Threads and Static Data

[Robert Fraser]

Craig Black wrote:
> I'm in the process of hashing out a design for multi-core support for a 
> large API developed by myself and a couple other people.  I realized 
> that static data can be problematic for multiple threads.  In many 
> cases, it seems that static data should be instantiated on a per-thread 
> basis.  My solution to this problem is to use a template class called 
> "Threaded" that instantiates data for each thread.
> 
> static Threaded!(int) x;
> 
> Then to access the value, there would have to be a thread ID passed into 
> it. So to increment the value you would have.
> 
> int temp = x.get(threadID);
> x.set(threadID, temp+1);
> 
> (Or, I guess you could use a pointer.)
> 
> int *ptr = x.getptr(threadID);
> (*ptr)++;
> 
> This solution will do the job, but it is a little clumsy.  This seems 
> like this is a common problem that warrants better syntax.  Ideally, I 
> would like to be able access a "threaded" variable just like any other 
> so that the above example is simply "x++".  I don't have extensive 
> experience with D templates and operator overloading.  It it possible to 
> make this work transparently with all operators?  I want to support all 
> basic types as well as structs and classes.  Could someone with more 
> experience fill me in on the caveats involved in implementing something 
> like this?  Has anyone else already solved this problem?  This seems 
> like a feature that should be included in the standard library.
> 
> -Craig

Tango has tango.core.Thread.ThreadLocal for thrad-local storage. I don't 
know about phobos, but if it's not there it should be.