• sybrandy (9/62) Aug 29 2009 Hello,
• Sergey Gromov (14/22) Aug 30 2009 The thread local/shared storage doesn't seem to work well currently.
• sybrandy (4/4) Aug 30 2009 Thanks for the info. I was hoping that there would be a different

sybrandy <sybrandy gmail.com> writes:

Hello,

I've been learning D for some time now and I recently was trying to do 
some work with threads, but I'm having a problem getting it to work. 
I'm trying to create a singleton that can be accessed between threads, 
however I get an access violation when I try to run the following code. 
  If I make the variable "instance" shared, I get a compilation error. 
Is there something I'm missing?

Thanks in advance.

Casey

 import std.stdio;
 import core.thread;
 
 class Simple
 {
     string buff;
 
     public:
 
         static Simple instance;
 
         void setMsg(string msg)
         {
             buff ~= msg;
         }
 
         string getMsg()
         {
             string temp = buff.idup;
             buff.length = 0;
             return temp;
         }
 
     private:
         this() {}
 
         static this() { instance = new Simple; }
 }
 
 class ThrTest : Thread
 {
     this()
     {
         super(&run);
     }
 
     private:
 
         void run()
         {
             auto var = Simple.instance;
             var.setMsg("foo");
             writeln("message: " ~ var.getMsg());
         }
 }
 
     void main()
     {
         Thread t = new ThrTest();
         t.start();
         t.join();
         writeln("Finished testing Simple.d");
     }

Sergey Gromov <snake.scaly gmail.com> writes:

Sat, 29 Aug 2009 22:03:47 -0400, sybrandy wrote:

 Hello,
 
 I've been learning D for some time now and I recently was trying to do 
 some work with threads, but I'm having a problem getting it to work. 
 I'm trying to create a singleton that can be accessed between threads, 
 however I get an access violation when I try to run the following code. 
   If I make the variable "instance" shared, I get a compilation error. 
 Is there something I'm missing?

The thread local/shared storage doesn't seem to work well currently.

Your original snippet doesn't work because there is a separate
"instance" variable for every thread, but the static ctor is only
executed once, in the main thread.  The Simple.instance stays null in
ThrTest, and that thread crashes.

Making Simple.instance shared is incorrect I think because the class
must be thread-aware as well.  The correct way would be to make the
whole Simple class shared.  When I do this I still get errors though.
One in the constructor which cannot cast "this" from Simple to
shared(Simple).  Another is in main() which thinks shared is not
mutable.

I think we should wait for another couple compiler releases for this
feature to stabilize enough to be usable.

sybrandy <sybrandy gmail.com> writes:

Thanks for the info.  I was hoping that there would be a different 
solution, but I guess I should have expected that I may have to wait for 
the feature to stabilize.

Casey