Is D right for me?

[Walter Bright]

Jacob Carlborg wrote:
> I don't know how you have implemented TLS on Mac OS X but it does 
> support TLS via the Posix API pthreads. This is the only page from 
> Apple's documentation I could find for now (I'm certain I've seen a 
> better page) 
> http://developer.apple.com/macosx/multithreadedprogramming.html .

Yeah, I know about pthreads TLS, but that's wholly inadequate.

> According to these: 
> http://lifecs.likai.org/2010/05/mac-os-x-thread-local-storage.html and 
> http://lists.apple.com/archives/darwin-dev/2005/Sep/msg00005.html the 
> implementation of TLS in the Posix API on Mac OS X should be as fast as 
> the EFL implementation. As the blog post mentions, there is an inline 
> version of pthread_getspecific. I also have to add that I have no idea 
> if the pthreads can be used to implement TLS in the compiler.

With gcc on OSX, try this:

    __thread int x;

It will fail. Furthermore, OSX has no documented way to allocate TLS static data 
in the object file. I spent considerable effort figuring out a way to do this 
and get around the numerous bugs in the OSX linker that tried to stop me.

There's good reason for Windows, Linux, FreeBSD, etc. to support the declaration 
of TLS in the C source code.

BTW, the dates on the second article postdate the D TLS implementation by years. 
Perhaps Apple has improved things. The third article just points out problems 
with the TLS.

Anyhow, the source is here:

http://www.dsource.org/projects/druntime/browser/trunk/src/core/thread.d

and the function you're interested in is ___tls_get_addr. You're welcome to make 
improvements to it.