#include <iostream>

#pragma GCC visibility push(default)
#include <boost/thread.hpp>
#include <boost/thread/locks.hpp>
#include <boost/filesystem.hpp>
#pragma GCC visibility pop

using namespace std;

boost::shared_mutex mutex_;

int pos = 0;

time_t startTime = time(0);

int getSleepTime()
{
   static int sleepTimes [12] = {5, 5, 5, 5, 6, 6, 7, 8, 8, 8, 8, 8};
   return sleepTimes[pos++];
}

#define whoAndWhen __func__ << "(" << myPos << ") at " << (time(0) - startTime) 

void reader()
{
   int myPos = pos;
   int sleepTime = getSleepTime();

   cerr << whoAndWhen << " sleeping " << sleepTime << endl;
   ::sleep(sleepTime);
   cerr << "                             " << whoAndWhen << " trying to acquire lock " << endl;

   boost::shared_lock<boost::shared_mutex> sharedLock(mutex_);
   cerr << whoAndWhen << " got lock " << endl;

   ::sleep(5);

   cerr << "                                                         " << whoAndWhen << " finished " << endl;
}

void writer()
{
   int myPos = pos;
   int sleepTime = getSleepTime();

   cerr << whoAndWhen << " sleeping " << sleepTime << endl;
   ::sleep(sleepTime);
   cerr << "                             " << whoAndWhen << " trying to acquire lock " << endl;

   boost::unique_lock<boost::shared_mutex> uniqueLock(mutex_);
   cerr << whoAndWhen << " got lock " << endl;

   ::sleep(5);

   cerr << "                                                         " << whoAndWhen << " finished " << endl;
}

int main()
{
   boost::thread_group threads;

   for (int i = 0; i < 2; ++i)
   {
      threads.create_thread(reader);
   }

   for (int i = 0; i < 2; ++i)
   {
      threads.create_thread(writer);
   }

   for (int i = 0; i < 2; ++i)
   {
      threads.create_thread(reader);
   }
   threads.create_thread(writer);

   for (int i = 0; i < 2; ++i)
   {
      threads.create_thread(reader);
   }

   // Wait for all threads to finish
   threads.join_all();
}