Question

I have a simple threading question – how should the following be synchronized?

I have main thread and a secondary thread that does something only once and something – more that once.

Basically:

Secondary thread:

{
   Do_Something_Once();

   while (not_important_condition) {
      Do_Something_Inside_Loop();
   }
}

I want to suspend my main thread unless Do_Something_Once action is done and right now I use a plain bool value is_something_once_done = false; to indicate if the action is finished.

Hence, the code of my main thread looks like this:

{
   Launch_Secondary_Thread();

   while (!is_something_once_done) {
      boost::this_thread::sleep(milliseconds(25));
   }
}

which obviously isn’t the best way to perform such kind of synchronization.

Any alternatives (better if boost::thread – powered)?

Thank you

Answer 1

This is a job for condition variables.

Check out the Condition Variables section of the boost docs – the example there is almost exactly what you’re doing.

Whatever you do, don’t do a busy-wait loop with sleep