12-4.cpp

#include <iostream>
#include <boost/thread/thread.hpp>
#include <boost/thread/condition.hpp>
#include <boost/thread/mutex.hpp>
#include <list>
#include <string>

class Request { /*...*/ };

// A simple job queue class; don't do this, use std::queue
template<typename T>
class JobQueue {
public:
   JobQueue( ) {}
  ~JobQueue( ) {}

   void submitJob(const T& x) {
      boost::mutex::scoped_lock lock(mutex_);
      list_.push_back(x);
      workToBeDone_.notify_one( );
   } 

   T getJob( ) {
      boost::mutex::scoped_lock lock(mutex_);

      workToBeDone_.wait(lock); // Wait until this condition is
                                // satisfied, then lock the mutex
      T tmp = list_.front( );
      list_.pop_front( );
      return(tmp);
   }

private:
   std::list<T> list_;
   boost::mutex mutex_;
   boost::condition workToBeDone_;
};

JobQueue<Request> myJobQueue;

void boss( ) {
   for (;;) {
      // Get the request from somewhere
      Request req;
      myJobQueue.submitJob(req);
   }
}

void worker( ) {
   for (;;) {
      Request r(myJobQueue.getJob( ));
      // Do something with the job...
   }
}

int main( ) {
   boost::thread thr1(boss);
   boost::thread thr2(worker);
   boost::thread thr3(worker);

   thr1.join( );
   thr2.join( );
   thr3.join( );
}