Re: [boost] Re: Threads docs updated in CVS

From: Scott McCaskill (scott_at_[hidden])
Date: 2001-08-13 09:24:31

> This assumption is dangerous. I would say that "most people" simply either
> don't understand the issues involved, or don't care.
> 
> I'm not afraid to admit that I fall in the first category.
> 
> For instance, what is the boost.threads way to do the following:
> 
> void thread_function()
> {
>   init();
> 
>   for(;;)
>   {
>     waitForMultipleEvents(wakeup_event, terminate_event);
>     if(terminate_event signalled) break;
>     do_work();
>   }
> 
>   cleanup();
> }
> 

How about this:

boost::mutex theMutex;
boost::condition theCondition;
volatile bool terminateFlag = false;
volatile bool wakeupFlag = false;

void thread_function()
{
  init();

  for(;;)
  {
    {
      boost::mutex::scoped_lock lock( theMutex );
      while ( !terminateFlag && !wakeupFlag )
      {
        // (release the mutex and wait for notification;
        // when this returns, we have the mutex again)
        theCondition.wait( lock );
      }
      if ( terminateFlag )
        break;
      if ( wakeupFlag )
        wakeupFlag = false;
    }
    do_work();
  }

  cleanup();
}

void tellThreadToStop()
{
  {
    boost::mutex::scoped_lock lock( theMutex );
    terminateFlag = true;
  }
  theCondition.notify_one();
}

void tellThreadToWakeUp()
{
  {
    boost::mutex::scoped_lock lock( theMutex );
    wakeupFlag = true;
  }
  theCondition.notify_one();
}