...":

http://appcore.home.comcast.net/vzoom/refcount/

;^)

If you set your algorithm up right, the low-level nature of the API allows 
you to do perform lock-free naked loads for the CAS 'compare' logic. You can 
take advantage of its ability to allow you to know when you can make use of 
no/basic/strong thread-safety guarantees'. This is a reason why I like to 
make the API abstractions of my prototypes in a fairly low-level fashion... 
As soon as I add the rest of the code and the draft-level descriptions that 
go along with it to my paper; it has to reference atomic reference counting 
/w CAS anyway it anyway:

http://appcore.home.comcast.net/vzdoc/atomic/static-init/

Luckily, I don't have to use DWCAS, and Boost can use it because its my 
prior art/invention. I do have to say that its performance is definitely not 
in the same league as my Virtually Zero-Overhead Object Management (vZOOM) 
solution, or some the zero-overhead algorithm that Joe Seigh has been 
inventing over at c.p.t. And, FWIW, here is a implementation of a 
smart-pointer that has lock-free atomic swap/cas, however, it uses SMR which 
has that memory barrier, and that patent application:

http://appcore.home.comcast.net/

Enjoy!

;^)