12-2.cpp

#include <iostream>
#include <boost/thread/thread.hpp>
#include <string>

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

   void enqueue(const T& x) {
      // Lock the mutex for this queue
      boost::mutex::scoped_lock lock(mutex_);
      list_.push_back(x);
      // A scoped_lock is automatically destroyed (and thus unlocked)
      // when it goes out of scope
   } 

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

      if (list_.empty( ))
         throw "empty!";     // This leaves the current scope, so the
      T tmp = list_.front( ); // lock is released
      list_.pop_front( );
      return(tmp);
   } // Again: when scope ends, mutex_ is unlocked

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

Queue<std::string> queueOfStrings;

void sendSomething( ) {
   std::string s;
   for (int i = 0; i < 10; ++i) {
      queueOfStrings.enqueue("Cyrus");
   }
}

void recvSomething( ) {
   std::string s;

   for (int i = 0; i < 10; ++i) {
      try {s = queueOfStrings.dequeue( );}
      catch(...) {}
   }
}

int main( ) {
   boost::thread thr1(sendSomething);
   boost::thread thr2(recvSomething);

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