Async messages to a thread.

[lindenk]

Hello!
This is partially a general question as I don't know what this is 
called or if it exists. Say for example I want to do something 
like the following -

import std.concurrency;

void main()
{
     void foo() {
         try
         {
             while(true)
             {
                  do_some_blocking_function();
             }
         } catch(GotAMessage msg){}

         // clean up
     };

     tid = spawn(&foo, thisTid);

     // do stuff / wait for some condition

     send(tid, "STAHP!");
}

One solution I've used in the past is setting a timeout for the 
blocking function then polling to see if the thread should exit. 
The disadvantage is it causes extra, unnecessary checking and has 
a delay before it gets the message and exits.

This is a fairly simple example but the idea should be the same, 
is there a way to pass a message or signal to a thread to cause 
it to branch to some other location?